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This is to certify that the

thesis entitled

AMwo Am) Drugs-“5mm AND HlTKOCaEN

UTtUZATloN or: CORN HYBRIDS FED To
(allowqu pads

presented by

JANET LVNN SNow

has been accepted towards fulfillment
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M.S. degree in _Anima.LScience
/ Major professor
Datew

0.7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

PLACE IN RETURN BOX to remove this checkout from your record.
To AVOID FINES return on or before date due.
MAY BE RECALLED with earlier due date if requested.

 

DATE DUE

DATE DUE

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1/” W14

AMINO ACID DIGESTIBILITY AND NITROGEN UTILIZATION
OF CORN HYBRIDS FED TO GROWING PIGS

By

Janet Lynn Snow

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTERS OF SCIENCE
Department of Animal Science

1998

ABSTRACT

AMINO ACID DIGESTIBILITY AND NITROGEN UTILIZATION
OF CORN HYBRIDS FED TO GROWING PIGS

By

Janet Lynn Snow

Protein quality of seven corns (high oil (HO), isogenic high oil (IHO), waxy
(WX), isogenic waxy (IWX), high lysine (HL) and two yellow dent corns (STD 1, STD
2)) were investigated using growing barrows. Apparent ileal digestibilities (AID) for
amino acids (AA) between the corn hybrids were investigated. Numerically higher AID
resulted for H0 and WX compared to IHO, IWX and STD 2 (P > .1). The AID were
lower for HL compared to STD l (P S .1) and similar to STD 2 (P > .1). In the second
experiment, the barrows were fed a casein and a protein fi'ee diet to determine true ileal
amino acid digestibilities (TID). Secretions of AA (P .<_ .1) were greater with casein
compared to protein free for all essential AA (P > .1) and both treatments had TID close
to 100 % for the majority of AA, therefore TID could not be determined. The objective
of experiment three was to determine the coms' nitrogen utilization. Nitrogen (N)
retention was similar between HO vs IHO, WX vs IWX and HL vs STD 1, but all hybrids
were superior to STD 2 (P > .1). Overall, protein quality of HO and WX were superior
compared to isogenics and STD 2 (P > .1). Significantly lower AID (P < .05) but similar

N retention (P > .1) was reported for HL compared to STD 1.

I would like to dedicate this work to the people I love most: my husband and my
two wonderful families. My husband helped me through the collections and the rigors of
this degree. He was my loving supporter through it all and for that he deserves this
dedication and my thanks. In addition, I dedicate this to my families who gave me
continuous support and words of encouragement after long days and a lot of time spent

apart.

iii

ACKNOWLEDGMENTS

I would like to thank Dr. Nathalie Trottier first and foremost for the opportunity
to accomplish my Masters degree. Secondly, I would like to thank the Michigan Corn
marketing board for the financial support for this research. I also thank Dr. Pao Ku for
his infinite insight into the analysis and procedures involved in my project. Fourth, I
would like to thank all of the wonderful graduate students and staff at Michigan State
University that assisted by lending a hand or by giving advise. Specifically, I want to
thank Lara Andersen, Renee Bell, Michelle Smiricky, Pasha Lyvers, Jenifer Fenton,
Xinfu Guan, Mara Preisler, Doug Mashek, Kent Tjardes, Bob Burnett, Jane Link, and
David Main. There were also many other people who assisted with the responsibilities of
this project that deserve my thanks: Dr. Hans Stein, Dr. Kent Ames, Holly Neff, Alyson
Wilson, Sara Moyer, Johnna Seaman, and Heather Nederveld. In addition, I thank the
great people at the Michigan State University Swine Teaching and Research Farm,
especially A1 Snedegar, Ray Kromer, Dwayne Simon and Brian Story who taught me
everything else about swine management. Finally, I cannot forget to thank God for

giving me the fortitude and guidance to achieve one of my dreams.

iv

TABLE OF CONTENTS

LIST OF TABLES ......................................................................................................... vii
LIST OF FIGURES ...................................................................................................... viii
INTRODUCTION ........................................................................................................... 1
LITERATURE REVIEW ................................................................................................ 2
Nutrient composition of the standard yellow dent corn ............................................... 2
Specialty corns ............................................................................................................. 5
Protein digestibility and utilization in swine .............................................................. 12
Conclusion .................................................................................................................. 17

CHAPTER 1: APPARENT AND TRUE ILEAL AMINO ACID DIGESTIBILITIES

OF CORN HYBRIDS FED TO GROWING PIGS ....................................................... 20
Abstract ...................................................................................................................... 20
Introduction ................................................................................................................ 21
Materials and Methods ............................................................................................... 21
Results ........................................................................................................................ 25
Discussion .................................................................................................................. 28
Implications ................................................................................................................ 29

CHAPTER 2: COMPARISON OF ENDOGENOUS AMINO ACID SECRETIONS

FROM GROWING PIGS FED CASEIN AND PROTEIN FREE DIETS ................... 40
Abstract ...................................................................................................................... 40
Introduction ................................................................................................................ 41
Materials and Methods ............................................................................................... 42
Results ........................................................................................................................ 43
Discussion .................................................................................................................. 44
Implications ................................................................................................................ 45

CHAPTER 3: EFFECTS OF CORN HYBRIDS FED TO GROWING PIGS ON

NITROGEN METABOLISM ....................................................................................... 51
Abstract ...................................................................................................................... 51
Introduction ................................................................................................................ 52
Materials and Methods ............................................................................................... 52
Results ........................................................................................................................ 54
Discussion .................................................................................................................. 55
Implications ................................................................................................................ 57

SUMMARY AND GENERAL CONCLUSION .......................................................... 62

VITA .............................................................................................................................. 64

APPENDICES ............................................................................................................... 65

Appendix A ................................................................................................................ 66
Appendix B ................................................................................................................ 67
Appendix C ................................................................................................................ 68
LITERATURE CITED .................................................................................................. 72

vi

LIST OF TABLES

Table 1: Apparent amino acid digestibilities for normal and high—oil corn based on

swine ileal digesta collections (Adapted from Carr, 1994) ............................................... 19
Table 2: Apparent digestibilities of amino acids (Adapted from Soltwedel, 1996) ......... 19
Table 3: Nutrient composition of corn hybrids on a dry matter basis .............................. 30
Table 4: Amino acid concentration as a percent of total nitrogen .................................... 31
Table 5: Particle size of the corn used in experimental diets (mm) .................................. 32
Table 6: Composition of experimental diets on as-fed basis (%) ..................................... 33
Table 7: Nutrient composition of the diets on a dry matter basis ..................................... 34
Table 8: Amino acid top dress composition ..................................................................... 35
Table 9: Apparent amino acid digestibilities ( % ) of the corn hybrids ............................ 36
Table 10: True amino acid digestibilities (%) of the corn varieties .................................. 37

Table l 1: Endogenous amino acid losses (mg/kg dry matter intake) at the terminal

ileum determined by feeding a casein diet ........................................................................ 38
Table 12: Apparent digestibility of casein diet (%) .......................................................... 39
Table 13: Experimental diets on as-fed basis (%) ............................................................ 46
Table 14: Nutrient composition of the diets on a dry matter basis ................................... 47

Table 15: Endogenous losses in casein and protein free diets (mg/kg dry matter intake) 48

Table 16: True amino acid digestibilities ( % ) of the corn varieties ................................ 49
Table 17: True amino acid digestibilities ( % ) of the corn varieties ................................ 50
Table 18: Experimental diets on as-fed basis (%) ............................................................ 58
Table 19: Amino acid top dress composition ................................................................... 59
Table 20: Nutrient composition of the diets on a dry matter basis ................................... 60

Table 21: Nitrogen utilization and dry matter digestibility of the corn-based diets ......... 61

vii

LIST OF FIGURES

Figure 1: Diagram of a com kernel ..................................................................................... 3
Figure 2: Re-entrant carmula ............................................................................................. 18
Figure 3: Simple T cannula ............................................................................................... 18

viii

INTRODUCTION

Corn is the number one cereal grain produced in the U. S. and the major energy
source in diets fed to livestock. Even though corn provides sufficient energy, a diet
containing corn alone does not provide an adequate source of nutrients, especially for
swine. The protein requirements in swine diets are commonly balanced by the addition
of soybean meal and synthetic amino acids to corn. Specialty corns have the potential to
be used in the swine industry as an alternative nutrient dense feedstuff, but the protein
quality has not been evaluated. This question is addressed in the following chapters.
Protein quality is characterized by the following components: the concentration and
profile of amino acids, the digestibility, and utilization. Chapters one and two will
specifically address the first two components of protein quality in high oil, high lysine
and waxy corn. Protein utilization will be addressed in the third chapter. While some
information exists on the nutrient profile of specialty corns, protein digestibility and
utilization have not been studied extensively. As the swine industry moves towards
formulation of diets on a digestible basis and the use of models, as was evident in the
recently published National Research Council nutrient requirements for swine (1998),
data regarding the protein digestibility and utilization in corn hybrids, with potential for

swine, are essential.

LITERATURE REVIEW

Corn is the number one cereal grain used in livestock diets in the United States,
but corn alone is not a adequate source of nutrients. Many researchers have developed
corn hybrids with increased nutrient concentrations that offer advantages over standard
yellow dent corn. Some examples of "value added" or "specialty corns" that currently
exist are high oil, high lysine (opaque-2) and waxy corn. In the past, the production of
these corns had not been feasible because of low yields and poor agronomic traits, but
research and field tests have lead to corn with a more nutrient dense kernel and yields
similar to conventional com. This provides a potential nutritional tool for swine
producers, but before the use of these hybrids can be advocated the protein digestibility

and utilization must be researched.

Nutrient composition of the standard yellow dent corn

The corn kernel consists of four major parts: germ, endosperm, pericarp and tip
cap. A standard kernel contains approximately 70 % starch, 8.5 % protein and 4.4 % oil
(Boyer, 1994). Constituents of the kernel can be genetically manipulated to change the

corn nutrient profile (Figure 1).

 

Endosperm- energy
and protein source and

 

 

 

 

 

 

Pericarp — h 1 represents about 80 %
that protects of the dry weight of
kernel
Germ- contains enzymes, vitamins,

 

 

 

 

minerals, high quality protein and the

 

 

 

  
 

Tip Cap- attachment
point to the cob

 

 

 

Figure 1: Diagram of a corn kernel _
Adapted from the Ohio Corn Marketing Program web site (1997)

Cornstarch

Eighty to 90 percent of the total starch in standard com is found in the endosperm
(Boyer, 1994). Cornstarch exists in two major forms, amylase and arnylopectin.
Amylose, a linear starch, has primarily OH, 4 linkages of D glucose units; arnylopectin, a
globular starch, contains small chains of or-l, 4 linkages with an a-l, 6 linkage every 20
to 25 glucose residues (Rooney and Pflugfelder, 1986). The or-l, 6 linkages of
arnylopectin create a randomly branched structure endosperm (Boyer, 1994). An
intermediate starch polymer is also present in minute amounts, but is hard to identify
because it has characteristics of both amylose and arnylopectin. Amylose, arnylopectin
and the intermediate starch are packed together in tiny, insoluble granules in the kernel.
The exact arrangement of the starch granule is unknown. Once mixed with water and
heated, the breakdown of hydrogen bonds causes starch to become soluble.
Gelatinization, the breakdown of the starch molecule by water, swells the molecule and

increases its flexibility (White, 1994). Fats and protein can be bound to the starch

molecule and can hinder gelatinization (Rooney and Pflugfelder, 1986; White, 1994).
The swelling of the starch allows the majority of amylose to leach out of the granule and

exposes the starch to catabolic enzymes.

Corn proteins

The majority of the protein in standard corn is found in the endosperm and germ
portions of the kernel. Standard kernel protein is composed of 7 % albumins, 5 %
globulins, 52 % prolamines (zeins) and 25 % glutelins on a percent nitrogen basis (Boyer,
1994). Albumins, glutelins and globulins are the most soluble proteins in the kernel and
provide a better balance of essential amino acids (AA) for animals than prolamines
(V asal, 1994). Prolamines contain disproportionately large amounts of glutamine,
proline and alanine, which are non-essential AA in swine. The endosperm, the largest
component of the kernel, may contain up to 80 % of the total kernel protein. The
endosperm accounts for 60 % of the kernel prolamines and 34 % of the kernel glutelins.
The germ, only 8-10 % of the dry matter of the kernel, consists of primarily albumins (6O
%) and a small portion of prolamines (5-10 %). High quantities of prolamines in the
whole kernel protein do not provide sufficient essential AA such as lysine and tryptophan

for swine (Boyer, 1994).

