Parâmetros produtivos e nutricionais de ovinos em pasto de capim-marandu diferido com diferentes estratégias de rebaixamento

Abstract

The objective of this study was to evaluate which strategy to reduce the height of Urochloa brizantha cv. Marandu (Marandu grass) at the beginning of the deferral period that results in better grazing pasture and optimizes the productive and nutritional parameters in sheep during a dry period. The experiment was conducted at Capim Branco Experimental Farm, which belongs to the Faculty of Veterinary Medicine of the Federal University of Uberlândia (UFU), in Uberlândia, MG. Twenty-one crossbred females, ½ Dorper + ½ Santa Inês, non pregnant, aged between 4 and 5 years and with initial average body weight of 57.5 kg were used. The animals were allocated to 12 Marandu grass paddocks, which underwent three lowering strategies at the beginning of the period of difference: 1) maintenance of 15 cm grass for 5 months before the period of difference (15/15 cm); 2) maintenance of 25 cm marandu grass since October / 2017, but at the beginning of the period of difference or pasture was reduced to 15 cm (25/15 cm); and 3) maintenance of 35 cm grass from October / 2017 until the beginning of a period of difference, when the step was reduced by 15 cm (35/15 cm). The following variables were measured: average daily gain (GMD), dry matter intake and digestibility (DMS), crude protein (DPB) and neutral detergent insoluble fiber (DFDN). Two indicators were used: LIPE as external indicator to measure fecal excretion and NDF as internal indicator to estimate pasture intake. Apparent digestibility of nutrients was calculated by the amount ingested minus the excretion divided by the nutrient intake. The determination of DM, CP, NDF was made according to methods proposed by INCT-CA.. The experiment was conducted in a completely randomized design with six replications (animals) and time measurements (beginning, middle and end). No interaction was observed between grazing period and lowering strategies (P> 0.10) The different lowering strategies did not affect sheep intake and nutrient digestibility. Grazing period affected DM intake when expressed as percentage of body weight (% BW), CP intake (P <0.10) and NDF digestibility (P> 0.10). In the middle of the grazing period, lower NDF digestibility was identified, which was due to the higher proportion of dead stem in the pasture. The nutrient digestibility improved at the end of the grazing period due to regrowth caused by the beginning of the rainy season. It was concluded that different pasture lowering strategies at beginning of the deferral do not affect nutrient intake and digestibility. Higher dry matter intake is observed at the beginning of the grazing period due to the better pasture structure that facilitates apprehension by animals. Adult sheep in deferred pasture during the dry season maintain weight throughout the dry season, so deferral is a technique that can be used to maintain the body weight of animals in the dry season, and is a good strategy for animals that will enter mating season.