Efecto del nivel de voluminoso en la recría a corral sobre el desempeño animal invierno-primavera

Abstract The current study evaluated the effect of feedlot feeding calves and the level of roughage (RL) in the diet on average daily gain (ADG) and feed efficiency (FE) during the winter-spring period (190 days). Thirty-two Hereford heifers, blocked by weight (149 ± 13 kg), were randomly assigned to one of four winter treatments (110 d): oat grazing a rate of 5 kg of dry matter (DM) per 100 kg live weight (LW) and three total mixed rations fed ad libitum in the feedlot, differing in RL (Setaria italica, hay): 0 %, 35 % and 70 % DM. During spring (80 d), all treatments grazed a mixed grass and legume pasture (6 kg DM/100 kg LW), in weekly plots, independent by repetition (n = 2 plots/treatment). The experiment was analyzed as a randomized block design, using orthogonal contrasts to compare the effect of the feeding system, feedlot (SAC) vs grazing (SAP), and the effect of RL (0 RL, 35 RL and 70 RL) in the diets. A lower ADG was achieved in SAC treatments during the 14 days post-feedlot period, independently of the RL of the diet (P > 0,05). However, during the whole winterspring period, animals from SAC showed greater ADG (0,64 vs. 0,43 kg/day, P 0,05). Sin embargo, en la totalidad del período invierno-primavera, los animales provenientes de SAC, respecto a SAP, presentaron mejores GMD (0,64 vs. 0,43 kg/día, P < 0,001) y EC (8,74 vs. 11,27, P = 0,0013), siendo el tratamiento 0NV el de mayor peso final (282 kg/cab, P < 0,01). La recría invernal de terneros en confinamiento permite alcanzar mayores pesos a fin de primavera y una mejor eficiencia de conversión global. Palabras clave: confinamiento, crecimiento, eficiencia de conversión, ganado vacuno, período de transición. Resumo Foi avaliado o efeito da alimentação de bezerros confinados e do nível de volumoso (NV) da dieta sobre o ganho de peso diário (GMD) e a eficiência de conversão alimentar (EC) durante o período inverno-primavera (190 dias). Trinta e dois bezer