Consumo e desempenho de ovinos em pasto diferido manejado com quatro alturas iniciais

Abstract

Deferred pastures are generally characterized by low nutritional value, which results in limited consumption and, indeed, no or modest animal performance. However, management actions, such as changing grass height at the beginning of the deferment period, can improve pasture nutritional value and animal performance. Thus, this work was developed with the objective of verifying the effect of different grass heights of Urochloa brizantha cv. Marandu, at the beginning of the deferment on the intake, nutrient digestibility and performance in sheep in the dry season. The experiment was carried out in a pasture of Marandu grass, subdivided in 12 pickets of 800 m2 each, in the Experimental Farm Capim Branco of the Faculty of Veterinary Medicine, Federal University of Uberlândia, from February to September 2013. Combinations between four medium pasture heights (15, 25, 35 and 45 cm) at the beginning of the deferment period and the pasture utilization times ( (DM), digestibility of DM, CP and NDF, and mean daily gain (GMD) were evaluated. To estimate fecal excretion, purified and enriched lignin (LIPE) ® was used, through the relationship between dose and fecal concentration of the external indicator. Indigestible neutral detergent fiber (NDFI) was used as an internal indicator for estimation of pasture consumption. The animals were weighed, after a 15-hour fast, immediately before being distributed in the experimental units and soon after the end of the experiment, to determine the GMD. The apparent digestibility of the nutrients was calculated by the amount ingested minus the excretion divided by the intake of the nutrient. The determination of the contents of MS, PB, NDF was done according to the methods proposed by INCT-CA. The experimental design was a completely randomized design, with three replicates, .. Deferred pastures with 35 and 45 cm had a greater forage mass than those deferred with 15 and 25 cm, and in addition deferred pasture with 15 cm had a higher percentage of live leaf and lower percentage of dead stalk. At the beginning of the deferment period, the pastures lowered to 15 and 25 cm had higher levels of crude protein (CP) and dry matter, potentially digestible (MSpd). The highest CMS and CP consumption (g / day) were identified at the beginning of the grazing period, and higher intakes of NDF (g / day) occurred at the beginning and end of the grazing period. The CMS ranged from 1.10 to 1.63% PC values that were lower than predicted by the NRC (2007) which is 2.86% of the PC. The sheep that remained in the deferred pastures lowered to 15 cm had the highest average daily gain (ADG), but did not change consumption. It was concluded, therefore, that the growing sheep fed with deferred pasture, lowered to 15 cm at the beginning of the deferment period, presented higher performance.