RESUMO
The genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population were estimated by applying the Average Information Restricted Maximum Likelihood method to an animal model. Data from a flock supported by the Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC) were used. The traits studied included birth weight (BW), weaning weight (WW), slaughter weight (SW), yearling weight (YW), weight gain from birth to weaning (GBW), weight gain from weaning to slaughter (GWS), weight gain from weaning to yearling (GWY), age at first lambing (AFL), lambing interval (LI), gestation length (GL), lambing date (LD - number of days between the start of breeding season and lambing), litter weight at birth (LWB) and litter weight at weaning (LWW). The direct heritabilities were 0.35, 0.81, 0.65, 0.49, 0.20, 0.15 and 0.39 for BW, WW, SW, YW, GBW, GWS and GWY, respectively, and 0.04, 0.06, 0.10, 0.05, 0.15 and 0.11 for AFL, LI, GL, LD, LWB and LWW, respectively. Positive genetic correlations were observed among body weights. In contrast, there was a negative genetic correlation between GBW and GWS (-0.49) and GBW and GWY (-0.56). Positive genetic correlations were observed between AFL and LI, LI and GL, and LWB and LWW. These results indicate a strong maternal influence in this herd and the presence of sufficient genetic variation to allow mass selection for growth traits. Additive effects were of little importance for reproductive traits, and other strategies are necessary to improve the performance of these animals.
RESUMO
Avaliaram-se as frações nitrogenadas e de carboidratos e os parâmetros cinéticos de degradação damatéria seca (MS) e fibra em detergente neutro (FDN) de cinco silagens produzidas com Tifton 85: Tifton85 exclusivo; Tifton 85 adicionado de resíduo de beneficiamento de milho; Tifton 85 adicionado de fubáde milho; Tifton 85 inoculado com Lactobacillus e Tifton 85 pré-seco. Os carboidratos totais variaram de66,32 a 73,12%; a fração B2 de 35,09 a 52,27 %; e os carboidratos não estruturais de 8,61 a 38,03%. Osvalores obtidos para as frações protéicas variaram de 68,08 a 82,70% para a fração A; de 1,14 a 2,97% paraa fração B1; de 7,46 a 13,71% para a fração B2; de 6,09 a 12,60% para a fração B3; e de 0,36 a 6,71% paraa fração C. Os valores de degradação efetiva variaram de 46,93 a 63,49% para MS; e de 33,47 a 37,84%para FDN. A utilização de resíduos de beneficiamento de milho e fubá de milho para produção desilagens favoreceu a degradação efetiva da MS e FDN, proporcionando maior disponibilidade energéticapara microbiota ruminal.
It was determined the nitrogen and carbohydrate fractions and dry matter (DM), and neutral detergent fiber (NDF) degradation kinetics in five silages prepared with Tifton 85 grass forage: exclusive Tifton 85, Tifton 85 silage added of corn industrial residue, Tifton 85 silage added of corn meal, Tifton 85 silage inoculated with lactobacillus and Tifton 85 silage pré-dry. The values of total carbohydrates varied from 66.32 to 73.12%, the B2 fraction varied from 35.09 a 52.27 %; and non-structural carbohydrates varied from 8.61 to 38.03%. The values obtained for the protein fractions varied from 68.08 to 82.70% for A fraction; from 1.14 to 2.97% for the B1 fraction; from 7.46 to 13.71% for the B2 fraction; from 6.09 to 12.60% for the B3 fraction; and from 0.36 to 6.71% for the C fraction. The values of effective degradability of dry matter varied from 46.93 to 63.49% for the DM, and from 33.47 to 37.84% for the NDF. The corn industrial residue and corn meal used for silage production favored the effective degradation of DM and NDF, and offered highest energy readiness for ruminal microorganisms.
