Performance, metabolic and hormonal responses on the peripartum of grazing beef cows supplemented during the pre-partum

Abstract

Background: Strategies for feeding supplements during the pre-partum are usually adopted because nutritional status upon calving is the main factor to affect reproductive performance. Metabolic parameters that relate nutritional status to physiological processes can be used to better understand the effects of supplementation. This study evaluated the effects of 60-day pre-partum energy-protein supplementation on performance, metabolic and hormonal responses during the peripartum of grazing beef cows. Thirty-eight pregnant multiparous Nellore cows were assigned to a completely randomized design with two treatments: control with no supplement and supplementation on the last 60 gestation days (1.5 kg/d). Results: The supplemented cows had higher ADG during the pre-partum (P<0.10), but ADG did not differ between treatments during the postpartum. Nonsupplemented cows’ ADG did not change during these periods (P>0.10). Supplementation did not affect (P>0.10) BCS and calves’ BW upon calving on days 45 and 90, milk yield and composition (P>0.10). No differences (P>0.10) were found for forage intake and neutral detergent fiber digestibility. The intake and digestibility of CP and OM increased (P<0.10) with supplementation. An interaction occurred (P>0.10) between supplementation and peripartum days for BUN, βHB, T3 and T4. Concentration of others blood parameters significantly changed (P<0.10) along peripartum days. There was no difference in pregnancy rates and days from calving to conception among treatments (P>0.10). Conclusions: Providing energy-protein supplement for grazing Nellore cows on the last 60 d of gestation improve energy balance during pre-partum, however, no carryover effects are seen for pre-partum supplementation on post-partum physiological responses. Keywords: nutrition, metabolism, parturition, Zebu