AN INVESTIGATION OF WOOL CHARACTERISTICS, GROWTH AND SKIN FOLDS IN A CROSS BETWEEN RAMBOUILLET AND BLACK TOP DELAINE SHEEP By YOUSSEF SALAH ELDIN GHANEM A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Animal Husbandry 1951 ProQuest Number: 10008694 All rights reserved INFORM ATION TO ALL USERS The quality of this reproduction is-dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10008694 Published by ProQuest LLC (2016). Copyright o f the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 ACKNOWLEDGMENTS The investigator wishes to express his indebted­ ness to Professor R. H. Nelson, head of the Animal Hus­ bandry Department, for his helpful suggestions and criticism during the preparation of this manuscript, and for his constructive guidance. The great concern with which Professor H. R. Hunt head of the Zoology Department, has planned this experi­ ment, collected the data and actually taken part in meas uring the wool characteristics, was indispensable for the successful completion of the experiment. This, to­ gether with reviewing the manuscript, constant supervi­ sion and kind suggestions are deeply appreciated by the author. He is also thankful to Professor W. D. Baten of the Mathematics Department for his valuable assistance in the statistical analysis of the results. Grateful mention is hereby made of the Egyptian Government Scholarship, which made it possible for the author to complete this investigation. VITA Youssef Salah Eldin Ghanem was born in Cairo, Egypt on November the 13th, 1924. He completed his primary and secondary school education in Egyptian Government Schools. In June, 1946, he obtained the B.V.Sc. degree from the Veterinary College of Fouad I University, Gizah. He was employed as a demonstrator in that college In August, 1946, and was later appointed as a member of its Educational Mission to the U. S. A. In this country, he entered Cornell University, Ithaca, N. Y. where he obtained his M.S. degree in Animal Psychobiology in September, 1949. He then entered Mich­ igan State College, East Lansing, Michigan as a candi­ date for the Ph.D. degree, with Animal Breeding as major and Genetics and Statistics as minor subjects. After returning to Egypt, the author will teach Animal Breeding and Genetics at the Veterinary College of Fouad I University. TABLE OF CONTENTS Page INTRODUCTION................................ 1 THE PROJECT.................................. 3 SKIN FOLDS . . . . . . ........................ 9 ................................ 9 Literature Material and Methods. . . . . . ............... Results.................................... Neck Values .......................... 11 12 12 Body Values................................ 14 Combined Neck and Body values............... 24 WOOL CHARACTERISTICS........................ Literature ... Fiber Length ....... . . . . . . . . . . 28 28 .................... Fiber Diameter and C r i m p ................. Material and M e t h o d s ....................... Results...................................... 28 30 34 37 Fiber L e n g t h ...................... 37 Fiber D i a m e t e r ............................ 40 C r i m p ...................................... 40 Grease Fleece Weight ....................... 44 G R O W T H ........................................ 49 Li terature.................................. 49 Material and M e t h o d s ......................... 51 V Page Results . . . . . .......................... 52 Growth Curves ............................ 54 RELATIONSHIPS AMONG THE CHARACTERS STUDIED Correlations ... 62 .............................. 62 Descriptive Statements ... ............... 65 DISCUSSION OF THE RESULTS..................... 66 Skin F o l d s ...................... .......... 66 Wool Characteristics 68 ......... . . . . .. . Fiber L e n g t h .......................... 68 Fiber Diameter and C r i m p ................. 69 ..................... 70 Grease Fleece Weight Shoulder versus Hip Samples . . . . Growth ....... .................................. Relationships Among the Characters Studied . . 70 71 72 ............................ 74 POSTSCRIPT.................................. 75 SUMMARY..................................... 79 A P P E N D I X .................................... 81 CONCLUSIONS BIBLIOGRAPHY................................. 103 LIST OF TABLES Table I Page Annual Precipitation and Precipitation from April to November in Lansing* Mich. (1930-1937) ..................... II II-A III Averages and Standard Deviations of Neck Fold Values at Yearling Age ... 13 Analysis ofVariance of Neck Values ... 15 ... 16 Averages and Standard Deviations of Body Fold Values at Yearling Age III-A Numbers andBody Values of Groups and Sexes III-B ............................ 19 Completed Analysis of Variance of Body Values III-D 18 Numbers and Mean Body Values in Both Sexes of the Four G r o u p s ............. III-C 8 ........................ 21 Calculating the Weighted Mean Dif­ ference Between the Rambouillet and F^ Groups IV ............... 23 Averages and Standard Deviations of Combined Neck and Body values at Yearling A g e ...................... IV-A 25 Completed Analysis of Variance of Combined Neck and BodyValues.......... 26 vii Table V Page Average Fiber Lengths of the Shoulder and Hip Samples of a 365 Days Wool G r o w t h ............................ V-A 38 Completed Analysis of Variance of Average Fiber Lengths of Shoulder and Hip Samples............. . . . . VI 39 Average Fiber Diameters of the Shoulder and Hip Samples During January Approximately VI-A ..................... 41 Completed Analysis of Variance of Average Fiber Diameters of Shoulder and Hip Samples..................... VII 42 Average Number of Crimps per Two Centimeters in the Shoulder and Hip Samples VTI-A ........... 43 Completed Analysis of Variance of Average Number of Crimps per Two Centimeters in the Shoulder and Hip Samples . . . . VIII Average Unscoured Fleece Weights of a 3 6 5 Days Wool G r o w t h ............. VIII-A 45 46 Completed Analysis of Variance of Unscoured Fleece Weights ........... 48 viii Table IX Page Averages and Standard Deviations of Body Weights at 6 , 16 and 52 Weeks of Age, Adjusted to a Female Single Basis IX-A ......................... 55 Completed Analysis of Variance of Average Body Weights at 6 , 16 and 52 Weeks of A g e ...................... X 56 Coefficients of Correlation Between Skin Folds, Wool Characteristics and Body Weight....................... 64 LIST OF FIGURES Figure Page 1. Crosses in the Parental Generation .... 2. Matings in the F^ Generation. . . . . . . 3* Growth of the Female S i n g l e s ..... 58 4. Growth of the Male S i n g l e s ....... 59 5. Growth of the Female T w i n s ....... 60 6. Growth of the Male T w i n s ......... 6l 5 6 INTRODUCTION Crossbreeding in sheep has been extensively prac­ ticed for different purposes. Experimental crosses have been carried out to discover the mode of inheritance of various traits (Tomhave and McDonald, 1920, Ritzman, 1923, Jones, et al*, 1946, etc.). New breeds of sheep have been developed through the crossing of the older breeds, while occasional outcrossing has been practiced for improving the breeds in general. Crossbreeding has also been used widely by sheepmen for commercial lamb production. However, the crosses that have been studied and reported were mostly between fine-wool and muttontype breeds or between two mutton-type breeds. The present study deals with a cross between two fine-wool breeds, the American Rambouillet and the Im­ proved Black Top Delaine Merino. The American Rambouillet Breed was derived largely from the French Rambouillet sheep imported into this country as early as 1840. The French Rambouillets were developed from Spanish Merinos brought to Rambouillet, France, in 1 7 8 6 and 1801 from Spain (Dickson and Lush, 1933)• The Rambouillet is a very popular breed in the United States, especially in the western states where it is used in the range flocks because it combines good 2 wool characteristics with mutton qualities unparalleled by any of the other Merino breeds. Mature Rambouillet rams weigh on the average about 225 pounds, and mature ewes, about 155 pounds. The fleece of the Rambouillet is similar to that of the Delaine Merino (Vaughan, 1948), but has slightly coarser fibers, and the length of a twelve months growth of staple is about 2^ to 3 inches. The Rambouillets also have smooth bodies, with two or three neck folds and an apron. The Improved Black Top Delaine breed was developed in Washington County, Pennsylvania, from the American Merino, which in turn originated from the Spanish Merino. The "Improved Black Top Delaine Merino Sheep Breeders' Association" was established in 1 8 8 5 . The rams of this breed weigh on the average about 180 pounds and the ewes, about 130 pounds. The Improved Black Top sheep have smooth bodies and long, or "Delaine," wool. These and other strains of the Delaine Merinos are becoming less popular than they were at the time this experiment was started. THE PROJECT1 The objective of the project was to learn more con­ cerning inheritance in the sheep, and if possible to im­ prove the Rambouillet breed. The traits studied were wool characters (fiber length, crimp, fiber diameter and unscoured fleece weight), skin folds, and growth during the first year of life. The animal breeding point of view was to improve the wool bearing qualities of the Rambouillet, and to secure a type that combines the long wool of the Delaine with the growth qualities of the Rambouillet. The experiment was started in 1929 by crossing a registered yearling Rambouillet ram with 15 Black Top Delaine ewes of varying ages (from 2 to 7 years old). Later, in 1931* another registered Rambouillet ram was crossed with four Black Top Delaine ewes. ewes were from the 15 ewes crossed in 1929sheep were raised. Two of these Twenty Ten were males and ten were females. ^ Professor H. R. Hunt, the head of the Zoology Department at M. S. C., started the experiment in 1929, in collaboration with Prof. G. A. Brown, the previous head of the Animal Husbandry Dept., for the Michigan Agricultural Experiment Station. All the wool samples, fleece and body weights and photographs were collected by Prof. H. R. Hunt. Measurements of the samples were made by Prof. H. R. Hunt, Prof. C. A. Lawson and the author. The statistical analysis was performed by the author. 