Divergent Selection for Growth in Japanese Quail Under Split and Complete Nutritional Environments.

Divergent Selection for Growth in Japanese Quail Under Split and Complete Nutritional Environments. 6. Differential Body Weights in Reciprocal Crosses HENRY L. MARKS USDA, Agricultural Research Service, Southeast Poultry Research Laboratory, c/o University of Georgia, 107 Livestock-Poultry Building, Athens, Georgia 30602-2772 ABSTRACT Growth patterns were investigated in reciprocal crosses of quail lines divergently selected for 4-wk BW. In Experiment 1, quail from two sets of high lines (H), and two sets of low lines (L), and their reciprocal crosses (HL and LH) from Generation 23 breeders were reared intermingled and fed a 28% CP diet. Individual BW data were collected weekly through 9 wk. Experiment 2 involved only reciprocal cross progeny (HL, LH) from Generation 26 breeders with quail placed in divided decks of battery brooders to allow collection of feed intake and feed efficiency (FE) data. Feed intake data were collected from 0 to 38 days and BW data from 0 to 69 days. Quail from the LH cross were significantly (P < .05) larger than quail from the HL cross from 0 to 14 days and 0 to 69 days in Experiments 1 and 2, respectively. Initial BW differences were expected because of the large egg size difference between H and L line dams; however, persistent BW differences were not anticipated. Initial feed intake was greater (25%) for LH than HL quail; however, when adjusted for BW, HL quail consistently consumed more feed per gram of BW than LH quail. Feed efficiencies were not significantly different for the two genotypes; however, smaller HL quail tended to have superior FE after 2 wk of age. Initial relative growth rates were 17 to 38% higher in HL quail; however, after Week 2 absolute gain was essentially identical for the reciprocal crosses. (Key words: growth, crosses, feed intake, feed efficiency, genotype) 1993 Poultry Science 72:1847-1854

INTRODUCTION The additive nature of genetic variation for growth has resulted in considerable improvement in BW of broilers as a result of individual phenotypic selection (Chambers, 1990). Although heterosis normally plays a more important role in nonadditive than additive genetic traits, the opportunity for the expression of heterotic effects is present in the sire line by dam line cross that produces commercial broiler chicks. Fairfull (1990) has suggested that heterosis for BW is close to zero at 1 wk of age and earlier, but increases to about 2 to 10% by 8 to 10 wk

Received for publication March 8, 1993. Accepted for publication June 24, 1993.

of age. Therefore, heterosis is important as broilers now reach market size as early as 42 days or less. In most cases reciprocal effects (deviations between crosses in which the role of male and female parent are reversed) have been dismissed as unimportant and have received little theoretical consideration. In commercial broilers, reciprocal performances are normally not considered given the performance and function of paternal crosses (Fairfull, 1990). A review of BW data (Darden and Marks, 1989) from reciprocal crosses arising from mating Japanese quail lines divergently selected for 4-wk BW reveal rather large reciprocal effects between crosses. Initial BW differences were expected because of the large egg size difference between high and low line

