lllll Hlll lllllllllllllllll lll ‘c 1293 01007 9956 - 1 L: '“fg ,4: “”52! ;"..‘_ -._-'_:I-'_-""y-4‘ i .......-_.._- v.3 “34.1.5." «I 1 -2---,.-_1 J-‘_-u..'ia,ka -1} This is to certify that the thesis entitled . (-\1 3- , l \. ' l .‘ 7. A ~' U .I 1 _ ‘ ‘ I. ‘ . "u . ‘ ' ' " ' ‘ ‘-" ‘\ A. _, r . I_ W "n . v f - :‘t’ ‘t‘. ‘ “ .v ‘ ‘1—' k' (L ’. ‘\"‘ \‘ ‘k, '-~-'"._V .J 'IXV'r-J‘! . " " h, ‘ 'k K‘ ' ‘ l \ ‘\ '\\ _ ‘. p - g| . A' - ‘ , I a c . - .. , - . 1‘ .;I ’ .‘ r ‘ w 4 ’ - . . r '5 -« s |n " . - 7 ‘ u , l r “‘ ,4 W \ \ . V‘ I .IC'JI . J_ .‘K‘ “,’ 'i'_’ J+ ' JJ‘.tx}w ' ‘ ‘ ‘n ‘. v . “-I v " ~\; 1- presented by has been accepted towards fulfillment of the requirements for 1/. . ’ . {‘3‘ ., I} ’ , ) g: ,\ \ r" :2 degree In I" f: / ,',.'-~.il(“trtr’tf‘w air/WWW» Major professor Date/”5’87 04639 MS U is an Affirmative Action/Equal Opportunity Institution rVIESI_J RETURNING MATERIALS: Place in book drop to LJBRARJES remove this checkout from .‘gszzggE-L. your record. FINES will be charged if book is returned after the date stamped below. asrlzl6199a NOV 21,71 2000 112 IDENTIFYING WC AND MANAGEMENT PARAMEI'EFB Fm THE USE OF SEPARATED DAIRY MANURE mLIIB AS FREE STALL BEDDING Fm DAIRY CATTLE Robert W . Gardner A THESIS Suhnitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Animal Science 1986 ABSTRACT IDENTIFYING ECONOMIC AND MANAGEMENT PARAMETERS FOR THE USE OF SEPARATED DAIRY MANURE SOLIDS As FREE STALL BEDDING FOR DAIRY CATTLE By Robert W. Gardner Economic justification of manure separation facilities occurs more readily on larger farms where increased bedding usage increases savings realized by replacing conventional bedding with dairy manure solids. Since a lower percentage of bedding savings of larger farms would go towards servicing the fixed costs of separation, variations in economic feasibility parameters (herd size-bedding price combinations) due to fluctuations in tax rate, rate of return and loan interest rate and repayment period are less pronounced than on smaller farms. Savings of $17.48 realized from a ton of bedding services variable costs and can be imputed to be the variable cost of a ton of dairy manure solids. Overall, passive composting dairy manure solids was inadequate in preventing rapid regrowth of coliforn bacteria once solids were placed in free stalls. Moisture seemed to be the determining factor as dairy manure solids with approximately 20% dry matter containing low levels of coliforn bacteria (103 per gram bedding wet weight) contained over 10‘ coliforms per gran bedding wet weight within four days after application to free stalls. Duration of exposure of teats to bedding containing high numbers of coliform bacteria may be a factor contributing to coliform mastitis. Sweeping dairy manure solids from the rear two feet of free stalls daily was apparently ineffective in preventing mastitis or maintaining low coliform numbers in our research. TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . iii LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . iv INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 REVIEW OF LITERATURE 0 O O O O O O O O O O O O O 0 O O O 0 O O 0 O 3 A. Economic Comparison of Bedding Materials . . . . . . . . 5 B. Relationship Between Bedding and Coliform Mastitis . . . 6 0. Free Stall Management . . . . . . . . . . . . . . . . . . 12 MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . . . . . 15 A. Objective 1 . . . . . . . . . . . . . . . . . . . . . . . 16 BO Objective 2 O O O O O O 0 0 O 0 0 O O O I O O O O O O O O 22 1 e Experimnt 1 e e e e e o o e e e e e o o e o e 22 2. Experiment 2 . . . . . . . . . . . . . . . . . 25 3 O Experimnt 3 O O 0 O I O O O O O 0 O O O O O O 25 RESULTS 0 O I I O O O O O O O O O O O O O O O O O O ..... O O O 28 A. Phase 1 . . . . . . . . . . . . . . . . . . . . . . . . . 28 B. Phase 2 . . . . . . . . . . . . . . . . . . . . . . . . . 30 1. Experiment 1 . . . . . . . . . . . . . . . . . 40 2. Experiment 2 . . . . . . . . . . . . . . . . . 41 3 Experimnt 3 O O O O O O O O O O O O O O O O O ‘7 DISCUSSION 0 O 0 O O O O O O O 0 O O O 0 O O O O O O O O O O 0 O O 55 SWY O O O O O O I O O O O O O O O O O O O O O O O O O O O O O O 62 C O O O O O O O O O O O O O O O 0 O O O O O O O O O O O O I 0 O O O O O BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 ii Table 10 11 LIST OF TABLES Comparison of Composted Versus Fresh Manure Solids . Comparison of Coliform Concentration and Moisture Percent in Experiment 1 . . . . . . . . . . . . Coliform Concentrations at Different Depths in Composting Piles . . . . . . . . . . . . . . . . . . . Ambient Temperature Versus Coliform Concentration and Moisture Percentage . . . . . . . . . . . . . . . Comparison of Coliform Concentration and Moisture Percent in Experiment 4 . . . . . . . . . . . . . . . Comparison of Manure Solid Samples Taken From Free Stalls After The Mastitis Outbreak With Previous Observations . . . . . . . . . . . . . . . . . . . . . Records of Cows Contracting Acute Mastitis . . . . . . Results When Dairy Manure Solids Used Continuously to Bed Low Milk Producing Cows . . . . . . . . . . . . . Effect of Sweeping Solids From Backs of Free Stalls of Lactating Cows Over Time . . . . . . . . . . . . . . . Comparisons of Dairy Manure Solids Used for Bedding Heifers on Swept and Unswept Free Stalls Over Time . Statistical Correlations of Studied Parameters Using All Data 0 O O O I O O 0 O O O O O O O O O O O O 0 iii 39 40 44 47 A8 49 50 51 52 53 54 Figure 1 2 10 LIST OF FIGURES DMS Analysis - Maximum Recommended Investment . DMS Analysis - Maximum Recommended Investment . Bedding Price - Herd Size Combinations Justifying Separation Systems . . . . . . . . . . . . . . . Varying Tax Rates on Acquisition of $30,000 Separation Facilities . . . . . . . . . . . . . Varying Rates of Return on Acquisition of $30,000 Separation Facilities . . . . . . . . . . . . . . Varying Loan Rates on Acquisition of $30,000 Separation Facilities . . . . . . . . . . . . . Varying Loan Length on Acquisition of $30,000 Separation Facilities . . . . . . . . . . . . Compost Pile Daily Temperatures . . . . . . . . . Compost Pile Coliform Numbers Versus Ambient Temperatures . . . . . . . . . . . . . . . . . . Compost Pile Moisture Percentages . . . . . . . iv 29 31 33 35 36 37 38 43 45 46 1mm The tram! of Midwest dairy fan-s is an increased herd size, with cold free stall bums being the predominant housing facility. Confinement housing for dairy cows requires roughly three pounds of bedding per cow per day (Dairy Chore Reduction, 1978). This, cost and availability of adequate bedding as well as its mtibility with mnure handling systems has become an increasingly important concern for dairy managers. Bedding should be easy to handle, Iaintain cow cc-fort and cleanliness and be constantly available at a low cost. Fm'thei‘ore, it should be compatible with mnure syste-s. Separatim solids frc- liquid mnure can be an ecmmical alternative of prodncim a constant, local supplyofbeddingthat iseasytohandlearmimrkswell indairy operatiais having liquid mnure system. Economic evaluation of mire separation system is difficult due to any varying costs an! returns associated with different farm. Size differences amg farm and differing prices paid for other types of bedding all affect the economic feasibility of separaticmi. Reports by Keys et a1. (1976) and Allen et a1. (1977) conflict on cost effectiveness of separating solids fr:- nnure for beddim. Keys et al. (1976) reported dewatered mnure solids cost over twice as Inh as sawdust to fill a free stall. Allen et a1. (1977) fund they could separate solids for battling for less than half the cost of Mira OJ .0 2 sawdust. Thus, any economic justification of a separation system must look at all costs associated with production of manure solids. Use of dairy manure solids in free stalls requires special wage-ant for proper results. The finely chopped organic nature of dairy mnure solids supports coliform bacterial growth. (Smith et a1. 1985) Courts of 10' coliforms per gram bedding (wet weight) have been shown by Bramley and Neave (1975) to be associated with an increased rate of new coliform infections. Carroll and Jasper (1978) and Bishop et a1. (1980) showed that composting dairy mnure solids effectively reduced coliform concentrations; however, coliforu concentrations of composted solids increased to infectionn levels shortly after the solids were placed in free stalls. Thus, proper augment is important in reducing coliform ustitis and consequently realizing the benefits of separating solids frcn mnure for use as free stall bedding. The objectives of this research are, firstly, to deter-ins pal-meters necessary to Justify investnent in facilities allowm separation of solids frc- liquid mm for use as bediing for dairy cattle am, secondly, to identify mt techniques which audience me of separated mire solids as dairy free stall bediim. MOP LITERA'HRE Free stall housing for dairy cattle requires bedding to enraourage free stall use and nintain cow cleanliness (Larsen et al. 1976). larsen et a1. (1976) fund that cows preferred deep bedded free stalls over concrete free stalls or concrete free stalls with rubber flats or indoor/outdoor carpet set an top. The authors also reported installation of bedding retainers with free stalls increased free stall use. Yangle et a1. (1974) reported cows peferred mt filled free stalls and were cleaner than cows using free stalls with indoor/(Indoor carpetim, plastic mats or heated concrete. thny bedding alternatives exist. Straw is sore absorbent than lost bedding on a dry weight basis (Battaglia and Phyrose, 1978) and is easily obtained. Long ste-ed straw is difficult to handle in large quantities, is (prickly dislodged frm free stalls, and cm plm nnure page (more Reduction, 1979). Allen et al. (1977) reported that chopping straw decwed its raoval fun free stalls; however, use of chopped straw proved not to be cost effective. Flu-time, Larsen et al. (1976) reported chopped straw pltuged slotted floors preventir' mmnepassegeaniencom‘agedcowstolieontheresultmt-manepack for‘ed inalleys. Theseresearchers also found 30%mtrechqmedstraw wasneededthansawthnttokeepfreestallsbedded. 