Effects of feeding program and crude protein intake during rearing on fertility of broiler breeder females

EDUCATION AND PRODUCTION Effects of Feeding Program and Crude Protein Intake During Rearing on Fertility of Broiler Breeder Females1 T. J. WALSH2 and J. BRAKE3 Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608 reduced rate of increase in feed allocation late in rearing that delayed oviduct development. In Experiment 2, pullets were fed to the same cumulative ME intake at 20 wk using either a concave or convex feeding program with respect to 0 and 20 wk reference points with two levels of dietary protein. The higher level of CP intake (1,363 vs 1,212 g) produced higher fertility. A significant feeding program by dietary protein interaction was found. Level of CP intake at photostimulation had no effect on fertility with the concave feeding program but the convex program decreased fertility at the lower CP intake as in Experiment 1.

(Key words: broiler breeders, fertility, crude protein, feeding programs) 1999 Poultry Science 78:827–832

McDaniel et al. (1981) demonstrated that feeding programs that best controlled BW during the laying period resulted in improved female fertility. Furthermore, Lilburn and Myers-Miller (1990) suggested that the pattern of feed allocation during rearing could significantly influence early egg production of broiler breeders even when there were no differences in total feed consumed. Therefore, it was of interest to determine whether a feed allocation program would modify the effects of cumulative protein intake during rearing on fertility. The objective of the present study was to determine the effects on subsequent broiler breeder fertility of different female feed allocations (feeding programs) when fed isocalorically or isonitrogenously on a cumulative basis to 20 or 24 wk of age.

INTRODUCTION The female broiler breeder has been implicated as playing a major role in determining fertility. VanKrey and Siegel (1974) demonstrated that female lines genetically selected for high 8-wk BW not only had lower levels of fertility but also a shorter duration of spermatozoal storage. Although reports have suggested that this decrease in fertility is due to genetic selection per se, Walsh and Brake (1997) have suggested that this decrease in fertility may be the result of feeding programs designed only to achieve a standard BW without regard to specific nutritional intakes. Walsh and Brake (1997) suggested that a cumulative CP intake of at least 1,180 g per pullet at 20 wk of age (photostimulation) was needed to achieve acceptable persistency of fertility during lay. They further demonstrated that BW was not a good indicator of cumulative protein intake.

MATERIALS AND METHODS

Rearing Management Received for publication February 2, 1998. Accepted for publication February 25, 1999. 1The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products mentioned, nor criticism of similar products not mentioned. 2Present address: Novus International, Inc., 530 Maryville Centre Drive, St. Louis, MO 63141. 3To whom correspondence should be addressed: john_brake@ ncsu.edu 4Plasson, Diversified Imports, Inc., Lakewood, NJ 08701.

Two experiments were conducted using Arbor Acres feather-sexable yield females and Yieldmaster males. In both experiments, chicks were placed in a 20-pen growing house with 16 pens for females and 4 pens for males. Each 3.96 × 3.96 m pen was equipped with 750 cm of linear feeder space (six-tube feeders) and two automatic waterers.4 At placement, there were 88 females and 75 males in each female and male pen of Experiment 1, 827

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ABSTRACT Arbor Acres broiler breeder pullets were grown from hatch to 24 wk on one of four feeding programs that achieved similar cumulative intakes of ME and CP at 24 wk, but not 20 wk (photostimulation), in Experiment 1. Graphing the four programs in terms of feed per bird per day by week of age gave the general shapes of linear, convex, concave, and deeply concave with respect to 0 and 24 wk reference points. The linear program, which achieved 1,192 g CP at 20 wk (photostimulation), as compared to < 1,150 g CP for the two concave programs, exhibited the best fertility. Although the pullets reared on the convex program consumed 1,255 g CP, fertility was poor, probably due to the

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WALSH AND BRAKE TABLE 1. Composition of grower, prebreeder and breeder diets, Experiment 1 Diets Grower

Prebreeder

Breeder

Corn (8.5% CP) Soybean meal (48.3% CP) Wheat middlings Dicalcium phosphate Limestone Salt Mineral premix1 Choline chloride Vitamin premix2 DL-Methionine Coccidiostat Bacitracin Lysine HCl Alfalfa meal (17% CP) Feather meal Calculated analysis Crude protein,3 % ME, kcal/g Lysine, % Methionine + cystine, % Calcium, % Available phosphorus, %

