Variations of breeding success with age have been studied largely in iteroparous species and particularly in birds: survival of offspring increases with parental age until senescence. Nevertheless, these results are from observations of free-living individuals and therefore, it remains impossible to determine whether these variations result from parental investment or efficiency or both, and wh...

We investigated post-natal development of the adrenocortical stress-response system in captive American kestrels (Falco sparverius) by measurements of baseline and stress-induced levels of corticosterone at ages 10, 16, 22, and 28 days post-hatching. Baseline levels of corticosterone increased significantly during post-natal development and although chicks aged 10- and 16-days old exhibited com...

Two experiments were conducted to determine: first, the best time of excreta collection after force feeding of broilers to yield the maximal amount of excreta, and second, nitrogen-corrected true metabolizable energy contents of some poultry feedstuffs including yellow corn, soybean meal, corn gluten meal, canola meal and poultry by-product meal by a new precision-fed chick assay using 3-week-o...

Coccidia oocysts were demonstrated in the faeces of 53 (about 34%) of 156 apparently healthy ostrich chicks. Young chicks had the highest proportion of infestation while those more than 9 weeks old had no oocysts at all in their faeces. These coccidia may be considered no pathogenic since the infected chicks grew normally without any evidence of diarrhoea.

In two experiments, the effects of dietary fat and breeder hen age on relative yolk sac weight (RYSW) and total serum cholesterol (CHOL), high (HDLC) and low (LDLC) density lipoprotein cholesterol, triglycerides (TRI), and glucose (GLU) were monitored in broiler embryos and chicks. In Experiment 1, embryos at 18 d of incubation and chicks at hatch were sampled from eggs laid by breeder hens at ...

Life histories are state-dependent, and an individual’s reproductive decisions are determined by its available resources and the needs of its offspring. Here we test how a chick’s needs for food and protection influence parental decisions in the Antarctic petrel, Thalassoica antarctica , where the parents, due to their long breeding lifespan, are expected to give priority to their own needs bef...

The present work was performed to study the effect of vaccination with Cocci Vac B on cellular and humoral immunity of chickens. The study comprised 70 chicks hatched from hens none vaccinated against coccidiosis. The chicks were subdivided into 4 groups. The 1st group comprised 25 chicks, kept as apparently healthy control, the 2nd group consists of 10 chicks, infected with 10000 mixed sporula...