4 Larsen et a1. (1974) reported sawdust and wood chips caused no problems with plugged slats or manure handling quiirmrent. Sawdust works well on hard surfaced free stalls; however, difficulties with coliform mastitis have been experienced when used as a deep bedding (Chore Reduc- tion, 1978). Allen et al. (1977) reported sawdust was an excellent bediing but cost and unavailability forced them to explore other alternatives. Janzen et a1. (1982) smested crushed limestone as an econmical bedding alternative. The high pH of crashed limstone inhibited bacterial growth thus reducing risk of mstitis. Crushed linestaie was more expensive per unit of volume than either sauhst or wood shavings; however, substantially less crushed limestone was needed to keep free stalls bedded. The authors reported an overall savims in bedding costs of 30% by replacing sawdust or wood chips with crushed limstone. Primaryconcemswhenusingcnishedlimestcneormarxiasbeddingare the abrasiveness to manure handling equllnent and the tendency to settle out in manure pits and plug pipes (Chore Reduction, 1977). Separating dairy manure solids fro. liquid name, if the solids are properly composted and dried, provides an alternative bedding source (Carroll and Jasper, 1978). are drawback is the incompatibility of separation system with dairy operations not having liquid nnure systans. Separation systems require large investmrts and try not always be economical. 5 Ecamic Mison of W Average total costs of a new investment (acquisition costs and con- tinuing costs) .181: be less than current costs of the existing system to econrnically justify any investment. Economic justification of separation facilities occurs when average total costs of separation facilities are less than average total costs of acquiring carventiaral beckiing. Investment analysis using average annufl costs does not adequately handle monetary flows over time. Ihrsh et. a1. (1981) report errors can be substantial if the period of analysis of an investnrt is ten or lore years and interest or discount rate is relatively high. Order these circumstances, capital buigeting, which accounts for varying cash flows over tine, is Inch sore accurate. Keys et al. (1975) cormhrcted a buiget analysis of three types of bailing; dewatered mnure solids (29% dry utter). mud lemme solids (90% dry matter), and sawmnt. Total energy, labor, and depre- ciation costs necessary to produce a ntric ton of dehydrated ans! de- watered mnure solids were calculated and med with the cost of having a aetric ton of Mt delivered to their facility. Using this information, the authors then calculated it cost. 92.63, 811.46 and 91.27 to fill a 122x 213 cafree stall toadepthof lOmwith dswatered mire solids, chhydrated manure solids, an! sathat, respectively. Moore et a1. (1977) evaluated ”capital recmrery costs," repair ocean-taxes, insurance costs, savings fra bediing Willi, energy costs, laborcosts, anddrangeinvalueofmneinanecormicsimla- tionstudyofmnesystems. Capital recoverycostsweredefinedas expenses of mail ownership of a piece of a piece of equirnsnt or a 6 structure. Included were value of the item when purchased, value when salvaged, expected life and current interest rate or cost of noney. All theabovecostswereusedtodetemineaverageannualcostsof separation. The authors conclu‘led that uder Oregon conditions an extra enamel cost of $7389, $7132, ard $6875 would be incurred by installing a separation systa into a lagoon-flush systm on 100, 200 and 300 dairy cow facilities, respectively. Thus, manure separatiar systm proved ureconomical urder all circumstances. White et al. (1978) evalmted herd sizes of 200 ard 500 dairy cows in an economic simlation study of dairy waste systems in wars, huid; hot, hmid; and warm, arid regions. The researchers analyzed all costs ardretrmrsonanarmmlpercowbasis, ardcalculatedarmmnlreturnson a per cow basis. Savings free use of separated manure solids as bedding were not considered. Annual costs of separation syste- were $15.52 per cowinaZOOcowherdandSILOZpercowinthe500cowherd. Ting Relationship Between Bedding ard Coliform Mastitis The association of finely chopped, organic bediing with acute astitis caused by coliform ard streptococcal bacteria has presented another drawbsdr with the use of dairy nnure solih for bending (Mth et a1. 1985). hith et al. (1985) report coliform mtitis is capable of seriom ard explosive mnifestations; especially in minfected, high producing, mture cows in the first 90 days of lactation. Cows healthy at calving, with bacteria free quarters, have been known to develop peracute colifon mstitis ard die within ten hours (Jasper et al., 1975). 7 Coliform bacteria are Gran-negative, lactose fermenting bacteria. Escherichia coli is the predominant species of coliform bacteria causing mastitis in dairy cows followed by Klebsiella mengonia and Erierobpficter semenes (Jasper et al., 1975). There are many different strains of coliform bacteria which vary widely in pathogenicity ad infectiousness to the ndder (Eberhart et al., 1977). Coliforn bacteria, upon introduction to a susceptible udder, proli- ferate quickly (from as few as 50 teeteria to 26 million per .1 in 10 to 15 hours (Colifornm Research Cmittee, 1975) until my defense factors can accumilate to pinagotize the coliforl bacteria. Phagotized coliform bacteria release an endotoxin which produces an inflantory response in the udder. This erdotoocin can, in more serious cases, enter the blood strea- causing the toxelmic signs of acute coliforl mstitis (Schaln et al., 1971). Coliforl infectians are not highly contagionn; that is, transmission fro. one quarter or cow to another quarter or cow is musnnl (Eberhart et. al., 1977). ColiforI bacteria are poorly arbpted to survival on norml teat skin ard, thus, colonization on teat drin or test canal by this bacteria is uncom-Jn (Bishop et. al., 1981). Since there is little evidence that colonization occurs before infectian, transient test and contamination rather than oolanization predicates coliform mstitis (Brnley et.al. , 1975) . Thirty three percent of cows with teats dipped inediately before milking or indiately after lilkim with a broth containing 10' colony forming units of Escherichia coli per ml becme infected with g; 911; (Deflart et al., 1975). Cows not dipped with the Wichia coli broth 'a 8 at milking had no coliform infections. DeHart et a1. (1975) concluded that teat exposure to coliform bacteria between milkings can predicate coliform infections though time of exposure of the udder to the organisms was unimportant. Rendos et a1. (1975) monitored bacterial populations in sawdust, wood shavings, and wheat straw and on teat ends of cows placed on these bedding. Cows on sawdust bedding had greater teat end populations of coliform bacteria, while cows on straw bedding had greater populations of streptococcal bacteria. Teat end populations of various organisms appeared to be related to bacterial populations in bedding. From their data, Rendos et al. (1975) suggested a possible relationship between mnbers of organisms reaching the teat end and incidence of new intra- manlnry infections. Bramley and Neave (1975) studied the effects of coliform concen- tration of bedding in five different yards on the rate of new coliform infections. Four situations where coliform numbers were between 10‘ and 105 coliform per gram bedding wet weight resulted in no new coliform infections of cows kept in these yards. Coliform mstitis did occur in cows kept in a yard where coliform counts in bedding approached 10" coliforms per gram bedding wet weight. The authors concluded that a relationship exists between coliform levels in bedding mterials and the rate of new coliform infections. In contrast, Natzke and leClair (1975) compared cows on sawdust where Escherichia coli cancentrations were nintained at 10' coliforms per gram bedding wet weight with cantrol cows bedded on dry shavings. Cows were in early lactation ranging in production from 31 to 40 kg per 9 day. Cows on contaminated bedding experienced no new coliform infections despite increased contamination of teat ends and low average cow somatic cell concentrations ranging frm 233,000 to 428,000/ml. Thoma et al. (1983) found coliform bacteria concentrations were independent of coliform mastitis at his facility. The authors noted.a relation between stage of lactation and incidence of coliform mastitis as heifers had.lowest levels of coliform mastitis and cows in early to mid-lactation had the highest colifor- mastitis incidence. These reports suggest coliform.mastitis might have multiple causes besides exposure of udders to high coliform bacteria.numbers in bedding. Schalm (1975) claim milk of uninfected cows has a natural reduction of mammary defense factors, such as leukocytes and polymorplmnucleocytes (W’s). In fact, the Colifom Research Ccnnittee (1975) reports it\is impossible to superimpose a coliform infection on another infection due to presence of these defense factors. Carroll (1977) cites 500,000 leukocytes per ml is necessary in foremilk to adequately protect udders from invasion by coliform bacteria. Leukocyte reduction can result fromnmany factors. Carroll (1977) showed stress causes an increase incorticoid.levels and.a corresponding reduction of leukocytes predicating coliform lastitis. Stress from calving, heavy feeding, and high milk production are reasons early lactation cows are prone to coliform nstitis (Carroll, 1977). Smith et al. (1985) reports stress from hot, hunid anio summers my have caused the increase in cases of coliform mastitis at this facility during that period. 