Corn lipids

The standard corn kernel contains approximately 4.4 % oil, the majority of which
is found in the germ (83-85 %) (Boyer, 1994). Endosperm, pericarp and tip caps,
together, contain 10 to 13 % of kernel oil. Triacylglycerides, a mixture of unsaturated

and saturated fatty acids, are the major component of corn oil. Corn oil is comprised of

50 % linoleic (18:2), 40 % oleic (18:1), 12 % palrnitic (16:1), 2 % steric (18:0) and 1 %
linolenic (18:3) acid (Boyer, 1994). Several fatty acids (FA) are essential for different
species, but swine require linoleic and arachidonic acid. Arachidonic acid can be
synthesized in vivo from linoleic acid, therefore only linoleic needs to be supplemented in
swine diets. Corn oil is a high quality fat source because of the large percentage of
linoleic acid and low linolenic acid (Boyer, 1994). The digestibility of fats is affected by
the FA chain length and the degree of unsaturation. Short chain FA are easily digested,
although, as the chain length increases to 20 carbons or more, the degree of unsaturation

also increases, which augments the digestibility of the longer chain FA.

Specialty corns

Waxy Corn

Waxy com, a genetic mutant discovered in China in the early 19005, was
differentiated because of its dull and waxy-like kernel appearance. This is caused by a
single gene recessive mutation that occurs on chromosome 9 (F ergason, 1994). The
homozygous recessive plants only produce the granular starch arnylopectin. Other
variations of the waxy mutant (Argentine waxy) produce small amounts of amylose (< 5
%). The waxy gene is epistatic to all known endosperm mutants, thus causing the
absence of amylose (White, 1994). Today, the backcross method is the most popular

breeding method for the waxy trait (F ergason, 1994).

Agronomic considerations

Waxy corn is not commercially produced by most seed corn companies for

livestock feeds, although it is relatively competitive in yields when compared to standard

corn. Yield comparisons indicate that waxy corn differs by less than 5 % compared to
normal yellow dent. Evidence exists that attests to waxy grain having a higher test
weight than normal corn, which should offset the minimal yield differences (Fergason,

1994).

Practical applications of waxy corn

Currently, most production of starch fiom waxy corn is used in paper, textile,
corrugating and adhesive industries. Waxy corn is not used in commercial animal feeds,
and very little information exists on the nutritional value of waxy corn. Some research
has shown a potential for waxy grain feeds compared to normal dent as demonstrated by
increases in average daily weight gains in lambs (McDonald, 1973). In addition,
McDonald also showed that waxy based diets had improved feed efficiency in finishing
beef cattle. Carcasses of beef fed waxy corn had lower back fat and higher carcass
grades (F ergason, 1994). Waxy corn has been tested in nursery pigs compared to yellow
dent corn and found to have no effect on average daily gain, average daily feed intake, or
feed conversion (Johnston, 1991). A grow-finish study using waxy and normal corn
reported similar results as the nursery study, where no differences in performance
between the waxy fed and non-waxy fed pigs were found (Hanson, 1946). Utilization of
waxy corn has been minimal because its use has not been advocated and publicized.
Therefore, there is little to no demand for production of this potentially valuable corn

from the animal industry.

High lysine or opaque corn

Lysine and tryptophan are severely deficient in corn and breeding efforts have
been targeted towards improving lysine and tryptophan content of corn to improve
overall protein quality. Prolarnine, the most abundant protein fraction in corn, is low in
lysine and tryptophan. High lysine or opaque breeding programs have decreased the
prolamine content and increased content of albumins, globulins and glutelins (Wilson,
1992). Developments in altering the prolamine fraction led to high lysine varieties with
decreased prolamine content by approximately 50 % which in term amplified the
remaining high quality protein types and increasing lysine content by 62 % (Boyer,
1994). Increases in other AA (percent increase in parentheses) such as tryptophan (30
%), histidine (17 %), arginine (33 %), aspartic acid (49 %) and glycine (20 %) has been
reported to be associated with the high lysine corn (Pond and Maner, 1984; Vasal, 1994).

Inheritance of the opaque characteristics are achieved by a backcross system and
the opaque kernels are then inter-mated further until a hybrid of desirable quantities of
the high lysine and tryptophan is created. Discovery of this mutant spurred the search for
new mutants with different alterations of the germ-endosperm ratio. Another effort has

begun to attempt to combine mutants to create a more ideal hybrid (Ahmadi et al., 1995).

Agronomic considerations

Many different chromosomes with a completely recessive inheritance modulate
opaque characteristics. The mutations affect the zein synthesis when the homozygous
recessive genotype is present. All opaque mutants have three things in common,
including low prolamine portion, a sofi chalky endosperm (that is why it was named

opaque), and a deficiency in the amount of dry matter produced (Boyer, 1994). In

addition, several poor agronomic effects are associated with the opaque gene, which
include lower yields compared to standard corns due to lower endosperm size and
reduced kernel weight. The sofi chalky appearance of high lysine kernel is not desirable
to producers and it causes lower kernel density. Finally, other problems such as
increased moisture content, higher incidence of ear rot, greater damage by stored grain
insect pests, poor germination, increased kernel breakage, thicker pericarp, larger germ

size, and reduced cob weight have discouraged crop producers from planting this corn.

Practical applications of high lysine corn

Nutritionally, the opaque and high lysine varieties, in rats, have been shown to
have a protein efficiency ratio (PER) similar to casein and a higher niacin availability,
respectively. In pigs, high lysine corn is adequate as the only source of protein for the
finishing, pre-gestation and gestation periods (Hawton et al., 1996). Burgoon et al.
(1992) tested high lysine corn in starter and finisher pigs and found that it was not
adequate for starter pig but was sufficient for finishing pigs. Cromwell (1984)
investigated opaque-2 hybrids modified with single mutant genes (i.e. sugary-2, floury-2,
waxy) and found that when these corn replaced normal corn, it tended to increase the rate
and efficiency of gain in 14-kg pigs. Baker (1970) studied opaque-2, normal corn and
' com-soybean meal based diets fed to first parity gilts during pregnancy and lactation and
found that gilts receiving the opaque corn lost less weight during lactation and supported
good postparturient performance of offspring when compared to those receiving the other
treatments. Even with the agronomic disadvantages of the high lysine com, the protein

quality offsets the lower agronomic performance (West and Kincer, 1985). Grain and

livestock producers may find that growing and feeding high lysine corn might be less

expensive than supplementing diets with soybean meal and synthetic AA.

High-oil corn

High-oil corn is characterized by oil contents greater than 6 % while normal corns
usually range from 3.5 to 5 % (Lambert, 1994). The manipulation of the germ affects the
rate of oil accumulation in the kernel from day 15 to 45 after pollination (Brunson et al.,
1948). In addition to the increasing oil content, the composition also changes; the oil in
corn was reported to contain higher concentration of linoleic acid (Alrefai et al., 1995).
Alteration of the germ not only increases oil in high-oil corn but also the protein content.
This is believed to occur because the genetics of high-oil corn also affects the germ to
endosperm ratio.

The University of Illinois started one of the earliest breeding programs for high-
oil corn. Initially, a backcross system was initiated to augment the oil content of com.
This system produced an oil content 20 % higher than the normal corn average (Sprague
and Brimhall, 1948). Another breeding system recently developed by DuPont (Optimum,
a trademark of DuPont), consists of a "topcross" system where a 90-92 % male sterile
hybrid seed corn is mixed with 8-10 % high-oil pollinator. The top cross system usually
equates to corn with oil contents of 6-8 %, similar to what is obtained with the backcross

method.

Agronomic considerations

The major problem with the backcross genetics system is that yields are sacrificed

at oil levels greater than 8 % (Lambert, 1994). Undesirable agronomic traits of the

backcross high oil corn have prevented planting and harvesting at the same rate as normal
yellow dent. For example, high-oil corn has been reported to produce reduced ear length,
smaller ear diameter, lighter kernel weight, reduced plant and ear height and early
flowering. On the other hand, on a energy per acre or a lysine per acre basis, the added
value of high oil corn may offset the disadvantages. In contrast, the top cross system has
an advantage over backcross system because it has yields, ears, oil content and weights
similar to normal corn (Hawton et al., 1996). In addition, the top cross system can easily
incorporate other value added traits into the corn produced by altering the genetics of

sterile corn seed.

Practical applications of high oil corn

Nutritional benefits of the high oil-com are numerous. The energy per unit of
feed being greater than normal yellow dent varieties could be useful in diets where fat is
usually added to increase the energy density and palatability. Lactation and nursery diets
may be an area where high-oil corn could have an impact (Trottier and Snow, 1997). As
stated earlier, the increase in oil content is associated with an increase in protein resulting
from an increase in the germ to endosperm ratio, therefore a higher protein quality
(Lambert, 1994).

In swine, high oil corn has been tested in grower and finisher diets to evaluate the
nutritional potential. Feed efficiency was increased with decreased feed intake in grower
and finisher pigs (Orban et al., 1994). In a study by Nordstrom et a1. (1972) the high oil
corn reduced by 6 % the feed necessary to reach market. Gestating sows fed high-oil
corn diets during the last 30 d of gestation gained more weight and had higher fat levels

in colostrum, but no effects on litter size, birth weight or weaning weights were found

10

(Boyer, 1994). Average daily gain was shown to increased by 9 % in pigs fed diets
containing high oil corn as compared to pigs fed normal corn diets (Pettigrew and Yang,
1997)

These studies indicate that kernel oil is as readily used as the normal fats added to
diets and yet use of high-oil corn eliminates many problems associated with the addition
of animal fats to diets. Diets using high oil corn have also seen benefits besides the
nutritional applications. Diets including high oil corn have had increased storage time
and feed flow from feed storage bins and feeders (Adeola and Bajjalieh, 1997).
Although, pigs utilize extracted fats more efficiently than in-seed fats, Adams and Jensen
(1984) noted that it was much easier to handle high oil corn. Also, types of oils fed to
weanling pigs to improve dry matter digestibility were investigated. It was determined
that corn oil possessed the highest digestibility compared to lard and tallow (Cera et al.,
1988). The only detrimental effect to feeding high-oil corn was shown when finishing
pigs were fed diets with large inclusions rates of high oil corn, fat quality was "soft" and
of poor appearance (Monahan et al., 1992). On the other hand, a 15 % inclusion of high-
oil corn in the diet did not produce soft fat in a study published by Nordstrom (1972).

Added value corns such as waxy, high lysine and high oil have potentially great
advantages over the normal yellow dent variety in swine diets. Waxy corn maybe
beneficial with its increased digestible starch. Opaque or high lysine corn provides a
better balance of AA and could decrease the inclusion rate of synthetic AA and soybean
meal. The higher oil and protein content in the high-oil corn could also decrease the

inclusion rate of synthetic AA and eliminate the need to add fat to diets.

ll

Protein digestibility and utilization in swine

Minimal data has been published on the protein digestibilities of specialty corn
hybrids. Carr (1992) looked at the apparent protein digestibilities of high-oil corn
compared to normal yellow dent. The essential AA digestibilities are summarized in
Table 0.1. High-oil and waxy corn were evaluated for protein digestibilities and found
that the digestibility coefficients were similar between corn hybrids (Soltwedel, 1994).
Results of essential AA digestibilities from Soltwedel (1994) are summarized in Table
0.2. Only two studies have looked at the protein utilization of high oil corn, but waxy
corn has not been evaluated for nitrogen utilization (Adeola and Bajjalieh, 1997; Carr,
1994). Limited data are available on the protein utilization and digestibility of high
lysine corn. Burgoon (1992)looked at high lysine com storage and moisture effects and
reported a few values for nitrogen utilization and digestibility, but no other research has
been done. It is evident that more research is necessary before the true value of these
potentially valuable corn hybrids in swine diets is known.

Digestibility of AA can be measured by two different methods. One is the direct
and the other is the indirect difference method. The direct method usually involves cereal
grains that pigs will willingly consume when formulated into single feed ingredient diets.
The single ingredient supplies the only source of dietary protein therefore the digestibility
can be directly determined by the difference between the amount ingested and the amount
at the terminal ileum. The indirect difference method is usually used with feedstuffs that
are unpalatable or cannot be investigated with the direct method. Digestibility is
measured indirectly by the addition of a cereal grain to make a complete diet along with

using a diet that is primarily comprised of the cereal grain. Then, by difference, the

12

 

digestibility of the test feedstuff can be determined. Also, digestibility can be measured
by obtaining two types of samples, feces and digesta from the terminal ileum. It has been
stated that the use of ileal digesta is the preferred and most accurate site to determine
digestibility (Moughan and Smith, 1985; Sauer et al., 1989). Reasons for the preference
of measuring ileal digestibility values instead of fecal is because of the microbial activity
in the colon alter AA resulting in higher fecal digestibilities than the ileal method
(Moughan and Smith, 1985; Sauer et al., 1977). In addition, the ileal method was shown
to be more sensitive for measurement of AA in grains (T avemer and Farrell, 1981).
Using either the direct or indirect difference method leads to three types of digestibility
coefficients that can be calculated which are discussed in the next section (Sauer et al.,

1989)

Factors aflecting amino acid digestibility

Digestibility can be affected by many factors that can potentially increase or
decrease the AA digestibilities. Some of the factors include age, fiber content, particle
size of the diet, protein intake, antibiotics (den Hartog et al., 1989; Donkoh and
Moughan, 1994; Laplace et al., 1989; Sauer et al., 1989; Stein, 1998). Stein found that
different age pigs particularly, growing pigs and sows in different physiological states,
had different digestibility coefficients. Fiber was shown to decrease AA digestibilities
Laplace (1989), Grala (1998) and Schulze (1994). Wondra et al.(l995) demonstrated that
decreasing particle size increased protein digestibility. Protein intake is also been
reported to increase apparent AA digestibility by Donkoh and Moughan (1994) and Sauer
et al (1989). Some antibiotics have also been shown to increase apparent AA

digestibility by decreasing microbial activity (den Hartog et al., 1989).