4 Five of the males were castrated and sold after weaning. Thus it was possible to obtain yearling data on five F-^ males and 10 F^ females. Figure 1 shows the parental crosses and the F-^s. One crossbred (F-^) ram was mated to the 10 cross­ bred females during the period from 1931 to 1937* F^ ram was mated to four F^ females. The total number of F^fs produced was 45* 27 males and 18 females. Data were obtained on 22 male and 15 female F^ individuals. 2 Another Figure shows the F^ matings and the F ^ s produced. Control sheep were used during the experiment. However, they were all born between 1933 and 1937, in­ clusive, during which period the F^ animals were born. There were no control sheep in 1930 and 1932 when the F^ animals were born. The control sheep represented the two parental breeds, Top Delaine. the Rambouillet and the Black There were 16 Rambouillet controls (4 males and 12 females) and 18 Black Top Delaine controls (7 males and 11 females). All the animals used during the experiment be­ longed to Michigan State College, and the facilities of its Department of Animal Husbandry were used for raising and feeding the sheep. 1 Castration was not desirable, but was necessary due to lack of space in the barn. Q> •C cf « s pH If? ^^ $ o+ o'!3 | , b ^o 0+ K in the Parental Generation vs XI s& a Js; O Ctf r-H PQ ffj o Of 5\f SOS I ^ * <\j C* 0 + Os Os i*\l v$ <\l 7^ 0+ 1 J* **> CH I > <0 <\j 5! ‘Vi o <\i £ $ *Vi ‘Xl *s Of Qf Of Of 5J? § i i * *> jv>5> I * I Vb o _T J IT & K £ Vo £ $ *\i C hk Of Ox Of $ £ § I J 1 & U* hSLr Crosses 2 O o Eh 1. •H Figure r~l rH 0 « a* vs T \> o 'g ^b^b^b^b^b !b 2? I o+ X)^OX> O O V >*C IV . o^ *3 $Site ft o fot f ot k o Ho. (v!j>. So <\jqj) SC v£ *n 9* Ib ' CH N. 0 + \)T)^D^D OK) o+ Jj!:v* v y> ^p k S * os f ot \ l y$)N* 54^5j 0 0 * 0 2>^sT ?>?>*> £} > K r> o *5 O Ni <*>S Jo Vs ■S'*? ! 5 ) w s. k < Q 0 O0 % £> *o >ip ^ ^ ^ ^ ^ v X )ooocrfb o o. ^ ^ x> *bo+o *b o o ^ >|^f>so 3 3 *> ? * & § * $ N. I Figure 2* & V O K vr f ft ot o JO Matings in the F*. Generation > sn ^ N. k T w> ^ Or>^ *5 o ***** The lambs were docked shortly after birth and stayed with their mothers until weaning time at about 120 days of age. They were raised under barn conditions until about the end of May, when they were put to pas­ ture. They stayed on pasture until toward the end of November, when they were returned to the barn to stay until the next pasture season. Conditions in the barn were kept constant from year to year as much as possible. The pasture, however, varied from year to year due to different precipitation during different years. Table I shows the annual precipitation and the precipitation from April to November in Lansing during the years 1930 to 1 9 3 7 # inclusive. 8 o tPO ON H PO LfN * LfN CM VQ « PO PO 1 0 P — I>PO ON G cd bO *H XS O ■H s pH vo LfN VO • ANNUAL PRECIPITATION AND PRECIPITATION PROM APRIL TO NOVEMBER IN LANSING, MICH. (1930-1937)* PO ON rH o CM OJ CX3 CM • rH PO LfN PO ON i—1 PO ON i—1 «\ cd 40 cd Q Ct'— • 0 > •H P cd G cd ["—• CO • 00 rH O O • i—1 CV1 00 CM • LfN PO VO LO * i—1 CM • CM CM bO G •rH 0 C cd i-5 ft a o G o fH X! c •H * IS G «* iH P >> 60 PO PO ON H pH PO CM VO • PO CM CM CM • CM PO ON «H ^sPO rH PO ON i—1 Phi *rt os x : S O S *H G s GQ •» p H bO cd G O H •H 09 bO G O cd rH 1-5 O PO VO • 00 G -v o G 0 cd P 0 0 G s 3 VO o • l'- CM rH rH PQ cd G * * O LfN • 00 o PO ON i—i G 0 G XI G P < cd ts 0 Js 0 CM CM • rH i—1 rH x: p G O •H -P cd -P -p •H rH cd G G G < ft *H O O 0 & (X, G • 0 O u rH P G ft s 0 CD U ft S o G ft * <$ GO 0 •H ft *H * P G o •ri P cd < > o * * to o P cd P *H ft •H O 0 G ft rH cd p o p pH cd G G G cd * t— P ro 0 ON Cd rH 0 rH rO C 0 cd XI p -= s t000 Cd rH 0 0 G tH cd x: 0 Eh * * p *> <2 x: i •* 0 Js; XI p c O ft o £ P 0 0 p SKIN FOLDS Literature Most sheep of the fine-wool type are character­ ized by having skin folds or wrinkles. These are caused by faster growth of the skin in proportion to the other components of the body during the early stages of life. Studies on the inheritance of skin folds have been conducted by various workers. Jones, et al. (1936, 1937* 1 9 3 8 * 1 9 3 9 and 1 9 ^0 ) reported on the inheritance of skin folds in the Rambouillet sheep. Their reports indicate that the number of genes involved is relatively small, and that the genes for freedom from skin folds appear to be dominant. Similarly, Jones, et al. (1946) in a study of a cross between Rambouillet and Corrledale (smooth) sheep, concluded that the lack of skin folds is due to dominant multiple genes. Madsen, Esplin and Phillips (1943) in a report on skin folds in the Ram­ bouillet showed a relationship between the number of folds on the dams and on their offspring. The correla­ tion between dams and daughters at yearling age, with the sire held constant, was + 0.17. In another study of neck folds in Rambouillet lambs by Terrill and Hazel (1946), the average heritability was O .3 9 ± 0 .0 5 . They found significant variations in neck folds between inbred 10 lines. In the yearling ewes, the same authors (Terrill and Hazel, 1943) found that heritability was 0.26 for neck folds and O .3 2 for body folds. The effects of some environmental factors on skin folds have also been reported. Carter (1941) found that the development of neck and body folds in the Australian Merino sheep was reduced on a low plane of nutrition and augmented on a high plane. Burns (1935) observed a three to three and a half times increase of skin area between the ages of one month and twelve months. Madsen, Esplin and Phillips (1943) also found an increase in skin folds as the sheep matured. Hazel and Terrill ob­ served that folds were more extensive on single sheep and those from mature dams than on twins and those from 2 -year-old dams respectively, both at weaning (1945) and yearling (1946) ages. They also found that ram lambs had more extensive folds than ewe lambs. Jones, est al# (1946) also found that males had significantly greater skin-fold values than females. Skin folds are in many ways related to wool pro­ duction. However, the older view that the greater the folds, the heavier the fleece, has been proved mislead­ ing. Fleece from the more wrinkly sheep shrinks more than fleece from the smoother type according to a study by Jones, et al. (1944). They did not find a significant 11 difference in clean (scoured) wool produced by the wrinkly and smooth type Rambouillet sheep. In the same study, Jones, et al. found a small but significant difference in staple length in favor of the smooth type. They indi­ cated that there is greater uniformity of fineness of fibers in the smoother type. The smoother type sheep are also easier to shear (Madsen, Esplin and Phillips, 1943) and are less susceptible to blow flies, than the wrinkly type (Jones, et al., 1937)Material and Methods Photographic pictures of the F-^s, the Fg ' 3 ana ToJ ID ON • n c— D— OO • CTn O rH P PK*S O PQ 0 1 —1 ctf S 0 I—I 0 B 0 fo B I O Eh rH 00 Oh 43 -P U P £ fc*n * t>- 43 3 55 rH aJ p o Eh oo m • B 3 CO §3 § 19 •? rH o oo c— * OJ 1 t— 00 t• i—1 VO tn o o o 1 —1 • 04 bMO VO VO • OJ rH LO 1 • OJ • o in 00 • OJ 00 VO OJ * I—t 1 rH o in r00 • t— 0oo 1 —1 • LO rH OJ OO • LT\ VO (J\ m • t** (—l OJ OJ • tn OJ £■— oo o rH -3i—i t— LO oo 00 OJ rH oo OJ <—1 • 0 - oo -=i~ iH a 0 rv 3 S 15 1* 0 • o m * co o o VO • m rH s rH CO i—i 0 C •H rH a 3 o u -p (D tH iH *H rH 00 i—1 • o I VO 1 —1 • O 1 OJ 1* 0 M M M t— • _rj- • A O VO 0 Q ft o Eh 00 00 C7\ -=*• m rH 3 O rQ s Ph o Cj rH rH 0J NOTE; 3 LA VO Body values signify skin folds on the body from the shoulder to the hip* OO OO oo Sum of squares for sexes » (SWD)2/SW = (-0.181)2/l5*4988 = 0.0021 Sum of squares of sexes from Table III-A = (159*99)2/29 + (2 2 7 *5 B) 2/ 3 9 - correction term - 1 ,6 8 7 1 Correction for interaction « 1 ,6 8 7 1 - 0 .0 0 2 1 = 1 .6 8 5 0 Sum of squares of groups from Table III-A = (4 3 .0 3 )2/10 + . . . + (l64.17)2/32 - correction term = 9 2 .9 2 0 9 Corrected sum of squares for groups = sum of squares of groups from the table - correction for interaction » 9 2 .9 2 0 9 - I.6 8 5 O « 9 1 *2 3 5 9 Interaction sum of squares ~ SWD p p - (SWD) /SW = 2 6 .5 8 2 0 - 0 .0 0 2 1 « 2 6 .5 7 9 9 Then the complete analysis of variance table was constructed (Table III-C) The individuals mean square was used as an error term for testing the mean squares for groups, sexes and interaction. The following is an example of the procedure used in the F-test: ■p, * _ groups groups mean square Individuals mean square _ ** 30.41 6 . $3 j, ” Jlcr * 21 TABLE III-C COMPLETED ANALYSIS OF VARIANCE OF BODY VALUES Degrees of Freedom Sum of Squares Mean Square Groups 3 91*2359 30.41** Sexes 1 0 .0 0 2 1 0 .0 0 2 1 Interaction 3 2 6 .5 7 9 9 Individuals 60 Source of Variation 8 .8 6 6 .8 3 ** Indicates significance at Ifo level. NOTE: Body values signify skin folds on the body from the shoulder to the hip. 22 At 3 and 60 degrees of freedom 4-.45 