10 Hnysiological factors associated with periparturient cows can also predicate mastitis. Carroll (1977) cites existing H'lN’s are partially inactivated by fat and case in newly present milk of fresh cows. Also, lactoferrin, another protective factor in the mamnary glannd, disappears just before parturition leaving periparturient cows more susceptible to coliform mastitis (Neave and Oliver, 1962). Lastly, nutritional factors have been blamed for inncreased coliform infections. Weigt (1980) observed many coliform infected cows exhibited mild secondary acetonemia. This was attributed to high grain, low fiber diets fed to fresh cows. Consequential dysfunction of the leukocyte system could have predicated coliform mastitis. Deficiencies of Vitamin E and seleniunn have also been implicated. Smith, et. al. (1984) found dairy cows deficient in Vitamin E exhibited an elevated incidence of clinical mastitis. Coliform bacteria and species of streptococci other than Streptococcus agalactiae were isolated from 70% of these clinical unstitis cases . sti Composting is an aerobic process based on microbial self-heating in organic wastes (Finstein et al. , 1983). It is a dynamic process which can reach temperatures of 60-7000. (Finstein et al., 1975). Tanperatures of 60-7000 during composting for three days will destroy pathogenic bacteria (Wiley and Westerberg, 1969). Composting also serves to dry separated mnure solids as most of the heat generated by cmposting is lost as moisture (Willson, 1971). 11 Finstein et al. (1986) reports composting involves conversion of organic matter (volatile solids) to (D3 . However, evaluation of completeness of composting by measuring decrease in volatile solids (volatile solids = total solids - ash) lacks sensitivity due to the diversity of organic compounds present, low percentage of ash in compost, and heterogeneity of most composts (Finstein et al. , 1986). Willson (1971) reports that type and rate of composting is primarily influenced by aeration, amount and type of bedding present, settling, and nnoisture percentage. Long steamed bedding in appreciable amounts enhances oxygen diffusion by creating pores. Settling and excess moisture (greater than 70 to 75%) can limit porosity of compost piles which restricts oxygen diffusion and, thus, inhibits composting. Mixing of compost piles counteracts settling and water migration by unplugging pores to allow increased oxygen diffusion and better composting (Willson, 1971). Carroll and Jasper (1978) reported composting of dairy manure solids for several months effectively reduced coliform concentrations in these solids. The authors reported composting temperatures and moisture percentages reflected ambient conditions; wet and cold during their Californnia winters and hot and dry during sunners and that composting temperatures increased with increased depth into the pile (0 cm, 15 cm, and 60 cm). Consequently, coliform concentrations are lower in the sunner months and towards the middle of the pile. Bishop et al. (1980) monitored temperatures and took random samples from piles of dairy mnure solids as they composted for twelve days. Initial concentrations of coliform bacteria were approximately 2 X 107 . The authors found 12 temperatures near the centers of these piles rapidly increased, peaking at 71.5°C in twelve days and reducing average coliform concentrations during this time to less than the 10° coliform per gram bedding wet weight level found by Bramley et al. (1975) to cause new infections of coliform mastitis. Free Stall Management Once dairy mnure solids were placed in free stall, Bishop et al. (1980) report, coliform concentrations inncreased above 10‘ coliforms per gram bedding (wet weight) within 14 days. The authors attributed this to the optimal environment offered by dairy nnanure solids coupled with increased temperature and moisture associated with cow contact. Zehner et al. (1986) inoculated sterilized bedding samples of dairy manure solids, fine hardwood chips, chopped newspaper, softwood sawdust, and chopped straw with Escherichia coli, Klebsiella gneunoniae, annd Streptococcus uberis. The researchers found that when these samples were incubated at 37°C for five days, growth of the coliform bacteria occurred quickest in the dairy manure solid samples. Bramley et al. (1975) monitored coliform growth in used sawdust bedding samples incubated under laboratory conditions at varying tannperatures. He found that temperatures of 30°C and 44°C produced an inncrease in coliform numbers, 22°C mintained initial mmbers and 50°C eventually killed the organisms. Thus, cows coming in contact with bedding in free stalls could cause bedding temperatures to increase above 22°C which could promote coliform regrowth. 13 Francis et al. (1981) monitored temperatures, moisture percentages and coliform concentrations of bedding in free stalls of high and low producing dairy cows. The researchers reported higher producinng cows lyinng in free stalls caused free stall temperatures to increase 5°C 'Iore than low producing cows. Bedding moisture content was lower in free stalls of high producers; yet, coliform populations were higher indicatinng a potential positive relationship between free stall temperature and coliform growth rate in bedding. Janzen et al. (1982) unnsuccessfully tried to alter this optimal environment by adding crushed limestone to dairy manure solids at a rate of one part limestone to one part dairy manure solids. They bedded free stalls with dairy manure solids, crushed limestone and this dairy manure solid-limestone mixture. They found coliform bacteria, which are sen- sitive to changes in pH, grew less in crushed limestone bedding than bedding containing dairy nanure solids. There was, however, no difference in coliform counnts between dairy mnure solid bedding and the dairy manure solid-limestone bedding. Gram negative bacteria such as coliform bacteria are very susceptible to drying, suggesting moisture plays a role in regrowth of coliform bacteria (Carroll, 1977). Allen et al. (1977) dried dairy manure solids to at least 60% dry matter via composting in their climate. This allowed use of dairy manure solids as bedding without the associated fear of coliform nnastitis which the authors were unable to do when dairy nnanure solids were 25% dry matter. Smith et al. (1985) cited elevated temperature and hunidity of Ohio sunlners to explain increased coliform bacterial growth in dairy manure solids used during this 14 season. Thomas et al. (1983) reported increased coliform growth in bedding during wet weather. These researchers attributed this rise to increased moisture associated with the humidity. Bramley (1985) found leakage of milk from the udder onto bedding resulted in rapid coliform growth in that area. Daily removal of the rear meter of bedding from free stalls where moisture tended to accumulate resulted in a 100 fold reduction in coliform numbers. Dodd et al. (1984) investigated a 100 cow dairy farm with 146 coliform.mastitis cases a year. Sawdust used.as bedding in free stalls had damp patches where udders touched. Free stalls were sanitized and bedding in backs of free stalls was swept out and replace daily. This procedure reduced incidence of coliform mastitis to 17 cases per year. MATERIAIS AND METHODS Research was conducted at the Kellogg Biological Station Dairy Canter starting in early spring and going through the sunner. Cows were housed in a cold free stall barn with a center drive through feeding area and flush mnure system. Four sets of 32 free stalls maintain 117 lactating dairy cows with a 365 day herd average of 18,500 pounds of milk per cow. Somatic cell counnt for the herd was 200,000 cells/ml at the start of the research. Free stalls are four feet wide and seven feet longandhaveateninnchcurb. Neckrails set 18t022 inches from the front prevant cows frcmn depositinng mnure in free stalls. Two sets of 32 free stalls are dirt based. (he set of these dirt based free stalls had tires buried in one half of the free stalls to prevent pitting. The other two sets of 32 free stalls are conncrete based with a rat filled with straw or straw and wood shavings set on top. The drive thronuh feeding area divides free stall sets so that one dirt and one concrete based free stall set are at each side. Alleys are flushed at regular intervals to rmove mire. Resultant liquid mnune flows to pick up channels and than flows via gravity to a collection pit. The collection pit is under a separate building which houses a stationary sieve separator and four bins for storing dairy manure solids. 15 16 A 25 hp punp agitates the liquid mnure (approximately 3.5% dry matter) and punps the manure to the screen. As liquid manure passes down the screen, the liquid portion goes through the holes while solids (approximately 18% dry matter) are washed down the screen by liquid remaining on the surface. A roller press at the base of the separator screen further squeezes out moisture. Effluent (approximately 1% dry matter) is punped to an outside lagoon. Dairy manure solids are conveyed to one of four 15 feet by 15.5 feet storage bins for a one week interval. Piles were kept to a height of four feet. This process is continued among the four bins allowing dairy manure solids to compost three weeks before use as a free stall bedding on a weekly basis. Composting dairy manure solids were mixed weekly by loading solids onto a mixing wagon. Solids were mixed for approximtely five minutes than unloaded back into the appropriate bins . Objective 1 The objective of the first part of this research was to determine parameters necessary to justify investment in facilities allowing separation of solids from liquid manure for use as free stall bedding for dairy cattle. Manure separation becomes econanically feasible whan average total cost of bedding with Immune sol ids becans less than average total cost of using conventional bedding such as straw or sawdust. In this evaluation, all costs were put in terms of net present values (Capital Budgeting) as this method accounts for varying money flows over time and consequently is useful in investment annalysis. A 17 Lotus spread sheet was used for computer analysis as this is instrumental in budgeting work (Hughes and Ochi, 1984). Costs and returns were assigrned to best mimic actual acquisition of separation facilities. However, we assumed all income and expenses were incurred at the end of each year. In practice this is not true; however, adjustments necessary to account for this are innsignificant (Harsh et al., 