The first objective of this study on broiler breeders was to investigate the genetic basis of variability in hatchability over age using a longitudinal model. Weekly percentage hatch of fertile and hatch of set eggs were available for 23,250 dams mated to 3,106 sires of the same age between the 28th and 54th week of life. Hatch of set was very highly correlated with fertility and showed a simil...

Experiments with broiler breeder hens were undertaken to determine effect of feeding time and environmental temperature on various production variables, body weight, and feed consumption. Two temperature treatments were used: low cyclic temperature (10 to 25 C), and high cyclic temperature (21 to 39 C). The three feeding treatments were: fed one daily meal either at 0700 h (Treatment 1) or 1800...

An experiment with laying hens and broiler breeders of two ages (young 22 vs. 36 weeks, old 83 vs. 64 weeks) and at temperatures of 20 and 28°C was carried out to evaluate the interactions between oviposition time (7:30; 11:30, and 15:30 h), age, and temperature on the one hand and egg quality on the other. A significant interaction (P ≤ 0.011) was determined in oviposition time. The highest nu...

The present study was conducted to determine the adverse effects of high temperature and humidity not only on live performance and egg quality but also on immune function in commercial laying hens. One hundred eighty 31-wk-old laying hens at peak production were used in this study. Hens were housed in cages (15 cages of 4 birds/cage) in each of 3 environmental chambers and received 1 of 3 treat...

A 112-day trial was carried out to evaluate the effect of dietary calcium level and limestone particle size on the egg quality of 288 HyLine Brown semi-heavy layers, with 83 weeks of age at the beginning of the experiment. A completely randomized experimental design was applied in a 2x3 factorial arrangement, with two dietary calcium levels (3.5 and 4.0%) e three limestone particle size composi...

Environmental stress boosts the levels of stress hormones and accelerates energy expenditure which subsequently imbalance the body's homeostasis. L-ascorbic acid (L-AA) has been recognized to mitigate the negative impact of environmental stress on production performances in birds. The present investigation was carried out to elucidate the effect of different dietary levels of L-AA on production...

two experiments were conducted to determine the effect of phytase supplementation on layer hens and broiler chickens performance and compare the use of phytase nutrient equivalency values in feed formulation with those fed conventional diet. in the first ex-periment, 640 commercial broiler chicks were used from 11 to 49 days of age. the ex-perimental units were allocated at random to 4 dietary ...

An animal model analysis was used to estimate simultaneously additive (sigma 2a) and dominance (sigma 2d) variances for egg production traits within three White Leghorn lines. The data consisted of information for three generations on egg number (EN) produced at 18 to 25 (EN1), 26 to 65 (EN2), and 18 to 65 wk of age (EN3); egg weight (EW) measured at 30 to 35 (EW1) and 40 to 45 wk (EW2); and eg...