13

Mearsurements of digestibility: apparent digestibility

Apparent digestibility measures the difference between the AA ingested minus the
AA in the ileal digesta. The main disadvantage of measuring apparent digestibility
underestimates the actual digestibility of a feedstufi‘ because it does not take into account
endogenous nitrogen secretions. However, many researchers report apparent digestibility
only due to the labor and complications associated with trying to estimate endogenous

nitrogen (Leterrne et al., 1991; Southern, 1991)

True digestibility

True digestibility modifies the apparent digestibility measurement by taking into
account the endogenous nitrogen (Stein, 1998). Therefore, true digestibility would be the
most accurate estimation of digestion of the AA by taking samples at the ileum. But, as
mentioned earlier, the lack of accurate methods results in many complications with

estimating endogenous losses.

Methods for estimating endogenous losses

Endogenous secretions are proteins that originate from saliva, gastric secretions,
pancreatic juice, bile acids, and intestinal secretions (Grala et al., 1998). Estimation of
endogenous losses in the gut can be measured by several methods. The regression
method utilizes the feeding of incremental levels of crude protein (CP) in several diets to
determine a linear relationship between CP intake and the percent nitrogen in the digesta.
Once the linear relationship is established, the y-intercept, which is equal to endogenous
losses, is extrapolated (Fan and Sauer, 1994). This method assumes that endogenous

losses are constant with varying CP levels (de Lange et al., 1989). Another method is

14

feeding a protein free diet (de Lange et al., 1989). This diet is fed and the ileal samples
are collected and analyzed for endogenous losses (Donkoh and Moughan, 1994). The
problem with this method is that the absence of protein per se may not be reflective of the
endogenous secretions produced by a protein-containing diet. Therefore, it assumes that
there is no relationship between CP intake and endogenous losses (Southern, 1991). For
this reason, the protein free diet is now more commonly used to evaluate the non-diet
specific endogenous losses that are discussed below. A casein diet is another method for
estimating endogenous losses where the animal is fed a diet that contains a readily
available protein source: casein (Chung and Baker, 1992). The procedures are the same
as for a protein free diet. In this case, casein is assumed to be absorbed completely and

the animal maintains a close to normal plane of nutrition (Stein, 1998).

Factors that affect endogenous secretion

Increased dry matter intake, specifically increased protein and fiber levels, was
shown to augment endogenous nitrogen secretion (Sauer et al., 1977). Moreover,
increased fiber intake increased the total dry matter flow at the terminal ileum, reduced
nitrogen utilization, and resulted in a increase endogenous and undigested dietary
nitrogen (Schulze et al., 1995). A study by den Hartog (1989) showed that increased
fiber in protein free diet increased the endogenous nitrogen at the terminal ileum and was
thought to increase sloughing off of mucosal cells and increase mucus production. In
addition, dietary protein source and intake was shown to be positively related to
endogenous nitrogen secretions (den Hartog et al., 1989). It has also been shown, in the
same review, that increased poorly digested proteins in diets resulted in increased enzyme

secretion.

15

 

u.l"?'..‘l' .r

Standardized ileal digestibility

In the past decade, new research from France has addressed the problems
associated with measurement of true digestibilities and estimation of endogenous losses.
They have proposed the idea of standardized ileal digestibilities (SID). Standardized ileal
digestibilities separate endogenous losses into two categories: specific endogenous losses
and non-specific endogenous losses (Jondreville et al., 1995). Specific endogenous
losses are related to the nutrient quality of a feedstuff. For example, if a feedstuff is high
in fiber the specific losses would be related to the amount of fiber in the feedstuff. Non-
specific endogenous losses are influenced only by the amount of dry matter intake. At
the Technical Institute for Cereals and Forages (ITCF, Paris, France), non-specific
endogenous losses are typically estimated by feeding a protein free diet. Consequently,
the feedstuff specific endogenous losses are estimated with a model approach. With
these two endogenous estimations they can modify the apparent digestibilities to

standardized ileal digestibilities.

lleal cannulation

Cannulation of the terminal ileum is a common procedure for obtaining ileal
digesta samples. Re-entrant cannulas, one of the first methods for obtaining ileal digesta,
(Sauer et al., 1989) need no dietary markers to estimate the percentage of sample
obtained because of a total diversion of the digesta (Figure 2). This total diversion of the
gastrointestinal tract can influence the normal functioning of the small intestine(Easter
and Tanksley, 1973). In addition, the surgery to place the cannula is intricate and

disrupts the electrochemical pulses in the intestine (Sauer et al., 1989). However, this

16

 

older method is not used as commonly today as the simple T cannula and the ileo-cecal
shunt.

The simple T cannula method requires a dietary marker because only a portion of
the digesta is sampled (Figure 3; (Gargallo and Zimmerman, 1980; Hamilton et al.,
1985). The surgery is less stressful on the gastrointestinal tract compared to the re-
entrant method (Sauer and Ozimek, 1986; Stein et al., 1998). The functioning of the small
intestine is not impaired. It has become the most common method for measuring
feedstuff ileal digestibility in pigs and dogs (Hill et al., 1996) (Muir et al., 1996). The
simple T method seems to be the best for obtaining samples from the ileum.

Within the last ten years, a method called the ileo-cecal shunt has been developed.
This procedure separates the ileum from the cecum and attaches it to the rectum. This
way digesta samples can be collected directly from the anus. This method is commonly

used in European countries where digestibility trials are frequently performed.

Conclusion

From the above literature review, it is evident that there are many nutrient
advantages for the specialty corn hybrids. Although, the amount of swine research
available on the digestibility and utilization of these hybrids is scarce, the potential these
corns offer to swine nutrition warrant further investigation. Protein digestibility and
utilization of the corns must be researched more extensively before they can be advocated
for use in swine diets. Several methods have been identified in this review to enable the
investigation of protein metabolism. Therefore, it was the objective of this thesis to

examine the protein digestibility and utilization of high oil, waxy and high lysine com

17

'1': “ am

Removable tube

1

Small Intestine

 

Figure 2: Re-entrant cannula

Removable Cap

1

Skin

Small
Intestine

 

Figure 3: Simple T cannula

l8

Table 1: Apparent amino acid digestibilities for normal and high-oil corn based on swine
ileal digesta collections (Adapted from Carr, 1994)

 

Essential Normal corn High-oil Difference P-value SEM
Amino Acid TC-2

Arg (%) 65.26 72.62 7.36 .005 1.53
His (%) 69.07 74.14 5.07 .021 1.52
Ile (%) 73.95 77.41 3.46 .045 1.30
Leu (%) 70.31 76.25 5.94 .015 1.62
Lys (%) 83.99 83.84 -0.15 .897 1.10
Phe (%) 74.93 80.95 6.03 .004 1.20
Thr (%) 72.82 73.31 0.49 .759 1.50
Val (%) 67.23 72.48 5.26 .018 1.51

 

Table 2: Apparent digestibilities of amino acids (Adapted from Soltwedel, 1996)

 

Essential High-oil /
Amino Normal Waxy High-oil High - oil Waxy High-oil SEM
Acid (2560) (X571-20) (X577-3) (X577-14) (7003.08)
Arg (%) 88.72 72.99 76.20 80.05 71.56 72.10 2.85
His (%) 70.69 72.56 72.87 73.11 66.72 67.77 1.83
Ile (%) 75.95 76.44 75.79 76.97 72.33 72.76 1.45
Leu (%) 73.80 76.96 75.91 77.31 69.00 71.55 1.89
Lys (%) 82.43 83.20 84.21 85.08 82.97 83.54 0.69
Met (%) 86.29 81.98 86.66 76.84 81.51 81.35 1.06
Phe (%) 80.12 73.66 81.75 75.23 73.28 70.22 1.68
Thr (%) 70.17 68.36 76.91 72.44 66.60 65.43 1.41
Trp (%) 78.42 59.79 77.43 77.47 74.47 78.52 1.23
Val (%) 73.32 72.09 72.63 72.98 66.87 68.47 1.75

 

l9

CHAPTER 1: APPARENT AND TRUE ILEAL AMINO ACID DIGESTIBILITIES
OF CORN HYBRIDS FED TO GROWING PIGS

Abstract

Four barrows (52.8 i 1.7 kg) were used consecutively in two 4 x 4 Latin squares
to compare ileal amino acid digestibilities between different corn hybrids, (high lysine
(HL) vs standard yellow dent l (STD 1), high oil (HO) vs isogenic high oil (IHO), waxy
(WX) vs isogenic waxy (IWX), and all specialty hybrids vs standard yellow dent two
(STD 2)). Each diet consisted of a test corn hybrid (96.62 %), dicalcium phosphate (1.25
%), limestone (0.88 %), vitamin premix (0.50 %), trace-mineralized premix (0.25 %), salt
(0.25 %), chromic oxide (0.25 %) and an amino acid top dress to meet or exceed NRC
(1988) amino acid requirements for growing pigs. Diets were offered in three equal daily
meals for a period of seven days and amino acid top dresses were discontinued on d 5. A
casein diet was fed at the end of the second square to estimate endogenous losses.
Apparent and true amino acid digestibilities were determined for all seven hybrids. All
amino acid digestibility coefficients were higher for H0 and WX compared to their
isogenics but not statistically different (P > .1). The amino acid digestibility coefficients
were lower for the HL corn compared to STD l (P S .1). All protein and amino acid
digestibilities were superior in the HO and WX compared to STD 2 (P > .1). High lysine
corn had superior digestibilities to STD 2 in Arg, His, Lys, Met, Gly, and Proline (P >
.1). Overall, STD l and H0 corns had the highest amino acids digestibility coefficients

of all the hybrids studied.

20

 

Introduction

Swine nutritionists are moving toward diet formulation on a digestibility basis in
an attempt to better meet the pig's nutrient requirements despite the lack of information
regarding digestibility coefficients for common feedstuffs (1998). Currently,
digestibility coefficients for amino acids (AA) exist for the yellow dent corn, but there is
no published data available on AA digestibilities of novel feedstuffs such as "value
added" or "specialty" corns. Several genetically engineered corn hybrids such as high
lysine (opaque-2), waxy and high oil corns have been suggested to offer nutritional
advantages in swine diets over standard corns (Pond and Maner, 1984) but no research
has been performed on their nutrient availability and utilization. The goal of this
experiment was to measure the apparent and true ileal amino acid digestibility of high

lysine, waxy and high oil corns in growing pigs.

Materials and Methods

Six corn hybrids high oil (HO; Cargill 5990 TC), isogenic high oil (1H0; Cargill
5990), waxy (WX; Pioneer 3528B), isogenic waxy (IWX; Pioneer 3527), high lysine
(HL; Crows), and yellow dent I referred as standard one (STD 1; Crows) were obtained
from different seed companies to investigate their amino acid digestibility in growing
pigs. Three seed companies provided a specialty hybrid and its respective isogenics. The
HI. corn did not have an isogenic so the company provided a standard corn with genetics
similar to the HL corn. These corns were planted at Michigan State University (MSU)
farms in 1200 it2 adjacent plots. The plots were monitored throughout growth for dry

matter, ear density and plot density. The centers of the corn plots were harvested

21

individually, at approximately 25 % moisture, using buffer rows to maintain identity of
the hybrids. All hybrids were commercially dried and shipped back to MSU for grinding
in 3 Raymond Mill (No. 82; Chicago, IL) and mixed into experimental diets. A second
standard yellow dent corn (STD 2) was purchased to represent a normal industry corn
which had no known genetic similarities to the six test hybrids.

The Michigan State University All University Committee for the Use and Care of
Animals approved all animal protocols. Initially seven Yorkshire pigs, with and initial
body weight of 40 kg, were fitted with simple T cannulas for a 7 x 7 Latin square design.
Cannulas were surgically inserted and maintained according to Stein et. a1. (1998).
Barrows were moved to individual pens (1.5 m x 2.75 m) and allowed fourteen days for
recuperation after surgery. Daily feed intake, body temperature, and integrity of the
cannula were monitored. Ampicillin was administered for the first three days post
surgery. All pigs were provided free access to water. After three pigs lost their cannulas
during the initial sampling period the pens were modified by adding smooth siding to
further ensure the integrity of the cannulas. As a result the four remaining littermate
barrows (52.8 i 1.7 kg) were rearranged into two consecutive 4 x 4 Latin squares. The
barrows were fed each of the seven diets with the STD 2 diet repeated in both squares to
allow pre-planned comparisons of the coms to be made across the two squares. The pigs
were allowed five days to adjust to the diets. On days six and seven of each period,
digesta from each pig was collected for 12 hours. Pigs were weighed weekly to monitor

growth. Environmental temperature of the room ranged from 16 - 29°C with a mean

temperature of 2 1 °C.

