Background: Supplementation programs for prepartum beef cows are usually adopted because the nutritional status of the cows upon calving is a main factor impacting reproductive performance of the next production cycle. This study evaluated the effects of 60-d pre-partum energy-protein supplementation on performance, metabolic and hormonal responses during the peripartum phase of grazing beef cows. Thirty-eight pregnant multiparous Nellore cows were assigned to a completely randomized design with two treatments: control (no supplement) and supplementation (1.5 kg of energy-protein per d with 30% crude protein, dry matter basis). Results: The supplemented cows had higher ADG pre-partum (P < 0.10), but postpartum ADG did not differ between treatments. Supplementation did not affect BCS and calf BW upon calving, on days 45 and 90, milk yield and composition (P > 0.10). No differences were found for forage intake and neutral detergent fiber digestibility (P > 0.10). The intake and digestibility of CP and OM increased in response to supplementation (P < 0.10). An interaction occurred between supplementation and peripartum days for BUN, βHB, T3 and T4, which had higher concentrations for supplemented cows at pre-partum period (P < 0.10). Concentration of others blood parameters significantly changed along peripartum days (P < 0.10). There was no difference in pregnancy rates and days from calving to conception between treatments (P > 0.10). Conclusions: Providing an energy and protein supplement to grazing Nellore cows over the last 60 d of gestation improved their pre-partum energy balance. However, no post-partum carryover effects were detected.

Background: Supplementation programs for prepartum beef cows are usually adopted because the nutritional status of the cows upon calving is a main factor impacting reproductive performance of the next production cycle. This study evaluated the effects of 60-d pre-partum energy-protein supplementation on performance, metabolic and hormonal responses during the peripartum phase of grazing beef cows. Thirty-eight pregnant multiparous Nellore cows were assigned to a completely randomized design with two treatments: control (no supplement) and supplementation (1.5 kg of energy-protein per d with 30% crude protein, dry matter basis) Results: The supplemented cows had higher ADG pre-partum (P<0.10), but postpartum ADG did not differ between treatments. Supplementation did not affect BCS and calf BW upon calving, on days 45 and 90, milk yield and composition (P>0.10). No differences were found for forage intake and neutral detergent fiber digestibility (P>0.10). The intake and digestibility of CP and OM increased in response to supplementation (P<0.10). An interaction occurred between supplementation and peripartum days for BUN, βHB, T3 and T4, which had higher concentrations for supplemented cows at pre-partum period (P<0.10). Concentration of others blood parameters significantly changed along peripartum days (P<0.10). There was no difference in pregnancy rates and days from calving to conception between treatments (P>0.10). Conclusions: Providing an energy and protein supplement to grazing Nellore cows over the last 60 d of gestation improved their pre-partum energy balance. However, no post-partum carryover effects were detected. Keywords: nutrition, metabolism, parturition, Zebu

No abstract

Background: Supplementation programs for prepartum beef cows are usually adopted because the nutritional status of the cows upon calving is a main factor impacting reproductive performance of the next production cycle. 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-d pre-partum energy-protein supplementation on performance, metabolic and hormonal responses during the peripartum phase of grazing beef cows. Thirty-eight pregnant multiparous Nellore cows were assigned to a completely randomized design with two treatments: control (no supplement) and supplementation (1.5 kg of energy-protein per d) during the last 60 d of gestation. Results: The supplemented cows had higher ADG pre-partum (P<0.10), but postpartum ADG did not differ between treatments. Nonsupplemented cows’ ADG did not change during these periods (P>0.10). Supplementation did not affect BCS and calf BW upon calving on days 45 and 90, milk yield and composition (P>0.10). No differences were found for forage intake and neutral detergent fiber digestibility (P>0.10). The intake and digestibility of CP and OM increased with supplementation (P<0.10). 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 an energy and protein supplement to grazing Nellore cows over the last 60 d of gestation improved their pre-partum energy balance. However, no post-partum carryover effects were detected. Keywords: nutrition, metabolism, parturition, Zebu

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