The effect of stocking rate, fertilizer level and winter supplementation on the grazing performance of Senepol purebred and crossbred bulls

Abstract

The study consisted of a grazing and a grazing plus supplemental feeding phase. Forty-eight Senepol purebred and crossbred bull calves were assigned to the following treatments: T1: stocking rate (SR) 3.45 animals per hectare and 449.1 kg/ha of fertilizer; T2:T1 plus winter supplementation; T3: SR 1.85 animals per hectare and 224.5 kg/ha of fertilizer; and T4;T3 plus winter supplementation. The bulls were supplemented with a mix of poultry litter, molasses and corn gram at the onset of seasonal restrictions on pasture growth, During the grazing phase the effect of pasture management on average daily gains (ADG) and closing weights was not significant (P > 0.05). However, moderate pasture management systems (T1 and T2) produced 218 kg more weight gain per hectare (P < 0.05). Winter supplementation increased (P < 0.05) ADG; total weight gains per bull; and weight gains per hectare (+0.32 kg/animal/day; +37.1 kg/animal; +104.4 kg/ha of weight gain). Bulls in T2 and T4 consumed daily 2.33 and 1.44 kg of supplement dry matter (DM) per animal and had estimated feed conversions of 6.65 and 5.90 kg of DM) per kilogram of added gain (P > 0.05), respectively. Herbage mass decreased continuously and was significantly lower (P < 0.05) at the end of the trial. The mean production cost of the total weight gain for the entire study was $0.08/kg lower in T2 than in T1. Within supplemented treatments, animals grazing at a SR of 3.45 animals per hectare (T2) had the lowest cost per kilogram of gain.