Long term effects of the use of creep-feeding for beef calves under tropical conditions

Abstract

The objectives of this study were: to verify the systemic effects of the use of creep-feeding into beef cattle production system on weight variation of cows, the performance, intake and digestibility of calves during the suckling phase and also the residual effect in the post weaning phase. Thirty-six pairs of cows: calves [(year 1: 9 females and 9 males); (year 2: 14 females and 4 males), with initial weight of 550 ± 48 and 35.6 ± 5.5 kg, respectively, were used. The experimental design was completely randomized, factorial 2x2 (two treatments, control and creep-feeding and two calf sex, male and female). Experiment was divided into two phases: suckling (pre-weaning) phase and post-weaning phase. At pre-weaning phase, the animals were kept in an area of 6.2 hectares, divided into 20 paddocks (3,100 m2 each), composed of Brachiariabrizantha. The supplemented treatment calves received concentrated feed at the 0.5% level of BW daily. Milking of cows was performed monthly to estimate the milk intake of calves. Three behavioral trials were carried out along the suckling phase, evaluating the activities of grazing, idle rumination, and suckling time. At post-suckling phase, the calves were separated by sex and both received supplementation during the evaluation periods (winter, spring and summer) until they achieved 18 months of age. The level of supplementation for winter/spring and summer was 0.51% and 0.26% of BW, respectively. Supplemented calves weaned heavier than control (P <0.001). The same happened for sex, with male weaned heavier (P<0.001) and intake more milk than females (P < 0.0001). Supplementation reduced forage and milk intake of calves (P<0.097 and P<0.001, respectively) during the pre-weaning phase. Regarding to the behavior, supplemented animals spent less time grazing over time than control (P<0.020). At the post-weaning phase, animals that received creep-feeding during the pre-weaning phase were heavier during winter (P = 0.010) and spring (P = 0.080) but not at the end of experiment (18 months) (P = 0.291). Males ate more forage than females during rearing periods (P≤0.089) gain more weight (P < 0.0001). There was no effect on supplement intake at any phase of the experiment (P ≥ 0.172), butt males gain more weight in all experiment phase (P < 0.0001). The use of creep-feeding increased the weight gain in the breeding phase tends to be higher in males, males intakes more milk than females,but in the rearing, this gain tends to be partially lost.