Restrição intermitente na oferta de proteína bruta na dieta de ovinos

Abstract

Aiming evaluate the effects of intermittent CP restriction on intake, digestibility, N balance, performance, carcass trait, and meat quality of animals, 25 animals were used for the digestibility test and 38 animals for performance, with an average weight of 30.13 ± 3.00 kg and 22.47 ± 3.68 kg, respectively, ½ Santa Inês and non-castrated. The sheep were fed with Tifton-85 hay and a concentrated mixture of corn, soybean meal, and mineral salt. Two rations were formulated, one with 100% CP content for a daily gain of 200g according to the NRC (2007) and another with 64% CP content in relation to the control diet (restricted diet). The treatments were defined by the cycle of time in which the animals should be admitted to the diet: without restriction, 24 hours of restriction, 48 hours of restriction, 72 hours of restriction, and continuous restriction. The animals assigned for the digestibility test were confined for 22 days, and collections took place from the 11th to the 22nd day. During this period, total collections of leftovers, feces, and urine were carried out. The animals intended for performance were confined for 90 days. At the end of the performance trial period, the animals were exposed to a 16-hour fast, weighed and slaughtered for carcass characteristics spirituality. The physical-chemical, instrumental, and sensorial characteristics of the meat were evaluated. The data were submitted to analysis of variances. The restriction of CP intermittently led to a reduction in DM consumption and the variables TDN, CP and NDF accompanied this reduction. The urinary N excretion of treatments with intermittent restriction were above the double when compared to that of N. There was a reduction in weight gain for animals showing protein restriction. However, the FCR, carcass traits, and physicochemical characteristics of the meat were not affected by the treatments. In the sensory analysis, the flavor and odor variables presented the best evaluation for the 24h treatment, while for tenderness the 72h treatments and continuous restriction obtained the best evaluations. However, GA was similar between treatments. Therefore, the intermittent restriction of CP is favorable, due to the reduction of N excreted, reducing impacts on the environment, without prejudice to the carcass and meat characteristics of the sheep.