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Divergent Selection for Body Weight and Yolk Precursor in Coturnix coturnix japonica
Divergent Selection for Body Weight and Yolk Precursor in Coturnix coturnix japonica. 1. Selection Response1 KARL E. NESTOR, WAYNE L. BACON, and A. L. LAMBIO Department of Poultry Science, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691 (Received for publication March 2. 1981)
1982 Poultry Science 6 1 : 1 2 - 1 7 precursors, the low density fraction, was greater in t w o growth strains t h a n in an egg strain of turkeys. Total plasma p h o s p h o r u s during the laying period was chosen as a measure of yolk precursor in this study. Data from o u r laboratory (Bacon and Nestor, 1982) indicate that t h e correlation coefficient between total plasma p h o s p h o r u s and total lipid of t h e plasma form of t h e yolk low density fraction from laying female quail is extremely high ( +.96 based on 58 df). Also, Strong et al. ( 1 9 7 8 ) reported t h a t t h e genetic correlation between total plasma p h o s p h o r u s and t h e plasma c o n c e n t r a t i o n of a l i p o p h o s p h o p r o t e i n complex is positive and large. Published estimates of t h e heritability of b o d y weight of Japanese quail at four weeks of age when based on parent-offspring regressions and variance a m o n g sire and d a m families ranged from .14 t o .78 with an unweighted average of .38 (Marks and Lepore, 1 9 6 8 ; Marks, 1 9 7 1 , 1978; Sefton and Siegel, 1974). T h e realized heritability of 4-week b o d y weight based on selection for increased weight averaged .29 (Marks and Lepore, 1 9 6 8 ; Marks, 1970, 1 9 7 1 , 1978).
INTRODUCTION Rapid growth strains of chickens (Jaap and Clancy, 1968), t u r k e y s (Nestor et al, 1970), and Japanese quail (Bacon et al, 1973b) accumulate m o r e yolk material in their ovaries t h a n d o their egg p r o d u c t i o n c o u n t e r p a r t s . A higher percentage of t h e ovarian follicles are lost in the growth strains due to loss of yolks into t h e b o d y cavity, follicular atresion, production of defective eggs, or a c o m b i n a t i o n of these. J a a p ( 1 9 6 9 ) suggested t h a t selection for increased rate of growth in these birds m a y have resulted in t h e accumulation of genes which e n h a n c e d formation by t h e liver, and hence, an increased rate of yolk accumulation in t h e ovary. It has been established t h a t lipids synthesized in t h e liver of t h e laying female are t r a n s p o r t e d by t h e plasma in t h e form of lipoprotein complexes t o t h e ovary where t h e y are deposited i n t a c t in t h e follicles ( M c l n d o e , 1 9 5 9 ; Christie and Moore, 1 9 7 2 ; Hillyard et al, 1972). Bacon et al. ( 1 9 7 3 a ) found t h a t t h e total plasma pool of one of t h e yolk lipoprotein
Estimates of the heritability of plasma c o n s t i t u e n t s of Japanese quail have received little a t t e n t i o n . Strong et al. ( 1 9 7 8 ) reported estimates of .48, .19, and .34 for total plasma
'Approved for publication as Journal Article No 36—81 of the Ohio Agricultural Research and Development Center, Wooster, OH 44691. 12
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ABSTRACT From a randombred control population of Coturnix coturnix japonica, four strains were selected respectively for high and low 4-week body weight and high and low total plasma phosphorus (plasma yolk precursor). Based on seven generations of selection, die realized heritabilities plus or minus their standard errors for high and low body weight strains were .37 ± .05 and .44 ± .28, respectively. The total gain and gain per generation were greatest in the low weight strain, primarily due to greater selection differentials. Selection for plasma yolk precursor was more effective in the high than low strain. The respective realized heritabilities plus or minus standard errors were .32 ± .02 and .34 ± .03. The selection differentials were larger in the high strain than in die low strain. There was no significant change in plasma yolk precursor in the weight strains nor in 4-week body weight in die plasma yolk precursor strains, which indicated that the genetic correlation between body weight during the growing period and plasma yolk precursor during the laying period was close to zero. (Key words: body weight, yolk precursor, plasma phosphorus, Japanese quail, selection)
SELECTION FOR BODY WEIGHT AND YOLK PRECURSOR IN QUAIL phosphorus of the laying female based on sire, dam, and sire plus dam components of variance, respectively. The purpose of this experiment was to study the response to seven generations of bidirectional selection for 4-week body weight and total plasma phosphorus of laying Japanese quail, respectively. MATERIALS AND METHODS
