José M. da Silva

Desempenho animal e avaliação do potencial produtivo de forragens para ensilagem, por intermédio de diferentes fontes de suplementação nitrogenada

This study was conducted to evaluate the corn (Zea mays L.) AG 1051 and the sorghums (Sorghum bicolor (L.) Moench) AG 2006 and BR 303, for silage production, and the effect of substitution of soybean meal by urea (0,50 and 100%) in the concentrated diets for feedlot cattle. The silages were used in two experiments and the animals were alloted to a completely experimental design. In the first, 72 F1 crossbred Brown Swiss x Nellore bulls, with 20 months of age and 412 kg LW were distributed to a 3x3 factorial arrangement (corn silage and sorghums silage and level of substitution of soybean meal by urea). In the second, 48 Nellore steers, with 34 month of age and 378 kg LW, were allotted to a 2 x 3 factorial arrangement (sorghum silage and level of substitution of soybean by urea). There were no differences between the forages as for production/ha of total dry matter and leaves, stem and of ear/panicle ratio. The corn and sorghum BR 303 plants presented about 53% of ear/panicle ratio as compared to 45% of the sorghum AG 2006. There was no interaction between the silage and the nitrogen source. The corn silage provided better performance for the crossbred bulls. Economically, the highest profit was obtained by using corn silage and soybean meal. The performance of Nellore steers was not affected by silage type or nitrogen source. There were no differences in the economic return for the silages. However, for the nitrogen source, the higher economic return was obtained by the use of urea followed by soybean meal + urea mixture and, finally, by soybean meal.

Genetic parameters for faecal egg count, packed-cell volume and body-weight in Santa Inês lambs

Worm infection is one of the main factors responsible for economic losses in sheep breeding in Brazil. Random regression analysis was used to estimate genetic parameters for the factors faecal egg-count (FEC), packed-cell volume (PCV) and body weight (BW) in Santa Inês lambs. Data from 119 female, offspring of nine rams, were collected between December, 2005 and December, 2006, from the experimental flock of Embrapa Tabuleiros Costeiros, the Brazilian Agricultural Research Corporation located in Frei Paulo, SE, Brazil. After weaning, females were drenched until the faecal egg count had dropped to zero. Two natural challenges were undertaken. FEC heritability was extremely variable, this increasing from 0.04 to 0.27 in the first challenge and from 0.01 to 0.52 during the second. PCV heritability peaks were 0.31 and 0.12 in the first and second challenges, respectively. In the second challenge, BW heritability was close to 0.90. The genetic correlations among these traits did not differ from zero. There is the possibility of increasing parasite resistance in Santa Inês by selecting those animals with lower FEC. Selection to increase resistance will not adversely affect lamb-growth, although lambs with a slow growth-rate may be more susceptible to infection.