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Inheritance of rate of growth in domestic fowl II. Genetic variation in rate of growth from two to… Lerner, I. Michael 1932

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I U . B . C . LIBRARY I CAT, un^.fa-my ft*- frAff i \ INHERITANCE 01 BATE OF GROWTH IN DOMESTIC FOWL. I I . GENETIC VABIATION IN BATE OF GBOWTH FBOM TWO TO EIGHT WEEKS OF AGS IN S. C. WHITE LEGHOBNS. by I. Michael Lerner A Thesis submitted f o r the Degree of MASTER OF SCIENCE IN AGRICULTURE in the Department of Poultry Husbandry The University of B r i t i s h Columbia A p r i l , 1939". PART I. was presented by the author to the Faculty of A g r i -culture of the University of B r i t i s h Columbia in p a r t i a l f u l f i l l m e n t of the requirements f o r the Degree of Bachelor of Science i n A g r i c u l t u r e . A O U O . U I B 6 l i m The writer wishes t© express his indebt-edness to Br. V. S. Asmundson and to Prof. S. A, Lloyd, without whose valuable assistance this work would not have been completed. - 1 -INHERITANCE OF RATE OF GROWTH IN D0ME8TIC FOWL."" I I . GENETIC VARIATION IN RATI OF GROWTH FROM TWO TO EIGHT WEEKS OF AGE IN S. 0. WHITE LEGHORNS. In a previous report (Lerner and Asmundson, 1932) methods f o r a genetic study of rate of growth were presented. The rates of growth from three to eight weeks of Anconas, Light Sussex and their hybrids ( F 1 , Fg and baekcrosses) were reported, but due partly to small numbers and partly to v a r i a b i l i t y with-i n the breeds i t was not possible to draw f i n a l conclusions with regard to the mode of inheritance of rate of growth i n these breeds. The v a r i a b i l i t y i n the growth rate of birds of the same breed suggested the existence of genetic differences. To determine whether such differences exist, growth data for S. C, White Leghorns, c o l l e c t e d at the University of B r i t i s h Columbia, were analyzed and are presented i n this report. Data for 340 i n d i v i d u a l l y pedigreed S. C. White Leghorn chicks were used for t h i s study. The chicks were hatched i n four l o t s at f i f t e e n day i n t e r v a l s from March 10 to A p r i l 24, 1931. They were removed from the incubator when approximately 24 hours old, banded and weighed. They were also weighed at 2, 4, 6, 8, 12, 20 and 24 weeks of age, as counted from the day the chicks were banded. * Part I. was presented by the author to the Faculty of A g r i -culture of the University of B r i t i s h Columbia i n p a r t i a l f u l -f i l l m e n t of the requirements for the Degree of Bachelor of Science i n Agriculture. - 2 -The chicks in a l l l o t s were fed al i k e on a standard r a t i o n . As shown by Figure I, the growth of the chicks to eight weeks was s a t i s f a c t o r y . The chicks were divided in two groups, those in the f i r s t two hatches formed one. and those i n the t h i r d and fourth hat-ches the other. This was considered permissible since there was l i t t l e difference in the rate of growth of the chicks from the f i r s t two hatches, nor was there a s i g n i f i c a n t difference between the ehieks from the th i r d and fourth hatches. The weighted average differences in rate of growth were only 2.2 and 2.6 per eent. respectively. The males and females were con-sidered separately. There were thus four groups. This d i v i s i o n was followed throughout. It w i l l be seen ( F i g . I) that the rate of growth appar-ently changed from week to week, but since i t was not p r a c t i c -able to consider the growth rate for each two-week period separately, some longer period had to be adopted. The selection of a suitable period was based on rates of growth for various age intervals calculated from average weights of S. C. White Leghorn and Barred Plymouth Bocks. These figures w i l l be con-sidered i n greater d e t a i l elsewhere. It may be stated, here, however, that the period from 2 to 8 weeks was chosen as the most suitable sinee growth i n that period was more rapid than in subsequent periods. Moreover, the difference between the rate of growth of the two breeds was as great i n that period as in any other time i n t e r v a l considered. - 3 -The s t a r t i n g point of the period for the present study of genetic differences i n rate of growth was taken at 2 weeks of age rather than e a r l i e r , p a rtly beeause of the influence ex-erted by the siz e of the egg on the weight of the chick when hatched, and pa r t l y because there appears to be r e l a t i v e l y l i t t l e v a r i a t i o n i n rate of growth during the f i r s t 2 weeks after hatching. The modified formula of Minot (Brody, 1927) B S Tj."