1981). It was assured a loan would be taken for the total investment and payments amortized monthly. Length of loan and interest rate would be varied to observe their effects on investment feasibility. Insurance, repairs and taxes were estimted at 1% of initial cost of buildings (assured by us to be 1/3 of investmant) and 3% of initial cost of separator and allied components per year for machinery (asstmned by us to be 2/3 of investment) (Oregon State Extension Service, 1982) . Electricity use was estimated at 63.42 KW-HR per cow per year (Oregon State Unniversity Cooperative Extension Service, 1982) and priced at 3.08 per KW-HR (approximate farm rate for Michigan). This results in an annual electric expaditure of $5.10 per cow. Labor was priced at $4.00 per hour and estimted at .91 hours per cow per year (Oregon State Cooperative Extension Service, 1982). Thus, labor, also a function of number of cows, is priced at $3.64 per cow annually. Returns from invesment in separation facilities consisted primrily of savings of bedding costs. Bailing use is a function of number of cows and price paid for previous bedding an a per ton basis. Ahalftonofbedding isneededannuallytobeda1400pouddairycow (Chore Reduction, 1978). Tax write offs of all expaditures except principal payments were another return. A seven year double declining 18 balance depreciation was used to write off investments in machinery and buildings up to their salvage values. Salvage value of building after tan years was estimated at 30% of price paid for buildings and salvage value of machinery was 10% of price paid for machinery (Oregon State University Cooperative Ectension Service, 1982). Consequantly, depreciation and repairs, interest and taxes are in terms of percent investmant. A rate of return (discount rate) was needed to account for the time value of money. An inflation rate of 1.55% was used to estimte price increases in innsuence, repairs, taxes, electricity and bediing savings. This figure was estimted from the average inflation of prices paid by farmers from 1981 to 1985 (Agricultural Statistics, 1985). (hoe inflation adjustments were made and the required rate of return, tax rateardloan schedulewere input, allcashflowswouldbeinterm of percent of investment, nunber of cows, and price paid per ton bending. Bedding savings, the largest return frm this investment, is a function of amount bedding med, 1/2 ton per cow, and price pid per ton bediing. Depreciation, raking up the remaining returns, is a function of investmant. Expanditues consist prinrily of the loan takan for the investment which is also a function of investmant. The variable costs are electrical usage at $5.10 per cow and labor at $3.64 per cow. Justification of a separation system occurs when costs of acquirirng facilities eqnnl returns frcn the investmant. This is illustrated below where cost of separation (i.e. a loan for acquisition, insurance, repairs and taxes, and cost of operation of facilities) eqnls returns 19 frail separation (i.e. savings from not hnying bedding and depreciation credit from the separator acquisition). [can expaditues + Ins., Rep'rs, m + Variables Costs = Bsnflinl savings + Deueciatian credit These parameters are net presant values of cash flows over a ten year life investment. Putting parameters that are functions of investmant on one side and putting parameters that are functions of nn-ber cows of bedding prices on the other side gives us the following equation: loanexpaditues + Inns., Bsp’rs, Thess-Dsgecistian credit :BsnflingSsvims-VsriableOosts This can be put in a mthantical formla by settinng loan expan- ditures and tax savings as a percent (A) of maxim- invesmant (t) and setting this equal to bedding savings (.5XY) minus variable costs (5.13: + 3.64X) where X equals nunber of cows and Y equals price paid for previous bedding. Both bedding savinngs and variable costs wild be mnltiplied by a constant (B) since factors such as time, inflationn and taxes affect these parameters equally. A(.) = (.m " 807“)3 Thus, sexin- investmant (I) eqnnls B(.5XY - 8.74X)/A. This can be put in other tens as follows where K equals B/A. PPM?! '. ‘ ‘(t' ' ‘ -6 1 .71 9" ‘Y "' 111'“-$",l !', i ‘.{E r ':;,'(‘ 0 .',.’5‘., ~, J A. n ‘~’b.’.I-J: 16‘4'11 m fiflh‘i . -" - '- Jr‘ .'~""""1“*+ grid rinzr'nr" -- “r."‘n'FF' "w” .H * 20 (U = KX(.5Y - 8.74) Different values for X and Y were input to calculate minus investment (3) a farmer with X amount of cows and payinng Y amount for bedding could spad and receive the input return on his investmant. Effects of varying tax rates, rates of return and loan schedules on econalic feasibility were also investigated as they affect the canstant, K. The below work sheet ms used to annalyze the mentioned parmeters. 21 DMS INVESTMENT ANALYSIS 1. What is your yearly cost for bedding? If known enter here > 0 and go to step 2, then step 6. If unknown, enter 0 and go to step 2. 2. How many silking and dry cows do you have? ---------- > 500 Based on University data which estimates 1/2 ton bedding per 1400 lb cow is needed annually; 250 tons bedding is used in your milking herd annually. 3. Enter your estimate of tons bedding used annually.---> 250 4. What price do you pay for bedding ($/ton)? -------—-> 20 5. Using the above information in 2, 3, and 4: $5,000.00 is estimated spent annually for bedding. 6. Rate of return expected from this investment(%) ------ > 10 (Ten year treasury note produces 7.71%) 7. Tax bracket(%) -------- > 25 (25% is 'average'for a 100 cow operation) 8. Expected Annual Loan Interest Rate (%) > 12 9. Expected Loan Repayment Period (months) > 60 ASSUMPTIONS Equal monthly loan payments of $252.16 Two thirds investment goes to separator and allied components One third investment for buildings Seven year double declining balance depreciation allowance Inflation is 5.5% per year Labor at 4.00/hr $11,335.76 maximum can be justified for installing separation facilities in your operation Immune... ('77:! 22 Objective 2 'lhe objective of the accord part of this research was to determine augment practices which enhance use of separated mnure solids as free stall bedding for dairy cattle. Phnagement practices studied focused on minimizing coliform growth in dairy wire solids used to bed free stalls. Effects of composting, daily removal of bediing frm the back two feet of free stalls, free stall base (concrete versus dirt), and production levels of cows frequenting free stalls were studied. 1. Earperinent l Freestallswerebeddedweeklywithchirymnuresolidsatarate of approximately 90 panda dairy manure solids per free stall (one six foot skid loader bucket of dairy manure solids per four free stalls). All possible interactions of the above mentioned mters were studied by depositing meted dairy manure solids in the sixteen free stalls closest to the dead end alley ard depositing dairy mire solids fresh fmtheseparatorintherminingsixteenfreestalls farthestfrc- the dead end alley ard depositing dairy mire solids fresh fun the separator in the raining sixteen free stalls farthest frm the alley. Fresh dairy mnure solids were less than four days old, yellowish in appearance ard showed no signs of heating. Cmted dairy mn'e solids were piled for treaty days and were udisturbed (hiring ctr-posting in the this first trial. The sixteen free stalls located farthest frm the feedim alleyhaddairymnure solids renovedfronthehacktwo feet daily while dairy more solids in sixteen free stalls closest to the feeding alley were allowed to sou-date. lgél 23 The herd was divided into two groups of cows based on production level. Fifty eight cows averaging 72 ponds of milk per day were in the high production group ard 57 cows averaging 43 pourds of milk a day were placed in the low production group. Each production group of cows was equally divided by production so half of each production group was <11 dirt based free stalls ard the other on concrete based free stalls. This scheme is illustrated below. Eight samples of dairy mmrre solids were collected fraa each set of free stalls. All sasples of this bedding were taken approximately eighteen inches in fro. the rear curb of each free stall. Two samples were taken from free stalls where fresh solids were allowed to acmmlate, two from free stalls where caposted solids were allowed to accrmlate, two fr:- free stalls were calposted solids were swept frcl the rear two feet of free stalls daily ard the last two fun free stalls where fresh mnure solids were swept daily. Two sets of suples were to be taken weekly, once when free stalls were initially bedded with chiry mnure solids and one week later before free stalls were bodied again. Samples (approximtely 100 gram each) were placed in sterilised mlebags, placedoniceardtransportedtothelaboratorytobe tested for colifon mdaers, noisture percentage, ard ash cornentration. Colifor‘ raters were determined within 24 hours fun the tin that smies were collected. Coliforn mixers of a particular smile did not vary when tested at two or twelve hours after collection. Coliform radars were detemined using the lost probable mixer nethodwithalauryl tryptosebrothasdescribedinStardardMethods 24 for the Exaaimtion of Water ard Waste Water Text (1985). This procedm'ewasadaptedforourpurposesbyDr. FrankPeabody, Department of Microbiology, Michigan State University as follows: (he gran of dairy Ianure solids was added to 99 ml sterile distilled water to obtain 100 ml of solution (weiglnt/voh-e). This solution was then shaken mnually for approximme fifteen seconds and then added, one milliliter at a time, to eight sets of five feruntatian tubes: emh set of fer-entatian tubes being inoculated with a solution containing 1/ 10 the concentration of chiry Immre solids then received by the preceding set. These tubes were incubated at 35°C for 48 hours. Positive results were irdicated by gas production in the tubes. Coliform m-nbers were calculated by observing W of positive results in each dilutian’s fermentation tube set. Results irdicated number of colifor- bacteria per gru bediing wet weight of dairy mnure solids. To verify colifor- nuaber, rardr- manure solid saqnles were cultured by the Michigan State Veterinary Microbiology laboratory. Werecordedbegimingarderdingnoisturepercantages ofdairy unure solids to observe their effects on coliform growth. Moisture content was deteninsd by weighing samples on dried ard tared weighing containers then placing these samples in a drying oven at 1050C for 24-36 hours. Percent moisture was calculated by comaring initial ard erdjng weights of dairy mnure solid samples. (Percent moisture = l - dried weight/initial weidnt) . Ashpercentagesweredeterninedbyplacingdriedsamlesina llffle furnace set at 550.0 for at least six hours. Ashed angles were then allowed to cool overnight before being placed in a drying a. 25 oven at 105°C for 24 hours. Percent ash was calculatedby comparing initial dried sample weight with weight of resultant ash (percent ash = weight ash/weight dried sample). 