were used from any family. This reduced the selection pressure in females. Offspring from each strain were wingbanded and randomly assigned to sections in battery brooders in the first four generations of selection. Since there were large apparent differences in growth rate between sections, the strains were intermingled in each section in the last three generations of selection. The temperature in each section was maintained at approximately 35 C for the 1st week after hatching, then decreased 2.8 C weekly through the 4th week after hatching when supplemental heating was discontinued. Continuous lighting was provided during the first 2 weeks. At 2 weeks of age, the length of the daily light was reduced to 6 hr and was maintained at this level until the breeders were housed. When the youngest hatch was 10 weeks of age, the lighting was increased to 14 hr per day. A turkey starter diet (P—101—77, Table 1) was fed from hatching through 6 weeks of age. From 6 weeks of age, a turkey breeder diet ( P - 7 0 1 - 7 7 , Table 1), which contained 2.25% calcium and .43% available phosphorus, was provided. The amount of yolk precursor in the blood was estimated by the plasma level of total phosphorus during the 2nd or 3rd weeks of production for each hen. Blood samples were collected from wing veins into heparinized microhematocrit capillary tubes and total plasma phosphorus was measured by the method of Bacon and Musser (1974) as modified by Strong et al. (1978). In order to remove any possible influence of ovarian regression on plasma phosphorus levels, values for blood samples from hens which did not produce an egg during the 5 days following collection of blood were not used. Effective population culated by the formula:
size (Ne) was cal-
4N-2 N C =
2
+
Ok2
where N is the total number of parents and a^ 2 is the variance in family size (Falconer, 1964). The increase in inbreeding per generation (AF) for generations two through seven was estimated as half the reciprocal of Ne. In the first generation, AF = y^- (Falconer, 1964). The realized heritability of the selected traits was estimated by regressing the gains (deviations from R l ) on the accumulated actual selection differentials. The standard error of
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The base population for this study was a randombred control population of Japanese quail which had been maintained with a large number of breeders (greater than 100 of each sex) for more than 10 generations. Five sublines were developed from the base population. One of these (Rl) was maintained as a randombred control. Sublines were selected for high (HW) and low (LW) 4-week body weight and for high (HP) and low (LP) level of total plasma phosphorus (yolk precursor) during the early part of the laying period. The initial selection was based on a single hatch representing a 2-week collection of eggs from 192 parental pairs. The 452 male and 472 female offspring were wingbanded at hatching but were not pedigreed according to sire and dam. A random sample of both sexes was first chosen to produce R l . Then, random samples of both sexes were used to initiate the HP and LP strains. The remaining offspring were used to start the HW and LW strains. After the first generation of selection, offspring from one 2-week and one 1-week collection of eggs were used to reproduce the strains. Mass selection was used in the HW and LW strains. With the exception of the first generation of selection, females of the HP and LP strains were individually selected while males were selected on the basis of their full sisters' performance with the best 18 of 36 families being selected. Since the offspring were not pedigreed in the base generation, selection in that generation for yolk precursor was practiced on the females only. All strains were reproduced with 36 pairs (Nestor, 1977). Mating was random except that full sib matings were avoided. Prior to selection of breeders, one female, if available, was randomly selected from each family each generation for measurement of correlated responses. A few extra females were randomly selected to replace those families which had no available females. No more than two females
13
14
NESTOR ETAL. TABLE 1. Composition of the diets fed during the growing and laying periods
Ingredient
P-701-77
26.48 45.50 5.00 5.00 2.50 2.50 1.50
59.88 13.50 2.50 5.00 2.00 5.00 1.00
.40 .65 .75
1.00 3.80
6.15 2.50
5.00
.40
.50 .10 .10 .05 .05 .12
.50 .10 .10 .10 .22 .05
2800 29.4 1.33
2760 18.1 2.24
.67
.61
'Supplied the following per kilogram diet: vitamin A, 8756 IU; vitamin D 3 , 3750 ICU; vitamin E, 60 IU; menadione sodium bisulfite complex, 2.0 mg; thiamine HCl, 2.2 mg; riboflavin, 6.6 mg; niacin, 99 mg; calcium pantothenate, 15.5 mg; folacin, 1.2 mg; pyridoxine HCl, 2.2 mg; biotin, .17 mg; vitamin B 1 2 , 15 jug; ethoxyquin, 125 mg. 2
Supplied .2 mg Se/kg diet.
'Supplied the following (mg/kg diet): zine oxide, 147; manganous oxide, 152; copper sulfate, 35; ferrous carbonate, 72; potassium iodide, 1.5.
this regression coefficient provided an approximate standard error for the heritability estimate, An analysis of variance with strains, sexes,
and hatches body weight way analysis parisons of
as the main effects was used for data within generations. A onewas conducted for strain comtotal plasma phosphorus. In all
TABLE 2. Estimation of inbreeding (%) in Rl, HW, LW, HP and LP strains Generation
Rl
of
HW AF1
LW
HP
AF'
Total
1 2 3 4 5 6 7
.69 .42 .43 .43 .45 .40 .43
.69
.69
.69
.69
.69
1.11 1.54 1.97 2.42 2.82 3.25
1.10 1.06 1.45 1.15
1.79 2.85 4.30 5.45 6.19 7.64
1.47
2.16 2.85 3.86 4.63 5.52 6.53
.74
1.45
Total
Total
selection
' Estimated increase in inbreeding per generation.
