Effect of pre- and post-weaning supplementation on performance, nutritional, and metabolic characteristics in Nellore heifers under grazing

Abstract

Context Supplementation during the pre- and post-weaning periods is essential to improve the development of beef heifers in tropical pastures. Especially during the dry period, performance of heifers is limited due to low forage yield and poor nutritional value. Aim Evaluate the effect of supplementation during pre- and post-weaning periods on performance, nutritional, and metabolic characteristics in Nellore heifers under grazing. Methods Fifty-four Nellore heifers were randomly divided between the following four supplementation plans, with two replicates: NN, not supplemented in the pre- and post-weaning dry period; NS, not supplemented in the pre-weaning period and supplemented in the post-weaning dry period; SN, supplemented in the pre-weaning period and not supplemented in the post-weaning dry period; and SS, supplemented in the pre- and post-weaning dry periods; with 14, 13, 13 and 14 calves in each treatment respectively. In the post-weaning dry-to-rainy transition period, all heifers were supplemented. Key results Supplementation increased (P < 0.05) the intake of dry matter and crude protein on Day 56 (pre-weaning phase) and Day 168 (post-weaning dry period). Heifers supplemented during the pre-weaning phase had a higher final body weight (fBW) and average daily gain (ADG) on Day 112 (P < 0.05). Heifers NS and SS had higher fBW and ADG on Day 224 (P < 0.05). On Day 280, fBW were higher (P < 0.05) for heifers NS and SS. Insulin-like growth factor 1 was higher for heifers supplemented in the pre-weaning period on Day 112, and higher for NS and SS heifers on Day 224 (P < 0.05). Albumin concentrations were higher (P < 0.05) for heifers NS and SS on Day 280. Supplementation had no effect on either corpus luteum presence or concentration of progesterone (P > 0.05). Conclusions Supplementation during either pre- or post-weaning phases improved multiple performance, nutritional, and metabolic characteristics. The results due to supplementation post-weaning were independent of supplementation pre-weaning. However, supplementation did not result in an improved response to the puberty induction protocol used in this experiment. Implications For replacement heifers, it is important to maintain high weight gains at all stages of growth.