2. Experiment 2 The objective of this experimt was to better understand con- posting’s role in effectively reducing coliform concentrations in dairy mire solids. Composting temperatures were monitored daily by imerting thermocouples one, two, three and four feet into the center of 15 foot by 6 foot by 4 foot high piles of composting dairy manure solids. Ambient tenperatures were also nonitored. Dairy mnure solid samples were taken by digging to these different depths just before the pile was nixed. Coliform nn-bers were observed in the samples to determine the effect of temperature on coliform survival. Internal temperatures were again measured after mixing of the piles. Each pile was mixed in a mixer wagen before use and eight rantin- saqznles were taken as dairy mnure solids were being placed in free stalls. These samples were analyzed for colifonn miners and noisture percentages. Average coliform concentration and moisture percentage were plotted over time to analyze effects of a weekly pile-mixing regi-e ard flient telperature . 3. Experiment 3 The objective of this experiment was to identify if daily sweepim of the back two foot of free stalls affected incidence of colifora infections in lactating cattle. Two sets of 32 concrete free stalls 26 with nts were used for this experiment. Bedding (co.posted nanures solids only) was initially applied at a rate of 90 ponds per free stall. This was not sufficient to mintain adeqnnte bedding for one week so application rate was doubled to 180 pounds per free stall. One set of free stalls housed 30 cows averaging 78 pounds of silk per day and thirty cows averaging approximately 34 pounds of milk a day were housed on the other set of free stalls. Cows in each set of free stalls were separated into two groups of equal average .ilk prochction by a chain dividing each set of 32 free stalls into two absets of 16 free stalls. mnure solids were swept frm backs of one of the subsets of free stalls in each free stalls set daily while dairy mnure solids in the other free stall subsets were allowed to accn-nlate. Four bedding sunples fro. four different stalls (eighteen inches fral rear curb) were collected fro. each subset of 16 free stalls for a total of sixteen samples. These dairy mnure solid saples were taken when dairy mnure solids were first applied ard one week later Just before ackiition of fresh manure solids. These smuples were tested for colifor. m-bers and moisture percentage. Suples were also taken frm the front of stalls for caIparison with salples taken frcn the rear of stalls to analyze possible benefits of sweeping off the rear two feet of free stalls. In addition, effects of daily sweeping the back two feet of bare cesent free stalls on colifor. nn-bers when free stalls were subject to decreased animl contact was also emined. Amoximtely 35 heifers remingfrmBOOtollOOpoudswerebeddedonthesefreestalls. These heifers also had access to an outside lot when weather pemitted, fur sta UH I111 Sta sta col 27 further decreasing heifer contact with bedding plmd on these free stalls. The free stall set containing heifers had forty 3.5 foot by 6 foot concrete free stalls. Initially, an approximated 170 pomds of canposted dairy mnure solids were used per free stall to maintain mnure solids in free stalls for a period of two weeks. later this was reamed to approximately 110 pounds of manure solids per free stall. FM“ Dairy mnure solids were swept daily fro. the back two foot of free stalls located on one side of the free stall set. Dairy manure solids were allowed to accnmulate on free stalls on the other side of the free stall set. Samples were collected frm the rear of four free stalls in each side of the free stall set for a total of eight samples per collection period. Samples were taken from free stalls when dairy manure solids were first applied to free stalls, seven days after application ard two weeks after application (prior to addition of fresh mire solids). These samples were tested for coliform cencentration and moisture percentage. A three way factorial design was used to statistically analyze effects of free stall base, cmpostim, sweeping out the back two feet of free stalls and production level on final coliform concentration. Lastly, beginning moisture percentages, eding moisture percentages, beginning coliform concentrations and fiml coliform concentratien were statistically correlated. This showed the effect each paraneter has on final coliform counts to determine what parameters could possibly be altered to minimize colifom concentrations in free stalls. sew iDTE n5 kn RESULTS Parameters necessary to justify investment in facilities allowing separation of solids from liquid manure for use as free stall bedding are described by the below equation. In this equation, (I!) = maximum F m investment, X = number of cows, Y = price paid for previous bedding and K is a constant which accounts for other parameters. (‘) = KX(.5Y "' 8074) As can be seen, nunber of cows is directly related to mxinmm investment at a rate of (I!) = XT where T replaces K(.5Y - 8.74). Graph one illustrates the effect of increasing herd size on maximun investment lander four different bedding prices. Tax rate, return on investment, loan rate arnd loan length are held constant at 25%, 10%, 12% ard 60 months, respectively. The line at $30,000 is our approximation of the minimal cost of installing a separation system. 28 fit? in. 29 H ousmwm zoiono 4 zoio: o zeta». + 960 cum 2:: coo. com com con 30 con 8.. 8n P _ h L F F L r + P b P L guess“)! omn— zwcicoum 232.; m_m>1.4 um / wow Duvppaa 37 o madman R ms 0. R NJ + R h 2.60 accEzz 000 cm... 00* Omw. OCH omN CON On; _ L b F F IF 8 71/3! I A; (filly!!! .IILHHWHHHHWIIIr/I fl I? / / / dr /, I / / .. /. mQEBUa cosouoaom 80.0w.“ *0 COEGSUQQ co mmtom coon DEED.) 8.9.3 84.3 8.8» 8.8. 8.3. 8.8. 843 8. an. 8. mm» 8.3a 8.8. 8.16 8.3» 8.?» 8.8g 8.8a 8.13 8.8« uo; / aoud bugppag 38 a wuswfim .58»: 5:22 of + 9.50 83:32 O00 on... 00+ can OOn 0mm DON OO— 00— i . In L L IF 8 P T. /m/// T. / /./ rl / ./ 905.60... cozocoaom 80.2“ ab c0523oo¢ Co 59qu £004 @530», “coEsbaom 5:02 on D OO.NNM OO.+N¢ OO.mNfl OO.wN« DOOM“ OONM.“ 00.4%“ OO.©.M¢ OOOM.“ oodvu OO.N+0 OOJJH OO.m.+fi OO.Wvfl OO.DO« OO.Nnfi uoi / aoud bulppag 39 It is difficult to assess actual effects each parameter has due to interactions between parameters. Overall, these parameters seemed to affect smaller farms more where higher bedding prices had to be incurred to justify investment into a $30,000 separation facility. The dairy herd at the Kellogg Biological Station was divided for this next part of research by level of milk production and place on dirt and concrete free stalls bedded with composted and fresh dairy manure _..r.nr vv- finer Pm . . solids as described earlier. Composted dairy manure solids were dark brown and hot to the touch. Fresh solids were yellow and showed no signs of heating. Initial coliform concentrations, moisture percentages and ash percentages of composted and noncomposted dairy manure solids are compared below in Table 1. TABLE l--(X}‘IPARISON OF WTED VS FRESH DAIRY MANURE SOLIDS COMPOSTEDa NONCOMPOSTEDa (DLIFOIM CDNCEN'I'RATION 2.5 X 105 5.3 X 105 mISTURE PERCENTAGE 77.18’ 78.36‘ ASH PERCENTAGE 13.4 13.1 3 Results based on average of 16 observations ' Coliform bacteria per gram bedding net weight ‘ Denotes difference (p < .01) Composting did not have a significant effect on coliform concen- tration or percent ash, though observed differences were as expected. Composted dairy manure solids were slightly drier. 40 Table 2 sunmarizes coliform nunbers and moisture percentages of manure solid samples taken from free stalls four days after application. Dairy manure solids in dirt free stalls had some dirt mixed in. Approximately 80% of dairy manure solids placed on concrete free stalls with mats were removed by cows regardless of whether dairy manure solids in backs of free stalls were swept out daily or allowed to accumulate. Comparisons of final coliform concentrations and moisture percentages of each parameter ignored others parameters. For example, composted and fresh dairy manure solid samples were compared across all free stall sets, production groups and nanagement practices (sweeping versus accunulation) . TABLE Z-WIPARISON OF COLIFORM (DNCEN'IRATION AND PDISTURE PERCENT EXPERIMENT 1 CXMPARISONab COLIF’OIM CONCENTRATIONc PDISTURE PERCENTAGE Dirt Stalls 1.4 X 10" 49.5 Concrete Stalls 2.1 X 107 56.0 Composted Solids 2.7 X 107 54.6 Noncomposted Solids 8.7 X 10‘5 50.9 Swept Stalls 1.9 X 107 52.6 Accunulated Stalls 1.7 X 10" 52.9 High Producers 2.2 X 10" 53.5 Low Producers 1.3 X 107 52.0 ' Canparisons of each parameter ignores other parameters " Results based on averages of 16 observations taken 0 Coliform bacteria per gram bedding wet weight 41 Bedding in dirt based free stalls was drier than bedding in cement based free stalls in this first trial. Composted dairy manure solids had higher final coliform concentrations than uncomposted dairy solids despite lower initial coliform concentrations. Sweeping out dairy manure solids from the back two feet of free stalls daily had.no effect on coliform concentration or moisture percentages. There was a slight difference in coliform concentration or moisture percentages of bedding in free stalls between high and low production cows. A trend of higher coliform concentrations in free stalls containing wetter bedding was apparent. TWO of the 28 higher producing milk cows on dirt free stalls contracted coliform mastitis three days after dairy manure solid bedding was added. At time of infection, one cow was producing 74 pounds of milk daily and had a somatic cell count of 400,000 leukocytes per ml. The daily milk production of the other cow was unrecorded.due to recent freshening but it had a somatic cell count of 100,000 leukocytes per ml. The first cow freshened 58 days previous to mastitis and the second cow was 41 days postpartum. 