Desempenho de cordeiros confinados em dieta alto grão com diferentes tipos de processamento do milho

Abstract

Sheep farming is a livestock activity of great socioeconomic importance for Brazil, as it provides a diversity of products generated, and because they are animals that are easy to manage and have short production cycles. The use of high-grain diets has been studied with the aim of reducing the time animals spend in confinement. In this context, this work aimed to evaluate different types of corn grain processing in high-grain diets on the performance of lambs in confinement. 36 lambs were used, ½ Dorper blood, with an average initial age of 70 days, with an average initial weight of 16±3 kg. The animals were kept in a confinement system for 60 days and housed in a covered shed and kept in individual pens. Three types of corn grain processing were evaluated: 1) whole grain corn (MGI); 2) coarsely ground corn grain (MMG); 3) finely ground corn grain (MMF) and kernel specific for high grain diets. For the diet with coarsely ground corn, the grain was ground in a grain disintegrator using a 2 mm mesh sieve and for the finely ground corn, a 1 mm mesh sieve was used. The experimental diets were formulated following the proportion of 15% protein core and 85% corn. Data on nutrient consumption, performance, slaughter and carcass evaluation were evaluated. The data were subjected to analysis of variance according to an experimental design in randomized blocks and the means were compared using the Tukey test at 5% probability. Dry matter intake, carcass yield, live weight at slaughter and ruminal PH did not show a significant difference between treatments, with lambs from the whole corn grain treatment being those with the highest dry matter intake. Regarding the average daily weight gain, it was observed that the animals in the treatments based on whole corn grain and finely ground corn showed a greater average weight gain than those in the treatment with coarse ground corn (P<0 .05). For feed conversion there was a significant effect, where animals in the coarsely ground corn treatment had the worst average conversion rate (8.4). TDN consumption was satisfactory for the whole grain corn and finely ground corn treatments, while the coarsely ground corn treatment had consumption below ideal. Regarding protein consumption, all treatments presented values well below the requirement, which justifies the low daily weight gain found in this experiment. It was observed that animals in the coarsely ground corn treatment had a lower proportional consumption of the protein nucleus, which probably contributed to the decrease in rumen pH, which may have affected health and feed efficiency. The study indicated that lambs fed whole corn grain (MGI) and finely ground corn (MMF) had better average daily weight gain compared to coarse ground corn (MMG). Significantly worse feed conversion was observed in the MMG treatment, suggesting that coarse processing of corn may negatively affect feed efficiency. The decrease in ruminal pH in the MMG treatment may have compromised the health and consequently the performance of the lambs, highlighting the importance of correctly balancing the diet. Excess grain energy and low protein intake unbalanced the diet and affected the lambs' weight gain potential, highlighting the need for well-balanced diets.