The effects of light intensity (LI) from photostimulation to 45 wk of age on egg production parameters and egg size characteristics were examined in four layer strains. Floor housed pullets were raised in a light-tight facility from 1 d of age until housing in individually illuminated cages at 17 wk of age. At 17 wk of age, two white egg strains, ISA-White (ISA-W) and Shaver 2000 (S2000), and t...

Genotype x environment (GxE) interactions can reduce the accuracy of a model to predict the performance of an animal and have an undesirable influence if not accounted for when estimating breeding values. Consequently, identification of these GxE is necessary when considering a turkey breeding program. Reranking based on the genetic prediction of turkey egg production, fertility, and hatchabili...

Rice bran (RB) is a major by-product, produced from the rice milling process. This study was conducted to evaluate the performance, egg quality, and blood biochemical parameters of 288 Hy-line laying hens fed diets with rice bran and commercial microbial phytase Natuphos®5000. The experiment was a 4×2 factorial one with four RB levels (0, 5, 10, and 15%) by two phytase levels (0 and 5000 FTU/kg...

Many amphibians lay their eggs in gelatinous masses up to 10­20 cm in diameter, posing problems for diffusive oxygen delivery. Oxygen may also be provided by water convection between eggs or by oxygen production by endogenous algae. We studied egg masses of two local amphibians, Rana sylvatica and Ambystoma maculatum, to estimate the importance of each of these processes. We injected dye to...

1. In a study spanning two breeding seasons, we assessed the effect of different dietary energy and protein levels on body mass, body condition, and egg production of female ostriches. 2. During the first breeding season, groups were given diets with energy concentrations of 8.5, 9.5 and 10.5 MJ/kg dry mass (DM) metabolisable energy (ME) and protein concentrations of 135, 150 and 165 g/kg. In t...

A crossbreeding experiment was carried out between two Egyptian strains of chickens namely Mandarah (MM) and ElSalam (SS). The two purebred strains and their reciprocal crosses (MS and SM) were used to estimate the effect of crossing on egg laying and egg quality parameters, direct additive and maternal additive effects as well as heterosis and direct heterosis percentages for studied traits. R...

HE effectiveness of selection for genetic improvement of egg production in the fowl remains a controversial issue. Mass selection on annual egg records has long been regarded as ineffective as demonstrated by the early work of PEARL (1915), while selection based on family records and progeny testing has seemed to be the key to success as demonstrated by the long-time selection experiments of DE...

We investigated the effects of dietary supplementation of zinc (ZnO; 0, 40, 80, 120 and 160 mg/kg) and Vit E (α-tocopheryl acetate; 0 and 40 IU/kg) on egg production, egg quality and Zn content of egg fractions and tissues in Japanese quails. Using a 5 × 2 factorial design, a total of 960 Japanese quails (Coturnix coturnix japonica) at day 70 of age were housed in cages and randomly assigned in...

introduction: with using multiple linear regression (mlr), can simultaneously analyses several different variables, but to get the desirable results from the mlr, the samples must be much and accurate. therefore, this method has high sensitivity and may cause errors in results. in addition, to use this method, the variable must have normal distribution and modification follow from a linear rela...