2. Experiment 2 Ambient temperatures and temperatures one, two, three, and four feet into composting piles of dairy manure solids were monitored as «described.previously. Graph 1 illustrates temperature differences tvithin a pile over a period of time. Ambient temperatures are also Iilotted. Effects of mixing are illustrated between day 29 and day 30 as irliicated on the graph. A line placed at 60°C indicates temperatures 42 found to be lethal to coliform bacteria if exposed for three days during the composting process (Wiley and Westerburg, 1969). 43 m muswfim Roe. \. E058 4 8c 83.3.82“: 0 8.598... 3.... 95 8? mm}. mm? min I? Q... 8.8 8.6 2.6 .36 {a .96 mux+ a.) wuxn _ r M bl LI a _ — . hp . \x , Oh mumminz itch—4.00 m} mmzhéun‘mh Pzwaii mini HWOQEOO 44 Temperatures were highest two and three feet into a pile. As shown above in graph 1, temperatures immediately rose upon mixing, especially at depths of two and three feet. Temperatures one foot into a pile rapidly decreased within two days due to low ambient temperatures. Random coliform concentration tests done when a pile has been undisturbed for some time showed coliform bacteria were present at one foot into a pile and at four feet into a pile but not at depths of two or three feet. This is illustrated below in Table 3. Fresh manure solids not discolored by composting were found at depths of four feet. TABLE 3--CX)LIFORM CXJNCENTRATIONS AT DIFFERENT DEPI‘HS IN (XI‘IPOSTING PILES DEPTH OF SAMPLE (1)le CDNCENI’RATION 1 m 3.3 X 10‘ 2 m 0 3 m 0 4 moor 3.5 X 103 Graph 2 shows average coliform concentration and graph 3 average moisture percentages of manure solid samples taken from 16 compost piles after the piles had.been mixed and.were to be applied to free stalls. These compost piles were used at successive times as warmer weather approached. Ambient temperatures during composting is also plotted on graph 2 to illustrate any relationships. 45 w opswam C .v 2.5524. 0 {‘1 Ion .3. on .Om SfllmBO-SUMWBdV'BL “ on Ion OO w mwmnhémafwh >435 mini FWOQEOO 46 ow magmas muted men mxm on? PS as: as 3.3.. Nxh 3.6 9.6 .Cd .86 {c 56 mm}. 3}. .93 F .I P P P F a b e Ir P F L O \B I a \\ /./z, \ / Twila JR, // \ / \\ methszmmn. mmnhmfii m3 _ a ._.mOn_ 200 Oh SBOVINBCJHBd BHHLSIOH 47 Coliform bacteria nunbers varied greatly but remained primarily in the 105 range at the beginning of research and the 10’ to 104 range in later trials as ambient temperature increased. Freshly composted dairy manure solids tended to be drier in the beginning of research as sunner progressed. These observations are summarized below. TABLE 4--—AMBIENT TWERATURE VS CDLIFGIM WCENTRATIQJ AND FDISTURE PERCENTAGE Ambient Temperature Coliform- Moisture 12°C” 2.4 X 10II 77.1% 25°Cc 6.3 X 10° 78.1% I Coliform bacteria per gram bedding wet weight ' Results based on averages from first seven piles c Results based on average from last nine piles 3. Experiment 3 Research continued using only composted dairy mnure solids on the two sets of concrete stall with mats containing lactating dairy cattle W by production as described previously. mnure solids were kicked out by cows within four days of application when bedding was applied at the original rate. Final coliform mmbers and moisture percentages were detenined fran samples taken four days after application. Amlication rate was then doubled to mintain mnure solids in free stalls for one week. Three days after doubling the application rate of :13: in the the f1 of fn were I 0min were ' seem 48 of dairy manure solids to free stalls with lactating cattle, four cows in the high production group contracted acute mastitis; two cows form the free stall subset where dairy manure solids were swept out of backs of free stalls daily and two from the subset where dairy manure solids were allowed to accumllate. Plenty of bedding was present when cows contracted mastitis due to the increased application. Bedding samples F1 were taken from free stalls the next day. Statistical sunnaries of average coliform nunbers and moisture percentages of bedding taken from these free stalls during this part of research are shown below in Table J E 5. Comparisons of bedding from free stalls of different production " level cows ignored whether free stalls within each group were swept or allowed to accunulate. Similarly, effect of sweeping was observed across production level . TABLE SWARISON OF coupons (XNCENTRATIGJ AND PDISTURE W mm 4 (IMPARISONH comm WTIOW w emerge; Low Producers 9.0 x 10- 51.06% High Producers 1.4 x 10" 55.97% Swept Stalls 1.1 x 10" 55.39% Ana-listed Stalls 1.2 x 1m 51.65% O Results based on averages of 56 observations ' Comarison of each parameter ignores the other parameter ° Coliform bacteria per gram bedding wet weight E H.“ RU 49 The trend of increased coliform bacteria nunbers in bedding with higher moisture percentages was still apparent in free stall bedding of high production cows. Sweeping solids from the back two feet of free stalls still had no effect on coliform concentrations. Coliform numbers and moisture percentages of bedding samples taken after the mstitis outbreak were armlyzed. The results are shown below and capared with results of samples taken from the same free stalls before the mstitis outbreak. Also, records of cows that contracted acute mastitis are shown in Table 7. All infected cows, in the their first half of lactation, were producing over 73 pounds of milk, and all but one had a emetic cell count less than 400,000 cells per ml. Cow 122 had been infected for several days prior to acute manifestation. TAMG-CIMPARISONOFMANURBSOLIDSAMHBSTAKENMFREESPAHS AFTER THE MASTITIS (IIIBREAK WITH PREVIGJS (BSERVATIG‘IS PREVst OBSERVATIONS. LAST (BSERVATICNS' mm PDISTURE comma: FDIS'HRE Low Producers 9.0 X 10‘ 51.06% 5.8 X 10' 50.93% H1811 Prodlners 1.4 X 10" 55.97% 4.2 X 10' 59.89% ' Results bases on averages of 56 observations ' Results based (:1 averages of 8 observations ° Coliform per gram bedding wet weight after collie U511 freq 50 TABLE 7mm OF (1178 WING AGJTE MASTITIS (XX DAYS POSTPARTLM MILK PRODUCTION SCMATIC CELL (XIINT m. (lbs/day) 82 69 104 200,000 361 128 74 300,000 403 50 95 0 122 132 81 5 , 500,000 Coliform m-bers in bailing samples taken frm free stalls shortly after cows contracted acute mastitis were not greater than average coliform mmlbers of samples taken from these free stalls wider identical conditions before this outbreak. . However, bedding was setter and more manure solids mre present in free stalls when cows contracted acute mastitis. Coliform numbers of dairy manure solid samples taken frc- fronts of free stalls were compared with coliform counts of dairy manure solid samples taken from backs of free stalls. Based on 48 observations, manure solid samples from fronts of free stalls had an average of 3.9 X 10' coliform per gram bedding wet weight and samles taken frm backs of free stalls had an average of 9.4 X 10' coliform per gram battling wet weight. Coliform courts in both cases were still above the 10' coliforn bacteria per gram bedding net weight level fould to increase the coliform infection rate in lactating cows (Br-aley et al., 1975). After the second mastitis outbreak, research continued using the previous desim but only on low production cows on concrete free stall. tests file - item {m s free e stalls eolifor 51 stalls with ate and heifers on bare cement free stalls. Results of tests run on samples taken from free stalls with low production cows five and seven days after application are summarized below based on 56 observations each. Comparison of age of samples in free stalls ignored whether samples were taken from swept free stalls or free stalls where mnure solids were accumulated. Similarly, comparison of samples taken I frm swept free stalls and unswept free stalls ignored age of samples in free stalls. However, in table 10, effects of age of samples in free stalls on effectiveness of sweeping free stalls on maintaining low colifor‘ nt-ber is studied. Tmsnmmsmmmmmmsounsusmmmnsmm BEWMIIKWINGQNS cameram- - comm mum: macaw 11013111121: Asa-dated 8.7 x 10- 61.20 Siept 6.3 x 10. 64.40 Day 5 6.0 x 10" 64.46 Day 7 3.7 x 10" 61.56 ' Haunts based on averages of 56 observations * Caparison of each parameter ignores the other parmeter ° Coliform per grn bedding wet weight 3 Denotes difference (p < .1) I. 4" iept' ' C011 ' R251; 'n infec In A}? ' 5‘. ‘0‘! ed“ ~: I: '1 (x 52 TABIE 9—EFFKJTOFSWEEPINGKJLIDSFHMBM3KSOFFREESTAILS OF LACI‘ATING (INS CNER TIME m 222.! Coliform' Moisture Coliforml Moisture Accr-nlated' 5.5 X 10" 63.75% 1.1 X 10" 59.29% Swept) 6.7 X 10‘ 65.17% 6.0 X 10' 63.82% ° Coliform Concentration-coliform per gram bedding wet weight 5 Results based on averages of 28 observations ' Denotes difference (p < .01) Sweeping solids frm the back two feet of free stalls daily was once again ineffective in mintaining coliform numbers below the infectious level in free stall bedding of lactating cows. No difference was four! between coliform ntnbers in bedding of free stalls where mnure solids were swept off the rear two feet daily over a week’s time and beckiing from free stalls where mnure solids were allowed to soon-date. A trend in differences of moisture percentages and coliform numbers between bedding frcm swept free stalls and free stalls where mnure solids were allowed to accrmulate was apparent over tin. Hot, hmid weather prevailed during this phase of research with temperatures averaging approximme 28°C during the day. Samles of dairy mnures solids were taken frtn bare cement free stalls mintaining heifers with access to an outside lot. Comparisms 01’ coliform mmnbers and moisture percentages of swles in swept and mswept free stalls ignored age of mnure solids in free stalls. 