-*1.. 100 -- — — 1 tfhere - the weight of the chicks at 2 weeks and Wg the i r weight at 8 weeks ef age, was applied to the data for each chick. The period from 2 to 8 weeks was considered as a u n i t . The mean rates of growth, the standard deviations and co-e f f i c i e n t s of v a r i a b i l i t y for the four groups into whieh the chicks were divided, are presented in Table I. The e a r l i e r hatched chicks grew more ra p i d l y than the late hatched chicks, and the males grew more r a p i d l y than the females. These d i f -ferences are s t a t i s t i c a l l y s i g n i f i c a n t as i s shown in Table 2. It w i l l be observed that the differences are even more pro-nounced between e a r l i e r and l a t e r hatched chicks of the same sex than between males and females of the same hatch. There i s also some in d i c a t i o n that the difference between the r a t e of growth of the two sexes i s greater when they grow r e l a t i v e -l y r a p i d l y . Frequency d i s t r i b u t i o n s of the mean rate of growth are skewed towards the higher rate. - 4 -The standard deviation from the mean rate of growth i s s l i g h t l y lower for the e a r l i e r than for the l a t e r hatched chicles, but there i s no consistent difference between the males and females. The r e l a t i v e v a r i a b i l i t y i n rate of growth, as measured by the c o e f f i c i e n t of var i a t i o n , i s s i g n i f i c a n t l y greater f o r the l a t e r hatched males than for the e a r l i e r hat-ched males, and i s also greater for the l a t e r hatched females than for the e a r l i e r hatched females, although i n th i s case the difference i s not s t a t i s t i c a l l y s i g n i f i c a n t . As in the case of the standard deviation there i s no evidence here that the sexes d i f f e r consistently in v a r i a b i l i t y of rate of growth. The difference between the rates of growth of the e a r l i e r and l a t e r hatched groups demonstrate the influence exerted by the environment on rate of growth. This emphasizes the impor-tance of considering the environment when studying the i n h e r i -tance of a phys i o l o g i c a l character, sueh as rate of growth. Only such individuals as are raised under i d e n t i c a l conditions can be compared or, i f groups raised under similar conditions are considered together for comparison, they should, as in this case, show the same average rate of growth. Despite the l i m i -tations imposed by the conditions under which these birds were raised, i t was found possible to use some of the data on the rate of growth of t h i s flock of S. 0, White Leghorns to deter-mine whether there are genetic differences between families (the progeny of a single pair) with respect to rate of growth. Before proceeding to a comparison of individual families the progeny of d i f f e r e n t males w i l l be b r i e f l y dealt with. . „ . - 5 -The 340 chieks were a l l toe progeny of s i x males, bat fa m i l i e s of 15 or more chicks were only available from three of these six males. The progeny of these three males were divided into four groups as for Table 1, and the means and c o e f f i c i e n t s of v a r i a t i o n f o r rate of growth calculated. No constant or s i g n i f i c a n t differences were found between the progeny of these males, due partly, no doubt, to the fact that each group represents several d i f f e r e n t f a m i l i e s . Furthermore the progeny of these males did not d i f f e r s i g n i f i c a n t l y from the t o t a l population i n mean rate of growth or i n v a r i a b i l i t y i n rate of growth. The s i x largest families were selected for the purpose of compering t h e i r rates of growth. Four of these families were the progeny of