22

Diets

Experimental diets consisted of one of the respective test corns included at 96.62
% as the sole source of protein and energy. Vitamins, minerals, dicalcium phosphate,
limestone and salt were included at 3.13 % of the diet. All vitamins and minerals met or
exceeded NRC (1988) requirements. Chromic oxide was included in the diet as an
indigestible marker at 0.25 %. Barrows were provided ad libitum access to feed during
the post-surgical recovery period and then restricted to 90 % of ad libitum intake during
the experiment. Diets were offered in three equal daily meals. Amino acid top dresses
were added to the daily feed allotments during the adjustment period to meet the amino
acid requirements for the five deficient amino acids: isoleucine, lysine, tryptophan,
methionine and threonine (NRC, 1988). Amino acid top dresses were removed one day
prior to sampling of ileal digesta. At the end of the second Latin square, a casein diet was
fed to all four pigs at the same time to estimate endogenous nitrogen secretion at the
terminal ileum. The casein diet was a semi-purified diet consisting of 71.43 %
cornstarch, 11.75 % casein, 5.0 % Solka Floc, 4.0 % corn oil, 4.0 % sugar, 2.25 %
dicalcium phosphate, 0.32 % limestone, 0.50 % vitamin premix, 0.25 % trace mineral

mix, salt and chromic oxide (Table 6).

Sample Preparation and analysis

Digesta for each pig was homogenized and pooled over the two-day collection
and stored at -20 °C until samples were prepared for analysis. Digesta samples were
thawed, freeze-dried and finely ground using a coffee grinder for dry matter, crude

protein, amino acid, and chromium analysis. Dry matters of the corns, digesta and diets

were determined using a vacuum oven at 60 °C for twelve hours. A Hach-kjeldahl was

23

used to determine crude protein (Hach et al., 1987). Particle size was determined using
weight distribution over standard U. S. sieves according to Ensor et. al.(l970). Gross
energy of the corns and diets were determined via adiabatic bomb calorimetry (Parr
Instrument Co., Moline, IL).

Amino acid determination was performed using the Pic00Tag ® method (Waters
Co., Milford, MA) which included acid hydrolyzation in an autoclave for 24 hours at 110
°C. Samples were then brought up to volume and filtered. The amino acid filtrate was
then subsampled and dried using vacuum centrifugation. The AA hydrolysate was
reconstituted, dried again, derivatized with PITC® and separated using a Waters high
pressure liquid chromatographer (Waters, Co., Milford, MA) fitted with a 15 cm
hydrolysate column.

Chromium (Cr) was determined at two different laboratories. At Michigan State
University, a wet ash procedure was employed to oxidize the Cr (Bolin, 1952). One gram
of sample was digested using concentrated nitric acid and heat. After digestion
perchloric acid was added to oxidize the Cr 3+ to Cr 6+. Samples were then weighed,
diluted and shipped to a commercial laboratory to be analyzed by atomic absorption
spectrophotometry (University of Illinois, Urbana, IL; see appendix 2 for the AA
digestibility values using these results). Due to complications with the previous
mentioned procedure, a commercial laboratory also performed Cr analysis and these
values were used to calculate the digestibilities reported in this chapter (University of

Missouri Agriculture Experiment Station, Columbia, MO; (AOAC, 1990)).

24

’f.‘

 

Apparent and true amino acid digestibilities and endogenous amino acid losses
were calculated according to Stein (1998) and these calculations are summarized and

included in appendix 1.

Statistical analysis

Data was analyzed using both GLM and MIXED procedures of SAS (1990) in a
Latin square design. Data from the two squares were pooled and STD 2 corn was used as
the reference com. A linear model with main effects of square, collection nested within
square, diet and pig as a random variable were used in the statistical model. LSMEAN S
with stderr and pdiff options in GLM and pdiff option in MIXED were used to determine
difference between the following preplanned comparisons: HO vs IHO, WX vs IWX, HL
vs STD 1, HO vs STD 2, WX vs STD 2 and HL vs STD 2. Both analysis were evaluated
and the MIXED procedure was used for statistical difference because of the multiple

sources of variance in the model and MIXED ability to handle negative variance.

Results

The pigs remained healthy during this experiment and had an average daily gain
of 0.45 kg/d and an average daily feed intake of 2.70 kg/d. Table 3 represents the
‘ nutrient compositions of the seven corn hybrids. Dry matter, gross energy and ash were
relatively similar across all corn hybrids. The major differences in nutrient
concentrations were seen in crude protein and ether extracts. Crude protein (CP) ranged
from 8.36 to 10.81 % in the hybrids with the STD l and the HO having the first and
second greatest protein content, respectively. The HO also had the greatest ether extract

at 7.93 % while all of the corns ranged from 3.97 to 5.44. Amino acid contents of the

25

corn hybrids were also determined. The highest lysine contents were found in the HL
and STD] corns at 0.36 and 0.29 %, respectively. Arginine, methionine, threonine and
valine concentrations ranged from 0.45 to 0.61, 0.19 to 0.24, 0.26 to 0.36, and 0.43 to
0.54 %, respectively. These amino acids are reported as a percentage of the total CP in
table 4. Glutamic acid and leucine are the most abundant amino acids in the coms
providing approximately 17 % and 10 % of the total protein, respectively. High lysine
corn has a higher percentage of lysine (4.14) than the rest of the corn hybrids (3.23-2.57).
Arginine content in the HL corn is 1.26 % greater than the next highest concentration that
is in the STD 2 corn. Also, HL corn has less leucine as a percentage of total nitrogen at
7.24 % and the other hybrids have 10 - 11 %. The other essential amino acids as a
percentage of CP are similar across the hybrids. The mean particle size for each of the
corn hybrids are reported in Table 5. The particle sizes were similar across all corn and
ranged from 0.81 to 0.95 mm. Dry matter was comparable across all diets (Table 7).
Inclusion of the corn hybrids in the diets resulted in CP contents ranging from 8.27 to
10.93 %. Crude protein content of the casein diet was 12.06 %. Gross energy was
highest in the HO diet at 4.51 Meal/kg whereas all the other diets contained
approximately 4.36 Meal/kg. Average daily feed intakes (ADFI) ranged from 2.37 - 2.82
kg/d, but feed wasted by the pigs was not measured. Amino acid top dresses were used
to better meet the barrows requirements for the amino acids that were deficient in the
com-based diets. Inclusion rates of the five amino acids are reported in table 1.6 in g/kg
of diet.

Apparent ileal amino acid (AID) digestibilities are reported in table 9. Although

notable numerically higher, there were no differences ( P > .1) in AID between HO vs

26

 

IHO and WX vs STD 2 corns. When comparing WX to IWX, Arg, His, Phe, Val and Tyr
were higher (P S .1) and all other amino acids were similar. Histidine, Ile, Leu, Lys, Met,
Thr, Asp, Glu, Pro were lower (P S .l) in the HL compared to STD 1. In addition, Phe,
Val, Ala, Ser and Tyr were lower (P < .05) in HL compared to STD 1. When comparing
HO to STD 2, differences were seen in His, Ile, Leu, Lys, Met, Ala (P _<_ .1) and Pro (P <
.05). When HI. vs STD 2 AID were compared, Arg, Leu, Lys, Ala (P S .1) and Pro (P <
.05) were lower. Overall, STD 1 had higher absolute AID than all other hybrids.
Consequently, the STD 1 corn had the greatest mean protein digestibility followed by the
HO and the WX corn. Total AID were not different between HO vs IHO, WX vs IWX,
WX vs STD 2, and HL vs. STD 2. Significant (P .<_ .1) total AID were shown in the HL
vs STD 1 and H0 vs STD 2.

True ileal amino acid digestibilities (TID) were calculated using the endogenous
nitrogen losses reported in table 11. The five greatest endogenous amino acid losses
from highest to lowest were Pro, Glu, Ser, Leu and Val. These losses were crucial in
calculating the TID in table 10. True ileal digestibilities for the amino acids ranged from
70.12 to 130.93 %. There were no differences in TID when comparing between WX and
IWX. Differences between HO and IHO were found for Met and Gly (P S .1).
Differences in Lys, Met, Ala (P .<_ .1), Phe, Thr , Asp, and Tyr (P < .05) were found
between the HL and STD 1. Comparisons of the STD 2 corn to H0 digestibilities
showed differences for Glu and Pro at P < .05. Glu was the only amino acid that was
different in the WX vs STD 2 contrast. When comparing HL and STD 2 differences
were found for Phe, Tyr (P S .1), Thr, Ala, Glu and Pro (P < .05). Overall, total protein

TID did not differ between any of the six preplanned comparisons.

27

Apparent ileal amino acid digestibilities of the casein diet are reported in table 12.
Digestibilities range from 58.81 i 3.97 to 94.26 i 0.55 with a mean amino acid

digestibility of 84.73 :1: 1.09 %.

Discussion

Amino acid concentrations of the corn hybrids were similar to reported values for
other varieties of high oil, waxy, high lysine and standard yellow dent corns (Adeola,
1996; Adeola and Bajjalieh, 1997; Burgoon et al., 1992; Carr, 1994; Dupont, 1997;
Soltwedel, 1996). Some variations were seen with leucine across literature and hybrids
but all differences in concentrations were less than 0.20 %. In addition, the reported
ratios of amino acids as a percent of protein were similar to those reported by Pond and
Maner (1984) for HL and standard corns at 4.2 and 2.6 %, respectively. The high lysine
amino acid data (AA/ 16 g N) also demonstrate increases in arg, asp and gly, but
decreases in ala and leucine equivalent to the findings of Pond and Maner (1984).

Apparent amino acid digestibilities for high oil, waxy and standard yellow dent
corns were similar to other essential amino acid digestibilities reported for these corns
(Carr, 1994; Soltwedel, 1996; Southern, 1991). Differences in AID between hybrids and
standard 2 were seen for the non-essential amino acids, particularly for asp, glu, gly, pro,
and tyr (P < .05 ). The low AID for standard 2 corn reported by this study are difficult to
explain, but the low digestibilities may be a result of constant addition of amino acids by
the endogenous losses. Endogenous losses have been shown to include high proportions
of glu, gly and pro (Sauer et al., 1977). Apparent digestibility values for high lysine corn

were lower in this study than reported by Burgoon (1992). One possible reason for this

28

difference is that the pigs used in Burgoon's study varied between 97 and 73 kg whereas,
this study used smaller pigs (40 kg).

True digestibility values for these specialty corns have not been reported. In this
experiment, TID values from normal yellow dent corn were greater than reported by
Stein (1998) who also used a casein diet to estimate endogenous secretions or by
Southern (1991). True digestibilities in this study are higher because the estimations of
endogenous secretions from the casein diet were higher than others published for similar
size pigs (Stein, 1998). It is believed the overestimation of endogenous secretions were
the primary reason this study reported several TID greater than 100 %. This observation
raises the question of whether a protein free diet would give a more accurate estimation
of endogenous losses. This question is addressed in the next chapter.

When comparing the apparent ileal digestibilities of the casein diet to other
published values, it was found that the AID in this study were slightly lower than those
published by Stein (1998) and Chung (1992).

In conclusion, a definite difference in nutrient concentrations between corn
hybrids was found. The apparent amino acid digestibilities of waxy corn were similar
and high oil and high lysine corns were superior to the commercially purchased yellow

dent corn.

Implications

This study provides apparent amino acid digestibility coefficients for increasingly
popular corn hybrids, which will be valuable for the formulation of swine diets. In
addition, this study shows that the amino acids in specialty corns are adequately and in

some cases better digested when compared to standard yellow dent two com.

