Efeitos da suplementação com caroço de algodão sobre desempenho, metabolismo de nutrientes e qualidade da carne de ovinos

Abstract

The aim of this study was to evaluate sheep fed with whole cottonseed on performance parameters, nutrient metabolism, methane emission and meat quality, either the toxixity effect caused by the ingestion of high amount of free gossypol present in animals feed, ensuring food security. The experiment lasted 70 days, using 16 Santa Inês' sheep, with initial body mass of 44 ± 4,7 kg and mean age of 18 ± 2 months, distributed in Control Treatment (TC) and whole cottonseed Treatment (TCA). The feed were offered daily in two periods, consisting of 40% of Tifton hay (Cynodon spp) and 60% of concentrate (50% corn grains and 50% soybean meal, and 100% whole cottonseed, respectively for TC and TCA), also water and minerals were supplied ad libitum. The in vivo study was divided into three periods, performance assay (10 days of adaptation to treatments and 45 days of assay), apparent digestibility assay (5 days of adaptation and 5 days of assay) and enteric methane emissions (2 days of adaptation and 3 days of assay). Bromatological analyzes of feeds, leftovers and excrements were realized to characterize the components, and to determine consumption and weight gain of the animals; Evaluation of ruminal parameters of short chain faty acids (SCFA), pH, ammonia nitrogen (NH3-N) and free gossypol; also estimation of microbial production through the purine derivatives content in urine. After 70 days, the animals remained fasted (16h), then slaughtered and carcasses were evaluated. Physicochemical parameters, carcass yield, centesimal evaluation, meat quality and free gossypol were determined. The inclusion of 60% of whole cottonseed in the concentrate provided an increase in the intake, average digestibility of nutrients, also the nitrogen metabolism; allowing an environment conducive to the activities of ruminal microorganisms, evidenced by ruminal parameters SCFA, pH, NH3-N and CH4 production. However, the animals had lower weight gain in relation to the control diet. The criteria of carcass quality and centesimal composition did not differ between diets. The presence of free gossypol was not detected neither in meat nor in liver samples. Taking into account the quality of Santa Inês' meat, it is suggested that the inclusion up to 60% of whole cottonseed animals' feed, in the confinement termination period would be safe when in substitution of corn and soybeans, without causing intoxication or changes in the carcass, and therefore without risks to human health; contribuiting for the production of food in a secure, safety and sustainable way.