Performance of heifers supplemented with different levels of corn on pasture / Desempenho de novilhas em pastoreio suplementadas com diferentes níveis de milho

RESUMO

In southern Brazil, production systems are typically extensive and rely on grazing that often results in limited forage quantity and quality, decreasing efficiency and compromising reproductive tract development. The aim of this study was to evaluate the productive performance and reproductive tract development of heifers supplemented with different levels of corn on pasture. The following supplemental treatments were evaluated T0 [40 g trace-mineralized salt per heifer per day (80 g phosphorus/kg product)]; T1 [0.5% of body weight (BW) cracked corn + 40 g trace-mineralized salt per heifer per day]; T2 [1% of BW cracked corn + 40 g trace-mineralized salt per heifer per day], and T3 [1.5% of BW cracked corn + 40 g trace-mineralized salt per heifer per day]. Thirty-nine phenotypically homogeneous Brangus heifers (average BW = 184±17 kg, average age = 269±27 days) raised on winter pasture (Lolium multiflorum Lam.) were randomized to 13 paddocks (one hectare each), with three heifers/paddock, to evaluate the effect of feeding different energy levels. Body condition score, average daily gain, frame score, dry matter availability, reproductive tract score, and stocking density were evaluated. The body condition score, average daily gain, reproductive tract score and stocking density increased (P<0.05) with increasing level of corn supplementation. Daily supplementation levels lower than 1.0% on Lolium multiflorum Lam. pasture can compromise the target breeding weight at 13 months of age. Therefore, daily supplementation at 1.0% of BW after weaning is a strategy to improve the economic and biological efficiency of livestock production systems, allowing to increase stocking density and to anticipate the age of heifers at first breeding...