1847

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dams. However, large BW differences (15 CD-LH) were intermingled with sexes comto 24%) remaining at 4 wk of age were bined and placed in separate decks of the unexpected. The objective of this study same quail battery brooders on day of was to obtain additional information hatch. All quail had ad libitum access to the regarding the magnitude, duration, and 28% CP and 2,947 kcal/kg ME diet (Darden possible causes of reciprocal BW effects and Marks, 1988). Individual BW data were arising from crossing Japanese quail lines obtained on a weekly basis from 0 to 9 wk of divergently selected for 4-wk BW. age. The primary objective of this experiment was to remove possible pen or deck effects MATERIALS AND METHODS that might influence BW of the reciprocal Stocks used in this study were two crosses by rearing all crosses intermingled high-BW and two low-BW Japanese quail in the same pens or decks. A second lines developed by divergent selection for objective was to obtain BW data beyond 4 4-wk BW (Darden and Marks, 1988). In wk in order to determine the duration of one set of lines, quail were divergently reciprocal BW effects. selected for 4-wk BW under a 28% CP complete diet (CD), whereas in the second Experiment 2 set of divergently selected lines quail were provided a split diet (SD), which allowed This experiment involved only the four birds to self-select feed from two diets, reciprocal cross genotypes (SD-HL and SDone high in protein (47% CP and 2,351 LH; CD-HL and CD-LH). Male and female kcal/kg ME) and the other high in energy quail from the four genotypes were leg(9% CP and 3,332 kcal/kg ME). Two banded, weighed, and divided into five experiments were conducted with the first replicates consisting of 8 to 15 quail per utilizing quail progeny from Generation subgroup. Two five-deck battery brooders 23 breeders and the second utilizing quail were modified by placing a divider on each progeny from Generation 26 breeders. deck to allow within selection environment reciprocal crosses (HL and LH) to share the same water and heat source. This was done Experiment 1 in order to minimize the possible confoundThis experiment involved eight geno- ing of these variables with genotype effects types, four from each of the two selection associated with pen location. All quail environments (CD and SD). High line (H), received Diet CD as described in Experilow line (L), and reciprocal cross (HL and ment 1 above. Feed intake on a pen basis LH) quail from both CD and SD lines were was measured from 0 to 3, 6 to 10,13 to 17, leg-banded, weighed, and divided by geno- 20 to 24, 27 to 31, and 34 to 38 days, and type into six replicates at hatching. In individual BW data were collected at 0,3,6, reciprocal cross designations, the first letter 10,13,17,20,24,27,34,55,62, and 69 days of represents the sire and the second letter the age. In addition, pen BW data were coldam line code used to reproduce the cross lected at 31,38,44, and 52 days of age. Feed (i.e., HL = H line male x L line female and efficiency (gain to feed) was calculated for LH = L line male x H line female). Due to the same time frames in which feed intake data were collected. Relative growth rate differences in hatchability, from 9 to 12 data were calculated as BW gain per week quail of both sexes were available for divided by final BW of the previous week, assignment to each replicate subgroup. i.e., [(BW2 - BW1)/BW1] x 100. Because of large differences in BW, high (H The objectives of this experiment were: 1) x H) and low (L x L) CD and SD quail were assigned to different decks of the battery to obtain additional information regarding brooders from the HL and LH crosses. Body the duration of reciprocal BW effects of HL weight data from the H and L lines were and LH crosses; and 2) to investigate feed used only in the calculation of percentage intake and feed efficiency patterns asheterosis expressed for BW in the reciprocal sociated with reciprocal BW differences. An analysis of variance based on a crosses. Quail from the four reciprocal cross genotypes (SD-HL and SD-LH; CD-HL and completely randomized arrangement of

JAPANESE QUAIL SELECTED FOR FOUR-WEEK BODY WEIGHT

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replications was utilized in a fixed model on 23 females were 44 and 48% larger in H a within selection environment, age, and dams than in L dams in the SD and CD experiment basis. Under this design geno- environments, respectively. The magnitude types were the only main effect. Because of BW differences between crosses declined BW differences between sexes are small more rapidly in this study than in the earlier prior to 4 wk of age and at older ages report of Darden and Marks (1989). percentage differences in BW between Although absolute differences in BW reciprocal crosses for males and females between reciprocal crosses appeared to were similar, sexes were combined to remain fairly uniform across weeks, LH increase subgroup sizes and sex was not crosses were only 3 to 4% larger than HL included as a variable. The General Linear crosses by 6 wk of age (Table 1). The Models (GLM) procedures of the SAS decrease in percentage difference between Institute (1985) were utilized for analyses of reciprocal crosses from about 55 to 3 or 4 these data. was due to at least two factors. The first was higher initial relative growth rates of HL than LH crosses (Table 2). Higher relative RESULTS AND DISCUSSION growth rate of HL quail was primarily evident during the first 2 wk following Experiment 1. Generation 23 hatch. There were only small differences (4 Body weights of reciprocal (HL and LH) to 8%) in the relative growth rates for cross progeny from quail lines divergently Weeks 3 and 4 (Table 2) with essentially no selected under CD and SD environments differences after the age at which selection are shown in Table 1. Body weights of LH occurred (4 wk) in the parental H and L quail were consistently larger than those of lines. Possible differences in the amount of HL quail from 0 to 9 wk. These BW unabsorbed yolk may have influenced early differences were significant (P < .05) in SD growth patterns of the reciprocal crosses. If crosses through 2 wk and in CD crosses larger LH chicks had more unabsorbed through 6 wk of age. Percentage differences yolk, their "yolk face" chick weight would in BW (56 and 55%) between reciprocal have been less than actual hatch weights. crosses were present at hatch (0 wk) in SD Smaller BW at hatch would have resulted in and CD crosses, respectively. These differ- larger initial relative growth values for LH ences in part are related to differences in chicks and could be a possible explanation egg size between H (11.7 and 10.8 g) and L for the early differences in relative growth (8.1 and 7.3 g) dams. Eggs from Generation rate values between LH and HL quail.

