Desempenho produtivo, características de carcaça e comportamento ingestivo de ovinos submetidos a diferentes estratégias de suplementação

Abstract

The experiment was carried out at Experimental Farm of the Universidade Estadual de Montes Claros, in Janaúba County, in the North of Minas Gerais from 12 April to 14 June 2011 in order to evaluate the performance, carcass characteristics and ingestive behavior of sheep receiving different types of supplements. They were used 24 undefined genotype intact animals and average live weight of 20.58 kg, arranged in 4 treatments with 6 replications in a completely randomized design. The treatments consisted of 4 types of supplements: mineral supplement, mineral supplement with urea, protein mineral supplement and concentrated supplement. The animals were placed in individual stalls provided with food and water, with a total area of 3 m2 and covered with shade. The experimental period lasted 63 days, divided into three periods of 21 days. At the end of the experimental period the animals were weighed to obtain the final body weight and determining the average daily weight gain (ADG), feed conversion ratio and price per kilogram of live weight gain. For evaluation of ingestive behavior it was chosen a day of the last experimental period for quantifying of time intervals spent with eating, ruminating and idling, by means of visual observation of the animals every 10 minutes. In the same day were counted number of chews and the ruminating time spent per bolus, using a digital stopwatch. The efficiency of rumination was determined, expressed in g DM/hour g NDF/hour. Then morphometric measurements were made to compare the treatments to each other and to correlate them with ADG and hot carcass yield. Soon after, the animals were slaughtered, bled and removed the non-carcass. The carcasses were weighed and divided longitudinally in the midline in two half carcass with the aid of a chainsaw. The left half carcass was weighed to determine carcass yield and the right one was weighed and divided into six commercial cuts (neck, ribs, breast, shoulder, loin and leg) for determination of absolute weight and yield. The noncarcass constituents were also weighed and guts were emptied to obtain the empty body weight. The concentrated treatment provided the highest final body weight and average daily gain in body weight and the lowest feed conversion and cost per kilogram of live weight gain, and higher hot carcass weight, carcass yield in relation to body weight and final weights of meat cuts.. The treatments did not affect the percentage of non-carcass components. The concentrated treatment resulted in greater width of chest and leg circumference, measurements measured in vivo and carcass, respectively. The morphometric measurements on the carcass can be used to more accurately predict the average daily gain in live weight and hot carcass yields than morphometric measurements in vivo, highlighting the width of chest, and circumference of hip and of leg. Protein treatment was longer with feeding activity, whereas, for rumination activity, the urea treatment was longer than the others ones.