64.02 12.69 19.24 1.51 1.64 0.27 0.20 0.04 0.10 0.16 0.05 0.03 0.05 0.00 0.00

(%) 64.29 13.75 0.53 1.70 2.87 0.25 0.20 0.03 0.10 0.14 0.05 0.03 0.06 0.00 0.00

69.05 16.95 0.00 1.68 6.28 0.53 0.20 0.03 0.10 0.11 0.05 0.03 0.19 4.30 0.50

14.50 2.92 0.70 0.61 1.00 0.42

15.40 2.92 0.80 0.60 1.50 0.45

15.70 2.89 0.90 0.60 3.00 0.42

1Mineral premix contained the following in milligrams per kilogram of diet: manganese, 120; zinc, 120; iron, 80; copper, 10; iodine, 2.5; cobalt, 1.0. 2Vitamin premix contained the following per kilogram of diet: vitamin A, 13,200 IU; cholecalciferol, 4,000 IU; vitamin E, 66 IU; vitamin B12, 39.6 mg; riboflavin, 13.2 mg; niacin, 110 mg; pantothenic acid, 22 mg; vitamin K, 4 mg; folic acid, 2.2 mg; thiamine, 4 mg; pyridoxine, 8 mg; biotin, 252 mg; and selenium, 0.30 mg. 3Males grown sex-separate on a 18.9% CP diet to 20 wk.

respectively, and 75 females and 50 males in each female and male pen in Experiment 2, respectively. Access to water was limited by a time clock and solenoid system sufficient to control litter moisture and allow the birds to have unlimited access to water while feed was present. All birds were brooded with a 32 C heat source in each pen and with room temperatures ranging from 23.9 to 26.7 C. After brooding, interval timers were used to regulate the exhaust fans to maintain a house temperature above 18 C or below 32.2 C. All birds were reared in black-out houses to 20 wk of age under a 8 h light:16 h dark lighting program. Other details were as described by Brake and Baughman (1989).

Experimental Diets To avoid problems with amino acid digestibility, diets were formulated primarily with previously analyzed corn, soybean meal, and wheat middlings in Experiment 1 and corn, soybean meal, and alfalfa meal in Experiment 2, proportions of which were varied to achieve the desired calculated dietary percentage CP. Samples of all batches were analyzed for percentage CP to confirm the desired levels. The diets are shown in Tables 1 and 2. Lysine was

TABLE 2. Composition of grower, prebreeder, and breeder diets, Experiment 2 Grower diet protein Ingredients and analysis

14% CP

15.7% CP1,2

Breeder diet

Corn (8.5% CP) Soybean meal (48.3% CP) Alfalfa meal (17% CP) Feather meal Poultry byproduct meal Dicalcium phosphate Limestone Salt Mineral premix3 Choline chloride Vitamin premix4 DL-Methionine Coccidiostat Bacitracin Lysine HCL Calculated analysis Crude protein, % ME, kcal/g Lysine, % Methionine + cystine, % Calcium, % Available phosphorus, %

71.03 12.12 11.97 0.50 0.28 1.73 1.17 0.53 0.20 0.04 0.10 0.16 0.05 0.03 0.09

(%) 69.04 16.96 9.10 0.50 0.20 1.68 1.28 0.53 0.20 0.03 0.10 0.11 0.05 0.03 0.19

66.92 21.33 0.00 0.50 0.50 1.63 6.82 0.33 0.20 0.03 0.10 0.16 0.05 0.03 0.09

14.00 2.89 0.70 0.60 1.00 0.42

15.70 2.89 0.79 0.67 1.00 0.42

16.24 2.89 0.90 0.68 3.00 0.42

1Prebreeder

diet. growing diet. 3Mineral premix contained the following in milligrams per kilogram of diet: manganese, 120; zinc, 120; iron, 80; copper, 10; iodine, 2.5; cobalt, 1.0. 4Vitamin premix contained the following per kilogram of diet: vitamin A, 13,200 IU; cholecalciferol, 4,000 IU; vitamin E, 66 IU; vitamin B12, 39.6 mg; riboflavin, 13.2 mg; niacin, 110 mg; pantothenic acid, 22 mg; vitamin K, 4 mg; folic acid, 2.2 mg; thiamine, 4 mg; pyridoxine, 8 mg; biotin, 252 mg; and selenium, 0.30 mg. 2Male