29

Table 3:

Nutrient composition of corn hybrids on a dry matter basis

 

 

 

Corn hybrids
Items l-lO 1H0 WX IWX HL STD l STD 2
Dry matter, % 88.21 88.34 87.72 87.97 88.35 88.13 85.60
Crude protein, % 10.10 8.82 8.70 8.80 8.70 10.81 8.36
Ether extract, % I 7.93 5.44 4.49 4.49 3.97 4.96 4.23
Gross energy, Meal/kg 4.65 4.50 4.51 4.40 4.45 4.55 4.59
Ash, % 1.90 2.06 1.64 1.90 1.65 2.08 1.63
Amino acid, %
Essential
Arg 0.48 0.45 0.47 0.46 0.61 0.56 0.48
His 0.33 0.30 0.32 0.32 0.34 0.37 0.30
Ile 0.37 0.33 0.30 0.32 0.30 0.40 0.34
Leu 1.15 0.96 0.88 0.94 0.63 1.27 0.85
Lys 0.26 0.24 0.26 0.25 0.36 0.29 0.27
Met 0.24 0.21 0.21 0.22 0.20 0.24 0.19
Phe 0.49 0.42 0.40 0.42 0.33 0.54 0.40
Thr 0.33 0.30 0.30 0.30 0.32 0.36 0.26
Val 0.49 0.43 0.43 0.44 0.45 0.54 0.44
Non-essential
Ala 0.74 0.61 0.58 0.62 0.50 0.78 0.67
Asp 0.65 0.57 0.66 0.49 0.82 0.73 0.30
Glu 1.81 1.51 1.49 1.49 1.27 1.99 1.42
Gly 0.37 0.33 0.35 0.34 0.40 0.40 0.35
Pro 0.86 0.73 0.75 0.77 0.68 0.95 0.66
Ser 0.48 0.43 0.43 0.43 0.40 0.53 0.43
Tyr 0.34 0.31 0.31 0.29 0.30 0.37 0.30
ZAmino Acids 9.39 8.13 8.14 8.10 7.91 10.32 7.66

 

30

Table 4: Amino acid concentration as a percent of total nitrogen

 

 

m

Essential
Arg 4.75 5.10 5.40 5.23 7.01 5.18 5.74
His 3.27 3.40 3.68 3.64 3.91 3.42 3.59
Ile 3.66 3.74 3.45 3.64 3.45 3.70 4.07
Leu 11.39 10.88 10.11 10.68 7.24 11.75 10.17
Lys 2.57 2.72 2.99 2.84 4.14 2.68 3.23
Met 2.38 2.38 2.41 2.50 2.30 2.22 2.27
Phe 4.85 4.76 4.60 4.77 3.79 5.00 4.78
Thr 3.27 3.40 3.45 3.41 3.68 3.33 3.11
Val 4.85 4.88 4.94 5.00 5.17 5.00 5.26

Non-essential
Ala 7.33 6.92 6.67 7.05 5.75 7.22 8.01
Asp 6.44 6.46 7.59 5.57 9.43 6.75 3.59
Glu 17.92 17.12 17.13 16.93 14.60 18.41 16.99
Gly 3.66 3.74 4.02 3.86 4.60 3.70 4.19
Pro 8.51 8.28 8.62 8.75 7.82 8.79 7.89
Ser 4.75 4.88 4.94 4.89 4.60 4.90 5.14
Tyr 3.37 3.51 3.56 3.30 3.45 3.42 3.59

 

31

Table 5: Particle size of the corn used in experimental diets (mm)

 

 

 

Hybrids Geometric mean diameter'I Standard deviation by weight
HO 0.92 2.86
IHO 0.93 2.84
WX 0.95 2.90
IWX 0.92 2.86
HL 0.81 3.02
STD l 0.93 2.83
STD 2 0.85 2.93

 

j Coefficient of variation = 5.8 %

32

Table 6: Composition of experimental diets on as-fed basis (%)

 

 

 

Ingredients Com-based Casein
Com' 96.62 --
Cornstarchb . -- 71 .43
Casein° -- 1 1.75
Solka Flocc -- 5.00
Com oil‘l -- 4.00
Sugar -- 4.00
Dicalcium 1.25 2.25
phosphate
Limestone 0.88 0.32
Vitamin mix‘ 0.50 0.50
Trace mineral 0.25 0.25
mixf
Salt 0.25 0.25
Chromic oxide8 0.25 0.25

 

' Corn varieties used were STD 1, STD 2, HO, IHO, wx, rwx and HL.

" Argo Foods, CPC International, Inc, Englewood Cliffs, NJ 07632-9976.

‘ Harland Teklad, Madison, WI 53744-4220.

‘ Kraft Foodservice, lnc., Glenview, IL 60025.

‘ Provided the following per kilogram of diet: 4,583 IU vitamin A, 458 IU vitamin D3, 55 IU vitamin E, l 1 mg vitamin
K, 3.66 mg menadione, 0.0275 mg vitamin B12, 3.66 mg riboflavin, 14.67 mg d-pantothenic acid, 22 mg niacin, 0.913
mg thiamine, 0.825 mg pyridoxinc.

fProvided the following per kilogram ofdiet: 335 g Ca, 5 g Fe, 5 3 Zn, 5 mg Cu, 5 mg Mn, 150 ug Se, and 75 pg 1.

‘ Fisher, Itasca, IL 60143.

33

Table 7: Nutrient composition of the diets on a dry matter basis

 

 

 

Items HO IHO WX IWX HL STD 1 STD 2 Casein
Composition, calculated
Crude protein, % 10.06 8.54 8.56 8.56 7.93 10.36 7.75 11.16
Gross energy, Meal/kg 4.49 4.35 4.36 4.25 4.30 4.40 4.43 4.67a
Calcium, % 0.70 0.69 0.70 0.70 0.69 0.69 0.70 0.66
Phosphorus, % 0.57 0.57 0.57 0.57 0.57 0.57 0.57 0.55
ADFI, kg/d 2.37 2.51 2.63 2.82 2.35 2.51 2.55 2.76

Composition, analyzed
Dry matter, % 87.61 87.95 87.22 87.63 88.09 88.15 87.18 91.46
Crude protein, % 9.64 9.51 8.43 8.55 8.65 10.93 8.27 12.06
Gross energy, Meal/kg 4.51 4.36 4.39 4.36 4.33 4.38 4.30 4.38

Amino acid, %

Essential
Arg 0.47 0.42 0.42 0.39 0.64 0.50 0.40 0.58
His 0.36 0.31 0.30 0.29 0.38 0.38 0.27 0.48
Ile 0.38 0.32 0.29 0.31 0.28 0.39 0.26 0.73
Leu 1.09 0.98 0.86 0.87 0.62 1.30 0.74 1.14
Lys 0.25 0.22 0.25 0.23 0.34 0.26 0.23 0.96
Met 0.23 0.21 0.20 0.21 0.21 0.25 0.16 0.43
Phe 0.46 0.42 0.38 0.38 0.34 0.54 0.34 0.67
Thr 0.32 0.29 0.30 0.30 0.32 0.35 0.26 0.50
Val 0.47 0.43 0.40 0.40 0.45 0.51 0.36 0.85

Non-essential

 

Ala 0.70 0.63 0.58 0.57 0.51 0.80 0.51 0.43
Asp 0.62 0.56 0.58 0.58 0.80 0.69 0.49 0.81
Glu 1.69 1.46 1.35 1.44 1.26 1.89 1.16 2.67
Gly 0.34 0.31 0.32 0.31 0.39 0.38 0.30 0.26
Pro 0.80 0.76 0.73 0.72 0.68 0.95 0.60 1.26
Ser 0.48 0.42 0.42 0.40 0.41 0.53 0.37 0.73
Tyr 0.33 0.30 0.29 0.27 0.31 0.36 0.26 0.68
ZAmino Acids 8.99 8.04 7.67 7.67 7.94 10.08 6.71 13.18
‘ Calculated as DE/.90, Meal/kg

34

Table 8: Amino acid top dress composition

 

 

 

Amino acid,

g/kg of diet HO 1H0 WX IWX HL STD l STD 2
He 0.53 0.93 1.23 0.92 0.77 1.23 1.27
Lys 3.96 4.07 4.50 4.24 4.35 3.38 4.97
Met 0.60 1.22 0.98 0.65 0.69 0.74 1.02
Thr 1.79 2.15 2.29 2.12 2.16 2.21 2.40
Trp 0.15 0.15 0.15 0.15 0.15 0.15 0.15

 

35

Table 9: Apparent amino acid digestibilities ( % ) of the corn hybrids

 

 

Pooled
HO IHO wx rwx HL STD 1 SEM STD 2
Essential
Arg 73.19“ 66.04“ 67.49““ 56.76b 77.16““ 81.12“ 5.52 65.27 i 3.33“
His 76.32““ 69.73“ 71.07““ 58.76b 70.89““ 83.01b 5.10 64.57 i 2.95“
lle 76.17““ 68.60“ 68.83“ 58.95“ 51.90““ 80.05c 6.31 61.68 i 3.64“
Leu 82.89““ 78.17“ 78.15““ 69.19“ 60.79“f 87.99“ 4.73 73.39 :t 2.73“
Lys 64.67““ 52.27“ 54.90“ 43.05“ 58.12“ 73.76b 6.83 50.33 i 3.94“
Met 78.32“ 69.57“ 69.93“ 60.29“ 64.60““ 83.49“ 5.60 62.77 3; 3.23“
Phe 79.32“ 75.52“ 75.82“ 65.30“ 60.57“ 86.40“ 5.06 70.22 i 2.92“
Thr 56.89“ 52.68“ 53.94“ 39.07“ 35.45“ 72.82“ 8.72 43.08 :t 5.03“
Val 69.68“ 63.46“ 64.23“ 50.89b 54.19“ 78.98“ 6.41 57.10 i 3.70“
Non-
essential
Ala 72.30““ 71.51 “ 67.65 ““ 62.01 “ 50.27““ 81.52c 4.93 61.76 i 2.85“
Asp 78.17“ 68.53 “ 74.46““ 63.41 “ 73.58““ 89.45 b 6.68 76.32 :- 3.92“
Glu 78.59““ 76.07“ 75.60“ 69.63 “ 67.37“ 88.80“ 4.93 76.65 i 2.85“
Gly 39.16“ 17.05 “ 35.36““ 16.79“ 31.40“ 59.64“ 14.81 16.85 i 8.75“
Pro 57.35 “’ 24.72“ 16.22““ 11.82“ 33.16“f 63.36b 17.51 -930 i 13.26“
Ser 73.79“ 66.87“ 67.45 ““ 55.33 “ 58.59“ 82.56“ 6.18 64.17 i 3.57“
Tyr 63.25 “ 64.55 “ 63.02 “ 48.96b 52.45 “ 74.80“ 6.56 56.75 :t 3.78“
Mean AA 70.00 ““ 61.56“ 62.76““ 51.89“ 56.28 “ 79.23 “ 6.38 55.73 i 3.69“
‘ Digestibility

 

‘b Means in rows with different superscripts are different among these preplanned comparisons: HO
vs IHO, WXvs IWX, HL vs STD l (P s .10)

"° Means in rows with different superscripts are different among these preplanned comparisons: HO
vs IHO, WX vs IWX, HL vs STD 1 (P < .05)

‘L‘ Means in rows with different superscripts are different among these preplanned comparisons: HO
vs STD 2, WX vs STD 2, HL vs. STD 2 (P s .10)

d‘f Means in rows with different superscripts are different among these preplanned comparisons: HO
vs STD 2, WX vs STD 2, HL vs. STD 2 (P < .05)

Table 10: True amino acid digestibilities (%) of the corn varieties

 

Pooled
HO IHO wx wa HL STD 1 SEM STD 2
Essential
Arg 96.72 “ 91.76“ 92.83 ““ 93.05 “ 96.48 ““ 98.94 “ 3.45 94.86 i 2.73 “
His 95.24“ 92.44“ 93.88 ““ 89.66“ 92.37 “ 97.34“ 3.48 92.44 i 2.73 “
lle 118.13 “ 120.49“ 123.72 ““ 129.09“ 120.87 ““ 112.57“ 6.87 129.16 :1: 4.85 “
Leu 100.74“ 98.68“ 101.01 “ 100.07“ 100.85 “ 99.73 “ 3.48 101.42 :1: 3.16“
Lys 114.61 “ 105.01 “ 103.37“ 111.22“ 98.88 ““ 113.18“ 6.86 107.74 i 5.32“
Met 102.74 “ 97.42 b 98.17 “ 97.58 “ 97.65 “ 101.81 " 3.19 100.50 :t 2.82 “
Phe 99.37 “ 97.90 “ 99.79 “ 97.91 “ 94.60 ““ 99.91 “ 3.35 99.68 i 2.88 “
Thr 101.39“ 102.47“ 101.19“ 103.05 “ 86.88 “‘ 105.44“ 4.91 101.33 i 3.71 “
Val 111.79“ 108.99“ 112.01“ 116.07“ 106.80“ 109.79“ 6.95 114.40 1 5.93 “
Non-essential
Ala 94.86“ 98.40“ 95.67 ““ 98.25 “ 88.15 “’ 96.88 “ 3.71 97.43 :t 2.28 “
Asp 89.42 “ 81.83 “ 87.27“ 80.72 “ 83.42 ““ 97.57“ 4.87 92.39 :1: 2.81 “
Glu 96.30“f 98.58 “ 98.79 “‘ 98.49“ 97.29 “‘ 100.98 “ 4.50 106.13 1 4.06“
Gly 93.32 “ 70.12 “ 77.94 “ 81.99 “ 80.44 ““ 93.60 “ 9.35 78.21 i 6.83 “
Pro 111.96 “‘ 89.45 “ 79.92 ““ 92.55 “ 110.67 “‘ 97.88 “ 13.88 78.44 :1: 9.78 “
Ser 120.60 ““ 121.25 “ 121.45 “ 130.93 “ 124.66“ 116.56“ 9.50 129.86 x 8.20“
Tyr 93.13 ““ 96.77“ 95.82 “ 95.36“ 90.68 ““ 96.77“ 3.26 96.67 i 2.58 “
mess 102.52 ““ 98.23 “ 98.93 ““ 101.00“ 98.17““ 102.43 “ 3.91 101.29 :1: 3.30“