is found to exceed the F value (4.13 according to F-table) needed for reach­ ing significance at the one-per cent level. It is to be concluded that variance caused by the differences be­ tween group means is significant at the one-per cent level. This means that only once in every 1 00 times can one expect to obtain an F value of 4.13 by chance alone. When the sums of squares for sexes and interaction were tested they were found not to be significant* The next step was to test the differences between each two group means. As an illustrative example the difference between the Rambouillet and F-^ group means is tested as follows: The numbers and means of the Rambouillet and F-^ groups in both sexes are put in a table (Table IIX-D) as mentioned by Snedecor (1946, page 290). Weighted mean difference = SWD/SW = 20.3825/5-B3 - 3.50 Variance of weighted mean difference = (Individuals mean square)/(SW) - 6.83/5.83 = 1.172 s « ^/l.l72 = 1.08 t «= 3.50 /1.08 = 3.24** At 60 degrees of freedom the t value of 3*24 Is found to be significant at the one-per cent level (look 23 TABLE III-D CALCULATING THE WEIGHTED MEAN DIFFERENCE BETWEEN THE RAMBOUILLET AND Fx GROUPS Rambouillet F1 Sex W kl X1 k2 D WD X2 Male 3 2-357 4 8.352 1-71 -5-995 -10.2514 Female 7 5.137 10 7.596 4.12 -2.459 -1 0 .1 3 1 1 5-83 20.3825 24 t-table). By performing similar tests, it was found that the difference between F-^*s and F ^ s was also sig­ nificant at 3$ level. Other differences were found not to be significant. Combined Neck and Body Values: The neck values were combined with the body values and averaged. The averages and standard deviation as shown in Table IV were: 9*92 + 3*42 for the Rambouillet controls, 10.74 t 4.85 for the Black Top Delaine con­ trols, 13*74 ± 2.59 for the F1*s and 10.57 ± 3-30 for the Fg's. By using the method of analysis described on page 14, the information in Table IV-A was obtained. The groups mean square was found to be significant at the 5-per cent level. The sexes and interaction mean square were found not to be significant. Then the t-tests were performed (see page 22) and the following results were obtained: The differences be­ tween the Rambouillet controls and the and between the F^'s and F2*s were found to be significant at the one-per cent level. The difference between the Black Top Delaine controls and the F-^'s was significant at 5 per cent level, while the differences between the Ram­ bouillet controls and Black Top Delaine controls, between 25 TABLE IV AVERAGES AND STANDARD DEVIATIONS OP COMBINED NECK AND BODY VALUES AT YEARLING AGE Group Number of Animals Average Standard Deviation Rambouillet controls 10 9-92 ±3-42 Black Top Delaine controls 12 10.74 +4.85 Fi's 14 13-74 ±2-59 F 2 's 32 10-57 ±3-30 NOTE: Combined neck and body values signify skin folds on the neck and body. 26 TABLE IV-A COMPLETED ANALYSIS OF VARIANCE OF COMBINED NECK AND BODY VALUES Degrees of Freedom Sum of Squares Mean Square Groups 3 1 1 8 .7 6 4 3 39-59* Sexes 1 0 .3 6 1 8 0 .3 6 Interaction 3 1 6 .7 6 3 0 5-59 Individuals 60 Source of Variation 1 2 .8 5 * significant at 5 per cent level. NOTE: Combined neck and body values signify skin folds on the neck and body. 27 the Rambouillet controls and the Black Top Delaine controls and the to be significant. d and between the s were found not It is worth mentioning at this stage that there is an Indication of heterosis in the as evidenced by a significantly higher average combined neck and body value than either one of the parental breeds (the Rambouillet and the Black Top Delaine). WOOL CHARACTERISTICS Literature Fiber Length: The length of the wool fiber is one of its most important characteristics. Wools of the same grade are classed into combing and clothing wools according to their staple lengths. The manufacture of fine worsted material depends on wools of the longer combing classes. Woolen fabrics are usually made from the shorter cloth­ ing wools. In this classification, staple length is used in reference to the length of the wool fibers. Staple length, as differentiated from fiber length, Is measured without stretching the fibers. In measuring the fiber length, the fibers are stretched to remove the crimps. According to Hultz (1927)* the length of the stretched fibers are directly related to the length of the staple. He found that, on an average, the staple lengths of the Rambouillet, were 66.54 per cent of their fiber lengths. Like most of the other economic characters, staple length is thought to be transmitted from parent to off­ spring through multiple-factor Inheritance (Ritzman and Davenport, 1 9 2 6 ). Hazel and Terrill (1945a) measured heritability of staple length in range Rambouillet 29 weanling lambs and found it to be 0.40. In the yearling Rambouillet ewes, they found heritability of staple length to be O.3 6 * Staple length is directly correlated with fleece weight, according to studies by Spencer (1925)* Spencer, Hardy and Brandon (1928), Lambert, Hardy and Schott (1938), Pohle and Keller (1943) and Jones et al, (1944). Staple length differs according to the part of the body in which the measurement is taken. Hultz and Paschal (1 9 3 0 ) found that staple length in the shoulder region was slightly more than staple length in the thigh region of Rambouillet sheep. Similar studies by Ensminger (1942) revealed that there was an inherent gradient in length from the fore to the rear part of the body, with the longest wool on the britch and the shortest on the head. Certain factors such as age, sex, plane of nutri­ tion and type of birth tend to influence staple length. At the age of one year, staple length was found to be significantly greater than at any of the subsequent ages up to eight years (Jones, et al., 1944). Lambert, Hardy and Schott (1938) reported that the correlation between weanling length of fleece and yearling length was +O.6 5 . Wilson (1930) found that staple length was greater on a high than on a low plane of nutrition. Hazel and Terrill 30 (1 9 ^5 ) observed that ewe-lambs at weanling age had longer staple than ram lambs, while at yearling age (Terrill, Sidwell and Hazel, 19^8), rams had greater staple length than ewes. Hazel and Terrill (1946) found that yearling ewes from two-year-old dams had shorter staple length than those from mature dams. They also found that sta­ ples of ewes from single births were longer than staples of twins and twins raised singly. Fiber Diameter and Crimp: Fiber diameter is the most important of all wool characteristics. The fine-wool breeds of sheep have smaller fiber diameters than the medium-wool or the longwool breeds. The systems of standardizing wool grades are based on the relative fineness (or diameter) of wool fibers. In the American system, the finest grade is called “fine," while the coarsest is called "braid." Fineness is associated with crimp, which causes the wool to have a wavy appearance. There is a negative correla­ tion between crimp and fiber diameter according to stud­ ies by Hultz (1927) and Darlow (1930). Different methods for measuring fiber diameter have been studied by Barker and King (1 9 2 6 ), Burns and Koehler (1925), Grandstaff (19^0)* Hardy (1935)* Hardy and Wolf (1939)> McNicholas and Curtis (1 9 3 1 ), Pohle 31 (1940), Phillips, Schott, Hardy and Wolf (1940) and others. The exact mode of inheritance of fiber diameter is, so far, unknown, but is believed to be through mul­ tiple factors (Ritzman and Davenport, 1 9 2 6 ). Crosses between fine-wool and medium-wool breeds of sheep pro­ duce blending in the progeny (Burns, 1924). Fiber diameter differs according to the location from which the sample is taken. Hultz and Paschal (1930) obtained a higher average fiber diameter from thigh sam­ ples than from shoulder samples of Rambouillet sheep. Ensminger (1942 and 1942a) reported that, in Shropshire and Southdown sheep, wool ranked from the finest on the head to the coarsest on the rump and britch. Similar results were obtained by Pohle and Schott (1942 and 1943) with Rambouillet sheep. Their results indicated a trend in average fineness from the smallest average diameter on the wither, shoulder, back and side to larger average diameters on the rump and belly, to the coarsest fibers on the thigh. Certain factors as age and plane of nutrition af­ fect fiber diameter. According to Pohle, Keller and Hazel (1945), fiber diameter decreases between six and eleven months of age, showing a slight increase there­ after. Lambert, Hardy and Schott (1938) found that in 32 the Rambouillet, the correlation between weanling and yearling fineness of wool was +0.40. Jones, et al. (1944) reported that the yearling fleece was slightly finer than fleeces at older ages. Wilson (1930) observed that wool fibers were 2 6 .5 per cent coarser at the base on a fat­ tening ration than on a submaintenance ration. Fiber diameter is directly related to fleece weight, according to studies by Spencer (1 9 2 5 ), Spencer, Hardy and Brandon (1 9 2 8 ), Jones, et al, (1944) and Slen (1949). Fleece Weight: Fleece weight is a composite character that de­ pends on other wool characters and is affected by a number of environmental conditions. While its inheri­ tance, like the inheritance of other wool characters, is not clear, it is believed to be transmitted through multiple factors. The heritability of unscoured fleece weights was found to be 0.28 by Terrill and Hazel (1943) in Rambouillet ewes. They estimated heritability of clean fleepe weight at 0 .3 8 . Rasmussen (1942) estimated the coefficient of repeatability at G .5 6 in range Ram­ bouillet sheep. Age, sex, type of birth, body weight and plane of nutrition are some of the factors that influence fleece 33 weight• In the Rambouillet sheep, Spencer (1925) and Spencer, Hardy and Brandon (1928) observed that the aver­ age fleece weights increased with the age of the sheep from yearling age up to three years, and then showed a decline after three years. Lambert, Hardy and Schott (1 9 3 8 ) found a positive correlation of 0.43 between the weanling and yearling clean fleece weights of range sheep. Correlation between fleece weight at one shear­ ing and the fleece weight of the same sheep at the sub­ sequent shearing was found by Lush (1922) to be +0.6149. Yearling Rambouillet rams produce heavier unscoured fleeces than yearling ewes, according to Terrill, Sidwell and Hazel (1948). In the same study, it was found that single rams had heavier fleeces than twins and twins raised singly. Rams from mature dams also produced heavier fleeces than rams from two-year-old dams. Sim­ ilar results were obtained earlier by Hazel and Terrill (1946) in yearling Rambouillet ewes. On a high plane of nutrition, Wilson (1930) found that the grease fleece weight was 343 per cent greater than on a low plane of nutrition. Beside being influenced by fiber length and fiber diameter (as stated above), fleece weight is affected by body weight, with which it is positively correlated (Spen­ cer, Hardy and Brandon, 1 9 2 8 and Jones, et al., 1944). 