females, No,I 17171, E 8132, K 2136 and X 2191, which were mated to male No. L 1520, and two were from females K 2136 and 3 373 which were mated to male K 585. A l l these fa m i l i e s were more or l e s s elosely r e l a t e d . The differences between the means of the male and female progeny of these s i x hens are presented In Table 3. These six progenies (families) f a l l roughly into three classes or groups on the basis of rate of growth. In the group with the highest rate of growth are the progeny of K 2138, E 2136 and I 17171. The progeny of K 2191 and K 2132 form an intermediate group, while the progeny of J 373 show the slowest rate of growth. The differences between the families within these groups are net s t a t i s t i c a l l y s i g n i f i c a n t . When, however, families in d i f f e r e n t groups are compared most of the differences are s i g -n i f i c a n t , e s p e c i a l l y so when the progenies that d i f f e r most are compared. Thus i t i s evident from Table 3 that the progeny of 3 373 d i f f e r s i g n i f i e a n t l y from the progeny of K 2138. JT 2136 and I 17171 i n rate of growth from two to eight weeks. That families d i f f e r i n rate of growth i s substantiated i n Table 4, whieh shows the average (mean) differences in the rates of growth of the s i x fam i l i e s , and the odds that these differences are s i g n i f i c a n t as calculated by the "Students" method. In t h i s table heavy l i n e s separate differences whieh are s i g n i f i c a n t from those that are not. The differences are small and i n s i g n i f i c a n t within the group i n which the progeny had the highest rate of growth. Thus the progeny of K 2138, E 2136 and I 17171 do not d i f f e r s i g n i f i c a n t l y i n rate of growth, but the f i r s t two families (progeny of £ 2138 and K 2136) have a higher rate of growth than the families with an intermediate rate of growth (progeny of K 2132 and K 2191) and the differences of over 4 per cent, are s t a t i s t i c a l l y s i g n i f i -cant. The progeny of I 17171 appear to be intermediate between those of K 2133 and K 2136 on the one hand, and K 2132 and K 2191 on the other. The progeny of J 373 are shown here to have grown at a s i g n i f i c a n t l y slower rate from two to eight weeks of age than the progeny of any of the other f i v e hens, the differences ranging from s l i g h t l y over 6 per eent. to over 10 per eent. In contrast to these differenees the progeny of K 2132 d i f f e r by le s s than one per cent, in rate of growth from the progeny of K 2191, whieh i s comparable to the d i f f e r -ence between the progeny of K 2136 and K 2138, The differences in the rates qf growth of these six fam-i l i e s indicates that the hens dif f e r in genetic constitution with respect to rate of growth. In this connection i t is of interest to note that K 2136 whose progeny are seeond highest in average rate of growth is a half sister of J 373, the mother of the slowest growing family. Moreover, these two hens were mated to the same male, so that the coefficient of relationship of their offspring is .3125. In spite of the close relationship, the growth rates of the two progenies differ by 10.5 per cent., which, as shown by the odds of 690 ; 1 i s s t a t i s t i c a l l y significant, Clearly, these two hens transmitted different gene complements to their progeny* The evidence so far considered indicates that there are genetic differences with respect to rate of growth within the White Leghorn breed, and that such differences can be demon-strated to exist between even such closely related individuals as f u l l sisters (J 373 and K 2136). It has previously been suggested (Xerner and Asraundson, 1932) that rate of growth i s determined by multiple factors. Some of the differences shown in Table 4 have a bearing on this question. If the differences between the groups with the high-est and the lowest rates of growth are averaged, these d i f f e r -ences are found to equal 10.155 per eent. The average d i f f e r -ence between the groups with the medium and the lowest rates of growth is 6.652 per cent. The average difference between the groups with the medium and the highest rates of growth