Estratégias de suplementação na recria de bovinos em pastejo e seu reflexo na terminação

Abstract

The objective of this study was to evaluate supplementation strategies and their effects on performance and ingestive behavior in the rearing, and the effects of grazing management on the finishing of grazing cattle. For this, the evaluations occurred during the seasons of dry, waters and water-dry transition. Twenty-four Nellore animals were used, whole males with a mean initial weight of 239.08 kg. The animals were kept in a grazing area of 4.8 hectares of Urochloa brizantha cv. Piatã during the rearing, divided into 24 paddocks of 0.2 ha, and 12 ha of pasture composed by Megathyrsus maximus and Urochloa brizantha cv. Piatã at the termination, divided into 24 paddocks of 0.5 ha, in an intermittent grazing system. The supplementation strategies consisted of supplemented nitrogen supplementation (MA) with 57% of CP (dry) and without PB in the water and transition; additived protein supplement (0.1%) with 45% CP (dry) and 30% CP (water and transition); and additive protein-energy supplement (0.3%) with 35% CP and 47% TDN (dry) and 25% CP and 47% TDN (water and transition). During the rearing and finishing phases, the animals receiving 0.3% protein supplementation and energy supplementation presented superior performance for all variables of production and productivity. In the dry period, there was additional individual gain above 0.130 kg animal day-1 compared to animals receiving MA or 0.1%. The proteinenergy supplementation of 0.3% of CP showed a higher average daily gain (ADG), with a mean of 0.276 kg animal day-1 (P<0.05), and treatments with mineral supplemented and MA and protein 0, 1% of CP, presented similar GMD of 0.106 and 0.142 kg of animal day-1, respectively. The same behavior was observed for stocking rate, animal load, total weight gain and productivity, in which the highest averages were for protein-energy supplementation of 0.3% of PC (P<0.05). Smaller grazing time and longer time were observed for other animal activities supplemented with 0.3% with averages 556.87 and 475.00 minutes respectively (P<0.05). In the rainy season the GMD was 1.056; 0.965 and 1.088 kg animal day-1 for MA; 0.1% and 0.3%, respectively. The stocking rate, animal load, total weight gain and productivity were lower for animals receiving MA, intermediates for 0.1% and higher for 0.3%. The productivity and economic indexes were also higher for animals receiving 0.3% supplementation during the rearing period and under the same feeding protocol as the other treatments during the finishing phase. The supply of protein-energetic supplementation in phases I and II and receiving 2.4 kg day-1 at the termination promoted superior performance to the other nutritional strategies evaluated, with heavier carcasses reflecting in best productivity and economic indicators.