RESUMO -Neste estudo, investigou-se o efeito da estação de nascimento sobre a puberdade de cordeiros Santa Inês criados no Distrito Federal. Utilizaram-se 33 cordeiros machos, inteiros, distribuídos em quatro lotes de grupos contemporâneos. A diferença de idade de cada grupo foi de 90 dias, abrangendo as quatro estações do ano. Foram realizadas coletas de dados mensalmente e a cada 15 dias, dependendo da presença ou ausência de espermatozóides no ejaculado de cada animal. A puberdade foi definida quando o sêmen do animal apresentou motilidade total de 10% e concentração espermática de 50 x 10 6 espermatozóides por mililitro (mL) de ejaculado. Após a definição da puberdade, procedeu-se a mais uma coleta e, após 15 dias, realizou-se a castração dos animais. A idade à puberdade dos animais foi de 194,57 ± 41,97 dias. A estação do ano afetou a idade à puberdade entre os grupos, principalmente em razão do fator nutricional, visto que os pesos à puberdade foram semelhantes. O grupo mais precoce (nascido em agosto) apresentou idade à puberdade de 162,56 ± 35,55 dias. Correlações significativas foram encontradas entre peso e circunferência escrotal (CE), comprimento e largura testicular, sugerindo que a CE pode ser utilizada como critério complementar para a seleção feita com base nos parâmetros produtivos. Palavras-chave: andrologia, biometria, sêmen, testículo Season of birth and puberty in Santa Inês lambsABSTRACT -The present study investigated the effect of calving season on puberty of Santa Inês ram lambs raised in the Distrito Federal, Brazil. Thirty-three ram lambs were assigned to four contemporary groups according to birth date, distributed in three months intervals. Data were collected monthly and every 15 days depending on the presence of sperm in each animal ejaculate. Puberty was defined when the animal presented total motility of 10% and sperm concentration of 50 x 10 6 per mL of ejaculated semen. This procedure was repeated after puberty and after 15 days the animals were castrated. Mean age at puberty was 194.57 ± 41.97 days. The season affected the puberty age, mainly due to the nutritional factor, since the puberty weights were not significantly different between groups. Average age at puberty for the youngest group (born in August) was 162.56 ± 35.55 days. Significant correlations were found between weight and the scrotal circumference (EC), length and width of testis, suggesting the use of EC as a complementary criterion for selection based on productive parameters.

-This study examined the effects of crossbreeding low genetic potential cows of Bos indicus origin characterized by Gyr crossed with Holstein-Friesian and Simmental bulls to produce animals in a low input dual purpose system. The farm is situated near Brasilia, in the savannah region of Brazil. The climate of the region is classified as Aw by Köppen.Data was available on 1580 calvings and completed lactations of cows with three genetic types: Gyr, Holstein-Friesian × Gyr and Simmental × Gyr. The bulls ran with the cows all year round and the diet comprised of pasture (mainly Brachiaria and Andropogon) during the summer (rainy season) and milled sugar cane with added urea during the winter (dry season). A mineral salt mixture was available ad libitum. Data was analysed using Statistical Analysis System. The results show that, under low input management conditions, the crossbred cows produce approximately twice the volume of milk per lactation, calve at a younger age and have a shorter open period, but there are no significant differences between crosses for growth rates of the calves or body condition of the cows. In this system, crossbred cows had production higher indices than zebu cattle. The best indices were found for cows calving in the rainy season (September to December) and thinner cows (with body condition 3-5 on a scale of 9).