AF'
.69
1.01 .77 .89
1.01
AF1 .69 .71 .67 .65 .80 .81 .78
LP
Total .69
1.40 2.07 2.72 3.52 4.33 5.11
AF' .69 .72 .76 .72 .79
1.00 .70
Total .69
1.41 2.17 2.89 3.68 4.68 5.38
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Corn Soybean meal, 44% Meat and bone meal, 50% Dehydrated alfalfa meal Dried whey product Fish meal, menhaden, 60% Dried fish solubles Salt Calcium phosphate (21.5% Ca, 18.7% P) Limestone Hydrolyzed animal-vegetable fat Wheat middlings Vitamin premix 1 Selenium premix 2 Trace mineral premix 3 DL-methionine, 99% Lysine HCl, 98% Choline CI, 50% Amprolium, 25% Calculated analysis: Metabolizable energy, kcal/kg Protein, % Ca, % P, available, %
P-101-77
SELECTION FOR BODY WEIGHT AND YOLK PRECURSOR IN QUAIL
15
TABLE 3. Intended and actual selection differentials obtained in the HW, LW, HP, and LP strains Generation of selection
Intended
Actual
Intended
Actual
Intended 1
Actual
Intended
Actual
1 2 3 4 5 6 7 Average b1
10.2 9.2 9.1 9.1 8.7 7.0 8.3 8.8 -.32
10.2 9.2 8.8 8.9 9.0 6.7 8.4 8.7 -.29
-11.3 -12.8 -11.8 -7.7 -9.8 -8.2 -10.9 -10.4 -.52
-11.3 -12.5 -12.0 -7.4 -8.7 -8.4 -10.4 -10.1 +.57
137.1 182.1 155.0 175.4 193.9 207.1 217.2 181.1 + 10.0*
138.9 184.3 151.4 171.2 196.2 205.5 220.6 181.2 + 10.5*
-110.3 -114.1 -116.1 -88.0 -99.7 -84.6 -121.1 -104.8 +1.4
-116.2 -114.0 -119.2 -90.0 -97.2 -81.4 -118.4 -105.2 +2.4
1
HW (g)
LW
HP
(g)
Og/ml)
LP (ug/ml)
Linear regression coefficient of selection differential on generations for generations 2 through 7.
cases, Harvey's mixed model least-squares and maximum likelihood computerprogram(Harvey, 1977) was used. RESULTS AND DISCUSSION Inbreeding estimated in the various strains is presented in Table 2. The total inbreeding occurring in any of the strains was probably not large enough to result in inbreeding depression or excessive genetic drift. The intended and actual selection differentials for all the selected strains were essentially the same, indicating that natural selection was not a factor in these strains (Table 3). The magnitude of the selection differential increased from generations two through seven in HP as indicated by the positive linear regression coefficient of selection differential on generation of selection. Based on the linear regression coefficient of gain on generations, the respective gains per generation for increased and decreased body weight were + 3.1 and - 4.2 (Table 4). There was no significant trend with generations in the randombred control population. The greater progress in 4-week body weight in LW was the result of larger selection differentials in this strain (Table 3) and a slightly higher realized heritability when selection was for lowered body weight. Realized heritability for selection for increased 4-week body weight (.37 ± .05) approximate the unweighted average of published estimates (.38) of heritability of 4-week body weight based on parent-offspring regressions
and variation among sire and dam families (Marks and Lepore, 1968; Marks, 1971, 1978; Sefton and Siegel, 1974). Estimates obtained in the present experiment were slightly lower than a similar estimate (.49 ± .06) obtained by Marks (1978) in a strain selected for 10 generations on a 28% protein diet. Hatch effects for 4-week body weight were highly significant in five of seven generations. The interaction of strain and hatch was also a
TABLE 4. Response in 4-week body weight (g) to divergent selection for 4-week body weight and total plasma phosphorus, hatches and sexes combined Generation of selection 1 2 3 4 5 6 7 b2 Realized h 2 + SE
Strain Rl 84 87 89 86 91 90 89
HW 1 +6 + 10 +11 + 11 + 19 +20 +26 .1! + 3 . 1 * * .37 + .05
LW 1
HP1
LP 1
-5 -12 -17 -17 -24 -28 -31 -4.2** .44 ± .28
+2 -1 -1 0 +1 -2 -3 - .5
+2 -2 -4 0 0 -3 -3 - .5
1 Selection response expressed from the Rl strain. 2
as a deviation
Linear regression coefficient of mean or response on generation. **P<.01.
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*P<.05.
16
NESTOR ET AL. TABLE 5. Response in total plast selection for 4-week body wei±
Generation of selection
Strain Rl 677 714 653 729 747 756 776
1 2 3 4 5 6 7 b2
Realized h 2 + SE
phosphorus (ng/ml) to divergent : and total plasma phosphorus
+ 17.0*
LP1
HP 1 +77
+126* +196** +267** +350** +373** +453*** +63.4** .34
±
.02
-14 -56 -108* -147** -155** -161** -249** -34.4** .34 ± .03
Expressed as a deviation from the R l strain. Linear regression coefficient of mean or response on generation.