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Ingredients and analysis

maintained at approximately 5.0% CP and methionine plus cystine at 85% or more of lysine to ensure a balance of essential amino acids in all diets similar to the practical diets normally fed to broiler breeder pullets. In Experiment 1, from hatch to 24 wk of age, females were grown with one of four different feeding programs with a grower diet that contained 14.5% CP (Table 1). The four feeding programs had the general shapes of linear, convex, concave, and deeply concave with respect to 0 wk and 24 wk time points (Figure 1). Males were grown sexseparate on an 18.9% CP diet to 20 wk. From 21 to 24 wk, all birds received a prebreeder diet, which was followed by a breeder diet from 25 to 64 wk (Table 1). At 24 wk of age, six birds per pen were weighed and killed per growing program in Experiment 1 and the oviduct excised and weighed. In Experiment 2, from hatch to 20 wk of age, females were grown with either a concave or convex feeding program with respect to 0 wk and 20 wk time points (Figure 2). Females were grown with one of two different diets that contained 14.0 or 15.7% CP (Table 2). Males were grown sex-separate with the 15.7% CP diet. From 21 to 24

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BROILER BREEDER FEMALE FERTILITY

TABLE 3. Cumulative intake of crude protein and metabolizable energy to 20 wk and female body weight at 20 wk, Experiment 1 Female feeding program

CP

ME

20 wk BW1

Concave Linear Convex Deeply concave

(g/bird) 1,145 1,192 1,255 1,120

(kcal/bird) 23,193 24,095 25,442 22,639

(kg) 2.00 2.01 2.07 1.98

1Based

wk, all birds received the 15.7% CP grower diet, which was followed by a breeder diet (Table 2) from 25 to 64 wk.

Breeding Management In Experiments 1 and 2, birds were moved to a 16-pen curtain-sided breeder house at 20 wk of age. Approximately 65 females and 6 males were housed per pen. Each 3.96 × 3.96 m breeder pen was equipped with two-thirds wood slats and one-third pine litter covered floors, two automatic waterers, four tube feeders, and one 12-hole galvanized nest box. Pen dimensions of the laying house were similar to those of the growing house. With the exception of hand feeding, the house and management

upon all birds being weighed.

were comparable to commercial standards. The photoperiod was extended with artificial light to 14 and 15 h at 20 and 22 wk, respectively, and to 15.5 and 16 h at 5 and 50% rate of lay, respectively. Other details of the general management were as described by Brake and Baughman (1989). Eggs were collected twice daily and stored in a cooler at 18.6 C and 70% relative humidity until incubated. Eggs laid on the floor and slats were collected separately and not incubated. There were 22 and 20 sets in Experiments 1 and 2, respectively, of approximately 60 eggs per replicate pen incubated between 28 and 64 wk of age. All unhatched eggs were opened and examined macroscopically for evidence of embryological development. Fertility and embryonic stage at mortality were determined. Broken eggs were deleted from the analysis.

Statistical Analysis The experimental design in Experiment 1 was a simple one-way design comprised of the four feeding programs fed to four replicate pens each to 24 wk of age. The experimental design in Experiment 2 was a factorial with the two dietary protein levels and two feeding programs comprising the main effects. All fertility data for both experiments were summarized on an overall cumulative pen basis to generate means and SE. The oviduct data of Experiment 1 were analyzed by one-way ANOVA using the General Linear Models (GLM) procedure of SAS software (SAS Institute, 1990). Variation among birds was used as the error term. Due to its distribution (Agresti, 1990), fertility data were analyzed as categorical (count) data where each individual egg was taken as a binomial event, either fertile or infertile. The categorical analysis uses the likelihood ratio test to generate an ANOVA table. Orthogonal contrasts were used to compare treatment probabilities in Experiment 1.