TABLE 1. Mean ± SEM BW of reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and complete-diet (CD) environments, Experiment 1 SD Crosses Age

HL

LH

(wk) -(g) 0 5 ± .lb 8 1 21 ± .5b 26 2 46 ± lb 51 3 70 ± 1 74 4 98 ± 1 101 5 116 ± 1 118 6 126 ± 2 130 7 131 ± 2 134 8 130 ± 2 133 9 135 ± 2 139

CD Crosses 1

Difference

HL

M

(%) ± .1» ± .6" ± 1» ±1 ±1 ± 1 ±2 ±2 ±2 ±2

56 24 11 6 3 2 3 2 2 3

Difference1

LH

5 17 39 60 87 105 117 124 125 129

± .lb ± .3b ± lb ± lb ± lb ± lb ± lb ± 2 ±2 ±2

\&

8 22 46 67 94 112 122 129 128 133

(%) ± .1* ± .3" ± 1" ± la ± la ± la ± la ±2 ±2 ±2

55 29 18 12 8 7 4 4 2 3

a-bMeans within SD and CD crosses within age with no common superscripts differ significantly (P < .05). difference (%) = (LH - HL)/HL x 100.

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TABLE 2. Relative growth rates of reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and complete-diet (CD) environments, Experiment 1 CD Crosses

SD Crosses Age (wk) 0 to 1 to 2 to 3 to 4 to 5 to 6 to 7 to 8 to

HL

LH

261 136 52 40 18 9 4 0 4

185 113 45 36 17 10 3 0 5

Difference2

HL

LH

76 23 7 4 1 -1 1 0 -1

226 144 54 45 21 11 6 1 3

189 109 46 40 19 9 6 0 4

(%) -

(%) 1 2 3 4 5 6 7 8 9

Difference2 37 35 8 5 2 2 0 1 -1

JRelative growth rate = [(BW2 - BW1)/BW1] x 100 (from means of crosses). difference = HL - LH.

These data indicate that on a percentage BW basis, growth of smaller HL quail was initially greater than growth of larger LH quail. However, a different interpretation emerges if BW of crosses is viewed in terms of absolute gain on a weekly basis (Figure 1). In SD crosses LH quail gained 2 g more than HL quail during Week 1; however, thereafter gains were almost identical (114 g in HL and 113 g in LH). In CD crosses, LH quail gained 4.3 g more than HL quail during Weeks 1 and 2. There was little evidence of differences in gain between CD reciprocal crosses after Week 2, which was similar to the lack of differences in gain between SD crosses after Week 1. These data indicate that after Week 2, the absolute gain in BW of smaller HL crosses was the same as the gain in larger LH crosses. The apparent conflict arising from the interpretation of growth patterns from relative growth rate as opposed to gain data is likely due to scaling associated with the calculation of relative growth rates. The larger relative growth rate values for HL quail were due to their 50% smaller body size at hatch in comparison to that of their LH contemporaries. These data indicate that the genetic potential for growth is apparently expressed independent of initial body size as dictated by egg size. Because crosses were reared intermingled in this experiment, the possibility exists that smaller HL quail may have been at a disadvantage in competition with

larger LH quail for feed. However, data obtained in Experiment 2 in which crosses were reared in separate pens to measure feed intake, BW changes for the crosses were similar to those in Experiment 1. Therefore, it appears that growth patterns

CD

LH

•

SD

4

5 Week

6

FIGURE 1. Mean weekly gain of quail from reciprocal crosses (HL and LH) from high- (H) and low- (L) BW lines selected under split- (SD) and complete- (CD) diets.

