Lipídeos na alimentação de ovinos confinados

Abstract

The aim of this work was to evaluate the effects of the lipid source and sexual class on animal performance, carcass and meat characteristics, digestibility of nutrients, nitrogen balance and blood parameters of feedlot sheep. Two experiments were conducted, in the experiment I, were used forty lambs crossbreed Dorper x Santa Inês, male, with body weight of 22.27±2.79 kg, which were distributed in a completely randomized experimental design with five treatments and eight replications. The diets were formulated to be isonitrogenous, with a roughage:concentrate ratio of 40:60. It was used as roughage tifton-85 hay. Five diets were formulated for each fat source (corn germ, whole raw soybean, soybean oil and protected fat as calcium salt fatty acids- CSFA) and the control diet (composed of soybean meal, ground corn, mineral premix and urea). The intake and apparent digestibility of the nutritional compounds was higher to the CSFA diet (p≤0.05). The lambs in the diet with CSFA had higher final body weight (p=0.0056), higher average daily weight gain (p=0.0013) and higher relative rate of growth (p=0.0209). No significant differences were observed in the urinary and blood parameters (p>0.05), except for the levels of blood triglycerides (p=0.0380), which were higher in the diets with whole raw soybean (44.7694 mg dL-1). The amount of nitrogen consumed was higher in the control and CSFA diets (p=0.0038), however, the diet with CSFA provided higher nitrogen absorption. The largest chewing time and the largest chewings number for bolus occurred in the diet with soybean oil (p≤0.05), while the greater efficiencies of rumination of dry matter and NDF that with CSFA. The lower carcass performance and meat production were observed in the diets with raw whole soybean and corn germ (p≤0.05) and the highest finishing index, loin eye area and loin weight were observed in the diet with CSFA (p≤0.05). In the experiment II, were used twenty male lambs with mean body weight of 22.49 ± 2.78 kg and twenty female lambs with mean body weight of 20,59 ± 3,37 kg, crossbreed Dorper x Santa Inês, in a completely randomized experimental design with a factorial arrangement 4x2,xxi with four diets and two sexual classes. The diets were formulated to be isonitrogenous, with a roughage:concentrate ratio of 40:60. It was used as roughage tifton-85 hay. Were formulated three diets referents each fat source (raw whole soybean, soybean oil and fat protected as calcium salt fatty acids) and the control diet (composed of soybean meal, ground corn, mineral premix, and urea). The nutritional compounds intake was higher (p≤0.05) in the animals fed with the control and fatty acids calcium salts diets. The digestibility of nutritional compounds and the performance measures were higher (p≤0.05) in the animals fed with the fatty acid calcium salt diet. No differences were observed (p>0.05) in the measures of ingestive behavior and, urinary and blood parameters between the diets evaluated. There was higher (p≤0.05) intake of nutritional compounds in male lambs. The body weight, weight gain, feed efficiency and relative rate of growth were higher for the male lambs, however, the feed conversion was higher for the female lambs. We found higher intake and nitrogen retention in the male lambs, while in the female lambs there was higher absorption and excretion of nitrogen. The animals fed with the fat source, fatty acid calcium salts, showed better results when compared with the other lipid sources.