Impacto da oferta de forragem durante os terços médio e final da gestação no desempenho do par vaca/bezerro Nelore até o desmame
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2021-02-23
Autores
Souza, William Luiz de
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste experimento foi avaliar o impacto de duas ofertas de forragem no desempenho do par vaca/bezerro Nelore durante a fase gestacional e de lactação. Foram utilizadas 72 vacas Nelore gestantes de machos [peso corporal (PC) = 444 ± 42 kg e escore de condição corporal (ECC) = 3,66 ± 0,28] mantidas em pastagem de Urochloa brizantha cv. Marandu, sob duas ofertas de forragem [baixa oferta (BOF): 2,81 e alta oferta (AOF): 7,58 kg de matéria seca (MS)/kg de PC] durante os terços médio e final da gestação (d-151 até o parto; d0) e nas mesmas condições na fase de lactação (d1 ao d240). O delineamento foi em blocos casualizados (6 vacas/piquete, 6 piquetes/tratamento), contendo 6 blocos e a unidade experimental foi o piquete. O método de pastejo utilizado foi o contínuo com carga fixa e a massa de forragem foi estimada utilizando-se o método da dupla amostragem e as características qualitativas foram realizadas utilizando o pastejo simulado. Como esperado, houve diferença (P<0,01) entre as ofertas de forragem, influenciando nas características quantitativas e qualitativas do pasto (P≤0,05). No período de gestação, a massa de forragem apresentou variações de 5022 para 3478 kg MS/ha com uma redução de 31,9% para a BOF e de 5193 para 7188 kg MS/ha com um incremento de 40,7% para AOF. Houve interação entre oferta de forragem × período (P<0,01) para PC e ECC. Sendo que, vacas mantidas em AOF apresentaram maior PC (+43kg) e ECC (+0,40 pontos, P<0,01) durante a gestação. Durante a lactação, o PC foi similar para vacas mantidas em BOF e AOF (média de 422 kg), enquanto o ECC no desmame foi maior para vacas mantidas em AOF (+0,20 pontos, P<0,01). A prenhez na estação de monta (após 2 IATF) subsequente não foi afetada pela oferta de forragem durante a gestação, com média de 66% (P=0,90). As medidas de ultrassonografia de carcaça das vacas apresentaram interação oferta de forragem × período (P≤0,03) para área de olho de lombo (AOL; cm² e cm²/100 kg de PC), marmoreio e espessura de gordura subcutânea (EGS; mm e mm/100kg de PC). A AOL em vacas da BOF reduziu 12,1% na gestação e manteve-se na média de 52,2 cm² na lactação. Já vacas da AOF mantiveram-se na média de 57,4 cm² de AOL na gestação e reduziram 9,09% na lactação. A AOL/100kg de PC apresentou uma redução de 6,60 e 6,85%, respectivamente para BOF e AOF no período de gestação. Vacas da BOF mantiveram uma média de 12,1 cm²/100 kg de PC e as vacas mantidas na AOF apresentaram uma redução de 9,98% na lactação. O marmoreio reduziu 10,4% na BOF e manteve-se na média de 3,83% na AOF no período avaliado de gestação e um aumento de 21,3 e 12,6% na lactação na BOF e AOF, respectivamente. Vacas mantidas na BOF apresentaram uma redução na EGS e EGS/100kg de PC em 20,5 e 14,6%, respectivamente na gestação, e mantiveram-se as médias de 3,19 mm de EGS e 0,77 mm de EGS/100kg de PC durante a lactação. No entanto, vacas da AOF mantiveram-se com uma média de 3,91 mm de EGS e 0,86 mm de EGS/100 kg de PC na gestação, já na lactação ocorreu uma redução de 13,4% EGS e uma 7,05% na EGS/100 kg de PC. A oferta de forragem não afetou (P>0,21) a produção e composição do leite em nenhum período avaliado da lactação (30,120 e 210 dias pós-parto). Bezerros filhos de vacas mantidas na AOF apresentaram maior (P<0,01) PC ao nascimento (34,9 vs. 39,1 kg), peso ajustado aos 120 dias (123 vs. 136 kg) e peso ajustado aos 205 dias no desmame (174 vs. 188 kg) comparado a bezerros de vacas mantidas na BOF. Houve efeito de período (P<0,01) para ganho médio diário (GMD). O GMD foi maior durante o nascimento até 120 dias em comparação com 121 dias até o desmame (0,777 vs. 0,608 kg/dia). As medidas de ultrassonografia de carcaça dos bezerros não foram influenciadas (P≥0,13) pela nutrição materna, exceto uma tendência (P=0,10) para maior marmoreio (2,30 vs. 2,53%) em bezerros filhos de vacas mantidas na AOF durante gestação. Conclui-se que a alta oferta de forragem proporciona melhor condição corporal para as vacas no parto, entretanto, não afeta a reprodução, produção e composição do leite. Além disso, a alta oferta de forragem na nutrição materna promove bezerros mais pesados do nascimento até o desmame.