JAPANESE QUAIL SELECTED FOR FOUR-WEEK BODY WEIGHT TABLE 3. Percentage heterosis1 for BW in reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and complete-diet (CD) environments. Experiment 1 Week

SD Crosses

0 1 2 3 4 5 6 7 8 9

-1.0 0 6.5 4.0 1.4 1.3 2.0 0 -3.0 -1.5

Percentage heterosis values ranged from -3 to 6.5 and were mostly positive in SD crosses, whereas values ranged from -6.4 to 3.3 and were mostly negative in CD crosses. Of the 20 values, 11 were negative, 2 were zero, and 7 were slightly positive. Therefore, it appears that crosses of H and L lines fail to demonstrate heterosis for BW at the age of selection and at either older or younger ages. These data agree with the report of Darden and Marks (1989), which also found a lack of positive heterosis up to 4 wk for BW in these lines following the first 12 generations of selection.

CD Crosses •

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( % )

3.3 -6.4 0 -1.5 -2.7 -2.3 -1.6 -1.2 -2.7 -2.0

Experiment 2. Generation 26

J

Mean crossline progeny/mean pureline progeny.

Body weights of reciprocal (HL and LH) cross progeny from Generation 26 breeders are shown in Table 4. In both sets of crosses in smaller HL quail were not adversely- (SD and CD) the BW of LH quail were significantly (P < .05) larger than those of influenced when reared intermingled with HL quail from hatch (0 days) through 69 larger LH quail. Mean mortality was 4.4% days of age. The BW of LH quail were 58 higher in HL crosses than in LH crosses. and 80% larger than HL quail at hatch in the This small difference, although consistent SD and CD crosses, respectively. As noted across comparisons, was not significant and in Experiment 1, these differences are at is not likely to allow differences in bird least partly related to the larger size of eggs density to be confounded with differences from H line dams compared with those in BW. Percentage heterosis values (mean of from L line dams. Differences in BW reciprocal crosses/mean of H and L lines) between reciprocal crosses of 20% or for BW from 0 to 9 wk are shown in Table 3. greater persisted through 17 days of age. There was little evidence of important Although there was a decline in BW heterotic effects in either SD or CD crosses. differences between LH and HL crosses

TABLE 4. Mean ± SEM BW of reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and complete-diet (CD) environments. Experiment 2 CD Crosses

SD Crosses Age

HL

(days) 0 3 6 10 13 17 20 24 27 31 69

5 8 14 26 37 53 65 82 93 103 138

LH •(g) ± .lb ± .2b ± .3b ± .6b ± .6b ± .8b ± lb ± lb ±2b ± 2b ±3b

8 ± .1^ 13 ± .1» 20 ± .3 a 34 ± .9" 46 ± 1' 64 ± 1» 77 ± 2a 94±2a 104 ± 2 a 112 ± 2a 151 ± 2a

Difference

1

(%) 58 50 45 33 25 20 18 15 12 8 9

Difference1

LH

HL

(r)

4± 7 ± 13 ± 22 ± 31 ± 45 ± 56 ± 71 ± 82 ± 94 ± 125 ±

.lb .2b .2b .7b .9b

lb lb lb lb lb 3b

\S>

8 12 19 30 41 56 68 84 95 105 137

(%) ± ± ± ± ± ± ± ± ± ± ±

.la .2a .6a .9a la la la la la la 2a

80 69 51 36 32 24 21 18 15 11 10

a
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across age, LH quail were approximately 9 to 10% larger man HL quail at 69 days. There is no apparent explanation for the presence of this large difference in this experiment as opposed to the smaller BW difference between reciprocal crosses after Week 3 in Experiment 1. The decrease in the magnitude of BW differences between LH and HL quail was due, at least in part, to higher relative growth rates in HL quail. From 0 to 13 days of age, the relative growth rates of HL quail exceeded rates of LH quail by a wide margin (Table 5). As in Experiment 1, higher relative growth rates of HL quail were present primarily during the first 2 wk (0 to 13 days). Also in agreement with data observed in Experiment 1 is a lack of difference between reciprocal crosses in relative growth rates after 4 to 5 wk of age (Table 5). It is obvious that scaling may also be involved, because a given increase in gain resulted in higher relative growth rate values in smaller HL quail than in larger LH quail. Absolute BW gains in LH and HL quail from 0 to 69 days of age are shown in Figure 2. From 0 to 20 days, larger LH quail gained 9 g more than smaller HL quail in the SD crosses, whereas from 0 to 24 days in CD crosses, LH quail also gained 9 g more than HL quail. Gains observed in the reciprocal crosses were similar in SD crosses after 20 days and after 24 days in the CD crosses. Therefore, the larger LH quail gained more weight on an absolute basis only during the first 3 wk after hatching.