LW1
+141
+95
+24 +66
+71 +73
+124
+120
*P<.05. **P<.01.
significant source of variation. The strain x sex interaction was significant in the last two generations of selection. The differences between sexes in 4-week body weight were larger in HW and smaller in LW than in the R l strains in both generations. This may have resulted from scaling effects. The difference between sexes was smaller for LP than for the R l strain. Since body weight was not greatly different between these strains, scaling effects should not be a factor. Selecting for an increased plasma level of yolk precursor (total phosphorus) was more effective than selecting for a low level even though the realized heritability in both directions was essentially the same (Table 5). The selection differentials were larger in HP than LP (Table 3). The total gain in HP was 453 yUg/ml versus 249 fig/ml in LP. The gain per generation was almost twice as large in HP (63.5 jug/ml versus 34.4 /Jg/ml). There was also a significant upward trend with generations in the randombred control (b = 17.0 fig). In the comparison of the selected lines with the randombred control, hatch effects and the interaction of hatch and strain were not significant sources of variation so a one way analysis of variance for strain effects was used. The realized heritabilities for total plasma phsophorus were identical to the estimate (.34 ± .18) obtained by Strong et al. (1978) based on variance components.
Genetic changes in plasma yolk precursor in HP and LP had no significant effect on body weight during the growing period (Table 4) when measured by the linear regression coefficient of difference from R l on generation of selection. Conversely, the total plasma phosphorus of unselected HW or LW laying females did not differ significantly from Rl females (Table 5). In Table 5, the comparisons involving Rl, HW, and LW were based on a smaller number of observations than the comparisons of R l , HP, and LP and, as a result, the deviation in the former comparison had to be larger to be significantly different. Strong et al. (1978) reported positive genetic correlations between total plasma phosphorus and body weight during the laying periods. REFERENCES Bacon, W. L., and M. A. Musser, 1974. Estimation of low density lipoprotein fraction concentration in blood plasma of laying turkey hens using density gradient centrifugation. Poultry Sci. 53:2015— 2019. Bacon, W. L., and K. E. Nestor, 1982. Divergent selection for body weight and yolk precursor in Coturnix coturnix japonica. 2. Correlated responses in plasma lipoproteins and lipids. Poultry Sci. 61:161-165. Bacon, W. L., K. E. Nestor, and M. A. Musser, 1973a. Relative concentration and plasma content of yolk lipoprotein precursor in three lines of turkeys. Poultry Sci. 52:1185-1187. Bacon, W. L., K. E. Nestor, and P. A. Renner, 1973b.
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1 2
HW1
SELECTION FOR BODY WEIGHT AND YOLK PRECURSOR IN QUAIL
weight in Japanese quail under two nutritional environments. Poultry Sci. 50:931—937. Marks, H. L., 1978. Long term selection for four-week body weight in Japanese quail under different nutritional environments. Theor. Appl. Genet. 52:105-111. Marks, H. L., and P. D. Lepore, 1968. Growth rate inheritance in Japanese quail. 2. Early response to selection under different nutritional environments. Poultry Sci. 47:1540-1546. Mclndoe, W. M., 1959. A lipophosphoprotein complex in hen plasma associated with yolk production. Biochem. J. 72:153-159. Nestor, K. E., 1977. The use of a paired mating system for the maintenance of experimental populations of turkeys. Poultry Sci. 56:60—65. Nestor, K. E., W. L. Bacon, and P. A. Renner, 1970. Ovarian follicular development in egg and meat type turkeys. Poultry Sci. 49:775-780. Sefton, A. E., and P. B. Siegel, 1974. Inheritance of body weight in Japanese quail. Poultry Sci. 53:1597-1603. Strong, C. F., Jr., K. E. Nestor, and W. L. Bacon, 1978. Inheritance of egg production, egg weight, body weight and certain plasma constituents in Coturnix. Poultry Sci. 5 7 : 1 - 9 .