3^ Material and Methods Two samples of wool were taken from each sheep at yearling age* 1 One sample was clipped from the mid­ dle of the shoulder, while the other sample was clipped from the area directly behind the point of the hip. Care was taken to clip close to the skin. Each of the two samples was labeled and inserted in a dry bottle. The bottles containing the samples were stored in a dry storage room until they were taken out for measure­ ment. The lengths of individual fibers were measured. The wool sample was first soaked in xylol (a fat solvent) until the grease was dissolved. After drying the sample, twenty-five fibers were drawn individually at random. Every fiber was stretched between the jaws of two pairs of forceps until the crimps barely disappeared, and then the length, in millimeters, was measured with a ruler on a black piece of velvet material. The average fiber length of the sample was then obtained by computing the mean of the twenty-five measurements. This was corrected to a 3 6 5 -days growth by using linear interpolation. The following is an example of the method used: 1 None of the parents was less than two years old at the beginning of the experiment; thus yearling samples were not available for the parents. 35 If the age of the animal at the time the sample was taken was 406 days, and the average length of twentyfive fibers from the sample was found to be 8 7 .5 milli­ meters, the corrected 3 6 5 -day fiber length would be 87-5 x 3 6 5 / ^ 0 6 » 7 8 .7 mm, approximately. The fiber diameters were then measured. After dissolving the grease with xylol, the sample was divided into 10 subsamples. A wisp was taken from each sub­ sample, and all the wisps were put together to form a combined sample. An attempt was made with each sample to measure the diameters of those sections of the fibers that grew during the month of January. It was assumed that conditions during the month of January in successive years were more constant than pasture conditions during the grazing season. The method can be illustrated by the following concrete example: Suppose a sample of wool had a staple length of 75 mm. This length of wool grew during about 12 months; so, the monthly growth was about 6 mm. Suppose the wool sample was taken from the sheep about the middle of March. The most proximal section of each fiber must have grown in March; immediately distal to this was the section grown in February, followed by January growth. If 9 millimeters (li months x 6 mm. = 9 mm.) were cut from the proximal end of the sample, the cut surface of 36 the sample would belong to wool that grew in January. A section of this January growth was cut off with scis­ sors, immersed in xylol, placed under a cover glass, and the diameters measured. A microscope equipped with a filar micrometer was standardized and used to measure the fiber diameters. measured at random. The diameters of fifty fibers were The average fiber diameter of the sample was then obtained by computing the mean of the fifty measurements and converted from micrometer units to microns. The number of crimps (or curls) per two centi­ meters were obtained from four different places in the wool sample. The four measurements were then averaged to represent the average ”crimp11 of the sample. The weights of the unscoured yearling fleeces of the F2*s an<1 con'trols were obtained. For statis­ tical analysis, the fleece weights were adjusted to a 3 6 5 -days growth by using linear interpolation which can be illustrated by the following example: If the fleece weight was 10.5 pounds and the age of the animal at shearing time was 400 days, the adjusted 3 6 5 -days fleece weight would be: 10.5 x 365/400 = IO.3 6 lbs., approximately. 37 Results Fiber Length; Average fiber lengths of the shoulder and hip sam­ ples were computed for each of the four groups of sheep used in the experiment. tained. Table V shows the averages ob­ The average fiber lengths of the shoulder sam­ ples were 82.86 + 10.82 mm for the Rambouillet controls, IO3 . 5 4 + 7*58 mm for the Black Top Delaine controls, 82.49 1 15*09 mm for the F ^ s and 9 2 .6 5 ± 9*86 mm for the F^'s. The average fiber lengths of the hip samples were 64.53 + 9 . 8 2 mm for the Rambouillet controls, 8 3 .4 2 + 11.66 mm for the Black Top Delaine controls, 61*37 ± 11.84 mm for the F^*s and 74.17 + 10.73 nun for the F2*s. An analysis of variance was performed (see page 14) and an F test revealed significant differences among groups in both the shoulder and hip samples (Table V-A). By using the t test on the weighted mean differ­ ences (page 22) it was found that, in case of the shoulder samples, the differences between any two of the four group means, except that between the Rambouillet controls and the F-j^'s, were significant at the one per cent level. The difference between the Rambouillet controls and the F^*s was found not to be significant. In case of the hip sam­ ple the results were similar, as far as significance of differences is concerned, except in case of the difference 38 TABLE V AVERAGE FIBER LENGTHS OF THE SHOULDER AND HIP SAMPLES OF A 365 DAYS WOOL GROWTH Shoulder Groups Number of Animals Hip Average Fiber Length in mm Stand­ ard Devi­ ation Average Fiber Length in mm Stand­ ard Devi­ ation Rambouillet controls 16 8 2 .8 6 ± 1 0 .8 2 64.53 + 9 .8 2 Black Top Delaine controls 18 103.5^ ±7.58 83.42 +11.66 F-^s 15 82.49 ± 1 5 .0 9 61.37 +11.84 F 2’s 37 92.65 ± 9*86 74.17 ±10-73 39 TABLE V-A COMPLETED ANALYSIS OF VARIANCE OF AVERAGE FIBER LENGTHS OF SHOULDER AND HIP SAMPLES De­ Source grees of of Vari­ Free­ ation dom Shoulder Sum of Squares Hip Mean Square 1 6 7 5 .3 0 ** Sum of Squares Mean Square 1 5 9 8 .26 ** Groups 3 5025.9097 Sex 1 1.4574 1.46 4 3 6 .7 9 2 3 4 3 6 .7 9 Inter­ action 3 321.7300 107.27 4 4 0 .7 3 9 3 146.91 Indi­ vid­ uals 78 4 7 9 4 .7 7 8 1 116.64 ** significant at one-per cent level 112.56 40 between the F2*s and the Black Top Delaine controls, which was found to be significant only at the five per cent level. giber Diameter; The average fiber diameters of the shoulder sam­ ples (as shown in Table VI) were: 18.11 + 2 .98 /xfor the Rambouillet controls, 17*57 ± 3.24/4 for the Black Top De­ laine controls, 2 0 .6 1 + 1 .59 /^ for the F-^'s and 1 8 .8 6 + 2.91/*for the F2*s. For the hip samples, the averages were 19*24 + 3 *6 1 /4 in the Rambouillet controls, 18.95 ± 3.19/4 in the Black Top Delaine controls, 21.80 ± 1 .35/Yin the F-j^s, and 20.48 + 3 .^6// in the F2fs. An analysis of variance was performed in the man­ ner described above (page 14). The F test revealed a significant difference only among group means of the shoulder samples (Table VI-A). A t test was performed for the shoulder sample only and a significant difference was obtained between the F1*s and any of the control groups or the F2's. Other differences were found not to be significant. Crimp: The average number of crimps per two centimeters was computed for the shoulder and hip samples (Table VII)• The average crimp in the shoulder samples of the 41 p 73 O 5h *H «J +> ^3 aj • P *H aj > -P 0 oo ft rH LA OO vo -=i- oo +• rH + 1 (J\ rH VO • oo OO +1 • • +* a •H AVERAGE FIBER DIAMETERS OF THE SHOULDER AND HIP SAMPLES DURING JANUARY APPROXIMATELY ffi ^ 0 0 bO ^P aj 0 0 U rQ £ 0 *H aJ > pq vH dj aj U O *H s • o\ iH S3 Lf\ CT\ • OO (—1 o CO H" CM ov LA • i—1 CM CO -H* • o CM f t «rH 73 5=1 O P-i *H a j -P 73 aJ S3 -H aJ > •P 0 0 CO ft CO aj P o aj 0 0 *rl ^ Q g; 0 *h aj > Ph tH S3 _ +> 0 rH a. P o u a rH t/3 ■H i—1 P O Sh ft +5 £ P aJ o 03 o o P< O £h 0 S3 Jbd *H o nj ai H rH 0 PQ f t M i—1 O P -P p O o •» 1—1 P=* CM fX| 42 0 CJ aj cd si I Eh M OS OS Kt £3 t3 Pm O O« 0) C cd cd ps O $P| Xi CO aj S PS ps a1 DO CO CO CO M Pm coo CVJ 00 00 CO • CO 00 o -=*• o 1—I -=J* a\ i —i * a\ • CVJ vo 1 —1 CO H-l CO o cd Ch *H P* £* O aj CO t> •H -P 03 a. PS o u cpj O a} 00 t— CO rH aj PS rO > X (4 © -P Tj CO H JH 0 C •H ss significant at 5 per cent level i M W c < CM Pm H OW Mg B o ^3 73 P cd 73 P cd P > B < $ 3 ^ • Hi CO S Pi O B *H CV| P O P CD A S O dj P S LOi LOi * rH + * -=*vo • CVJ +» -H- o• VO « no i—i cvj 1—1 0) P rH O P P P o o Pi O OQ E-1 O H P o «H P o cd p Cd rH C rH ej a fh « j 0 cs VO CP CO VO O o 0 u aS on on vo CP o CM CVJ LTV i —• I S oo• VO ft on • i Eh u 0 T ( —SI 3 o sx JS O 3 CO av