Desempenho e comportamento ingestivo de ovelhas em lactação alimentadas com dietas contendo diferentes níveis de fibra em detergente neutro

Abstract

The study was carried out the Department of Animal Science of the Federal University of Santa Maria, with the objective to investigate the effect of the supply of diets with different levels of neutral detergent fiber (NDF) on the nutrients intake, daily milk yield (MP), milk composition (MC) and ingestive behavior of lactating ewes. Eighteen ewes, proceeding from the alternated crossing between Texel and Ile de France breeds were used, housed indoors in individual cages. The animals were distributed on three treatments: 34, 43 and 52% NDF in the diet, in dry matter basis (DM) to consist in the treatments. Equal protein diets, with 13% of PB (crude protein) content, in DM basis, was composed of total mixed ration of corn ensilage (Zea mays L.), and a concentrate mixture based on fragmented corn, soybean bran (Glycine max L.) and mineral mixing. The food supply was ad libtum, done twice a day, in set up times at 8:30 AM and 4:30 PM. An entirely randomized design was used, with three treatments and six repetitions each. The results were submit of the analysis of variance and regression study. The addition of increasing in NDF levels result in quadratic effect (P<0,05) on the intake of dry matter (DMI), organic matter (OMI), crude protein (CPI), ethereal extract (EEI), total carbohydrates (TCHOI), and non-structural carbohydrates (NSCI), neutral detergent fiber (NDFI) and acid detergent fiber (ADFI), expresses in kg/day, % PV and g/kg PV0,75. The maximum DMI corresponded to 42.7% NDF level in the diet. Do not significant effect (P>0.05) of the diets on the variations of average weight daily gain (GMD). The body score condition (CC) presented quadratic behavior (P<0.05). Quadratic effect was verified (P<0.05) on the milk yield in function of the treatments, that was maximum with 39.8%NDF level of in the diet. The crude protein milk (CP) values presented quadratic variation (P<0,05). The milk fat contents (Gord), express in g/day, and the density, had diminished linearly with the NDF increasing in the diet. The total solids contents, express in g/day, density, 3.5% and 4% fat corrected milk yield had varied in quadratic way (P<0.05), in function of the treatments. The stage of lactating influenced on milk production (P<0.05), resulting quadratic effect for 34% and 43% NDF levels, and linear effect for the 52%NDF level in the diet. Quadratic effect (P<0.05) were verified in the resting, rumination, intake and total chewing times in function of the NDF levels in the diets. The feeding and rumination efficiency of the NDF is increased with the increase of the level of this fraction in the diet. Lactating ewes confined present greater concentration of activity of feeding during the day and rumination during the night.