The genetic variability of various local chicken populations derived from Bolivia, India, Nigeria and Tanzania was evaluated with 22 microsatellites. Between two and 11 alleles per locus were detected. All populations showed high levels of heterozygosity with the lowest value of 45% for the population named Aseel from India and the highest value of 67% for Arusha from Tanzania. A dendrogram was constructed based on CHORD distance by upgMa analysis. Within this tree the populations were assorted according to their geographical origin. Bootstrapping values within the dendrogram were between 37 and 99%. The contribution of the determination of genetic variability with genetic markers to the decision on conservation and/or further use of the populations in crossbreeding programs designed to create genetic stocks with improved adaptability and productivity in tropical countries is discussed.

No abstract

No abstract

The productive performance of major genes for feather reduction (naked neck and frizzle) and body size reduction (dwarf) in a dual-purpose layer strain was evaluated in the subtropical coastal region of southeast Africa (Maputo, Mozambique). The experimental material consisted of eight different genetic groups, two diets (14.4 and 16.2% crude protein) and two climatic seasons. Birds were caged individually in a laying house with natural light and ventilation. Traits measured were: temperature and relative humidity, body weight, age at first egg, egg number and weight, feed intake and mortality. The following were calculated: persistence, egg mass, feed efficiency, feed conversion, biological efficiency (EMD/BW 0.75 ) and productivity (EN/BW 0.75 ). The main results show that: (1) none of the feather-reducing genes significantly improved egg production or feed efficiency, although the naked neck (Na) excelled in terms of biological efficiency and productivity; (2) the dwarf gene (dw) was associated with delayed sexual maturity, production of fewer and lighter eggs, higher persistence, better feed conversion and higher survivability; (3) elevated temperatures restrained voluntary feed intake, egg number and weight, and body weight gain; (4) the lower dietary protein content resulted in decreased body weight. It was concluded that the genes were not equally responsive to the environments, which offers the opportunity for selective breeding.

No abstract