should then be 10.155 - 6.652 = 3.503 per cent, i f the factors - 8 -for high rate of growth lacking in the medium group are the same as some of those lacking i n the group with the lowest rate of growth. The actual average difference between the groups with the medium and the highest rates of growth i s 5.516 per eent, whieh i s i d e n t i c a l to the f i r s t decimal place with the expected f i g u r e . This may be interpreted as addition-a l evidence Indicating that rate of growth depends on multiple f a c t o r s . SUMMARY. The rate of growth from two to eight weeks of age was computed for 340 S, 0. White Leghorn chicks by a modified formula of Minot. The ehieks were divided into four groups on the basis of sex and time of hatch. Comparisons were made between the progeny of three males and between six more or less elosely r e l a t e d families, each of 15 or more chicks. The r e -s u l t s obtained may be summarized as follows: 1. The males grew more rapidl y than the females and the e a r l i e r hatched ehieks grew more ra p i d l y than the l a t e r hatched ehieks. 2. There was no s i g n i f i c a n t difference i n the average rate of growth of the progenies of the three males. 3. The s i x fam i l i e s could be divided approximately into three classes: (a) three families with a com-paratively rapid rate of growth (average per cent. 143.36); (b) two families with an intermediate rate of growth (average per cent. 139.86), and (c) one family with the slowest rate of growth (average per - 9 -cent. 133,21), There was no s i g n i f i c a n t d i f f e r -ence i n rate of growth between families within any one of these classes, the differences rang-ing from 0,8 to 1,8 per cent. Families, not i n the same class, d i f f e r e d i n rate of growth by from 2,0 to 10.8 per cent., and these d i f f e r -ences were, in most eases, s t a t i s t i c a l l y s i g n i -f i c a n t . The average difference between elasses (a) and (b) was 3.50 per cent.; between classes (b) and (e) 6.65 per cent.; and between elasses (a) and (e) 10.15 per cent., which equals (a - b) + (b - c ) . These r e s u l t s point to two general conclusions: (a) That there are genetic differences with respect to rate of growth within this s t r a i n of the White Leghorn breed, and (b) that these differences i n rate of growth are deter-mined by multiple f a c t o r s . - 10 -REFSBSHOES BBODY, S.t 1927. Growth and development I I I . University Of Mo. Bes. Bui. 97. LSBNER, I., and ASMUiYDSON, ¥.S., 1932. Inheritance of rate of growth i n domestic fowl I. Methods and preliminary report on r e s u l t s obtained with two breeds. S e i . A g r i c . 12: 652-664. A P P S J...3). I X TABLE I Constants for Bate of Growth from Two to l i g h t Weeks of Ag for the Jour Groups of S.C. White Leghorn Chicks. Sex Hatch No. of Chicks Mean Standard Deviation C o e f f i c i e n t u of " a r i a t i o n . Wale 1 + 2 54 146,468 £.384 4.184£ .272 2.857-t .186 3 + 4 110 136,730±.551 8.578£ .390 6.2694 .284 Female 1 -V 2 53 141.©44*.500 5.3921 .353 3.823± .251 n 3 + 4 123 134*298^.390 6.420-t .g76 4.780^ .206 TAB LJS S„ DIFFERENCES BETWEEN THE VARIOUS GROUPS OF CHICKS CALCULATED FROM TABLE I. Differene* between: Meeja D/l C o e f f i c i e n t of Variation D/I Males,B.l+2 - Males,H.3+4 9.738±.672 14.5 -3.406*.338 10.1 Females, H.1+-2 . mmlm,H.3+-4 6.746l:.635 10.6 - .952+T.325 2.9 Males,H.1+-2 - * H.l+g 5.424±.631 8.6 - .972*.312 3.1 Males,H.3-1-4 - » H.3+4 2.432±.676 3.6 1.482f.349 4.2 m E H a ft U o £t 00 S> © • H a i s at o a a> 0 « • H W a © © © o l *t e e +» 60 Tl -o o o rl 4-4 A » O u & <n O © +» a 05 © © © © 4-1 p <0 CO 61 p « o © © P rH ts H o o © u © 4H 4-1 • H P P 0V e o © rt © 4-1 4H • H - E L P to r-i © o © u © 4t 4H «rt _P P to es to © o Ft © u © 4-t 4-t fi o © CQ O » S3 W to to in o o • * rH H o o . • CO tO _ l CO CO o o LO 00 o to IO rH +<• o o LO I tO H • • O «# to «* H CO *# 02 to is to o ft-IO CO o «* CO o> o> CO o> CO • •w O ts o to in <o • • o tO co <oi 01 Ol in o oo o ts • 02 r-i +< +l| IO t> (O to to to oj + H tO ^ 0 CO to w IO CO CO o ca oj to co co to to co .  • rH OJ +i to to to to rH in com •- • rH CVJ IS to m to to ts +/ + o o o o in ># ftJ •# to oj o> CO to «o m to to to • O CD to in o> in • • m in M< to H! © o to 01 rH 0>j OH-0J O CO 02 r-i oi m ' » rH . -r o o o o o o • » to oi en o» 02 in f-H in o m • rH H +1 O 0} o CJ in • ' • ts to ^ CO o -in. to to oo co • o o o o o n to is in • • O Ok ^r IN H r-i +1 -W in o to o rH O C» «* r H OJ ^ rH tO to CO rH 03 o o * • rH tO m +t ts at in c\j in to tO CS CO'* • . « » • o to o to to to CO w in o> o> dt 10 00 • • '• • H rH r H rH + ' 4-1 O N o GO ts « 6 co in ol m in co to « to 00 CM tO H co^i 'I •« o o tO • • to to CO • • •# ts CO 0» O o H O 02 «o to CO o rH 02 <# to ts co| o to tol o «# H o o o o in • ts ts • • 02 00 Cfi o> o> 0} W CO • 02 r-i +t +lj .m. o to O H O tO to 02 H to ^* • • Jo o o o CO H 02-rs o to in rH ts in to Oj tr OJ IS O of| *-( 4-Cs OOJ to to ts H rH «* OJ o> o 00 02 O, • 03 OJ ts O to m rH Ol O rH 02 •* rH CO CH-OI tO| « • O O to O 00 O CO CO +r ^  O 02 ©I OJ O © in <o co oi A rH' •fl +1 O CO O 00 to in [to in in • • OJ 0> r-H a> et 0» H i • r-i 02 H O CR m 02 <* rH to| ^3 CO rH OJ M IS LO CQ O p CO ' • • to tO ts i» m et oj o ©| O o o oo CO «<J" OJ r-i tO OH-ts H 01 tol " * t r l OJ to CO ts • rH •H ^ I in o to o rH m m o 01 <sH r-i toj ^O OJ to rH 02 M oo to • • oj to 00 H i «o I +1 • 1 O OJ| © to tol 0J «*l H to| CM-•8 EH 03 © H at a © *» • ©» o N ^ © *» « O <-)Hf» «0 o © © max* ra &« © 60 t*. © o x* e m © © © 95 © H IB a -P O © H fp © O © o rt © © U •rt « to to r H « rt ' ° S to rt <d 60 o © •H CM to H °-s ra rt •d IH o o 1-4 •rl n r rt -ri o *u •rt n rt o © •rl 3 -r rt *H o vr ©I f t : O m rt rt Hj i H O o © TH" a O Vi 1-15 » « rti •0 t£ ©j •d «rl O O © •rt CM to Cft ..is. at 00 CO H to CM to CM to 01 00 - • to to 6} 10 to in * -(O to to to 0> w • H m CO to r-l CO o> to to CO © H £0 to M «o • • o o> to I S ; to o to CO rH cvj M to -• CO «0 o> o • IS H o H O to o !S H CO CM «o to H W M. « u o u © » ra o <D : r-i ra as or © & © +» X I .rt 00 dO <D •rl tA m © O 4» +> «rt .rt O 6= Se E-< • a ° a • O 03 u © © Xi u *» .rt © 14 %4 0 O v< ra o © • r t © fl <p © © 60 £3 o f« At o 10 •p rt <a +» ra rt o o rt <* © © u to At ra © © H .rt © o a 4> © © © © Pi © © >-i x\ © o a +» © © «# >»• rt <*$ © o u ra Pt © © o « © M rt =a © iJOi-t o fn ra p. © .rt © © H ' 4 » © © © • 4* 4-4 *4 >rt © O rt © © o S=5 o ^ • • » *H © rt © © \* rt o «* © tl © o © T? © a o *4 o to +t o to CO to +1 CO OS to o» • to Cft t l CO • IO to to o • to i n to r-i to to 00 to ts to o» to «o CO to to o 00 o> • +1 r-i co CVJ CvJ to • •H <* ts « to ts t© to H o CO to to r-i CVJ CvJ to H to to 02 r-i CM • t t 03 m • -OJ r-i • •M to to • to o t o ' to 00 +1 to to « <# rH 02 tO ' rH IS • CvJ to • 60" rH CvJ o to » to r-i £0 IO • •H o e-• to "FT H f l i n to to o to o 01 in-to i H CD O to o CVJ J± TAB LI 4 Relationships Between Six Families of S.C. White Leghorns Family Bo. Mother Mother *s father Mother* s mother Father Father * s father Father's mother 3 I 17171 420 § D 2444 L 1520 E 2390 I 17140 5 E 2132 H 488 I 17171 t* * •» 1 E 2138 n * ti n 4 E 2191 I 17130 w n 2 E 2136 H 58? H 11917 E 585 H 488 » 6 J 373 H 755 If 6H U o © -a! a • © © © «H *» 0 .4 a) <H M fl o o •p A o © © 0 +» © i H rl .fl XI • m • O CQ rl M 4* CO o to © -p id w aJ © o in CO © to to CO rH CO «* CO CO • • • • W - P rH rH rH to 4-1 & ts fl o o m O o o to a> u CO in in m © rj> ts co o» rH • • . • • o C M CM to to «0 rH rH rH rH a l l to «* in © i n - rH CO to m C M at <et m CO « +=" • • • 4 H m to o o o o O CM r H « i K in in to to C M © cS o> to o M • • • » «—» m m o to in to -* to rH H rH r-i •<*' in in C O «n CO o to © o> to ts in •p ts in C M o> a) A • • • • « -P r-i rH rH 4-i £ ' to O O o C B fl o o CM in in m H «* h ts C M W © CjJ • • • m to to •># rH to rH •4 rH to rH • w £ A M ' co m to CO ES rH ts to to to rH CM W CM CO to rH C M W o , r i -© © -p at A « -P 4-1 Its Pi O O a*, u © cd £ x W O O © p al A « P -4H * fl CJ O d fn © O o ^ is; o o © •p a) .fl K -P 4-t IB fl o o at h © & • -H CQ O 4 X g o o •p. ^ o © CO to CO to o in co C M o r-i O in co • o CO co C M • r H r> rH rH • in rH to tO tO to tO o in • -o> co to C M O m CO to to o ts o to in • to to C M o» o GO O in to H rs C M Q, C M ts ts o (O to <# H in to CM C M rH to C M H tO to CO o o CM • to to rH ts C M C M IO • C M CO o in to in to © rH (0 3 

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