Energy-protein supplementation before and after parturition of Nellore primiparous cows in the Brazilian tropical savannah

Reproduction is associated to the profitability of beef herds, which affects level productivity and influenced by nutritional level. The objective this study was evaluate effect protein energy supplementation, before after parturition, on reproductive variables Nellore primiparous cows extensively raised in Brazilian tropical savannah. Eighty pregnant heifers with parturition estimated for a 45 d period during dry season were randomly divided into four treatments: Control, received mineral salt urea mixture pre postpartum; PRE, protein-energy from 210th gestational day until parturition; POS, 90 afterwards; PREPOS, protein/energy 90th parturition. Number days complete uterine involution (UI) 37.0 (Control); 31.3 (PRE); 33.1 (POST) 25.3 (PREPOST) differences (P<0.05). Calving Interval (CI) 370.4 (Control), 369.5 365.9 343.7 days, Pregnancy rate (PR) 64.7%; 76.5%; 65.0%; 55.0%, respectively, CONTROL without difference (p>0.05). In conclusion, energy-protein supplementation extensive systems under conditions, reduces calving interval.