53 Similarly, comparisons of samples taken at one week with samples taken at two weeks ignored whether samples were from swept or unswept free stalls. The results of these ccmnparisons are shown below. TABLE IOWARISCNS 0F DAIRY MANURE SOLIIB [BED Fm BEDDING HEIF’ERSONISWEPTANDUNSWEPI‘FREESTAHSOVEZTDE (XI‘PARISON' 5 (ELIE!!! WRATIQJ‘ % I‘DISTLRE (he week old bedding 1.6 X 10‘ 65.63% Two week old bedding 1.7 X 10‘ 53.67% Swept stalls 2.1 X 10' 60.32% Accumnlated stalls 1.3 X 10' 58.99% ° Results based on 16 observations ° Each parameter oomared ignoring other parameter c Coliform per gram bedding wet weight : Denotes difference (p < .01) Sweeping dairymnuresolids fromtheback twofeet ofbarecement free stalls was ineffective in maintaining low coliform counts. Coliform concentrations remined fairly constant over time thonflh moisture percentages decreased. During hot weather, heifers tended to congregate in inside free stalls which happened to be free stalls havim mnure solids swept from the back two feet daily. Final analysis of all data involved statistically correlating beginning coliform count, ending coliform count, beginning moisture and ending moisture. These results are shown below in Table 12. .i 54 TABLE 11--STATISTICAL WATERS OF STUDIED PARAMETERS USING ALL DATA MARISCN SIGNIFICANCE Initial Colifor- vs Final Colifom n.s. Initial Colifom vs Beginning Moisture 99.9% Initial Moisture vs Final Moisture 90% r Initial Moisture vs Final Coliforl n.s. i In Final Pbisture vs Final Colifor- 5’ [a 1 Initial noisture content was inversely related to beginning colifon cmcentration. There was so-e relationship between initial misture content and final moisture content but no relation of initial moisture cmtent, final moisture content, or initial coliform numbers to final coliforn nunbers. Overall, there was no method of maintaining colifon m-bers below 10' coliform bacteria per gran bedding wet weight in free stalls bedded with dairy mnure solids during Michigan st-ers; even when the back two feet of free stalls were swept clean of dairy mnure solids daily. Probably because of this, high silk producing cowe in early lactaticm with low somatic cell counts contracted acute Institis when bedied with dairy mnure solids . DISGJSSIW fine first part of the research looks at parameters affecting mi..- investment a farmer can justify spending on facilities to separate solids from liquid mnure for use as free stall bediing. larger herds can afford to invest proportionally mm for separation facilities than smller herds assnning other parameters are held constant; however, bedding price is also an important consideration as seen in the first graph where a 1000 cow facility cannot justify investment in separation facilities if alternate bedding can be obtained for $20 a ton. Overall, since smaller bench use less bedding, they must incm' higher battling prices before investment in a separation system can be justified. Effects of tax rate, required rate of return, loan rate and loan repaymt period on Justification of separation facilities are difficult to assess die to interactions between these parameters. These effects are more punnounwd on miller farm where a larger percentage of bedding savings goes towards covering fixed costs due to economies of scale. Phnagalent practices whidn enhance use of mnure solids as free stall bedding are not clear frm this stuiy. Ideally, dairy mnure solids should be at least 60% dry mtter or higher and have coliform counts below 10‘ per gram bedding wet weight (Allen et al., 1977). Despite high inner pile temperatures that decreased colifon miners as 55 56 low as 103 per gram wet weight, static composting was inadequate as moisture percentages and coliform nunbers were not reduced enough to prevent rapid regrowth once placed in free stalls. At the start of research in early spring, low ambient temperatures (never above 15°C) and high pile moisture levels (approximtely 77% water) were most obvious inhibitors of composting. Ur-ixed piles hmi temperatures considered lethal to coliform bacteria only at depths of two and three feet. Temperatures at depths of one and four feet were adequate for coliform growth. Depressed temperatures at four foot depths were probably due to decreased oxygen diffusion from wet pile conditions as increased moisture blocks oxygen diffusion necessary for adequate composting (Willson, et al., 1980). Temperatures at the one foot level were probably influenced by ambiennt conditions as low ambient temperatures result in lower composting temperatures (Carroll et al. , 1977). Decreased oxygen diffusion would affect deeper levels equally or more so. This is important as over 40% of a mat pile volnmne was located within one foot of the surface in our four foot piles. Effects of settling and moisture acct-nation on composting (Willson, 1980 )were evident as tanperatures at all depths decreased with tin. Coliform nunbers would consequently be expected to rise as tauperatures fell towards temperatures supporting coliform regrowth (Carroll and Jasper, 1978 and Bishop et al., 1980). Mixing piles of composting (hiry nnure solids caused tanperatures to increase above the 60°C lethal range at all monitored depths within one day. Temperatures at one foot fell below this me within two days; presunably due to effects of ambient conditions. Bishop et al. 57 (1980) showed average colifom nunbers in composting piles of dairy unure solids leveled off after four days to a level of approximately 105 coliform per gram wet weight and remained constant until pile use at 12 days. Theoretically, since a temperature of 60.0 for three days is lethal to coliform bacteria, daily mixing of a outpost pile, which increases temperatures above 60° C at depths of one, two, three and four feet for at least one day, should be adequate to optimlly reduce coliform nunbers if continued daily for three days before we. Thisprocedurewouldbeinadequatewherecomposting isusedasamethod of drying solids. To improve composting, piles were mixed on a weekly basis. Average coliforI m-bers were erratic ranging frm approximtely 10‘ to almost 10‘ coliform per gram wet weight. This variation was probably caused by other unidentified factors . As sum-er advanced average coliform miners were canstantly decreased to levels of approximately 10‘ coliforms per gram wet weight with composting due to increased adnient temperatures (Carroll and Jasper, 1978). These lower coliform miners were sometimes obtained with weekly pile mixing during the cold months early in this study. However, lower coliform mmnbers (less than 10‘) did not prevent coliform regrowth when these solids were added to free stalls. Average moisture percentages of freshly cmposted mnre solids ruined consistently high. An inverse relationship existed (p < .001) between coliform levels and moisture levels in freshly caposted solids. Increased ambient temperatures during sn-er months caused decreased coliform nuiners in piles; however, moisture percentages unexpectedly increased. Dale et al. (1975) cites increased huidity retards drying . E f?“ ‘- ”El 58 of manure solids in free stalls. High hunidity during simmer months my have retarded evaporation in compost piles causing higher moisture percentages. Coliform nunbers were higher in composted dairy manure solids than fresh dairy manure solids four days after application of these solids to free stalls despite equivalent initial coliform numbers and lower moisture percentages. High final moisture contents and high temperatures on day of application my have resulted in higher f inal coliform concentrations in the composted solids. Coliform regrowth above levels of 10° occurred under all conditions of free stall base, daily sweeping of dairy manure solid bedding from backs of free stalls and production level of dairy cows frequenting free stalls. Milk production levels of cows frequenting free stalls had no effect on final coliform concentrations in bedding though an increase in coliform concentration in bedding of high producing cows was expected due to higher bedding temperatures (Francis et al., 1981). Daily sweeping the rear two feet of free stalls also did not affect coliform concentrations. Coliform nunbers did not vary between backs and fronts of stalls. Bramley (1985) reported a 100 fold decrease in coliform umber in bedding of free stalls when bedding was swept from the back meter daily. Thus , factors other than cow contact were apparently contributing to increased coliform growth in bedding of our free stalls. A trend of higher coliform concentrations in bedding with high moisture percentages was apparent. Statistical analysis correlating final moisture with final coliform nunbers showed no relation existed. This was probably due to data where coliform nunbers increased and 59 moisture percentages decreased.with time. Carroll (1977) cites moisture plays a role in regrowth of coliform bacteria. Freshly composted manure solids in this research contained approximately 77% water, far above the 40% minimun suggested by Carroll et al. (1977) necessary to prevent rapid coliform regrowth. Dale et al. (1975) reports ambient hunidity decreases drying of manure solids in free stalls. Consequently, high ambient hunidity, which decreased drying of the wet manure solids (77%), and high ambient temperatures may have served as the parameters other than cow contact in stimulating coliform growth in dairy manure solids in free stalls. This agrees with Smith et al. (1985) who cites high temperatures and humidity of Ohio summers to explain increased coliform bacterial growth in dairy manure solids. Since ambient conditions cannot be economically controlled and initial coliform counts were unrelated to final coliform counts, decreasing initial moisture would be one method of controlling bacterial regrowth. Composting in our area