PSXIII-21 Animal performance and reproductive development in heifers fed with r-zeta® in high-concentrate diets.

Abstract Nutritional management in replacements heifer is important to optimize the profitability of livestock farms. Food resources with high conversion rates offered in self-feeders achieve efficiency with easy management. It´s possible that the use of high-concentrate diets with the inclusion of additive to regulate intake contributes to increase animal performance and reproductive development in heifers. The aim of this work was to evaluate different rearing diet strategies with r-zeta® additive on replacements heifer performance and reproductive. One hundred twenty Hereford heifers (9,1± 1,7 month and 192,6 ± 19,0 kg body weight -BW-) were assigned to different treatments according to different diets to evaluate r-zeta® additive that regulate intake and modulate the ruminal microbiota. The defined treatments were HR+CS (hay roll and daily control supplementation at 1% BW); HR+Sr-zeta® (hay roll and daily balanced pellet r-zeta® supplementation at 1% BW); HR+SFr-zeta® (hay roll and self-feeding balanced pellet r-zeta®) and SFr-zeta® (self-feeding balanced pellet r-zeta®). In treatments with supplementation, ration was offered in linear feed bunks (daily supply) and in treatments with self-feeders was offered weekly. Triticale hay rolls were offered ad libitum. The control supplement and the balanced pellet were formulated with 36% PC/kg DM and 2.4 Mcal ME/kg DM. And the hay roll had 7.9% PC/kg DM and 1.3 Mcal ME/kg DM. The BW were used to adjust the supplement supply in the treatments HR+CS and HR+Sr-zeta®. Average daily gain (ADG), dry matter intake (DMI) and conversion (C) were estimated. Reproductive tract scoring (RTS) was measured at the final of the experience (day 83) and each heifer was scored from 1 (prepubertal) to 5 (cyclic). Data were performed using Infostat. The continuous variables studied were analyzed by ANOVA and RTS was compared by using a chi-square analysis. Significant differences were considered at p≤ 0.05. Heifers fed with r-zeta® in treatments with balanced pellet offered in self-feeders had higher ADG regarding those supplemented (1.2 vs. 0,7 kg/d). Total DMI (% LW) was lower in SFr-zeta® regardless to other treatments (2.4 vs. 2.6 to 2.8 % LW). In this sense, best conversion was in treatments with self-feeding balanced pellet with r-zeta® regardless of hay roll inclusion (Table 1). Finally, treatments with inclusion of the multifactorial additive had a higher proportion of heifers with good reproductive development (RTS 4 and 5). In the HR+CS, only 13% of the animals had this condition while in the HR+Sr-zeta®, HR+SFr-zeta® and SFr-zeta®, the 30, 39 and 37% were into RTS 4 and 5. In conclusion, r-zeta® additive in high-concentrate diets could be a strategy to use in raising heifers to improve their growth and reproductive development.