18'

16 14 12 10-

8 6 4' 2 0

16 14.

12 10 8. 6 4 2 0 Day

FIGURE 2. Mean BW gain (g) from 0 to 69 days of age of reciprocal crosses (HL and LH) of high- (H) and low- (L) BW Japanese quail lines selected under split(SD) and complete-diets (CD).

Growth data observed in both Experiments 1 and 2 were consistent in that initial BW of LH quail were larger, and initial (0 to 3 wk) BW gains were superior to those of HL quail. However, smaller HL quail had higher relative growth rates from 0 to 3 wk

TABLE 5. Relative growth rate1 of reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and complete-diet (CD) environments. Experiment 2 SD Crosses Age (days) 0 to 6 to 13 to 20 to 27 to 34 to 44 to 52 to 62 to 1

HL

LH

169 164 75 43 15 22 8 0 0

144 130 67 35 11 20 9 0 0

CD Crosses

Difference2

HL

LH

25 34 8 8 4 2 -1 0 0

195 138 81 46 22 19 4 0 0

141 116 66 40 15 18 5 0 0

(%) -

(%) 6 13 20 27 34 44 52 62 69

Difference2

Relative growth rate = [(BW2 - BW1)/BW1] x 100 (from means of crosses). difference = HL - LH.

54 22 15 6 7 1 -1 0 0

JAPANESE QUAIL SELECTED FOR FOUR-WEEK BODY WEIGHT

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TABLE 6. Mean ± SEM feed intake of reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and <:omplete-diet (CD) environments Feed intake (grams per bird per day) SD Crosses Age (days) 0 to 6 to 13 to 20 to 27 to 34 to

HL 3 10 17 24 31 38

2.0 5.8 10.1 13.0 13.5 16.6

± .03b ± .12b ± .28b ± .22 ± .07 ± .45

CD Crosses 1

LH (g) 2.8 7.4 11.6 14.1 13.2 16.7

. ± .07' ± .13<» ± .20» ± .34 ± .43 ± .56

]Difference

HL

(%) 37 27 15 8 -3 1

2.3 6.0 9.3 13.0 14.0 16.4

Difference1

LH ± .35b ± .17b ± .18b ± .64 ± .47 ± .38

(g) 2.9 6.8 10.4 13.2 13.8 15.7

•

± ± ± ± ± ±

.14" .18> .27' .24 .21 .25

( % )

29 15 13 2 -2 -4

ab

' Means within SD and CD crosses with no common superscripts differ significantly (P < .05). difference (%) = [(LH - HL)/HL] x 100.

and had similar BW gains to those of larger advancing age. The unusually high adLH quail after 2 to 3 wk of age. justed feed intake value in the CD crosses Feed intake data (grams per bird per for HL quail was associated with excessive day) from 0 to 38 days for the SD and CD feed wastage and slow growth from 0 to 3 reciprocal crosses are presented in Table 6. days. All adjusted feed intake values Larger LH quail consumed significantly (P declined with age, which indicated that as < .05) more feed than HL quail from 0 to 17 quail become larger feed intake per gram of days of age. Feed intake patterns were BW decreased. These data are in agreement similar for HL and LH quail from 20 through 38 days of age. When feed intake with observations that although total feed was adjusted on the basis of BW (grams of intake increases, grams of feed per gram of feed/100 g BW per day), HL quail con- BW declines due to increases in body size sumed more feed per gram of BW than did (Marks, 1991). Mean feed efficiencies (grams of gain: LH quail (Table 7). Higher adjusted feed intake values for HL quail were observed grams of feed) for HL and LH quail are across all age periods. However, there was shown in Table 8. There appeared to be little evidence that the magnitude declined with if any difference between reciprocal crosses

TABLE 7. Mean ± SEM adjusted feed intake of reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and complete-diet (CD) environments, Experiment 2 Adjusted 1feed intake (grams feed/100 g BW per day) CD Crosses

