Relationships Between Dietary Protein, Dietary Energy, Rearing Environment, and Nutrient Utilization by Broiler Breeder Pullets

Abstract

The relationship between dietary energy and protein and their interaction with method of restriction and environment were studied. In Experiment 1, two isocaloric diets (2750 kcal/kg) formulated to contain either 13.5% or 15.5% protein were fed to broiler breeder pullets from hatching through 21 weeks of age. There were no significant differences in body weight due to dietary protein but chicks fed the 13.5% protein ration did require a significantly greater quantity of feed to produce an equivalent body weight. Sexual maturity, peak egg production, and egg size were not affected by the level of dietary protein but total egg production was significantly decreased in pullets fed the 13.5% protein diet. In Experiment 2, 2970 kcal/kg ration containing 15.5% protein was fed to pullets that were reared under two different lighting environments, natural daylength or 24 hr light for the first 7 days and 8 hr light per day thereafter. Pullets housed in the controlled environment and reared on an every-other-day restriction program had significantly improved feed utilization compared with similarly restricted birds kept under natural light. Environmental effects on feed utilization were not as great in the every day restriction treatment. Chicks exposed to natural daylight and fed 15.5% protein diets had similar caloric efficiencies (kcal/g) at 15 weeks of age in both experiments despite dietary density differences of 220 kcal/kg. This supports a hypothesis that above some minimal level of protein intake, caloric intake has the greatest control over body weight gain in restricted pullets, particularly where every-other-day feeding is used during part of the growing period.

Effect of Body Weight, Feed Allowance, and Dietary Protein Intake During the Prebreeder Period on Early Reproductive Performance of Broiler Breeder Hens

“…Thus, they support the concept that BW alone, while still the best management tool available to the individual grower, is not a totally accurate predictor of reproductive preparedness. In other reports demonstrating the beneficial effect of increased protein intake during the prelay period, most of the observed improvements did not occur during the initial stages of production (Brake et al, 1985;Lilburn et al, 1987). This observation was partially the case in Experiment 2 as those pullets within both rearing treatments which consumed the HIGH-PRO diet from 18 to 24 wk had significantly improved production from 28 to 32 wk, whereas significant improvement (P<.05) was observed only for the HIGHPRO-HEAVY treatment from 24 to 28 wk.…”

“…Within each feed treatment (LOW, MED, HIGH), however, the goal was to keep the LBW pullets at approximately 85% of the BW of the corresponding HBW birds through the onset of sexual maturity (24 wk) and then increase the percentage to 95% by 28 wk of age at which time all treatment groups received peak feed allow- ances. All birds were fed a commercial grower diet (Lilbum et al, 1987) until 22 wk of age at which time they were given a commercial breeder diet (Lilburn et al, 1987).…”

“…Feed utilization associated with feeding regimen and age suggest that the pattern of feed allocation during rearing could significantly influence early production even where there are no differences in total feed consumed (Lilbum et al, 1987). For a specific nutrient, it has been reported that differences in protein intake during the prelay period can specifically increase early egg production (Cave, 1984;Brake et al, 1985;Lilburn et al, 1987) independent of any significant changes in BW gain.…”

The effect of dietary energy and protein levels on production in breeding female ostriches

“…If energy or nutrients are limiting, birds can compensate by reducing egg size or the number of eggs laid, or by increasing the laying interval and spreading the cost of egg formation over a longer period. Young breeder fowls given diets containing different amounts of protein, for example, laid similar sized eggs but those given low-protein diets laid significantly fewer eggs (Lilburn et al, 1987). In ostriches, egg production was not affected in birds fed on diets containing between 8 .…”

Growth and Development of Broiler Breeders.

“…It is within this range of dietary constraints in the starter and grower feeds that the question arises, can the diet influence skeletal development independent of any changes in the pattern of BW gain? Leeson and Summers (1984) and Lilburn et al (1987) reported that very low levels of dietary protein can significantly decrease shank length during the ad libitum starter period. Once chicks are fed a common diet or feed intake is restricted, however, these differences in shank length disappear.…”