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The objective of this study was to evaluate the impact of three nutritional strategies and their interactions on age at puberty in Nellore heifers. The treatments were arranged in factorial design (2×2×2), including three periods of supplementation: Period I – Pre-partum dam supplementation with protein (n=122; 0.5 kg soybean meal/cow, daily) during the last trimester of gestation or no supplementation (n=115); Period II – Creep-feeding (n=120; 22% CP and 72% TDN) to heifer calves for 95 d before weaning or no creep-feeding (n=117); and Period III – Post-weaning feedlot from 7 to 11 month of age (n=117; 17% CP and 58% TDN) or no feedlot (n=120; only pasture). There was no interaction among periods of supplementation. At weaning, pre-partum dam supplementation ( P =0.91) and creep-feeding ( P =0.89) did not affect BW of heifer calves. At the end of the post-weaning feedlot (Period III) BW was greater ( P P =0.88) or creep-feeding ( P =0.57). However, the post-weaning feedlot treatment anticipated ( P =0.06) the age at puberty. At 18 month of age, the percentage of pubertal heifers was increased by post-weaning feedlot (31.7 vs. 13.3%; P

The aim of this study was to evaluate luteolysis using three doses of PGF2α on Day 5 or Day 7 of the estrous cycle in nonlactating Nellore (Bos indicus) cows. Cows (n = 323) were assigned within date of estrus (Day 0 of estrous cycle) to receive 12.5, 25.0, or 50.0 mg of PGF2α on either Day 5 or Day 7 of the estrous cycle in a 3 × 2 factorial arrangement. Blood samples for progesterone (P4) concentrations were collected at 0, 24, 48, and 72 hours after PGF2α to assess luteolysis (L). Luteolysis was defined on the basis of P4 concentrations at 72 hours using either less than 0.5 ng/mL (L0.5) or less than 1.0 ng/mL (L1.0) as the cut off. Luteolysis was considered "partial" when P4 concentration declined within 24 hours after PGF2α but failed to decline further or, in some cases, increased. Incidence of luteolysis was less (P