We tested the hypothesis that mother birds counterbalance the negative effects of hatching asynchrony for later-hatched chicks by increasing the yolk androgen concentrations in consecutive eggs of their clutch. In doing so, they may adaptively tune each offspring's competitive ability and, thus, growth and survival. However, evidence in support of this hypothesis is contradictory. The yolk conc...

background: it has been demonstrated that performing a mock embryo transfer (et) significantly improves the pregnancy rate in ivf cycles. the mock et could be performed prior to the stimulation cycle or immediately before real et. the problem of the first procedure is the possibility of variation in the uterine position and or cervico�uterine angle. objective: the purpose of this study was to d...

background: natural endometrium in frozen-thawed embryo transfer (fet) may have some benefits upon implantation in patients with repeated implantation failure (rif). it might be due to possible differences between natural and stimulated endometrial growth factors and cytokins secretions. objective: the objective of this study was to compare the pregnancy rate of fet on modified natural cycle ve...

The changes in body weight and composition were examined in broilers that either had immediate access to feed and water or had not been fed for 48 h posthatch. Chicks without access to feed decreased in BW by 7.8% in the 48 h posthatch, which was equivalent to 5.3 kcal/45 g chick/d. However, during this period the small intestines increased in weight and protein content by 80% or more. The decr...

The development of gull chicks is typically considered semi-precocial, because the birds remain in or near the nest for some days after hatching and depend on parental care, but hatch with downy coverings and possess some thermoregulatory ability (Drent 1967; Palokangas and Hissa 1971; Dawson et al. 1972, 1976; Dunn 1976; Dawson and Bennett 1980. 1981). Newlv hatched chicks of several gull spec...

Abstract Snails infected by trematodes may increase or decrease their reproductive activity in response to the presence of infection. Our aim was verify alterations Subulina octona after infection Paratanaisia bragai. The snails were individually exposed for 24 hours 20 parasite eggs and four groups formed (10, 20, 30 40 d.p.i.- days infection), along with control groups. Every 10 days, number ...