Effects of Creep-Feeding Supplementation on Growth Performance of Nellore Calves and Milk Yield of Dams

Abstract The study aimed to evaluate the effect of creep-feeding on growth performance of beef calves and milk yield of dams, during nursing phase. The experiment lasted 170 days, from December/2021 to May/2022, the calves were born in September/2021 and creep-feeding supplementation started from approximately 70 days of life until weaning. The experimental design used was a randomized block [blocked by body weight (BW) of calves]. The experimental units were the paddocks (8 units per treatment, and ten replicates per paddock), totalling 156 pairs cow/calf (86 pairs of male calves and 70 pairs of female calves). The treatments consisted of creep-feeding or not creep-feeding the calves: control treatment (CONT; mineral supplement ad libitum) and creep-feeding treatment (CREEP; energetic protein supplement; 5 g/kg of BW· animal-1· /day-1). There was mineral supplement ad libitum for all the dams. The pairs cow/calf were kept in an area of Urochloa brizantha cv. Marandu. The data were analyzed using the SAS PROC MIXED. Male calves subjected to CONT showed less BW (-15 kg) at weaning and decreased average daily gain (ADG; -100g/day) until weaning (P < 0.01; Figure 1), while female calves showed no difference in BW and ADG (P > 0.12; Figure 2). The dams did not show difference in milk yield until weaning (P > 0.27) for male and female calves (Figure 3). This difference in results related to gender is explained by the fact that there are differences in the performance of males and females, mainly due to hormonal issues. Usually, females are born lighter than males and tend to have decreased performance throughout the whole production cycle. For milk yield and performance of dams, our results agree with what is found in the literature. There are some studies which also evaluated milk production of dams when the offspring were creep-fed, and found similar milk yield for those whose offspring received supplement in relation to those who did not receive it. This is likely because calves prefer milk, supplement, and forage, in that order, so it seems unlikely that calves would replace milk with supplements. And these results show us that the difference in the BW at weaning of males was caused by the creep-feeding supplementation.