PSII-9 Drylot weaned calves at dry-to-rainy transition and rainy season and their effects on the growing phase

Abstract

Abstract The objective of this study was to determine the best nutritional strategy for weaned calves at dry-to-rainy transition and rainy season and their effects on the growing phase. One hundred sixteen Nellore weaned males (initial BW of 173±23 kg; 10 months) were used in a randomized complete block design (blocked by BW) in a 2×2 factorial arrangement of treatments (divided in 12 lots with 9 or 10 animals/lot). Factor 1 was the strategy in the dry-to-rainy season transition (period I; pasture vs. drylot) and factor 2 was the strategy for the rainy season [period II; mineral salt ad libitum (MS) vs. supplement 3 g/kg BW]; consisting of four treatments: pasture in period I and MS in period II; pasture in period I and protein-energy supplement in period II (PEII); drylot in period I and mineral salt in period II; drylot in period I and PEII. At period I, all animals received a protein-energy supplementation (5 g/kg BW). The experiment lasted 244 days. Data were analyzed using the PROC MIXED of SAS. In period I, animals from drylot had highest final BW and ADG (P < 0.01; Table 1). There was no interaction among factors (P ≥ 0.772) in period II. In period II, ADG and carcass gain were highest from pasture animals (P < 0.01). Final BW and HCW were similar (P >0.788) at the end of period II, showing that animals recovery BW. Among strategies at rainy season, animals fed PEII had greater final BW and ADG (P < 0.01). Overall growing phase, HCW and carcass gain were greater for animals fed PEII (P < 0.01). Regardless of the strategy used in the dry-to-rainy season transition, animals were able to equalize final BW at the end of growing phase. In addition, protein-energy supplement at rainy season improves animal performance at the end of growing phase.