tn • EH• - O i—1 CO w £ 0 O 0 rs u 0 b0O 0 0 Ft Q *fc« on on Ci tn d 0 c o ♦H +> O 0 c s O Ti 04 C 0 O o 00 o 4-5 •H Ft 0 u 2 > o X Ft C5 0 CO aj -p G HI CO eh- 0 r—i 0 3 TS ♦H > •o C M •H 46 c O *rl P Cd C *H cd > P CD CO Q p P* • rH + 1 CT\ CVJ • OJ +1 rH CT\ * rH +» t— IS• 1—1 +1 Q) « hO 03 Cd O rH CD > C p © CO Q CO Eh w o H W o w a pH Q £ > o © rH Cd S © • bo ca Cd £ © > • OJ rH -p © rH rH •H 3 O P © rH O Sh P ec cd o cr; o OJ P* O © FH © rH co o cd P cd rH rH © O £ PQ ft © t—1 PH “ cvj PH 47 An analysis of variance (see page 14) was per­ formed and by applying the F test the mean squares for groups and sexes were found to be significant at the one per cent level (Table VIII-A). By applying the t test, it was found that the differences between the F ^ s and any of the control groups or the F2‘s were significant at the one per cent level* The differences between the Rambouillet controls and the Black Top Delaine controls and between the Ram­ bouillet controls and the F2fs were significant at the five per cent level, while the difference between the Fg1s and the Black Top Delaine controls was found not to be significant* 48 TABLE V I I I - A COMPLETED ANALYSIS OF VARIANCE OF UNSCOURED FLEECE WEIGHTS Source of Variation Degrees of Freedom Sums of Squares Mean Square Groups 3 1 8 8 .6 3 4 9 6 2 .88 ** Sex 1 1 2 1 .5 5 9 5 1 2 1 .5 6 ** Interaction 3 3 9 .1 5 6 0 Individuals 77 ** significant at one per cent level 1 3 .0 5 6 .1 3 GROWTH Literature Growth in sheep is a very important trait. It is only second in importance to wool production in the fine wool breeds. Body weight and height are the two measure ments generally used as indicators of growth. In this experiment, body weight only was used to measure growth. Body weight Is a heritable character, which is believed to be transmitted by means of multiple factors. The weaning weight of range Rambouillet lambs was stud­ ied by Hazel and Terrill (1945a) and its average heritability was estimated at 0.30. In the yearling range Rambouillet ewes, the estimate of heritability was 0.40 (Terrill and Hazel, 1943)# Nelson and Venkatachalam (1949) estimated heritability of weaning weight in lambs at 0 . 3 0 + 0 .0 8 , using a weighted average of two methods. Certain factors such as age, sex, type of birth, and weight at birth influence growth in body weight. Ritzman (1917) studied growth of lambs in body weight during their first year of life. He found that they made about 60 per cent of their gain In weight during the first 3 months, 20 per cent during the second 3 months, 15 per cent during the third 3 months and 5 per cent during the last 3 months. Jones, et al. (1944) 50 reported that body weight increased in the Rambouillet sheep from birth up to and including the sixth year of life, and then showed a decline. Phillips (193 6 and 1937) and Phillips and Dawson (1937) observed that the lambs that were heavier at birth also tended to make greater gains during their first year of life and were heavier at 3> 4, 6 and 12 months of age than the lambs that were lighter at birth. Single lambs are heavier than lambs from multiple births (twins or triplets), both at weaning age (Hazel and Terrill, 1945* and Nelson and Venkatachalam, 1949) and at yearling age (Hazel and Terrill, 1946, and Phillips and Dawson, 1937)• Phillips, Stoehr and Brier (1940) found that single lambs were heavier than twin lambs, on the average, throughout the first year. Male sheep are heavier than females at weaning age (Phillips, Stoehr and Brier, 1940, Hazel and Terrill, 1945, and Nelson and Venkatachalam, 1949) and at yearling age (Hazel and Terrill, 1946, and Terrill, Sidwell and Hazel, 1948). Hazel and Terrill (1945) and Nelson and Venkatachalam (1949) found also that lambs from mature dams were heavier at weaning age than those from two-year old dams. Similar results were obtained at yearling age in ewes by Hazel and Terrill (1946) and in rams by Terrill, Sidwell and Hazel (1948). Lambs that are born earlier in the season are heavier at three 51 months of age than late lambs, according to a study by Phillips and Dawson (1937)« Differences between aver­ age weights of lambs in different years were found to be significant (Phillips, Stoehr and Brier, 1940, Blunn, 1944, and Hazel and Terrill, 1 94 5 and 1946)* The role that nutrition plays in growth is very important. For literature concerning the effects of nutrition and management on growth, Morrison’s book, "Feeds and Feeding," (1949) may be consulted. Material and Methods The weights, in pounds, of the F-j^ the F^ and the control lambs were obtained at two-week intervals up to six months of age, then at four-week intervals up to yearling age or later. It will be recalled that each year pure-bred Rambouillets and Delaines were selected as controls for the F^ and Fg generations. The age and sex distribution of the controls corresponded as nearly as possible with the experimental animals. The weights could not conveniently be obtained at exactly the same ages. For analysis, the data were corrected by linear interpolation to estimate the weights of the animala at 6, 8, 10, 12, 14, 1 6 , 20, 24, 2 8 , 3 2 , 3 6 , 40, 44, 48 and 52 weeks of age. The interpolation was performed on the assumption that the increase in weight during the 52 interval studied was linear. The following is an exam­ ple of the method used: Actual age in days Weight in pounds 132 55-5 146 59.5 The weight at 140 days (20 weeks) is computed as follows: 55-5 + (140 - 1 3 2 )/(146 - 1 3 2 ) (5 9 - 5 - 55-5) = 5 7 . 8 lbs., approximately. Weights at ages less than six weeks, including birth weights, were not available in most of the cases, and thus could not be included in the data. Results Body weight was studied at 6 , 16, and 52 weeks of age. In order to reduce the environmental effects of sex and type of birth (single birth or multiple birth) conversion factors were used. The conversion factor for sex was obtained in the following manner: The average 6 weeks1 body weight of all the female single sheep was divided by that of all the male singles (29.54/34.23 = O.8 6 3 ). Then the average 6 weeks* body weight of all the female twins was divided by that of the male twins (24.0/26.83 « 0.894). The average of the two values was obtained ([O.8 6 3 + 0.894]/2 = 0 .8 7 8 ) and called the conversion factor for sex. 53 Similarly, the conversion factor for type of birth was obtained by dividing the average body weight at 6 weeks of age of all the single females by that of the twin females (29*54/24.0 = 1.229). Then the aver­ age six weeks' body weight of all the single males was divided by that of the twin males (3 4 .23 / 2 6 .8 3 = I.2 7 3 ). The average of these two values was obtained ([1.229 + 1*2733/2 = 1.231) and called the conversion factor for type of birth. All the weights were then brought to a single female basis. The individual weights were multiplied by the suitable conversion factors for adjustment. A single male weighing 40.5 lbs. at 6 weeks of age was converted to 40.5 x 0 .8 7 8 = 35*6 lbs. A twin female weighing 2 7 * 3 lbs. would become 2 7 *3 x 1 .2 5 1 = 3 ^ * 2 lbs. 2 5 .0 A twin male weighing 25*0 lbs. would become x 1 .1 2 9 = 2 8 . 2 lbs. The same procedure was followed with body weights at 16 and 52 weeks of age. The conversion factors ob­ tained for those ages were: Conversion factor for sex at 16 weeks = O .8 3 2 Conversion factor for type of birth at 16 weeks = 1100 Conversion factor for sex at 52 weeks = 0.812 Conversion factor for type of birth at 52 weeks = 1.114 54 The averages and standard deviations of body weights at 6, 16 and 52 weeks, adjusted to a female single basis were calculated for each of the four groups of sheep used in the experiment, and are given in Table IX. An ordinary analysis of variance (Snedecor, 1946, page 2 3 2 ) with one variable (the differences among groups) was performed and the completed analyses of variances appear in Table IX-A. The F test revealed significance only at 16 and 52 weeks of age. cases. A t test was performed in these two At 16 weeks, it was found that the Rambouillet controls were significantly heavier than the Black Top Delaine controls. The s were significantly heavier than the Black Top Delaine controls. ences were insignificant. Other differ­ At 52 weeks of age, the F-^'s were significantly heavier (at one per cent level) than either one of the control groups (another evidence of heterosis in the Fj's). The F^fs were also significantly heavier (at the one per cent level) than the group. Other differences were insignificant. Growth curves. Growth curves were constructed for the male singles, the male twins, the female singles and the female twins for each group, using the original weights at 6, 8, 10, 12, 14, 16, 20, 24, 2 8 , 3 2 , 3 6 , 40, 55 i I vH S3 S3 T J > O 0 Ph 0 0 * r t rH «3 H CM +1 CO CM "M -H +1 o\ -=J- CO VO CO rH o • • • cn h- • CM i—I rH • 00 OV oo VO t> - • rH CM • 00 00 * CO 'H v o oo _ < o EhPQ O 0 Ph © iH P GQ 0 Q P CO Lft CON CM rH rH 00 00 • ON -=h rH rH CM • ON H~i * MO 0 -H 00 CO -=4“ IS • c— +1 X >H < « os w PQ f t ft< o 0 0 & VO rH m rH CO • ON -=3- & m CM CM 1 1 *CS * r l S3 S3 T5 t> O O ov 0 Sh 0 *rH P c tfQ P • -H* 00 m CO -H -=*+ i CM VO 00 1 SH © 0 0 hQ S3 P > OJ *H rH Eh O co M J> o> s g ft «0o <0 < 3 ft Eh o oo CO • in m • m m CO in m oo rH CM oo • S? O M < 3* • E— «3j o co EH Eh Q \ o 0 CM rH t— • • + 1 CO • CO H* i CO Ps! 0 0 VO 1 * fll 0 © 5 0 S3 P t> 0 *H rH © • m • • CO b CM CM CM CM O PqVO O rH CO •* MVD co ^ >mEh PI< o LTV 0 0 d £s d VO i 0 1 0 0 S 0 0 CO 0 d O *H P cd oo * tr— ir­ vo ON on on vo t— m CM CM o G \ CO CM ON o rH t- on ON rH VO in • rH CM 0rH0 ON ON rH cd P O Em oo on oo vo rH in • vo vo rH ON o S o1 0 CM N* CM d X vo oo CO Q m vo 0 5* • in £•— d d cd f oo o M ON 0 g * i x w in VO CM 00 on d *H jd P •H IS 0 ft d o d bO significant w w? oe < on -=*■ -=J* • ** PQ rH VO • t 10 0 B 0 0 £> rH rH H H O CVJ 4" OJ 00 OJ OJ CO vo 00 o JSt -4- -4" Age In Weeks Figure 6. Growth of the Male Twins 00 -4- CM LfS R E L A T IO N S H IP S AMONG THE CHARACTERS S T U D IE S Correlations The coefficients of correlation between the various characters studied were computed.. r The formula used was: = _______ SXY - r(SX)(SY)]/N_______ / s x z - (sx)2/n ’/sy2 - (SY)2/N where r ~ the coefficient of correlation between the two characters studied. SX * the sum of items in one character (inde­ pendent) . SX p = the sum of the squared items of the Inde­ pendent character. SY = the sum of items in the second (dependent) character. SY2 = the sum of the squared items of the depend­ ent character. SXY = the sum of the products of the two charac­ ters in each individual. The coefficients of correlation were tested for significance by referring to a convenient table (Snedecor, 1946, page ). The degrees of freedom used in each case were equal to the number of pairs studied (N) less one (i.