RESULTS FIGURE 2. Feeding programs during the rearing period in Experiment 2. Females received feed according to two feeding programs, from hatch to 20 wk of age, which had the general shapes of either convex or concave.

For Experiments 1 and 2, the cumulative intakes of CP and ME to 20 wk, the age of photostimulation, are shown in Tables 3 and 4, respectively. Female BW at photostimulation is also shown. Although considerable

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FIGURE 1. Feeding programs during the rearing period in Experiment 1. Females received feed according to four feeding programs, from hatch to 24 wk of age, which had the general shapes of linear, convex, concave, or deeply concave.

20-wk cumulative

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TABLE 4. Cumulative intake of crude protein and metabolizable energy to 20 wk and female body weight at 20 wk, Experiment 2 Female grower diet

Female feeding program

CP

ME

20-wk BW1

(% CP) 14.0 14.0 15.7 15.7

Concave Convex Concave Convex

(g/bird) 1,212 1,212 1,363 1,364

(kcal/bird) 25,029 25,045 25,029 25,046

(kg) 2.12 2.00 2.15 2.09

1Based

20-wk cumulative

upon all birds being weighed.

DISCUSSION Walsh and Brake (1997) were the first to demonstrate a female effect on fertility due to differences in cumulative CP intake during the growing period. They estimated that at least 1,180 g CP must be consumed prior to photostimulation in order to achieve persistent fertility. However, all of the studies of Walsh and Brake (1997) used linear or concave feeding programs. Previously, Lilburn and Myers-Miller (1990) suggested that the pattern of feed allocation during the growing period could affect egg production of broiler breeders, and the present study further demonstrates that female fertility may be affected by the pattern of feed allocation (program) during the rearing period. The diets of the present study were designed to reflect normal commercial diets for female broiler breeders in the U.S. with respect to protein:energy and amino acid ratios (Arbor Acres Farm, 1994). The dietary CP intakes of the present study reflect the balance of the essential amino acids (lysine, methionine plus cystine) normally found in practical diets used to rear broiler breeder pullets. Although the conclusions can be stated only in general terms, the results do provide insight into

TABLE 5. Broiler breeder fertility as affected by female feeding program, Experiment 1 Female feeding program1

Eggs set

Concave 5,149 Linear 5,110 Convex 5,110 Deeply concave 5,179 Orthogonal contrasts for categorical data analysis Linear vs convex Linear vs others Deeply concave vs others 1General

Infertile

Fertile

Cumulative fertility2

(n) 733 247 463 648

4,416 4,863 4,647 4,531

(%) 86.1 95.5 91.6 88.1

± ± ± ±

5.3 1.5 1.4 2.6

*** *** ***

shapes with respect to 0 and 24 wk reference points. See Figure 1 for details. ± SE for n = 4 calculated from overall pen means. ***Significant difference for probability of infertile or fertile eggs (P ≤ 0.001) with chi-square.

2Means

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differences in cumulative protein intake were accomplished, the female BW was not affected in either experiment. Pullets grown on the four feeding programs in Experiment 1 achieved the same cumulative ME (33,000 kcal per pullet) and CP (1,670 g per pullet) intakes at 24 wk but differed in cumulative ME and CP intakes at 20 wk as shown in Table 3. The 24 wk age represents the industry standard age of pullet capitalization where growing feed costs are compared and the 20 wk age represents a reasonable age for photostimulation. For Experiment 1, the effects of feeding (growing) program on female broiler breeder fertility are shown in Table 5. Overall, birds grown with the linear program, which consumed 1,192 g CP to 20 wk (Table 3), exhibited the highest fertility when compared either to birds grown on the convex program (1,255 g CP) or to birds on all other programs. The two concave feeding programs (1,120 and 1,145 g CP) (Table 5) exhibited decreased fertility relative to the other programs. The effects of female feeding program on BW and absolute oviduct weight at 24 wk of age for broiler breeder hens in Experiment 1 are shown in Table 6. No significant differences in BW were found at 24 wk of age, which was consistent with similar cumulative nutrient intakes. At 24 wk of age, the absolute oviduct weight for the birds grown on the convex feeding