SD Crosses Age (days) 0 to 6 to 13 to 20 to 27 to 34 to a b

HL

Difference1

LH

/~\ \b>

3 10 17 24 31 38

30 ± 29 ± 22 ± 18 ± 14 ± 15 ±

.3* .6 .4 .2 .5 .5

26 27 21 17 12 14

(%) ± .8b ± .5 ± .4 ± .2 ± .4 ± .3

-11 -8 -6 -7 -12 -5

lr\ y&

39 34 24 20 16 15

Difference1

LH

HL ± 2.0" ± 1.7» ± .7" ± .9" ± .8 ± .7

29 28 22 17 14 14

(%) ± ± ± ± ± ±

1.4b 1.3b .9b .5b .6 .5

-252 -19 -11 -15 -14 -12

- Means within SD and CD crosses with no common superscripts differ significantly (P < .05). tDifference (%) = [(LH - HL)/HL] x 100. 2 Excess feed wastage.

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TABLE 8. Mean ± SEM feed efficiencies (gain:feed) of reciprocal crosses (HL, LH) from matings of high- (H) and low- (L) BW quail lines selected under split- (SD) and complete-diet (CD) environments, Experiment 2 SD Crosses Age (days) 0 to 6 to 13 to 20 to 27 to

HL .56 .49 .40 .32 .18

± ± ± ± ±

.02 .02 .01 .01 .01

*&•& .56 .47 .38 .30 .12

± ± ± ± ±

.02 .02 .00 .01 .03

0 -4 -5 -6 -33

Difference1

LH

HL

(%)


3 10 17 24 31

CD Crosses Difference1

LH

1%)

Cr-rl

NA2 .41 ± .38 ± .30 ± .21 ±

.04 .00 .02 .01

\8-&) .50 ± .42 ± .35 ± .29 ± .18 ±

.03 .02 .02 .02 .01

2 -8 -i -14

difference (%) = [(LH - HL)/HL] x 100. Excess feed wastage.

2

in feed efficiency from 0 to 3 days. Although differences were small and not significant, there was evidence that HL quail, which had higher initial relative growth rates, had superior feed efficiencies from Days 6 to 24. Although feed efficiencies were superior in HL quail compared with LH quail from 27 to 31 days, the variation associated with this trait as birds reached maturity resulted in these differences not being significant. More efficient utilization of feed could have been at least partially due to lower maintenance requirements associated with smaller body size in HL quail. Data from this study indicate that although there may be large initial differences in the BW of quail from reciprocal crosses of H and L lines, actual gains in BW were not different after the first 2 wk. Higher relative growth rates during the first few weeks of smaller HL quail, resulting from higher feed intake per gram of BW, resulted in a marked reduction in the percentage differences in BW between reciprocal crosses with increasing age. There was evidence that the faster growing HL quail also utilized feed more efficiently. Therefore, it appears that quail of unusually

small size at hatch alter both feed intake and feed efficiency patterns in an attempt to reach their genetic potential for BW.

REFERENCES Chambers, J. R, 1990. Genetics of growth and meat production in chickens. Pages 599-643 in: Poultry Breeding and Genetics. R. D. Crawford, ed. Elsevier Publishers, Amsterdam, The Netherlands. Fairfull, R. W., 1990. Heterosis. Pages 913-933 in: Poultry Breeding and Genetics. R. D. Crawford, ed. Elsevier Publishers, Amsterdam, The Netherlands. Darden, J. R., and H. L. Marks, 1988. Divergent selection for growth in Japanese quail under split and complete nutritional environments. 1. Genetic and correlated responses to selection. Poultry Sci. 67:519-529. Darden, J. R., and H. L. Marks, 1989. Divergent selection for growth in Japanese quail under split and complete nutritional environments. 3. Influences of selection for growth on heterotic effects for body weights, feed and water intake patterns, abdominal fat, and carcass lipid characteristics. Poultry Sci. 68:37-45. Marks, H. L., 1991. Divergent selection for growth in Japanese quail under split and complete nutritional environments. 5. Feed intake and efficiency patterns following nineteen generations of selection. Poultry Sci. 70:1047-1056. SAS Institute, 1985. SAS® User's Guide: Statistics. Version 5 Edition. SAS Institute Inc., Cary, NC.