£., the degrees of freedom = N - 1). 63 Table X shows the coefficients of correlation that were obtained in the Rambouillet controls, the Black Top Delaine controls, the F^'s anc^ lations studied were: *^2ls* corre“ Between combined neck and body value and grease fleece weight, between combined neck and body value and body weight (at 52 weeks), between combined neck and body value and fiber diameter, between combined neck and body value and fiber length, between grease fleece weight and body weight (at 52 weeks), between grease fleece weight and fiber diameter, between grease fleece weight and fiber length, between fiber diameter and body weight, between fiber diameter and fiber length, between fiber diameter and crimp (number of crimps per two centimeters), between fiber length and body weight and between fiber length and crimp. By reference to Table X, it is observed that, In the control groups, relatively high correlations were obtained between grease fleece weight and body weight, between fleece weight and fiber diameter, between fiber diameter and body weight and between fiber diameter and fiber length. The correlation between fiber diameter and crimp was found to be negative in the two control groups. In the Fj group, the coefficients of correlation differed widely, in many of the cases, from those of the 64 * He :fc * 00 o o o -v o o o t>- LA 00 4 * O * • * o o o + + + to OJ 14 < * rH OVCOOO CT40 V 3- OJ LOCO A A O rH O 0— * # • • o o o o + 1 co «• rH fx, 11 <4 rH O to CMCOOO o o o ON00 cvj CVJ OJ rH * • • o o o H" + + U P P d O o u O O a O O 02 Eh G H ♦H O ^ a u O rH P a* o> a H Q PQ 9 E-* i-3 c o CVJ r— OJ * « 3^C * ov coco (0 (0 4 * VOVQ rH VO O OJ • • « O O O + + + • * * O O O + + 1 o o O O O o o *J“ I * *' * 0J rH CO c o o o VO * * 00 * • • LAiAOO CJV o \ CO CFV CVJ 4 * O (OVO o o n is (TV CO CVJ rH VO CM 00 vo CFV 4 - CM o O O O O O • * • 4 + l • • • o o + + + o O CO • * • + 4* ' * * * o o + + + d 0 (l> & -P 0) PQ 07 a> £ P Sh U rH 0 CD cd o p jG > Q) P 0 P 07 P g b O >s rH bO Cd d d ^ H *H (D O CD P rH P 0 £ W d d H- cd >> © -A fO A rH A * • * O O o + 1 1 4S vo O o ovovo LA 00 O 00 C— CVJ o o * •H P d p U d cd p •* P d CD cd U P P P p CD P P CD P CD P p P O P g bO P P bO C D bO 5 2 P faO CD bO cd P bO *H * 0 g CD >i Spencer, Hardy and Brandon (1 9 2 8 ), Lambert, Hardy and Schott (1938)> Pohle and Keller (1943)* Jones et al. (1944) and Slen (1949). The positive correlations between body weight and skin folds, grease fleece weight, fiber diameter and fiber length are supported by similar re­ sults obtained by Jones at al. (1944). In the F-^ group, the coefficients of correlation varied widely, in most of the cases, from those of the parental breeds. The fact that the F^* s constituted a peculiar group, differing from the parental breeds in most of the characters, explains the discrepancies in their correlation coefficients. The correlations in the F^ group approached the average correlations of the parental breeds in most of the cases. This seems to follow the pattern exhibited by the F2*s tlirouShout the experiment. CONCLUSIONS It is not a simple matter to derive positive con­ clusions from the experiment as a whole, In view of Its many limitations (these will be discussed in the next section)• None of the hybrid individuals combined the better mutton qualities of the Kambouillet with the longer wool of the Black Top Delaine. The Fx hybrids were growthy and had heavier fleeces but had inferior wool qualities to either parental breed and were too wrinkly. The P2fs were intermediate In most of the cases and none of them was found to be a superior indi­ vidual in all the characters examined. These results point to the possible use of the cross to raise hybrids up to yearling age, thus benefiting from the hybrid vigor in their body weights and fleece weights. From a breed or herd improvement standpoint, however, the cross is not recommended until further experimen­ tation shows its value. POSTSCRIPT All farm animals, including sheep, constitute a highly complicated experimental material, as far as genetics research is concerned. The following are some of the difficulties encountered by the experimental geneticist, once he endeavors to work with farm animals: 1. Fairly large numbers of animals are required for significant results from genetics research. Large numbers are not easily obtained in the case of farm animals for the following reasons: (a) The long gestation period of farm animals and the long time they require until they reach the age of useful reproductive activity. (b) A relatively small number of offspring Is pro­ duced by a single female farm animal (except the sow) during her lifetime. An average ewe, for example, can produce her first lamb when she is about two years old. Even if she con­ tinues producing every year, the ewe will not be able to produce more than 12-15 lambs during her lifetime. Compared with laboratory animals, this reproductive rate is extremely low. (c) Multiple birth is not a very frequent occurrence in farm animals (except swine), thus denying the experimenter of a valuable source of Informa­ tion about full brothers and sisters raised together (full sibs). In sheep, Identical twins, which offer a most im­ portant source of genetic Information, are very rare (Venkatachalam, 19^9)♦ The so-called "economic characters," such as wool characters, skin folds and growth In sheep, are apparently controlled by a large number of genes, and are further complicated by various forms of gene interaction. Environmental factors exert unmistakable effects on the more Important quantitative (or economic) characters. Farm animals are subjected to various weather and other environmental conditions (espe­ cially when on pasture) which are impossible to keep constant from year to year, or from one gen­ eration to the next. Although inbreeding has been practiced In many of the purebred sheep, it has not been practiced long enough to produce sufficiently homozygous stocks. To obtain homozygosity, intensive Inbreeding has to be practiced for a long period of time. This Is complicated, however, by the decrease of vigor ob­ served under such conditions. 7• Considerable financial assistance is needed for conducting experiments that deal with farm animals, for such experiments extend over long periods of time. Such financial assistance is not available in most cases, especially if the experiment is purely academic and the results have no immediate economic advantages. In the present experiment with fine-wool sheep, none of the difficulties mentioned above was success­ fully overcome. The shortcomings of the experiment will be immediately conceived if it is recalled that: 1. The number of animals used in the experiment was too small. 2. The parents were from a heterogeneous stock as far as age and breeding were concerned. 3. Very little information about the parents was avail­ able. 4-. Five F1 males were castrated and sold as weanlings before any of their data could be obtained. 5. Selection was practiced within the Fj males for pro­ ducing F2*s . 6. None of the controls that were used to represent the parental breeds and compare them with their Fx and F2 hybrids were born during the same year as the F ^ s 78 It was practically Impossible to plan and execute a scientifically satisfactory experiment in sheep breed­ ing with the existing limitations in space, labor and funds. SUMMARY Two Rambouillet rams were crossed with 19 Black Top Delaine ewes in order to improve the Rambouillet breed and develop individuals combining the length of fiber and heavy fleece of the Black Top Delaine with the mutton qualities of the Rambouillet. 37 were raised. Fifteen F-^s and Their skin folds and wool charac­ teristics at yearling age and their growth during the first year of life were studied and compared to those of 16 Rambouillet and 18 Black Top Delaine controls at the same age. 1. The The following results were obtained: had significantly more extensive skin folds, heavier unscoured fleeces and heavier body weights than either one of the parental breeds at yearling age. 2. The average fiber length in the F^*s was similar to that of the Rambouillet control group, while their average fiber diameter was more and their average number of crimps per two centimeters was less than in either of the parental breeds. 