The objective of this work was to study the reproductive behavior of two strains of R. (B.) microplus, one wild-caught (Native) and one reference strain (Media Joya) for two years, measuring the reproductive efficiency index (REI) and reproductive aptitude index (RAI). Engorged ticks from each strain were collected monthly from February 2002 to February 2004. These were weighed and kept in the ...

Pheasant eggs evaluated in the first period of egg-laying did not differ significantly in their weight and shape index and the values of both traits were, respectively, 30.7 to 32.2 g and 76.1 to 78.1%. Over the laying season the thickness of the shell decreased and its capacity for deformation and crush strength were greatest at the end of the laying season. The share of yolk in the egg was hi...

The reproductive success of wild birds has been affected by exposure to multiple contaminants. Reproduction of captive American kestrels (Falco sparverius) was suppressed when adult birds were exposed to dietary polychlorinated biphenyls (PCBs). In this study, the reproductive effects of in ovo exposure to PCBs is explored, along with determining effects on reproduction in second-generation bir...

Seasonal timing of reproduction and the number of clutches produced per season are two key avian life-history traits with major fitness consequences. Female condition may play an important role in these decisions. In mammals, body condition and leptin levels are correlated. In birds, the role of leptin remains unclear. We did two experiments where we implanted female great tits with a pellet re...

This study was undertaken to determine if pre-storage heating of broiler breeder eggs, stored for long periods, would improve the hatchability and chick quality. A total of 2400 broiler breeder eggs were obtained from a 46 weeks old commercial flock. Eggs were distributed in a 3 x 4 factorial design, with three pre-storage heating durations (0, 6, and 9 hours at 37.5° C and 56% RH) and four sto...

Broiler performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters and juvenile growth have received little attention. A total of 1,200 hatching eggs produced by Cobb and Ross broiler breeders of the same age were studied. At setting for incubation and between 66 and 130 h of incubation, egg re...

Athens Canadian Random Bred (ACRB) chickens, a 1955 meat-type control strain, were incubated with the 2013 Cobb 500 broiler to determine differences in egg composition, conductance values, incubation duration, hatch performance, and yolk utilization. Unincubated ACRB eggs had greater percentage solids than Cobb 500 eggs. The ACRB eggs had a greater solid portion as yolk, whereas the Cobb 500 de...