 

"b Means in rows with different superscripts are different among these preplanned comparisons: HO
vs IHO, WX vs IWX, HL vs STD l (P S .10)
"° Means in rows with different superscripts are different among these preplanned comparisons: HO
vs IHO, WX vs IWX, HL vs STD 1 (P < .05)
‘L‘ Means in rows with different superscripts are different among these preplanned comparisons: HO
vs STD 2, WX vs STD 2, HL vs. STD 2 (P S .10)
M Means in rows with different superscripts are different among these preplanned comparisons: HO
vs STD 2, WX vs STD 2, HL vs. STD 2 (P < .05)

37

Table 11: Endogenous amino acid losses (mg/kg dry matter intake) at the terminal ileum
determined by feeding a casein diet

 

 

 

Pig A Pig B Pig C Pig D Mean i SEM

Amino Acid

Essential
Arg 628.47 652.59 791.69 754.07 706.71 i 39.28
His 364.93 478.24 468.68 487.41 449.82 i 28.55
Ile 904.63 978.39 1137.25 1185.19 1051.37 i 65.92
Leu 1032.67 1184.84 1619.43 1255.24 1273.05 i 124.45
Lys 664.58 818.87 863.26 787.45 783.54 i 42.59
Met 323.39 348.32 434.86 374.93 370.38 1- 23.93
Phe 519.24 571.39 727.46 583.80 600.47 5: 44.58
Thr 734.14 835.46 999.71 1145.03 928.59 i 90.55
Val 1033.96 1206.63 1524.89 1296.15 1265.41 i 102.18

Non-essential
Ala 957.28 1148.06 872.63 1325.23 1075.8 :1: 101.14
Asp 342.99 469.66 557.04 493.18 465.72 :t 44.88
Glu 971.06 2498.90 1997.78 2760.28 2057.01 1 395.04
Gly 850.29 1303.77 953.34 1175.41 1070.7 :1: 103.13
Pro 2345.33 3642.31 1944.49 4277.69 3052.46 i 545.95
Ser 937.20 1508.41 1757.81 1664.81 1467.06 i 183.96
Tyr 568.51 621.98 681.14 661.10 633.18 :1: 24.81

 

Table 12: Apparent digestibility of casein diet (%)

 

 

 

Casein SEM
Amino Acid
Essential
Arg 87.73 0.68
His 90.67 0.59
Ile 85.65 0.90
Leu 88.83 1.09
Lys 86.78 1.29
Met 91.43 0.55
Phe 91.06 0.66
Thr 81.49 1.81
Val 85.10 1.20
Non-essential
Ala 75.24 2.33
Asp 94.26 0.55
Glu 92.28 1.48
Gly 58.81 3.97
Pro 75.80 4.33
Ser 79.80 2.53
Tyr 90.72 0.36
Mean AA 84.73 1.09
Digestibility

 

39

CHAPTER 2: COMPARISON OF ENDOGENOUS AMINO ACID SECRETIONS
FROM GROWING PIGS FED CASEIN AND PROTEIN FREE DIETS

Abstract

Four barrows (98.5 i 5.6 kg body weight) fitted with simple-T cannulas at the
terminal ileum were used to determine differences in endogenous amino acid secretions
between casein and protein free diets. A switch back design was used where pigs were
randomly allotted to treatments in pairs. The casein diet consisted of 71 .43 % cornstarch
and 11.75 % casein while the protein free diet consisted of 81.98 % cornstarch. The
remainder of the ingredients in both diets were Solka Floc (5 %), corn oil ( 4 %), and
sugar (4 % in the casein and 5 °/o in the protein free diet). Vitamins, minerals, dicalcium
phosphate, limestone and salt were included in both diets to meet or exceed NRC
requirements (1988). Chromic oxide was included in the diets as an indigestible marker at
0.25 %. Pigs were fed the diets for a period of seven days that included a five day diet
adjustment period followed by two days of ileal digesta collections (12 hours each day).
Digesta was pooled during the two day collection period and then analyzed for amino
acid content. In the casein and protein free diets, proline, glutamic acid, serine and
glycine were the amino acids secreted in the greatest amounts. Significant differences (P
s .1) in endogenous amino acid secretions were seen in all amino acids with the
exception of arginine, aspartic acid, proline and serine (P > .10). The casein diet resulted

in higher amino acid secretions than the protein free diet for all amino acids.

40

Introduction

True ileal digestibilities (TID) are a more accurate estimation of the digestibility
of a feedstuff than apparent digestibility because the calculation takes into account
endogenous secretions. Unfortunately, researchers have struggled with methods to
estimate endogenous losses at the terminal ileum for several years. Endogenous nitrogen
secretions originate from saliva, gastric juice, pancreatic juice, bile, intestinal juices,
mucosa and sloughed mucosal cells (Stein, 1998). Secretions of nitrogen are influenced
by several factors such as age, body weight, dry matter intake, quality of protein, and
fiber (Grala et al., 1998; Sauer et al., 1977; Sauer et al., 1977; Tavemer et al., 1981).
Many methods exist for the determination of endogenous secretions in the digestive
system of the pig, but none of them are without criticism. Several studies have
investigated the protein free diet (de Lange et al., 1989; de Lange et al., 1989; Sauer et
al., 1977; Tavemer et al., 1981) and the casein diet (Chung and Baker, 1992; Chung and
Baker, 1991; Stein, 1998). The protein free diet is believed to underestimate the
endogenous losses but it is advantageous because is the least expensive and easiest (Stein,
1998). Increased protein intake has been shown to directly increase endogenous amino
acid secretions in the gastrointestinal tract (Sauer, 1986 #36). The major disadvantage to
the protein free diet is that it does not estimate diet specific endogenous losses or account
for protein level specific endogenous secretions (Lewis and Bayley, 1995). The other
method that has been investigated is the casein diet. In this method casein is assumed to
be 100 % digestible and therefore any amino acids at the terminal ileum are of

endogenous origin. This method accounts for both the diet specific and the protein level

41

specific endogenous secretions. Baker and Chung (1992) tested the digestibility of casein
and found that is readily digested in pigs with true digestibility coefficients ranging fi'om
94.8 - 99.9 % for all essential amino acids. Therefore, it could be used to estimate
endogenous losses and assumed to be 100 % digestible. Stein (1998) used this method
but believed that the endogenous secretions obtained from this method were
overestimated. It was the goal of this experiment to investigate the endogenous
secretions at the terminal ileum in pigs fed both a casein and a protein free diet. In
addition, it was an objective of this experiment to how these diets would affect true ileal

digestibilities.
Materials and Methods

Animals, experimental design and diets were approved by Michigan State
University All University Committee for Animal Use and Care. Four, littermate barrows
(98.5 i 5.6 kg, Yorkshire), used in the previous experiment (chapter one), were randomly
assigned to diets and arranged in a switchback design (Gill, 1978; Neter et al., 1996) to
investigate the differences in endogenous secretion at the terminal ileum of pigs fed a
casein and a protein free diet. The two diets were fed to the four pigs such that six
individual observations were obtained for each diet. Environmental temperature in this
experiment ranged from 21-29°C with a mean temperature of 24°C. Housing, feeding

and digesta collection procedures were performed as described in chapter one.

Diets

The experimental diets are reported in table 13. The casein diet provided protein

and energy to the barrows whereas the protein free diet only provided energy. Vitamins,

42

minerals, dicalcium phosphate, limestone and salt were included to meet or exceed NRC
requirements (1988). Chromic oxide was included in the diets as an indigestible marker at

0.25 %.

Chemical analysis

Digesta, diets and corns analyses were performed as described in chapter one.

Statistical analysis

Data were analyzed using MIXED procedures of SAS (1990). A linear model
with no interactions was used and included pig and diet as main effects. Sequence and
carryover effects were evaluated and removed from the model because they were not
significant at the lowest P-values of .29 and .34, respectively. Least square means and

the pdiff option were used to determine differences between means.

Results

All pigs remained healthy during this study. Pigs on the casein diet had an ADFI
of 2.58 kg/d and an ADG 0.48 kg/d. The pigs on the protein free diet had an ADFI and
ADG of 0.054 kg/d and 2.03 kg/d, respeCtively. One pig in the last collection period
refused to eat the protein free diet so normal finishing diet was given and no digesta
sample was taken. Nutrient compositions of the diets are reported in table 14. The casein
diet provided 12.06 % crude protein to the barrows whose requirement was 13 % (NRC,
1988). In addition, the casein diet met or exceeded the barrows requirements for essential
amino acids and energy. On the other hand, the protein-free diet did not provide protein
but did provide adequate amount of energy. Table 15 reports the endogenous losses in

pigs fed the casein and protein-free diets. Differences in endogenous amino acid

43

secretions were found for His, Lys, Phe, Gly and Tyr (P S .1). In addition, Ile, Leu, Met,
Thr, Val, Ala and Glu were different at P < .05. Overall, endogenous losses at the
terminal ileum were greater for the casein diet compared to the protein-free diet. Tables
16 and 17 are calculations of TID using both the protein free and the casein diets,
respectively. The data are from the corns fed in chapter one. These two tables illustrate
the differences that diets for endogenous estimation can have on true ileal digestibilities
(TID). The range of TID values are 75.24 to 118.62 and 72.73 to 130.06 % for the
protein free and the casein diets, respectively. Overall, the TID using the casein are
greater than those for the protein free diet with the exception of three amino acids: Arg,

Asp and Pro.

Discussion

Tavemer's (1981) experiment where protein free diets were fed reported that the
most abundant amino acids in the ileal endogenous digesta were proline, glycine,
glutamic acid, aspartic acid, serine and threonine in order of most to least. Similar results
were seen in this study for endogenous losses in both the casein and protein free diet.
The most prevalent amino acids in the protein free diet (in order of highest to lowest)
were proline, glutamic acid, glycine, serine, alanine, leucine and valine. In the casein
diet, proline, glutamic acid, serine, glycine, valine, alanine and leucine had the greatest
amount protein in the endogenous digesta from highest to lowest.

The values obtained for endogenous losses from the casein diet were at least two
times the amount seen in the protein free diet. It is logical to attribute the differences in
endogenous secretions to the differences in crude protein between the two diets. Data

presented by J ondreville (1995) state that endogenous nitrogen has two fractions: the

44

protein that is secreted but it is not specific to the feedstuff (only affected by the dry
matter intake) and protein that depends on the composition of the feedstuff (affected by
the quantity and type of feed ingested). The researchers at the Technical Institute for
Cereals and Forages use a protein free diet to estimate the non-specific endogenous
losses. Therefore, in this study, the protein free diet only estimates the non-specific
endogenous losses and the casein diet estimates the diet specific endogenous losses and
the non-specific endogenous secretions. Since casein was used and not a corn based diet
the diet specific endogenous losses were thought to be overestimated.

Similar endogenous amino acid losses from the protein fiee diet were found when
compared to published values (Chung and Baker, 1992; de Lange et al., 1989; de Lange
et al., 1989; Sauer et al., 1977; Stein, 1998; Tavemer et al., 1981). Endogenous losses
from the casein diet were definitely higher than values published by Stein (1998) and

Chung and Baker (1992).

Implications

This study implies that neither the casein nor the protein free diet was adequate to

estimate endogenous losses for the corn diets.

45

Table 13: Experimental diets on as-fed basis (%)

 

 

 

Ingredients Casein Protein free
Comstarch' 71.43 81.98
Caseinb 11.75 ~-
Solka Flocb 5.00 5.00
Corn oilc 4.00 4.00
Sugar 4.00 5.00
Dicalcium phosphate 2.25 2.70
Limestone 0.32 0.07
Vitamin mixd 0.50 0.50
Trace mineral mixe 0.25 0.25
Salt 0.25 0.25
Chromic oxidef 0.25 0.25

 

' Argo Foods, C'PC International, Inc., Englewood Cliffs, NJ 07632-9976.

b Harland Teklad, Madison, WI 53744-4220.

° Kraft Foodservice, Inc., Glenview, IL 60025.

‘ Provided the following per kilogram of diet: 4,583 IU vitamin A, 458 IU vitamin D3, 55 IU vitamin E, 11 mg vitamin
K, 3.66 mg menadione, 0.0275 mg vitamin Bu 3.66 mg riboflavin, 14.67 mg d-pantothenic acid, 22 mg niacin, 0.913
mg thiamine, 0.825 mg pyridoxine.

‘Provided the following per kilogram of diet: 335 g Ca, 5 g Fe, 5 g Zn, 5 mg Cu, 5 mg Mn, 150 pg Se, and 75 pg 1.

‘rishcr, Itasca, IL 60143.