3. The Fg 1 s occupied an intermediate position between the parental breeds in most of the characters stud- Wool samples taken from the shoulder region of all the animals studied had, on the average, longer fibers, smaller fiber diameters and more crimps per two centimeters than those taken from the hip region of the same animals. In the control groups and the F^*3' positive correlations existed between grease fleece weight and body weight, between grease fleece weight and fiber diameter and between fiber diameter and body weight. There was a negative correlation between fiber diameter and crimp. The F-^s, constituting an unusual group, differed widely, in most of the correlations studied, from the other three groups. Under the limitations of the experiment, positive conclusions regarding the cross could not be given. However, it seemed from the results obtained, that the use of the cross should not be recommended for breed improvement until further experimentation shows its value. APPENDIX Statements about some F-^ and Fg individuals are cited on the following pages. The individuals are iden­ tifiable by sex, number and year of birth* Further identification can be obtained by referring to Figures 1 and 2 . 1 All the statements were given by Professor G. A. Brown except those for Fi males No. 3105 and No. 3110, and parts of those for Fi males No. 3102 and No. 3107 which were given by Mr. V. Freeman. SHEEP Female No. 3101 of 1930 Body. Wide, deep bodied, short legged, blocky, straight top and bottom lines. Well placed on legs, legs far apart. Wool. Three-inch length of staple. flowing oil. fleece. Good surface of fleece. Good free- Bright, lustrous Considerable kemp on neck wrinkles. Quality of fleece of low Delaine order because of coarseness on neck and britch. Head. Wool extending half-way from eyes to end of nose. Open under eyes. Wrinkles. dewlap. No wool over eyes. Heavy apron. Three neck folds. Heavy Considerable number of pin wrinkles. Male No. 3102 of 1930 Low, weak back; narrow chest; crooked hind legs; short fleece; wrinkled body; fair width of body; blocky head; dense fleece; second choice among the Body. Medium sized. pinched in heart girth. males. Fairly deep of body but Low in the back and not as deep as desirable in the fore flank. Back low in the dorsal region, very sharp on the shoulder. Knees and hocks 83 close together, slightly sickle-hocked. Fair to medium width of body. Wool. Excellent covering on legs and belly. Extremely dense, very uniform in density. length of staple, 2j inches. Heavy, thick sluggish oil. Fine crimp but lacking in luster. on fleece. Moderate Heavy, gummy surface Rather fine fibers over the body of the fleece, but the fleece was coarse in the wrinkles with a large amount of kemp. Head. Slightly narrow between the eyes, trifle long on the nose. Wide-spreading horns. Fair covering of the head with wool within two inches of the nostril. Wide-spreading horns. Good covering on the ears, ex­ tending to their end. Wrinkles. Rather heavy apron. going entirely around the neck. side wrinkles on the body. Three wrinkles Heavy dewlap. Tail rosette. wrinkles on the hip, and thigh wrinkles. Several Longitudinal Many pin wrinkles. Rather undesirable type because of heavy, shrink­ ing fleece, short staple, narrow chest, and too many wrinkles. 84 Female No. 3103 of 1930 Body. Very low set (short-legged), deep bodied ewe, with straight top and bottom lines, well placed legs, with straight knees and hocks. Heavy boned. Wool. About 3-1/4 inches long, lustrous, with free-flowing oil. Good wool covering on legs and belly. High Delaine quality of wool with moderate density. Wool light surfaced. Head. Moderately covered with wool extending down half-way between eyes and nostrils. Wrinkles. Rather heavy apron. Two lower neck folds (ji.e^, do not extend over top of neck). Very light dewlap. Probably the best of the older F^ ewes. Male No. 3 IO5 of 1930 Narrow body; crooked hind legs; wrinkled body; short fleece; dense fleece; oily fleece; deep chest; third choice among the males* Male No. 3107 of 1930 Little weak in the back; slightly narrow; fleece lacks density; large size; fleece long; head medium to long; smooth bodied; first choice among the males. 85 Body* Medium sized, good depth of body, fairly straight top and bottom line. shoulder. A little high at the Well placed on the legs* Both knees and hocks are straight (not sickle-hocked or knock-kneed). Fair to medium width of body. Wool. Excellent covering on legs and belly. Approximately three inches; clear, white oil. Very short, fine, even crimp with bright, lustrous fiber and free-flowing oil. fleece. Very fine fibers. A light shrinking Easily of Delaine standard from all standpoints. Practically no surface oil. Head. Excellent wool covering on head and ears; wool two inches from opening of nostril. Good length of wool on head. Spreading horns. Wrinkles. Moderate apron. a light dewlap. Head broad. One neck wrinkle and Wrinkles do not extend over top of neck* A very desirable ram. Male No. 3110 of 1930 To be eliminated; too slim of body; wrinkled body; high narrow back; droopy rump; light leg; narrow throughout; short, blocky head; crooked hind legs; lacks flesh; very wrinkly; no good. 86 Female No* 3114 of 1930 Body. Low-set, rather blocky, moderate width of body, little narrow at shoulders, and between the front legs. Wool. A heavy dense fleece, close and compact on the surface, with free-flowing white oil. three inches long. About Wool of a low Delaine quality. Head. Rather wide head, completely covered with wool, ears well covered, and the wool extends to within li inches of the nostril. Wrinkles. Heavy apron. Three neck folds extend­ ing all around the neck. Very heavy dewlap. Two light folds in the fore flank. Some folds on the thighs. Some kemp on the folds. A very desirable ewe. Female No. 3 H 5 of 1930 Body. Deep bodied, short legged, straight top line, little narrow at shoulder, shallow chested. Short, steep rump. Wool. Excellent wool covering, but staple is short, 2-1/4 inches long. black surface. Very oily fleece with heavy A bright, lustrous, fine fleece, but too short for Delaine quality. 87 Head. Short, broad head. Excellent wool covering on head extending down to two inches of nostrils. Wrinkles. Heavy apron. ing clear around the neck. Three neck folds extend­ Several body folds. Folds at the base of the tail and on thighs. An undesirable ewe from the standpoints of length of fleece and conformation. Female No. 3 116 of 1930 Body. Medium sized, low set. bottom lines. the shoulders. straight top and Body a little narrow, particularly through Legs a little close together. Wool. Excellent covering of wool* of staple (3 inches). heavy surface. Good length Free flowing white oil and rather Good density. Lustrous. Considerable kemp showing on neck wrinkles and thighs. Head. Short and broad, almost typically Ram­ bouillet, with wool extending down to within two inches of nostrils and extending well out on the ears. Wrinkles. Heavy apron; three neck folds com­ pletely circling the neck; several side wrinkles on the body; wrinkles about the tail, head and on thighs. 88 Female No. 3117 of 1930 Body. Low-set* deep bodied* good breadth of body throughout. Well placed legs. Wool* Excellent wool covering. of staple about three inches long. oil* very lustrous fleece. Moderate length Free flowing* white Quality of wool, of the lower Delaine order. Head. Well shaped head* with the covering ex­ tending 2 / 3 of the distance from the eyes to the end of the nose. Wrinkles. Moderate apron. surround the neck. Two neck folds that One light fold in the fore flank. A very desirable ewe. Female No. 135 of 1932 Body* Large, rugged* vigorous. conformation. Excellent body Straight top and bottom lines. Well placed legs. Wool. Excellent covering. - 3-1/4 inches. Clear, white* free flowing oil. Good surface of fleece. fine. Good length of staple Fair density. Very lustrous fleece. Extremely Good Delaine quality of wool. Head. Excellent head covering, wool extending 2 /3 of the distance from the eyes to the tip of the nose. 89 Wrinkles. Practically no apron. fold* Very light neck Very little dewlap. An excellent ewe. Female No. 1 3 6 of 1932 Same characteristics as for ewe 137 of 1 9 3 2 , ex­ cept (1 ) that 136 has more head covering with wool ex­ tending down to half-way between eyes and nostrils, and (2 ) 1 3 6 is not quite as wide in the chest as 1 3 7 . An exceptionally good ewe. Female No. 137 of 1932 Body. Low, thick-set, square bodied. lent body conformation. good width of back. Of excel­ Smooth shoulder, full chested, Well placed on the legs, which are wide apart. Wool. Excellent covering of wool over legs and belly. Good density. Good surface of wool. Three inches long. Clear, white, free flowing oil. Lustrous, with short, fine crimp. Fine grade of Delaine staple. Head. Practically no wool covering below eyes. Very little wool on ears. Wrinkles. Light apron. fold. Very small dewlap. A very desirable ewe. One medium-sized neck F2 sheep Male No. 132 of 1932 Body. Large, vigorous, heavy boned. depth of body. Short legged. Excellent Straight under line. Slightly low back of shoulders along the top line. Well placed legs, a little crooked at the hocks. Wool. 3~3/4 inches long. Free flowing oil. A light surface for the fleece (moderate amount of oil) about right for the surface. bright and lustrous. Fleece very dense. Wool Belly and legs well covered. A Delaine fleece. Head. Head rather long. narrow. Wide spreading horns. no wool below the eyes. Open faced, practically Ears well covered with wool. Wrinkles. Heavy apron. around the neck. Face rather long and Heavy dewlap. One wrinkle extends No body folds. Slight wrinkle at the