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Ovarian follicular development in egg and growth lines of Japanese quail. Poultry Sci. 1195-1199. Christie, W. W., and J. H. Moore, 1972. The lipid components of the plasma, liver and ovarian follicles in the domestic chicken (Callus gallus). Comp. Biochem. Physiol. 41B:287-295. Falconer, D. S., 1964. Introduction to Quantitative Genetics. Oliver and Boyd, Edinburgh and London. Harvey, W. R., 1977. User's guide for LSML76 mixed model least-squares and maximum likelihood computer program. Ohio State University, Columbus, OH. Hillyard, L. A., H. M. White, and S. A. Pangburn, 1972. Characterization of apolipoproteins in chicken serum and egg yolk. Biochemistry, 11:511-518. Jaap, R. G., 1969. Large broilers from smaller hens. World's Poultry Sci. J. 25:140-143. Jaap, R. G., and J. A. Clancy, 1968. Reproductive idiosyncrasies of the broiler pullet. Proc. 3rd Europ. Poultry Conf., Israel. Marks, H. L., 1970. Selection for four-week body weight in Coturnix. Poultry Sci. 49:1410. Marks, H. L., 1971. Selection for four-week body
17
1982 Poultry Science 6 1 : 1 2 - 1 7 precursors, the low density fraction, was greater in t w o growth strains t h a n in an egg strain of turkeys. Total plasma p h o s p h o r u s during the laying period was chosen as a measure of yolk precursor in this study. Data from o u r laboratory (Bacon and Nestor, 1982) indicate that t h e correlation coefficient between total plasma p h o s p h o r u s and total lipid of t h e plasma form of t h e yolk low density fraction from laying female quail is extremely high ( +.96 based on 58 df). Also, Strong et al. ( 1 9 7 8 ) reported t h a t t h e genetic correlation between total plasma p h o s p h o r u s and t h e plasma c o n c e n t r a t i o n of a l i p o p h o s p h o p r o t e i n complex is positive and large. Published estimates of t h e heritability of b o d y weight of Japanese quail at four weeks of age when based on parent-offspring regressions and variance a m o n g sire and d a m families ranged from .14 t o .78 with an unweighted average of .38 (Marks and Lepore, 1 9 6 8 ; Marks, 1 9 7 1 , 1978; Sefton and Siegel, 1974). T h e realized heritability of 4-week b o d y weight based on selection for increased weight averaged .29 (Marks and Lepore, 1 9 6 8 ; Marks, 1970, 1 9 7 1 , 1978).
INTRODUCTION Rapid growth strains of chickens (Jaap and Clancy, 1968), t u r k e y s (Nestor et al, 1970), and Japanese quail (Bacon et al, 1973b) accumulate m o r e yolk material in their ovaries t h a n d o their egg p r o d u c t i o n c o u n t e r p a r t s . A higher percentage of t h e ovarian follicles are lost in the growth strains due to loss of yolks into t h e b o d y cavity, follicular atresion, production of defective eggs, or a c o m b i n a t i o n of these. J a a p ( 1 9 6 9 ) suggested t h a t selection for increased rate of growth in these birds m a y have resulted in t h e accumulation of genes which e n h a n c e d formation by t h e liver, and hence, an increased rate of yolk accumulation in t h e ovary. It has been established t h a t lipids synthesized in t h e liver of t h e laying female are t r a n s p o r t e d by t h e plasma in t h e form of lipoprotein complexes t o t h e ovary where t h e y are deposited i n t a c t in t h e follicles ( M c l n d o e , 1 9 5 9 ; Christie and Moore, 1 9 7 2 ; Hillyard et al, 1972). Bacon et al. ( 1 9 7 3 a ) found t h a t t h e total plasma pool of one of t h e yolk lipoprotein
Estimates of the heritability of plasma c o n s t i t u e n t s of Japanese quail have received little a t t e n t i o n . Strong et al. ( 1 9 7 8 ) reported estimates of .48, .19, and .34 for total plasma
'Approved for publication as Journal Article No 36—81 of the Ohio Agricultural Research and Development Center, Wooster, OH 44691. 12
Downloaded from http://ps.oxfordjournals.org/ by guest on June 9, 2015
ABSTRACT From a randombred control population of Coturnix coturnix japonica, four strains were selected respectively for high and low 4-week body weight and high and low total plasma phosphorus (plasma yolk precursor). Based on seven generations of selection, die realized heritabilities plus or minus their standard errors for high and low body weight strains were .37 ± .05 and .44 ± .28, respectively. The total gain and gain per generation were greatest in the low weight strain, primarily due to greater selection differentials. Selection for plasma yolk precursor was more effective in the high than low strain. The respective realized heritabilities plus or minus standard errors were .32 ± .02 and .34 ± .03. The selection differentials were larger in the high strain than in die low strain. There was no significant change in plasma yolk precursor in the weight strains nor in 4-week body weight in die plasma yolk precursor strains, which indicated that the genetic correlation between body weight during the growing period and plasma yolk precursor during the laying period was close to zero. (Key words: body weight, yolk precursor, plasma phosphorus, Japanese quail, selection)
SELECTION FOR BODY WEIGHT AND YOLK PRECURSOR IN QUAIL phosphorus of the laying female based on sire, dam, and sire plus dam components of variance, respectively. The purpose of this experiment was to study the response to seven generations of bidirectional selection for 4-week body weight and total plasma phosphorus of laying Japanese quail, respectively. MATERIALS AND METHODS