46

Table 14: Nutrient composition of the diets on a dry matter basis

 

 

Experimental Diets
Items Casein Protein-free
Composition, calculated
Crude protein, % 1 1.16 0.00
Gross energy, Mcal/kg‘| V 4.67 4.64
Calcium, % 0.66 0.56
Phosphorus, % 0.55 0.46
Composition, analde
Dry matter, % 91.27 91.54
Crude protein, % 12.06 1.32
Gross energy, Mcal/kg‘I 4.38 3.97

Amino acid, %

 

Essential
Arg 0.58 "
His 0.48 "
Ile 0.73 "
Leu 1.14 "
Lys 0.96 "
Met 0.43 '°
Phe 0.67 "
Thr 0.50 "
Val ' 0.85 "

Non-essential
Ala 0.43 "
Asp 0.81 "
Glu 2.67 "
Gly 0.26 "
Pro 1.26 '
Ser 0.73 '
Tyr 0.68 "

EAmino Acids 13.18 ’

Yalcmatod as DE/.90

47

Table 15: Endogenous losses in casein and protein free diets (mg/kg dry matter intake)

 

 

 

Casein'i SEM Caseinb a; SEM Protein-free " :t SEM
Amino Acid
Essential
Arg 706.71 i 39.28 522.96 a 61.99“ 362.45 2t 69.31 “
His 449.82 2t 28.55 538.37 3: 69.19“ 255.10 1 77.35 “
Ile 1051.37 : 65.92 887.99 a: 79.08“ 288.45 i 86.43“
Leu 1273.05 a 124.45 1090.69 1: 147.10“ 473.09 a 163.89 “
Lys 783.54 i 42.59 914.68 a 143.04“ 373.82 a 159.92 "
Met 370.38 :1: 23.93 369.51 i 41.31 “ 173.82 1: 46.16“
Phe 600.47 :t 44.58 645.54 i 101.07“ 311.21 a 112.99d
Thr 928.59 a 90.55 907.15 :1: 80.42 “ 407.87 :t 89.92 “
Val 1265.41 :1: 102.18 1 194.32 2t 143.06“ 447.20 :1: 158.52 “
Non-essential
Ala 1075.80 : 101.14 1109.51 :t 128.85 “ 465.55 a 144.05 “
Asp 465.72 s. 44.88 627.42 3: 133.08 “ 386.54 1 148.79“
Glu 2057.01 i 395.04 2107.95 :1: 224.52 “ 717.17 :1: 251.02 “
Gly 1070.70 : 103.13 1295.63 i 190.36“ 647.71 i 212.83 “
Pro 3052.46 : 545.95 2419.47 :1: 580.81 “ 2047.65 i 606.96“
Ser 1467.06 a 183.96 1302.57 i 116.76 “ 487.71 i 129.89“
Tyr 633.18 a 24.81 605.28 i 85.81“ 307.23 1 95.94 "

 

-'_T‘he casein amino acid endogenous losses obtained from experiment 1 are shown here again for
comparison to the casein endogenous losses in this experiment. Data were not used for statistical
3 comparison.
b The casein and protein free diets were used in a switch back design.
°‘d Means within the same row with different superscripts are significantly different at P s .10
°" Means within the same row with different superscripts are significantly different at P < .05

48

using protein free diet for endogenous losses

Table 16: True amino acid digestibilities ( % ) of the corn varieties

 

 

HO IHO WX IWX HL STD 1 Pooled STD 2
SEM :t SEM

Amino Acid

Essential
Arg 91.66 90.83 91.81 90.16 92.62 94.39 2.29 91.75 i 2.45
His 93.23 95.79 97.14 92.77 90.16 95.20 1.65 93.60 i 2.25
Ile 96.49 96.84 98.87 96.54 87.35 95.41 2.43 93.60 :t 2.23
Leu 92.17 94.61 96.14 91.70 85.90 93.09 1.90 92.99 :1: 1.75
Lys 103.35 101.98 100.93 103.82 89.93 103.11 4.89 101.55 :1: 3.48
Met 96.06 95.70 96.37 93.47 90.07 96.04 1.47 95.28 i 1.93
Phe 95.97 98.31 100.06 96.38 91.38 96.83 2.18 98.70 :t 2.09
Thr 89.06 96.10 95.97 93.88 75.24 95.28 4.26 90.64 i 3.56
Val 93.64 96.13 98.42 94.94 86.10 95.46 3.02 95.38 i 2.70

Non-

essential
Ala 88.18 95.66 93.01 94.37 79.09 91.58 2.19 90.45 21: 1.42
Asp 91.24 91.68 96.99 90.29 85.50 97.70 5.34 102.49 i 4.56
Glu 88.60 92.79 93.14 89.84 86.20 95.12 2.66 97.35 i 2.49
Gly 93.89 83.68 89.75 97.81 77.57 92.01 6.29 85.10 i 7.25
Pro 118.62 105.30 92.96 109.65 114.35 101.22 13.70 93.11 1 22.08
Ser 100.64 100.62 101.14 100.57 97.33 101.70 3.07 104.68 :1; 1.91
Tyr 87.37 94.00 93.15 90.12 85.03 91.95 2.59 91.88 i 2.85

Mean AA 95.63 95.01 95.39 95.99 88.37 96.01 1.34 95.13 i 1.26

Digestibility

 

49

Table 17: True amino acid digestibilities ( % ) of the corn varieties

using caseinb diet for endogenous losses

 

 

HO IHO WX IWX HL STD 1 Pooled STD 2 i SEM
SEM

Amino Acid

Essential
Arg 89.47 89.16 90.39 88.79 89.78 92.92 2.68 88.63 3: 3.06
His 100.31 101.42 103.64 103.69 98.42 101.00 5.31 100.76 i 4.35
Ile 118.51 115.92 119.82 126.36 120.21 113.55 8.23 124.66 i 3.69
Leu 97.58 99.07 101.50 100.35 95.60 97.11 3.81 99.08 i 3.00
Lys 129.22 122.43 121.18 139.85 110.25 125.06 15.24 122.42 i 6.99
Met 103.48 101.73 102.82 103.76 99.00 102.08 4.27 103.54 i 3.39
Phe 101.08 102.47 105.02 105.37 98.10 100.77 5.24 103.27 i 3.53
Thr 101.10 106.38 105.76 109.09 86.70 104.89 6.08 102.97 i 4.54
Val 113.50 111.87 115.72 121.97 108.67 111.12 8.81 116411451

Non-essential
Ala 97.37 102.93 101.36 108.03 93.30 98.54 5.03 100.33 i 3.00
Asp 90.18 91.13 96.65 91.49 83.19 97.18 3.49 99.76 i 4.54
Glu 98.67 101.49 102.66 103.80 100.51 102.88 2.90 109.36 :1: 2.77
Gly 109.38 93.70 99.25 118.33 93.85 102.96 18.06 95.71 i 11.52
Pro 104.12 89.69 81.55 94.33 108.04 90.74 14.73 72.73 :t 17.68
Ser 122.43 119.02 120.01 130.06 125.22 118.76 8.86 129.05 1 3.59
Tyr 93.27 98.82 98.52 100.78 90.71 96.85 6.29 96.45 i 4.69

Mean AA 102.92 104.35 109.13 104.12 100.10 103.52 2.55 104.07 :1: 3.53

Digestibility

 

b Endogenous values from this experiment

50

CHAPTER 3: EFFECTS OF CORN HYBRIDS FED TO GROWING PIGS ON
NITROGEN METABOLISM

Abstract

Eight barrows (19.11 i 0.49 kg, Yorkshire) were arranged in two different 4 x 4
Latin squares to investigate the effects of feeding different corn hybrids on nitrogen
metabolism. The corn hybrids were: high oil (HO), isogenic high oil (IHO), waxy (WX),
isogenic waxy (IWX), high lysine (HL), standard yellow dent one (STD 1) and standard
yellow dent two (STD 2). Standard two corn was used in both Latin squares to serve as
the reference corn so that cross square comparisons could be preformed. Pigs within
each square were littermates. Pigs were fed com-based diets consisting of 96.87 % test
corn. Vitamins, minerals, dicalcium phosphate, limestone and salt were included at
levels to meet or exceed NRC requirements (, 1988 #231). Pigs were allowed an diet
adjustment period (5 days) followed by five days of total urine and fecal collection.
Feces and urine were pooled across collections and analyzed for nitrogen content using a
Hach-kjeldahl procedure. Nitrogen retained was not different between HO vs IHO, WX
vs IWX and HL vs STD 1 (P > .1). Nitrogen retention as a percent of N intake and N
absorbed was similar between HO vs STD 2 and WX vs STD 2 (P > .1), but was different
when HL was compared to STD 2 (P S .1). Nitrogen digestibility was highest with the
HO, STD land HL corns at 83.31, 83.30 and 81.06 % respectively. Overall, pigs fed the
STD 1 HL and H0 diet retained numerically more nitrogen consumed and absorbed than

all other corns.

51

Introduction

In the previous chapters the amino acid digestibility of the corn hybrids (high oil
(HO), isogenic high oil (IHO), waxy (WX), isogenic waxy (IWX), high lysine (HL),
standard one (STD 1) and standard two (STD 2) were investigated, but to fully
investigate the protein quality of these coms it is crucial to measure the nitrogen retention
and utilization. The objective of this experiment was to determine the nitrogen
digestibility, absorption and utilization in the growing pig fed different corn varieties.
Currently, there is not a plethora of data regarding the nitrogen retention of pigs fed these
corn hybrids. Therefore, it is important that nitrogen balance experiments be performed
on these hybrids to determine differences in utilization before they can be advocated for

use in swine diets.

Materials and Methods

Animals, diets and experimental design were approved by Michigan State
University All University Committee for Animal Use and Care. Eight barrows
(Yorkshire) with an initial average body weight of 19.1 :t 0.49 kg were used to
investigate nitrogen utilization of seven corn hybrids: high oil (HO), isogenic high oil
(IHO), waxy (WX), isogenic waxy (IWX), high lysine (HL), standard one (STD 1) and
standard two (STD 2). Pigs were randomly assigned to diets containing 96.87 % of the
respective corn hybrid and arranged in two 4 x 4 Latin squares. The diet assignments
within squares were the same as described in chapter one. Standard corn two was present
in both squares, as the reference corn and the pig within each square were littermates.
The test corns provided the only source of protein. Vitamins, minerals, dicalcium

phosphate, limestone and salt were included at levels to meet or exceed NRC

52

requirements (1988). Environmental temperature ranged from 16 - 27°C with a mean
temperature of 21°C. The metabolism room was mechanically ventilated to allow
adequate air exchange. Pigs were individually housed in stainless steel, metabolism
cages (1.2 m x 0.75 m) containing low-pressure nipple waterers that provided free access
to water. The metabolism cages allowed for separate collection of urine and feces.

Feed intake was adjusted to 90 % of ad libitum intake and maintained at that level
during the trial. Pigs were fed equal meals four times daily during the entire experiment.
Pigs were allowed five days to adjust to the diets followed by a five-day separate urinary
and fecal collection. Five grams of Ferric Oxide was mixed with 100 g of diet to be used
as an indigestible marker to mark the beginning and end of the fecal collection. Feces
and urine were collected once daily, with volumes and weights recorded. Urine was
preserved by the addition of 100 ml of 20 % sulfuric acid to each daily collection. Daily

fecal samples were pooled and frozen at -20°C, and 20 % of the daily total urinary

volume were pooled and frozen at -20°C until analyses were performed.

Chemical analysis

Fecal samples were thawed and homogenized in a Hobart mixer for 10 minutes
and sub-sampled. The sub-samples were freeze dried and ground through a 1 mm screen
i using a cyclone mill (Cyclotec Sample Mill 1093, Sweden). A 2 g sample of fecal
material was dried further in a vacuum oven for 12 hours at 60°C for determination of
total dry matter. Corn, diets, freeze dried feces and liquid urine were analyzed for

nitrogen using a Hach—kjeldahl procedure (Hach et al., 1987).

53

Statistical analysis

Data was analyzed using MIXED procedures of SAS (1992) in a Latin square
design. Data from the two squares were pooled and STD 2 corn was used as the reference
corn. The linear model included main fixed classification effects of square, collection
nested within square and diets; pig nested within square was included as a random effect.
Least square means with pdiff option were used to determine difference between the
following preplanned comparisons: HO vs IHO, WX vs IWX, HL vs STD 1, HO vs STD

2,WXvsSTD2andHLvsSTD2.