program was significantly less than that of birds grown on linear or deeply concave programs, with the concave program intermediate. For Experiment 2, the main effects of grower diet on female broiler breeder fertility are shown in Table 7. Overall, birds fed the 15.7% CP diet (1,363 g CP) exhibited higher fertility than the birds fed the 14% CP diet (1,212 g CP). Feeding program also affected fertility and a significant feeding program by female grower diet protein level interaction was found (Table 7). By inspection, it was determined that pullets fed the 15.7% CP diet (1,363 g CP) produced the highest fertility overall when grown with the convex program, whereas birds grown with the convex program fed the 14% CP diet (1,212 g CP) exhibited the lowest fertility. The lower protein diet had no such adverse effect when fed according to a concave model.

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BROILER BREEDER FEMALE FERTILITY TABLE 6. Effect of female feeding program on body weight and absolute oviduct weight at 24 wk of age for broiler breeder hens, Experiment 1 Female feeding program1

Body weight

Concave Linear Convex Deeply concave SE

2,477 2,345 2,152 2,509 189

Oviduct weight (g) 7.7a,b 8.8a 6.0b 9.7a 1.0

the interaction of nutritional, feeding, and lighting regimens during rearing of broiler breeder pullets. The four different feed allocation programs in Experiment 1 achieved a wide range of dietary protein intake at 20 wk of age (photostimulation) but similar intake at the 24-wk pullet capitalization age near the onset of egg production (Table 3). The concave and deeply concave feed allocation programs, which exhibited the lowest fertility overall, had a cumulative protein intake of 1,145 and 1,120 g per pullet, respectively. This protein intake was less than the previously demonstrated minimum cumulative CP intake per pullet of 1,180 g needed at 20 wk of age (photostimulation) to achieve acceptable persistency of fertility even when a proper BW was achieved (Walsh and Brake, 1997). Thus, the concave and deeply concave programs should have been expected to produce poorer fertility. The interesting result was that although the cumulative CP of the convex program was higher than that of the linear program and

TABLE 7. Broiler breeder fertility as affected by female feeding program and female growing diet, Experiment 2 Female grower diet

Female2 feeding program

Eggs set

Infertile

(% CP) Main effects

14.0 15.7 Interactions1 14.0 15.7 14.0 15.7 a,bTotals A,BTotals

Fertile

(n)

Cumulative fertility3 (%)

Concave Convex

9,535 9,421 9,428 9,528

632a 559b 651A 540B

8,903a 8,862b 8,777A 8,988B

93.4 93.9 93.1 94.3

± ± ± ±

0.8 1.2 1.1 0.8

Concave Concave Convex Convex

4,767 4,768 4,661 4,760

309 323 342 217

4,458 4,445 4,319 4,543

93.5 93.2 92.5 95.4

± ± ± ±

1.4 1.0 2.0 1.2

within column with no common superscript differ significantly (P ≤ 0.05). within column with no common superscript differ significantly (P ≤ 0.001) using categorical data

analysis. 1A significant feeding program by female grower diet interaction was found (P ≤ 0.001). 2Feed given with higher increments late in growing period in concave program and feed given with higher increments early in growing period in convex program. See Figure 2 for details. 3Means ± SE for n = 4 calculated from overall pen means.

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a,bMeans (n = 6) within column with no common superscript differ significantly (P ≤ 0.05). 1General shapes with respect to 0 and 24 wk reference points. See Figure 1 for details.