were used from any family. This reduced the selection pressure in females. Offspring from each strain were wingbanded and randomly assigned to sections in battery brooders in the first four generations of selection. Since there were large apparent differences in growth rate between sections, the strains were intermingled in each section in the last three generations of selection. The temperature in each section was maintained at approximately 35 C for the 1st week after hatching, then decreased 2.8 C weekly through the 4th week after hatching when supplemental heating was discontinued. Continuous lighting was provided during the first 2 weeks. At 2 weeks of age, the length of the daily light was reduced to 6 hr and was maintained at this level until the breeders were housed. When the youngest hatch was 10 weeks of age, the lighting was increased to 14 hr per day. A turkey starter diet (P—101—77, Table 1) was fed from hatching through 6 weeks of age. From 6 weeks of age, a turkey breeder diet ( P - 7 0 1 - 7 7 , Table 1), which contained 2.25% calcium and .43% available phosphorus, was provided. The amount of yolk precursor in the blood was estimated by the plasma level of total phosphorus during the 2nd or 3rd weeks of production for each hen. Blood samples were collected from wing veins into heparinized microhematocrit capillary tubes and total plasma phosphorus was measured by the method of Bacon and Musser (1974) as modified by Strong et al. (1978). In order to remove any possible influence of ovarian regression on plasma phosphorus levels, values for blood samples from hens which did not produce an egg during the 5 days following collection of blood were not used. Effective population culated by the formula:
size (Ne) was cal-
4N-2 N C =
2
+
Ok2
where N is the total number of parents and a^ 2 is the variance in family size (Falconer, 1964). The increase in inbreeding per generation (AF) for generations two through seven was estimated as half the reciprocal of Ne. In the first generation, AF = y^- (Falconer, 1964). The realized heritability of the selected traits was estimated by regressing the gains (deviations from R l ) on the accumulated actual selection differentials. The standard error of
Downloaded from http://ps.oxfordjournals.org/ by guest on June 9, 2015
The base population for this study was a randombred control population of Japanese quail which had been maintained with a large number of breeders (greater than 100 of each sex) for more than 10 generations. Five sublines were developed from the base population. One of these (Rl) was maintained as a randombred control. Sublines were selected for high (HW) and low (LW) 4-week body weight and for high (HP) and low (LP) level of total plasma phosphorus (yolk precursor) during the early part of the laying period. The initial selection was based on a single hatch representing a 2-week collection of eggs from 192 parental pairs. The 452 male and 472 female offspring were wingbanded at hatching but were not pedigreed according to sire and dam. A random sample of both sexes was first chosen to produce R l . Then, random samples of both sexes were used to initiate the HP and LP strains. The remaining offspring were used to start the HW and LW strains. After the first generation of selection, offspring from one 2-week and one 1-week collection of eggs were used to reproduce the strains. Mass selection was used in the HW and LW strains. With the exception of the first generation of selection, females of the HP and LP strains were individually selected while males were selected on the basis of their full sisters' performance with the best 18 of 36 families being selected. Since the offspring were not pedigreed in the base generation, selection in that generation for yolk precursor was practiced on the females only. All strains were reproduced with 36 pairs (Nestor, 1977). Mating was random except that full sib matings were avoided. Prior to selection of breeders, one female, if available, was randomly selected from each family each generation for measurement of correlated responses. A few extra females were randomly selected to replace those families which had no available females. No more than two females
13
14
NESTOR ETAL. TABLE 1. Composition of the diets fed during the growing and laying periods
Ingredient
P-701-77
26.48 45.50 5.00 5.00 2.50 2.50 1.50
59.88 13.50 2.50 5.00 2.00 5.00 1.00
.40 .65 .75
1.00 3.80
6.15 2.50
5.00
.40
.50 .10 .10 .05 .05 .12
.50 .10 .10 .10 .22 .05
2800 29.4 1.33
2760 18.1 2.24
.67
.61
'Supplied the following per kilogram diet: vitamin A, 8756 IU; vitamin D 3 , 3750 ICU; vitamin E, 60 IU; menadione sodium bisulfite complex, 2.0 mg; thiamine HCl, 2.2 mg; riboflavin, 6.6 mg; niacin, 99 mg; calcium pantothenate, 15.5 mg; folacin, 1.2 mg; pyridoxine HCl, 2.2 mg; biotin, .17 mg; vitamin B 1 2 , 15 jug; ethoxyquin, 125 mg. 2
Supplied .2 mg Se/kg diet.
'Supplied the following (mg/kg diet): zine oxide, 147; manganous oxide, 152; copper sulfate, 35; ferrous carbonate, 72; potassium iodide, 1.5.
this regression coefficient provided an approximate standard error for the heritability estimate, An analysis of variance with strains, sexes,
and hatches body weight way analysis parisons of
as the main effects was used for data within generations. A onewas conducted for strain comtotal plasma phosphorus. In all
TABLE 2. Estimation of inbreeding (%) in Rl, HW, LW, HP and LP strains Generation
Rl
of
HW AF1
LW
HP
AF'
Total
1 2 3 4 5 6 7
.69 .42 .43 .43 .45 .40 .43
.69
.69
.69
.69
.69
1.11 1.54 1.97 2.42 2.82 3.25
1.10 1.06 1.45 1.15
1.79 2.85 4.30 5.45 6.19 7.64
1.47
2.16 2.85 3.86 4.63 5.52 6.53
.74
1.45
Total
Total
selection
' Estimated increase in inbreeding per generation.