Results

During this experiment the pigs remained healthy with average daily feed intake
of 1.5 kg/d and average daily gain of 229 g/d. Diet compositions are reported in table 18;
the main difference between these diets and chapter one's diets is the exclusion of
chromic oxide, which accounts for the 0.25 % increase in test corn. Nutrient composition
of the diets is the same as those reported in chapter one (Table 20). Nitrogen utilization
and dry matter digestibility of the seven corn hybrids are reported in table 21. Initial and
final weights of the barrows were similar across the corn diets. Nitrogen intake did not
differ between HO vs IHO, WX vs IWX, and HL vs STD 1 (P > .10). However, nitrogen
intakes for the hybrids were higher when comparing WX to STD 2 (P S .10), HO to STD
2 (P < .05) and HL to STD 2 (P < .05). Fecal nitrogen was greater in WX compared to
IWX (P S .10). Urine nitrogen was similar for all contrasts investigated (P > .10). All
hybrids (HO, WX, and HL) had higher nitrogen absorbed when compared to the standard

yellow dent corn (P .<_ .1). Nitrogen absorbed was greater for the hybrids HO vs IHO (P S

.10) and lower for HL vs STD 1 (P S .10). Nitrogen retained was greater in H0 and HL

54

compared to STD 2 (P < .05). Digestibility of nitrogen was greater for H0 and HL vs
STD 2 (P < .05). Consequently, IWX had higher nitrogen digestiblity than WX (P S .1).
Nitrogen retention as a percent of nitrogen intake and as a percentage of nitrogen
absorbed was lower between of HL and STD 2 (P < .05). Significantly higher differences
in dry matter (DM) intake were found comparing HL to STD 1 (P < .05), WX to STD 2
(P .<. .10), HL to STD 2 (P < .05). Dry matter digestibility was significantly higher when
comparing HO to IHO (P < .05). Isogenic waxy and STD 1 had greater dry matter
digestibility than WX and HL, respectively (P < .05). Finally, HO corn was the only
hybrid to have a significantly higher DM digestibility compared to the STD 2 corn (P <

.05)

Discussion

Nitrogen metabolism in pigs fed specialty corns is an important topic to fully
understand the possible applications of these value-added corns. Published information
on this subject is clearly lacking. Carr (1994), using 63 kg pigs, investigated nitrogen
metabolism of HO corn varieties. Carr recorded ranges of nitrogen digestibilities for H0
corn from 61 to 77 %, nitrogen retention as a percent of intake from 59 to 81 % and
nitrogen retentions as a percent of absorbed from 75 to 76 %. Adeola (1997), using 25 kg
pigs, also tested varieties of HO corns and published nitrogen digestibilities of 76 %,
nitrogen retention as a percent of intake from 47 to 55 % and nitrogen retention as a

percent of absorbed from 62 to 72 %. The values obtained from this study, 83.31 i 2.13
% for nitrogen digestibility, 49.74 i 5.35 % retention as a percent of intake and 59.73 i

6.52 % retention as a percent of absorbed, are comparable to those published by Adeola

(1997)

55

Ashce (1986) reported nitrogen utilization of high lysine corn, using 35 kg
growing pigs. Nitrogen digestibilities varied from 79 to 80 % and nitrogen retentions
from 47 to 52 %. Values for nitrogen digestibility and retention in this study were
comparable with 81.06 i 2.13 % and 57.22 i 5 .35 %, respectively. The retention values
for standard yellow dent corn were also similar to other published values (Lin et al.,
1987) Adeola(l997) Asche(l986) (Carr, 1994). Ranges of nitrogen digestibilities for
standard yellow dent corns were 76 to 85 %. Nitrogen retentions as a percent of intake
ranged from 38 to 61 % and as a percent of absorbed were from 44 to 79 %. These
values are similar to data from this study: 74.12..+. 1.74 % for nitrogen digestibility,
38.48: 3.44 % for nitrogen retention as a percent of intake and 52.34 i 4.07 % for
nitrogen retention as a percent of absorbed. No published values for waxy corn were
available to compare to this study.

Nitrogen digestibilities of the corn hybrids were greatest for the high oil, standard
1, and high lysine corn. Interestingly, nitrogen utilization expressed as nitrogen retention
were greater for the standard 1 and high lysine compared to the high oil com. This
implies that the 20 kg pig was able to better utilize the protein from the standard 1 and the
high lysine corns. Nitrogen digestibilities and retentions for the waxy corn were similar
to standard 2 com. However, nitrogen digestibilities and retentions for the high oil and
high lysine corns were superior to those of the standard 2 corn that was the commercially
purchased corn. As a whole, STD 1, HL and H0 corns were superior to the other hybrids
for nitrogen digestibility, nitrogen retention as a percent of intake and nitrogen retention

as a percent of nitrogen absorbed.

56

Implications

This study implies that feeding the specialty corns will have result in similar and
in some cases superior nitrogen utilization by the growing pig compared to feeding
standard yellow dent two. Particularly, the high oil and high lysine hybrids should be

considered as the corn hybrids of choice for feeding swine.

57

Table 18: Experimental diets on as-fed basis (%)

 

 

 

Ingredients Experimental
Com' 96.87
Dicalcium phosphate 1.25
Limestone ' 0.88
Vitamin mix ° 0.50
Trace mineral mix ° 0.25
Salt 0.25

 

T Com varieties used were sin 1, STD 2, HO, IHO, wx, lwx and HL.
l’Provided the following per kilogram of diet: 4,583 IU vitamin A, 458 IU vitamin D3, 55 IU vitamin E, 11 mg vitamin
K, 3.66 mg menadione, 0.0275 mg vitamin Bu. 3.66 mg riboflavin, 14.67 mg d-pantothenic acid, 22 mg niacin, 0.913
mg thiamine, 0.825 mg pyridoxine. '
‘ Provided the following per kilogram of diet: 335 g Ca, 5 g Fe, 5 3 Zn, 5 mg Cu, 5 mg Mn, 150 pg Se, and 75 pg 1.

58

Table 19: Amino acid top dress composition

 

 

 

HO IHO WX IWX HL STD l STD 2
Amino acid, g/kg of diet
Ile 0.53 0.93 1.23 0.92 0.77 1.23 1.27
Lys 3.96 4.07 4.50 4.24 4.35 3.38 4.97
Met 0.60 1.22 0.98 0.65 0.69 0.74 1.02
Thr 1.79 2.15 2.29 2.12 2.16 2.21 2.40
Trp 0.15 0.15 0.15 0.15 0.15 0.15 0.15

 

Table 20: Nutrient composition of the diets on a dry matter basis

 

 

 

Items HO IHO WX IWX HL STD] STD 2
Composition, calculated
Crude protein, % 10.09 8.56 8.59 8.58 7.96 10.40 7.77
Gross energy, Mcal/kg 4.49 4.35 4.36 4.25 4.30 4.40 4.43
Calcium, % 0.70 0.69 0.70 0.70 0.69 0.69 0.70
Phosphorus, % 0.57 0.57 0.57 0.57 0.57 0.57 0.57
Composition, analyzed
Dry matter, % 87.61 87.95 87.22 87.63 88.09 88.15 87.18
Crude protein, % 9.64 9.51 8.43 8.55 8.65 10.93 8.27
Gross energy, Meal/kg 4.51 4.36 4.39 4.36 4.33 4.38 4.30
Amino acid, %
Essential
Arg 0.47 0.42 0.42 0.39 0.64 0.50 0.40
His 0.36 0.31 0.30 0.29 0.38 0.38 0.27
Ile 0.38 0.32 0.29 0.31 0.28 0.39 0.26
Leu 1.09 0.98 0.86 0.87 0.62 1.30 0.74
Lys 0.25 0.22 0.25 0.23 0.34 0.26 0.23
Met 0.23 0.21 0.20 0.21 0.21 0.25 0.16
Phe 0.46 0.42 0.38 0.38 0.34 0.54 0.34
Thr 0.32 0.29 0.30 0.30 0.32 0.35 0.26
Val 0.47 0.43 0.40 0.40 0.45 0.51 0.36
Non-essential
Ala 0.70 0.63 0.58 0.57 0.51 0.80 0.51
Asp 0.62 0.56 0.58 0.58 0.80 0.69 0.49
Glu 1.69 1.46 1.35 1.44 1.26 1.89 1.16
Gly 0.34 0.31 0.32 0.31 0.39 0.38 0.30
Pro 0.80 0.76 0.73 0.72 0.68 0.95 0.60
Ser 0.48 0.42 0.42 0.40 0.41 0.53 0.37
Tyr 0.33 0.30 0.29 0.27 0.31 0.36 0.26
ZAmino Acids 8.99 8.04 7.67 7.67 7.94 10.08 6.71

 

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61

SUMMARY AND GENERAL CONCLUSION

The goal of this thesis was to evaluate the protein quality of high oil, isogenic
high oil, waxy, isogenic waxy, high lysine and two yellow dent corns in growing pigs.

Apparent and true amino acid digestibilities were determined for each of the corn
hybrids. It was found that the high oil and the waxy corns had digestibilities superior to
the commercial yellow dent corn. In addition, high lysine corn had digestibilities similar
to commercial yellow dent corn two. When true ileal digestibilities were calculated, the
values were greater than 100 % and it was concluded that the casein diet overestimated
the endogenous losses. Therefore, we designed a second experiment to compare the
casein diet to a second method for determining endogenous secretions.

In the second experiment, a protein free diet was compared to a casein diet in an
attempt to better estimate endogenous losses and obtain accurate true amino acid
digestibilities. The results showed that the endogenous secretions from the casein diet
were two times greater than endogenous losses from the protein free diet. The study
proved that accurate true ileal digestibilities could not be obtained. Therefore, it would
be recommended that a protein free diet should be fed within the Latin square design
during the first experiment which may have given acceptable true ileal digestibility
Values.

Nitrogen utilization of the corn hybrids were determined in the third experiment.

The results showed that the nitrogen utilization of the high lysine com was definitely

62

superior to the commercial yellow dent corn and the other com hybrids. Waxy and high
oil corn were found to have nitrogen utilization similar to the commercial yellow dent.

In conclusion, this work suggests that the specialty corns, particularly high oil and
high lysine, are superior to the yellow dent hybrids. In addition to their superior nutrient
density and (or) profile, these specialty corns have higher protein and (or) nitrogen

digestibility and nitrogen utilization.

63

VITA

Janet L. Snow is originally from Columbia, Missouri where she was raised on a
commercial cattle farm. She was interested in animals since she was a child and was
involved in the husbandry of cattle, swine, sheep and poultry. She was an eleven year
member of 4-H and was involved in FFA in high school. She was active in showing
livestock and she participated in county fairs until her Sophomore year in college. In
1995, she married her high school sweetheart, Mr. Scott S. Snow. She received her
Bachelors degree in Animal Science from the University of Missouri-Columbia in May
of 1996 and then moved to Michigan in June to pursue her Masters degree in swine

nutrition at Michigan State University under the supervision of Dr. Nathalie L. Trottier.

64

APPENDICES

 

. ‘nlrl...
i.

Appendix A

Calculations for digestibilig:
Adapted from Stein, 1998

Apparent ileal digestibility (AID):
AID = (100 -[(AAd/AAf) x (Crf/Crd)]) x 100%

Where:

AAd = amino acid concentration in the digesta
AAf = amino acid concentration in the feed
Crf = Chromium in the feed

Crd = Chromium in the digesta

Endogenous amino acid loss (EAL):
EAL = (AAd x (Crf/Crd))

Where:

EAL = Endogenous flow of each amino acid, mg lost/kg DMI
AAd = Amino acid concentration in the digesta

Crf = Chromium in the feed

Crd = Chromium in the digesta

True ileal digestibility ( T ID):

TID = [AID + (EAL/AAD] x 100 %
Where:

AID = Apparent ileal digestibility

EAL = Endogenous flow of each amino acid, mg lost/kg DMI
AAf = amino acid concentration in the feed

66

Appendix B

Apparent ileal digestibility obtained from the chromium results
fi'om samples analyzed at University of Illinois
a

 

HO IHO WX IWX HL STD 1 STD 2
Essential
Arg 70.06 70.67 72.24 68.28 72.66 86.64 71.40
His 71.65 74.99 76.078 70.76 66.00 87.22 71.53
Ile 72.50 73.50 73.94 70.72 47.07 85.75 68.55
Leu 79.15 82.43 82.61 _ 78.59 57.07 90.64 - 78.19
Lys 56.68 61.77 64.67 61.35 48.96 79.70 59.46
Met 73.26 75.27 75.78 72.46 58.86 87.24 69.55
Phe 75.45 80.12 80.66 75.57 56.10 89.54 75.60
Thr 50.22 61.33 62.81 57.46 27.94 79.62 53.11
Val 63.86 70.28 71.35 65.67 47.53 84.07 64.79
Non-essential
Ala 67.77 76.57 73.20 73.70 46.15 86.31 68.51
Asp 73.56 75.27 81.67 74.99 67.23 90.16 81.43
Glu 75.58 80.03 79.62 78.56 63.45 91.23 81.80
Gly 28.73 31.98 48.88 42.91 16.97 69.49 34.37
Pro 43.99 41.45 29.38 40.21 19.38 71.20 14.05
Ser 69.58 72.36 72.94 67.94 53.38 87.01 70.76
Tyr 59.52 69.48 68.08 62.55 47.37 82.73 64.30
Total Protein 64.47 68.59 69.66 66.36 49.76 84.28 64.21

 

67

Appendix C

 

High Oil
Cargi115990 TC

 

Isogenic High Oil
Cargill 5990

68

 

High Lysine
Crows

 

Crows Standard
Yellow Dent 1

69

 

Waxy
Pioneer 3528 E

 

Isogenic Waxy
Pioneer 3527

70

 

Digesta collected from a cannulated pig

7]

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