tail head. Save for breeding with F2 ewes. Female No. 139 of 1933 Body. Medium sized for her age. Somewhat narrow of body. shoulder. Short legged. A little low back of the 91 Wool* Medium length of fleece, about 2-1/2 inches. Density fair. Head. Wool too short for Delaine quality. Wool covering extends about one inch below eyes. Wrinkles. Rather heavy apron. neck folds. body. Heavy dewlap. Two complete Several side wrinkles on Wrinkles on thighs and about the tail. Save for breeding. Male No. 140 of 1933 Body.Medium to small size. bottom lines. Rather narrow body. Straight top and Somewhat fine boned. Short neck. Wool. Good length of staple. surface of fleece. fleece lustrous. Light oil. No Wool lacking a little in density Wool would rate as low Delaine. Excel­ lent covering of legs and belly. Head. A very short, broad head completely cov­ ered with wool over nose and ears. Good spread of horns. Typical Rambouillet head. Wrinkles. lap. Heavy apron, one neck fold, heavy dew­ 92 Male No. 141 of 1933 Body. Rather large. at the shoulder. Large boned. A little high Stands a little close on his legs. Good width of body. Slightly crooked hocks. Heart girth a little small. Wool. About three inches long. Practically no surface of fleece. Lustrous fibers. Very light oil. Free flowing oil. Somewhat lacking in density. lent wool covering on legs and belly. Excel­ Low grade of Delaine. Head. Slightly long and narrow. closely spiralled. Horns a little Excellent wool covering of head and ears. Wrinkles. Light apron. Light dewlap. One light neck fold. No body on tail folds. A fair ram. Female No* 145 of 1933 Body. Medium sized. Good depth of body. Medium to fine boned. Wool. Three inch staple. fine wool. crimp. Medium density. Bright, lustrous, with a very fine, even White, free-flowing oil. Wool has a light sur­ face. Head. Very No wool on head below the eyes. 93 Wrinkles. Practically no apron. Only a trace of neck folds. A very desirable ewe. Save for breeding. Male No. 146 of 1933 Body. Rather small, narrow body. gether. Legs close to­ Fairly straight top and bottom lines. Slightly long of neck. Wool. Good wool covering on legs and belly; verylittle wool below eyes. Fair length of staple, about 2-3/4 inches. Clear, white, free-flowing oil with lustrous staple which was medium in density. surface of fleece. Light High grade Delaine quality of wool. Head. Rather pointed nose. Horns rather closely spiralled. Wrinkles. Light apron. lap. Light neck fold and dew­ No body folds. Not a good combination of characters. Male No. 119 of 193^ Body. Large, growthy lamb. Slack in heart girth (flat-ribbed and narrow-backed at the shoulder). sloping at the rump. Rather 94 Wool. Well covered head (too much covering; a Ramhouillet covering). A very dense, heavy, oily fleece, lacking a bit in quality of fleece. Wrinkles, Very heavy apron. Three neck folds. Wrinkled in the flanks; also at the tail. Discard him because he is too wrinkled an animal. Male No. 120 of 1934 Body. A trifle narrow in the body. sloping in the rump. A little Pair growth. Wool. Lacks character in the fleece. Head. Short, broad, Rambouillet head covered to within li inches of the end of the nose. Wrinkles. Heavy apron. Two neck folds. Wrinkles at the tail head. Keep for possible breeding. Female No. 121 of 1934 Body. Rather large and growthy with a wide, deep body. Wool. Fleece with good density, good length, and a very desirable Delaine quality. Head. Open face. Wool 1/2 inch below the eyes. Wrinkles. Body is smooth. Keep for a breeder. 95 Male No. 122 of 1934 Bocty. Low set and compact ; fair width of body. Wool. Excellent length of fleece; good covering; fair quality; fleece a bit lacking in density and oil. Head. Very short, broad, well covered head with wool to within two inches of the end of the nose. Wrinkles. One slight fold on the neck; otherwise the body is smooth. Keep for possible breeding. Female No. 123 of 1934 Body. Rather flat-ribbed and narrow-chested. little sloping on the rump. A Small in size. Wool. Very desirable fleece; excellent density; good quality, but a little heavy shrinkage. Fleece a little bit like that of Merino. Head. Rambouillet head covering to within one inch of the end of the nose. Wrinkles. Rather, heavy apron and lower neck folds. Wrinkles in flanks. Should be discarded. 96 Female No. 124 of 1934 Body. Rather small In size. spread of body. Lacking in width or Very crooked on hind legs* Short in both middle and quarters. Wool. Rather open fleece but with excellent length and quality. Head. Very complete head covering like Rambouillst. Wrinkles. Smooth body. Keep for a breeder. Male No* 126 of 1934 Body. A rather growthy lamb. Rather narrow body. Wool. Short, dry fleece, lacking character. Head. Short, broad head; well covered to within two inches of the end of the nose. Wrinkles* Very heavy apron. folds. A fold at the tail head. Three complete neck He is too heavily wrinkled. Discard him. Male No. 139 of 1935 Very small; undersized; narrow and shallow chest; drooping rump; thin pointed head and slender neck. inferior animal. Discard* Very 97 Female No. 140 of 1935 Looks unhealthy; very thin; fair boned; straight back, extremely thin and emaciated. Male No. 141 of 193 5 Rather large and rugged; heavy boned; growthy; discarding because he is light in the chest and very drooping in the rump. He is a fairly good ram. Discard. Female No. 142 of 1935 Medium growth; back is straight; medium boned; a good head with wool down to just below the eyes; very thin in flesh. Male No. 143 of 1935 A large, rugged, heavy-boned ram; deep chest; reasonably straight top (back); a little narrow in the forehead, rather crooked at the hocks; a fairly good animal. It had been sheared before this description was made. Keep this animal. 93 Male No. 149 of 1935 Medium sized; straight back; head fairly wide; body extremely narrow; flat-ribbed; drooping rump. A medium good animal. Discard. Male No. 150 of 1935 Small; fine-boned; undersized; slim-necked. A poor animal. Discard. Female No. 127 of 1936 Fairly, growthy. Moderately smooth bodied. width of body for a fine wool. head. Good back. Good Very good A little steep on the rump. Female No. 129 of 1936 Rather small. low chested. Narrow head and face. A little short in her quarters. Rather shal­ A little long in the neck. Male No. 131 of 1936 Good sized; growthy. Good width of body, wide chest floor, fairly square quarters. ers. Good depth of body. A little sharp at the with­ "A pretty decent sheep.11 99 Male No. 132 of 1936 Large, growthy animal. Good depth of body. width, being sharp at the shoulders. rib. Lacks A little flat of Long and narrow head. Male No. 133 of 1936 Rather small. flat-ribbed. Merino. Somewhat narrow chested. Lacks width of body throughout. A typical Short, broad head; head well covered with wool, and ears well covered with wool. neck. A little Heavily folded on the Heavy apron and two heavy neck folds. Female No. 13^ of 1936 A large growthy ewe. somewhat in width of body. Good depth of body. Lacking A little crooked in the hocks. A bit long in the neck. Male No. 10 of 1937 Smooth bodied. Heavily folded neck. ing extends two inches below the eyes. Head cover­ The fleece is very fine, and does not have too much oil. 100 Female No. 11 of 1937 A rather small ewe, lacking in body width. comes only down to the eyes. Delaine density. Wool The fleece is only of the Moderately heavily folded on the neck. Male No. 12 of 1937 Would pass for a Black Top Delaine. A rather growthy, smooth-bodied ram, free of wrinkles. ering extends to about an inch below the eyes. Wool cov­ Has a typical Black Top fleece. Male No. 13 of 1937 Smooth bodied; there are a few light folds on the neck. The head covering and character are very similar to the Hambouillet. Rather narrow bodied. Fleece is rather dry and lacking in density. Male No. 14 of 1937 Of B Merino type. many body wrinkles. Heavily folded neck and a good Rather small, fine boned, and nar­ rower bodied than the Rambouillet or Delaine. back to the American Merino type. fleece. A throw­ Has a very short, fine Completely covered on the head with fleece. 101 Female No. 15 of 1937 A rather small ewe; not growthy. boned. Short and compact. Somewhat fine Heavily folded on the neck. A very fine fleece of somewhat greater density than the Delaine. Male No. 16 of 1937 A rather growthy, very smooth-bodied ram. Delaine-type head. Lacks width of body. Has a Has very open, dry fleece, lacking in character. Female No. 17 of 1937 A rather large, strong-bodied ewe. the neck. Very complete head covering. Has folds on Fleece is of good length, is extra fine, and of fair density. The fleece is intermediate between a Rambouillet and Delaine in density. Lacking a little in body width. Female No. 18 of 1937 A very large, smooth-bodied ewe, free of wrinkles. Fleece extremely fine. laine. Density of fleece like the De­ Has extreme head and leg covering, like the Rambouillet. 102 Female No. 19 of 1937 A rather low, thick ewe. of the Rambouillet. Head and leg covering Extremely fine, very dense fleece of Rambouillet density. are large on the body. A good many pin wrinkles which BIBLIOGRAPHY Barker, S. G. and King, A. T. 1926 A Comparison of Diameters of Wool Fibers with the Micro-balance and the Projecting Microscope with Applications to the Determination of Den­ sity and Medulla (kemp) Composition. Journal of the Textile Institute, 17:68-74. Blunn. C. T. 1944 The Influence of Seasonal Differences on the Growth of Navajo Lambs. Journal of Animal Science, 3:41-49. Burns, R. H. 1924 Some Phases of Wool Inheritance in Fi Generation. 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