AF'
.69
1.01 .77 .89
1.01
AF1 .69 .71 .67 .65 .80 .81 .78
LP
Total .69
1.40 2.07 2.72 3.52 4.33 5.11
AF' .69 .72 .76 .72 .79
1.00 .70
Total .69
1.41 2.17 2.89 3.68 4.68 5.38
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Corn Soybean meal, 44% Meat and bone meal, 50% Dehydrated alfalfa meal Dried whey product Fish meal, menhaden, 60% Dried fish solubles Salt Calcium phosphate (21.5% Ca, 18.7% P) Limestone Hydrolyzed animal-vegetable fat Wheat middlings Vitamin premix 1 Selenium premix 2 Trace mineral premix 3 DL-methionine, 99% Lysine HCl, 98% Choline CI, 50% Amprolium, 25% Calculated analysis: Metabolizable energy, kcal/kg Protein, % Ca, % P, available, %
P-101-77
SELECTION FOR BODY WEIGHT AND YOLK PRECURSOR IN QUAIL
15
TABLE 3. Intended and actual selection differentials obtained in the HW, LW, HP, and LP strains Generation of selection
Intended
Actual
Intended
Actual
Intended 1
Actual
Intended
Actual
1 2 3 4 5 6 7 Average b1
10.2 9.2 9.1 9.1 8.7 7.0 8.3 8.8 -.32
10.2 9.2 8.8 8.9 9.0 6.7 8.4 8.7 -.29
-11.3 -12.8 -11.8 -7.7 -9.8 -8.2 -10.9 -10.4 -.52
-11.3 -12.5 -12.0 -7.4 -8.7 -8.4 -10.4 -10.1 +.57
137.1 182.1 155.0 175.4 193.9 207.1 217.2 181.1 + 10.0*
138.9 184.3 151.4 171.2 196.2 205.5 220.6 181.2 + 10.5*
-110.3 -114.1 -116.1 -88.0 -99.7 -84.6 -121.1 -104.8 +1.4
-116.2 -114.0 -119.2 -90.0 -97.2 -81.4 -118.4 -105.2 +2.4
1
HW (g)
LW
HP
(g)
Og/ml)
LP (ug/ml)
Linear regression coefficient of selection differential on generations for generations 2 through 7.
cases, Harvey's mixed model least-squares and maximum likelihood computerprogram(Harvey, 1977) was used. RESULTS AND DISCUSSION Inbreeding estimated in the various strains is presented in Table 2. The total inbreeding occurring in any of the strains was probably not large enough to result in inbreeding depression or excessive genetic drift. The intended and actual selection differentials for all the selected strains were essentially the same, indicating that natural selection was not a factor in these strains (Table 3). The magnitude of the selection differential increased from generations two through seven in HP as indicated by the positive linear regression coefficient of selection differential on generation of selection. Based on the linear regression coefficient of gain on generations, the respective gains per generation for increased and decreased body weight were + 3.1 and - 4.2 (Table 4). There was no significant trend with generations in the randombred control population. The greater progress in 4-week body weight in LW was the result of larger selection differentials in this strain (Table 3) and a slightly higher realized heritability when selection was for lowered body weight. Realized heritability for selection for increased 4-week body weight (.37 ± .05) approximate the unweighted average of published estimates (.38) of heritability of 4-week body weight based on parent-offspring regressions
and variation among sire and dam families (Marks and Lepore, 1968; Marks, 1971, 1978; Sefton and Siegel, 1974). Estimates obtained in the present experiment were slightly lower than a similar estimate (.49 ± .06) obtained by Marks (1978) in a strain selected for 10 generations on a 28% protein diet. Hatch effects for 4-week body weight were highly significant in five of seven generations. The interaction of strain and hatch was also a
TABLE 4. Response in 4-week body weight (g) to divergent selection for 4-week body weight and total plasma phosphorus, hatches and sexes combined Generation of selection 1 2 3 4 5 6 7 b2 Realized h 2 + SE
Strain Rl 84 87 89 86 91 90 89
HW 1 +6 + 10 +11 + 11 + 19 +20 +26 .1! + 3 . 1 * * .37 + .05
LW 1
HP1
LP 1
-5 -12 -17 -17 -24 -28 -31 -4.2** .44 ± .28
+2 -1 -1 0 +1 -2 -3 - .5
+2 -2 -4 0 0 -3 -3 - .5
1 Selection response expressed from the Rl strain. 2
as a deviation
Linear regression coefficient of mean or response on generation. **P<.01.
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*P<.05.
16
NESTOR ET AL. TABLE 5. Response in total plast selection for 4-week body wei±
Generation of selection
Strain Rl 677 714 653 729 747 756 776
1 2 3 4 5 6 7 b2
Realized h 2 + SE
phosphorus (ng/ml) to divergent : and total plasma phosphorus
+ 17.0*
LP1
HP 1 +77
+126* +196** +267** +350** +373** +453*** +63.4** .34
±
.02
-14 -56 -108* -147** -155** -161** -249** -34.4** .34 ± .03
Expressed as a deviation from the R l strain. Linear regression coefficient of mean or response on generation.