does not adequately dry solids and forced.drying is not usually cost effective. No relation existed between coliform nunbers in bedding and incidence of mastitis though coliform numbers were always above 10‘ in bedding of free stalls where cows contracted acute mastitis. Consequently, factors other than bedding numbers predicated acute mastitis. Carroll (1977) cites higher milk producing, uninfected cows in early lactation are more susceptible to coliform mastitis due to decreased somatic cell counts and increased stress from recent calving and high milk production. Our few cases of mastitis support results of Carroll (1977); infected cows were in the first half of lactation, 60 produced over 73 pounds of milk daily, and in all but one case had low somatic cell counts. Duration of exposure of teats to contaminated manure solids may have been another factor contributing to acute mastitis. Mastitis outbreaks occurred first with cows bedded with manure solids on dirt free stalls. Coliform numbers were similar for concrete and dirt based free stalls but a greater amount of dairy manure solids stayed on dirt based free stalls than on concrete free stalls with mats. The second outbreak of mastitis occurred with cows bedded on cement free stalls with mats but only when the application of dairy manure solids was doubled. Coliform concentrations in bedding of these free stalls previous to the outbreak were similar to coliform concentrations in the bedding when mastitis was observed. These increased bedding amounts could have potentially increased duration of exposure of tests to bedding containing high numbers of coliformlbacteria. Acute mastitis may have resulted from this increase exposure. Sweeping out solids daily from the rears of stalls may not have been enough to reduce exposure when application rate of solids to free stalls was doubled. Common practice in Michigan farms is to top freshly applied dairy manure solids with lime, sawdust, etc. to shield dairy cows from wet dairy manure solids until bedding dries. These farmers and farmers quoted by Carroll and Jasper (1978) cite mastitis outbreaks are possible if "wet" dairy manure solids are used.directly in free stalls. Bishop et al. (1981) found tests they sampled contained coliform bacteria. They concluded moisture from manure solids used at their facility (74.3% moisture) prcbably caused adherence of coliform bacteria to these tests 61 as coliform bacteria are poorly adapted to survival on normal teat skin. In the free stalls where cows contracted acute mastitis in the second phase of this research, composted manure solids were not only more abundant but were wetter than solids used in the same stalls previously. SUMMARY Economic justification of manure separation facilities occurs more readily on larger farms where increased bedding usage increases savings realized by replacing conventional bedding with dairy manure solids. Smaller farm must incur higher prices for bedding to generate enough savings to justify investing in separation facilities. Since more of bedding savings of small farms goes towards serving fixed costs, variations in economic feasibility parameters (herd size-bedding price combination) due to fluctuations in tax rate, rate of return and loan interest rate are more pronounced for these small farms. Savings of $17.48 realized from a ton of bedding services variable costs. This cost can be imputed to be the variable cost of a ton of dairy manure solids in other analyses. Overall, composting dairy manure solids was inadequate in decreasing coliform concentrations or moisture percentages enough to prevent rapid regrowth of coliform bacteria once solids were placed in free stalls. Moisture seemed to be the determining factor as coliform bacteria in solids containing 103 coliforms per gram bedding wet weight regrew to levels above 10‘ within four days. Duration of exposure of tests to bedding containing high numbers of coliform may be a factor contributing to coliform mastitis. Sweeping solids from the rear two 62 63 feet of stalls daily was apparently ineffective in preventing mastitis in two high producing, uninfected cows in early lactation. Consequently, herds with low somatic cell counts and.with no staphylococcal or streptococcal infections should not use dairy manure solids to bed early lactation cows with low somatic cell counts due to its association with coliform mastitis. Further research is needed to identify methods to maintain coliform numbers below 10‘ per gram bedding wet weight or to prevent normally susceptible cows from being infected. BIBLI(XIRAPHY BIBLIOGRAPHY Allen, Stan, Max Wallentine, Scott Austin, Paul Burch and Keith Hoopes. 1977. Recycled Manure Solids as Free Stall Bedding for Lactating Dairy Cows and its Association Mastitis.Report from the National Mastitis Council. 121-127. Battayler R.A. and V.B. Mayrose. 1981. Handbook of Livestock Management Techniques. Minnesota: Burgess. p. 558. Bishop, J.R., J.J. Jansen and A.B. Bodine. 1980. Effect of Ambient Environments on Survival of Selected Bacterial POpulations in Dairy waste Solids. J. Dairy Sci. 63:523-525. Bishop, J.R., J.J. Jansen, A.B. Bodine, C.H. Caldwell and W. Johnson. 1981. Dairy waste Solids as a Possible Source of Bedding. J. Dairy Bramley, A.J. 1985. Proc. 1985 Ann. Ntl. Mastitis Council. p. 4. Bramley, A.J. and Frank H. Dodd. 1984. Reviews of Progress of Dairy Science Mastitis Control-Progress and Prospects. J. Dairy Res. 51: 481-512. Bramley, A.J. and F.R. Neave. 1975. Studies on the Control of Coliform Mastitis in Dairy Cows. Brit. vet. J. 131:160—169. Carrol, E.J. 1977. Environmental Factors in Bovine Mastitis. J. Amer. Vet. Med. Assoc. 170:1143-1149. Carrol, E.J. and D.E. Jasper. 1979. Coliform POpulations in Bedding Materials and Coliform Mastitis Incidence. university of California, Davis, California. Carrol, E.J. and D.E. Jasper. 1978. Distribution of Enterobacteriacae in Recycled Manure Bedding on California Dairies. J. Dairy Sci. 61:1498—1508. Chore Reduction for Free Stall Dairy Systems. 1978. Boards Dairyman. Wisconsin. Coliform Research committee-A Subcommittee of the Research Committee of the National Mastitis Council. June, 1975. 65 66 DeHart, Dorothea A., R.P. Natske, and P.A. Oltenacu. 1975. Effect of Coliform Challenge at Milking Time on New Udder Infections. J. Dairy Sci. 59:1124-1130. Dodd, F.H., T.M. Higgs and A.J. Bramley. 1984. Cubicle Management and Coliform Mastitis. Vet. Record. 114:522-523. Eberhart, R.J. 1977. Coliform Mastitis. J. Amer. Vet. Med. Assoc. 170: 1160-1163. Eberhart, R.J. R.P. Natske, F.H.S. Newloud, B. Nonecke and P. Thompson. 1979. Coliform Mastitis-A.Review. J. Dairy Sci. 62:1. Finstein, M.S., F.C. Miller, P.F. Strom, S.T. MacGregor and K.M. Psarians. 1983. Composting Ecosystem Management for Waste Treat- ment. Bio/Technology 1:347-353. Finstein, M.S., and M.L. Morris. 1975. Microbiology of Municipal Solid Waste Composting. Adv. Appl. Microbiology. 19:113-151. Finstein, M.S., F.C. Miller and P.F. Strom. 1986. Monitoring and.EValua ting Composting Process Performance. J. water Pollut. Control Fed., 58:272-278. Francis, P.G., J. Summer and D.A. Joyce. 1981. Influence of Winter Environment of the Dairy Cow on mastitis. Bovine Practitioner. 16: 24-27. Hughes, Patricia J. and.Kaz Ochi. 1984. Financial Analysis with Lotus 1-2-3. Janzen, J.J., J.R. Bishop,.A.B. Bodine, C.A. Caldwell and D.W. Johnson. 1982. Composted Dairy Manure Solids and Crushed Limestone as Bedding in Free Stalls. J. Dairy Sci. 65:1025-1028. Jasper, D.E. J.D. Dellinger and.R.B. Bushnell. 1975. Herd Studies on Coliform Mastitis. J Amer. Vet. Med. Assoc. 166:778-780. Keys, J.E., L.W. Smith, and B.T. Weinland. 1976. Response of Dairy Cattle Given a Free Choice of Free Stall Locations and Three Bedding Materials. J. Dairy Sci. 59:1157. Larsen, R.J., G.H. Schlough and O. Conner. 1978. Chore Reduction Research-Final Report. Coll. of Agric. and Life Sci. Uhiv. of Wis.-Mbdison. Moore, James A. 1983. Manure System Costs Vary Greatly. Hoards Dairyman. 128:19. Natske, R.P. and Barbara J. LeClair. 1976. Coliform Contaminated.Bedding and New Infections. J. Dairy Sci. 59:2152-2154. 67 Oregon State University Ectension Service. 1982. Selecting a Dairy Waste Management System for the Oregon Coast. EC 1104. Rendos J.J. R.J. Eberhart and E.M. Kesler. 1981. Microbial Populations of Test Ends of Dairy Cows and Bedding Peterials. J. Dairy Sci. 64:706-711. Safley, L.M. and W.C. Fairbanks. Proc. 1983 Ntl. Dairy Housing Conference. Schalm, O.W., E.J. Carrol and N.C. Jain. 1971. Bovine Mastitis. Vol. 1. Lea and Febegers. Pennsylvania. Smith, K. Larry, H.H. Harrison, D.D. Hancock, D.A. Todhunter, and H.R. Conrad. 1984. Effect of Vitamin E Supplenentation on Incidence of Clinical Mastitis and Duration of Clinical Symptoms J. Dairy Sci. 67:1293-1300. Smith, K. Larry, D.A. Todhunter and P.S. Schoenberger. 1985. Environmental Phstitis: Cause, Prevalence and Prevention. J. Dairy Sci. 68:1531-1553. Thms, C.B., D.E. Jasper, M.H. Rollins, B.B. Bushnell and E.J. Carroll. 1983. Enterobacteriaceae Bedding Populations, Rainfall and mastitis on a California Dairy, Prevent. Vet. Med. 3:227-242. Weigt, V. 1980. Clinical Aspects of Coliform Mastitis in the Bovine. Vet. Res. Communications. 7:253-257. White, R.K. and D.L. Forster. 1978. Evaluation and Econanic Analysis of Livestock Waste Managenent System. E.P.A—600-78-102:200-201. Wiley, B.B. and 3.0. Westerburg. 1969. Survival of Hunn Pathogens in Composted Sewage. Appl. Micrcbiol. 18:994. Willson, G.B. 1971. Composting Dairy Cow Wastes. Proc. 1971 Intl. Symp. on Livestock Wastes. p.163. Willson, G.B. and J.W. Hnmel. 1973. Solid Composting of Dairy Phnure. Prcc. 1973 Intl. Symp. on Livestock Wastes. pp. 441-459. Yungblut, D.H., J.L. Albright, D.L. Hill, and N.J. Moeller. 1974. Effect of Stall Location and Surface mterial Upon Cow Preference, Stall Use, Cleanliness, Udder Health, and Laterality in Free Stall Dairy Barns. J. Dairy Sci 57:630 (Abstract). Zehner, M.M., R.J. Farnsworth, R.D. Apple-an, K. Lands and J.A. Springer. 1986. Growth of Environmental Pathogens in Various Bedding Materials. 69: 1932-1941.