well above the 1,180 g per pullet suggested by Walsh and Brake (1997), the convex program exhibited a lower overall fertility than the linear feeding program. The lower fertility demonstrated by the convex program is thought to be the result of the decreasing feed increments late in the growing period relative to increasing BW that negated the extra CP intake, whereas the linear program received more consistent feed increments relative to increasing BW through this period. It was obvious that increasing BW required a commensurate and proportional increase in feed allocation to supply the necessary ME for maintenance, growth, and reproductive development. Therefore, the convex feeding program birds must have been relatively ME deficient, which would require the diversion of CP to ME via gluconeogenesis (Scott et al., 1976) and away from reproductive development as was evidenced by similar BW at 20 and 24 wk (Tables 3 and 6) but reduced oviduct weight at 24 wk (Table 6). A relative deficiency of CP during this critical prebreeder period has been reported to adversely affect egg production (Cave, 1984; Brake et al., 1985). The increase in dry mass per cell in the oviduct during the prebreeder period has been attributed to soluble protein (Yu and Marquardt, 1973) that may be related to tissue responsiveness to endocrine signals. Consistent with the data of Walsh and Brake (1997), a significant fertility effect was found due to the level of dietary protein fed during the growing period in Experiment 2. Pullets fed the higher 15.7% CP diet (1,363 g CP) exhibited better fertility overall than the pullets fed the marginal 14% CP diet (1,212 g CP) (Table 7). A significant feeding program by female dietary protein interaction was observed. In Experiment 2, pullets were grown with concave or convex feeding programs that

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REFERENCES Agresti, A., 1990. Linear probability model. Pages 84–85 in: Categorical Data Analysis. John Wiley and Sons, New York, NY.

Arbor Acres Farm, Inc., 1994. Broiler Breeder Management Manual: Nutrition. Arbor Acres Farm, Inc., Glastonbury, CT. Brake, J., and G. R. Baughman, 1989. A comparison of lighting regimes during growth on subsequent seasonal reproductive performance of broiler breeders. Poultry Sci. 68:79–85. Brake, J., J. D. Garlich, and E. D. Peebles, 1985. Effect of protein and energy intake by broiler breeders during the prebreeder transition period on subsequent reproductive performance. Poultry Sci. 64:2335–2340. Cave, N.A.G., 1984. Effect of a high-protein diet fed prior to the onset of lay on performance of broiler breeder pullets. Poultry Sci. 63:1823–1827. Lilburn, M. S., and D. J. Myers-Miller, 1990. Effect of body weight, feed allowance, and dietary protein intake during the prebreeder period on early reproductive performance of broiler breeder hens. Poultry Sci. 69:1118–1125. McDaniel, G. R., J. Brake, and M. K. Eckman, 1981. Factors affecting broiler breeder performance. 4. The interrelationship of some reproductive traits. Poultry Sci. 60:1792–1797. SAS Institute, 1990. SAS User’s Guide: Statistics. Version 6 Edition. SAS Institute Inc., Cary, NC. Scott, M. L., M. C. Nesheim, and R. J. Young, 1976. Nutrition of the Chicken. Scott Publishing Co., Ithaca, NY. VanKrey, H. P., and P. B. Seigel, 1974. Selection for body weight at eight weeks of age. 13. Fecundity. Poultry Sci. 53:741–745. Walsh, T. J., and J. Brake, 1997. The effect of nutrient intake during rearing of broiler breeder females on subsequent fertility. Poultry Sci. 76:297–305. Yu, J.Y.-L., and R. R. Marquardt, 1973. Development, cellular growth, and function of the avian oviduct. I. Studies of the magnum portion of the domestic fowl (Gallus domesticus) oviduct during a reproductive cycle. Biol. Reprod. 8: 283–298.

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achieved the same 20-wk cumulative ME and CP dependent upon the level of dietary protein. By inspection of Table 7, it was apparent that the convex program had a negative effect on fertility at the marginal CP (1,212 g) intake but not at the higher CP intake. This finding agrees with the results of the convex program data of Experiment 1 at a similar marginal CP intake, although the effect was somewhat diminished due to the fact that the convex program was terminated at an earlier age. The increased fertility of the females that received the higher CP intake with the convex program resulted in an overall improvement in fertility due to the convex program. The results of the present study suggests that the pattern of feed allocation during the rearing period is also important to achieving maximum female fertility. The results of the present study suggests that it is possible to achieve the minimum quantity of CP needed for optimum female fertility with more than one feeding program, but the chances of maximizing fertility are decreased by having a convex pattern of feed allocation around the time of photostimulation when a marginal cumulative intake of CP is fed. The data also confirm the minimum quantity of 1,180 g CP at photostimulation required for optimum fertility (Walsh and Brake, 1997) as long as a convex feeding program is not employed.