14. Effects of Creep Feeding Supplementation and Growth-Promoting Implants on Preweaning Performance of Bos Indicus-Influenced Calves

Abstract Nutrition and management strategies during the preweaning phase, such as creep feeding and the use of growth-promoting implants, can have long-lasting effects on calf growth, metabolism, and overall performance. However, limited research has evaluated their combined effects during the suckling phase in beef cattle. The objective of this study was to assess the effects of limited creep-feeding supplementation and growth-promoting implants on the growth performance of beef calves. Seventy-two cow–calf pairs were stratified by body weight (BW) and allocated into 1 to 8 bahiagrass pastures (Paspalum notatum; 6 ha pastures; 9 pairs per pasture). Treatments were randomly assigned to pastures in a 2 × 2 factorial arrangement of treatments consisting of pastures with or without creep feeding and calves with or without implants. On d 0 (70 days before weaning), Bos indicus–influenced beef calves (n = 72; 210.4 ± 30.3 kg of BW) were randomly assigned to receive either no implant (n = 36) or a combination growth-promoting implant containing 100 mg progesterone and 10 mg estradiol benzoate (Zoetis Animal Health, Florham Park, NJ; n = 36). Body weight of cows and calves were recorded on d 0, 28, 56, and 70 (weaning). Calves in the limited creep-feeding group received a daily supplement of dry distillers’ grains (DDG) at 0.7% of BW. All groups had free access to water and a free-choice mineral supplement. Data were analyzed using R software (version 4.1; R Core Team, 2021) using a generalized linear mixed models. Fixed effects included creep feeding, implant, day, and their interactions. Pasture and animals were included as random effects, and initial BW (d 0) was included as a covariate. There was a significant creep × day interaction (P = 0.01) with calves receiving limited creep feeding supplementation averaging 17 kg heavier at weaning than non-supplemented calves. Calves that received implants also tended to be heavier at weaning. A significant creep feeding × day interaction (P = 0.01) was also observed for cow BW, as cows gained weight by weaning when their calves received supplementation. In conclusion, limited creep feeding with DDG was an effective management strategy to improve weaning weights of both calves and cows grazing bahiagrass pastures.