LW1
+141
+95
+24 +66
+71 +73
+124
+120
*P<.05. **P<.01.
significant source of variation. The strain x sex interaction was significant in the last two generations of selection. The differences between sexes in 4-week body weight were larger in HW and smaller in LW than in the R l strains in both generations. This may have resulted from scaling effects. The difference between sexes was smaller for LP than for the R l strain. Since body weight was not greatly different between these strains, scaling effects should not be a factor. Selecting for an increased plasma level of yolk precursor (total phosphorus) was more effective than selecting for a low level even though the realized heritability in both directions was essentially the same (Table 5). The selection differentials were larger in HP than LP (Table 3). The total gain in HP was 453 yUg/ml versus 249 fig/ml in LP. The gain per generation was almost twice as large in HP (63.5 jug/ml versus 34.4 /Jg/ml). There was also a significant upward trend with generations in the randombred control (b = 17.0 fig). In the comparison of the selected lines with the randombred control, hatch effects and the interaction of hatch and strain were not significant sources of variation so a one way analysis of variance for strain effects was used. The realized heritabilities for total plasma phsophorus were identical to the estimate (.34 ± .18) obtained by Strong et al. (1978) based on variance components.
Genetic changes in plasma yolk precursor in HP and LP had no significant effect on body weight during the growing period (Table 4) when measured by the linear regression coefficient of difference from R l on generation of selection. Conversely, the total plasma phosphorus of unselected HW or LW laying females did not differ significantly from Rl females (Table 5). In Table 5, the comparisons involving Rl, HW, and LW were based on a smaller number of observations than the comparisons of R l , HP, and LP and, as a result, the deviation in the former comparison had to be larger to be significantly different. Strong et al. (1978) reported positive genetic correlations between total plasma phosphorus and body weight during the laying periods. REFERENCES Bacon, W. L., and M. A. Musser, 1974. Estimation of low density lipoprotein fraction concentration in blood plasma of laying turkey hens using density gradient centrifugation. Poultry Sci. 53:2015— 2019. Bacon, W. L., and K. E. Nestor, 1982. Divergent selection for body weight and yolk precursor in Coturnix coturnix japonica. 2. Correlated responses in plasma lipoproteins and lipids. Poultry Sci. 61:161-165. Bacon, W. L., K. E. Nestor, and M. A. Musser, 1973a. Relative concentration and plasma content of yolk lipoprotein precursor in three lines of turkeys. Poultry Sci. 52:1185-1187. Bacon, W. L., K. E. Nestor, and P. A. Renner, 1973b.
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1 2
HW1
SELECTION FOR BODY WEIGHT AND YOLK PRECURSOR IN QUAIL
weight in Japanese quail under two nutritional environments. Poultry Sci. 50:931—937. Marks, H. L., 1978. Long term selection for four-week body weight in Japanese quail under different nutritional environments. Theor. Appl. Genet. 52:105-111. Marks, H. L., and P. D. Lepore, 1968. Growth rate inheritance in Japanese quail. 2. Early response to selection under different nutritional environments. Poultry Sci. 47:1540-1546. Mclndoe, W. M., 1959. A lipophosphoprotein complex in hen plasma associated with yolk production. Biochem. J. 72:153-159. Nestor, K. E., 1977. The use of a paired mating system for the maintenance of experimental populations of turkeys. Poultry Sci. 56:60—65. Nestor, K. E., W. L. Bacon, and P. A. Renner, 1970. Ovarian follicular development in egg and meat type turkeys. Poultry Sci. 49:775-780. Sefton, A. E., and P. B. Siegel, 1974. Inheritance of body weight in Japanese quail. Poultry Sci. 53:1597-1603. Strong, C. F., Jr., K. E. Nestor, and W. L. Bacon, 1978. Inheritance of egg production, egg weight, body weight and certain plasma constituents in Coturnix. Poultry Sci. 5 7 : 1 - 9 .
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Ovarian follicular development in egg and growth lines of Japanese quail. Poultry Sci. 1195-1199. Christie, W. W., and J. H. Moore, 1972. The lipid components of the plasma, liver and ovarian follicles in the domestic chicken (Callus gallus). Comp. Biochem. Physiol. 41B:287-295. Falconer, D. S., 1964. Introduction to Quantitative Genetics. Oliver and Boyd, Edinburgh and London. Harvey, W. R., 1977. User's guide for LSML76 mixed model least-squares and maximum likelihood computer program. Ohio State University, Columbus, OH. Hillyard, L. A., H. M. White, and S. A. Pangburn, 1972. Characterization of apolipoproteins in chicken serum and egg yolk. Biochemistry, 11:511-518. Jaap, R. G., 1969. Large broilers from smaller hens. World's Poultry Sci. J. 25:140-143. Jaap, R. G., and J. A. Clancy, 1968. Reproductive idiosyncrasies of the broiler pullet. Proc. 3rd Europ. Poultry Conf., Israel. Marks, H. L., 1970. Selection for four-week body weight in Coturnix. Poultry Sci. 49:1410. Marks, H. L., 1971. Selection for four-week body
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