The objective was to evaluate the impact of two forage allowances on the Nellore cow/calf pair's performance during the pregnancy and lactation phases. Seventy-two male pregnant Nellore cows were used [body weight (BW) = 444 ± 42 kg and body condition score (BCS) = 3.66 ± 0.28] were kept on Urochloa brizantha cv. Marandu, under two forage allowances [low (LFA): 2.81 and high (HFA): 7.58 dry matter (DM)/kg BW] from the middle to third of pregnancy (d-151) until calving season (d0) and under the same conditions in the lactation phase (d1 to d240). The experimental design was in a randomized block (blocked by initial BW; 6 cows/paddock, 6 paddocks/treatment), containing 6 blocks, and the experimental unit was the animal (paddock). The grazing method used was continuous with fixed load, the forage mass was estimated using the double sampling method, and the qualitative characteristics were performed using simulated grazing. As expected, there was a difference (P<0.01) between forage allowance, influencing the quantitative and qualitative characteristics of the pasture (P≤0.05). The forage mass showed variations, in the pregnancy phase, from 5022 to 3478 kg DM/ha with a reduction of 31.9% for LFA and from 5193 to 7188 kg DM/ha with an increase of 40.7% for HFA. There was an interaction between forage allowance × period (P<0.01) for BW and BCS. Since cows kept in HFA had higher BW (+ 43kg) and BCS (+0.40 points, P<0.01) during the pregnancy phase. During lactation, the BW was the same for cows kept on LFA and HFA (on average 422 kg), while the BCS at weaning was greater for cows kept on HFA (+0.20 points, P<0.01). The pregnancy rate in the subsequent breeding season was not affected by the forage allowance during pregnancy, with an average of 66% (P=0.90). There was an interaction between forage allowance × period (P≤0.03) for the rib eye area (REA; cm² and cm²/100 kg BW), marbling, subcutaneous fat thickness (SFT; mm and mm/100kg BW). The REA in cows fed LFA decreased by 12.1% in the pregnancy phase and remained at an average of 52.2 cm² in lactation. On the other hand, cows fed HFA maintained an average of 57.4 cm² of REA during pregnancy and a reduction of 9.09% in REA during lactation. The REA in cm²/100kg of BW showed a reduction of 6.60 and 6.85%, respectively, for LFA and HFA in the pregnancy phase. Cows fed LFA maintained an average of 12.1 cm²/100 kg of BW, and the cows fed HFA showed a 9.98% reduction in lactation. Marbling decreased 10.4% in the LFA and remained at an average of 3.83% in the HFA in the pregnancy phase and increased 21.3 and 12.6% in lactation in the LFA and HFA, respectively. Cows fed LFA showed a reduction in SFT and SFT/100kg BW by 10.5 and 14.6%, respectively, during pregnancy, and the averages of 3.19 mm and0.77 mm/100 kg of BW during lactation. However, cows fed HFA maintained an average of 3.91 mm in SFT and0.86 mm in SFT/100 kg BW during pregnancy, whereas in lactation, there was a 13.4% reduction in SFT and a 7.05 % in SFT/100 kg of BW. The forage allowance did not affect (P>0.21) milk production and milk composition in any evaluated period of lactation (30,120 and 210 days postpartum). Calves born from cows fed HFA had greater BW (P<0.01) at birth (34.9 vs. 39.1 kg), adjusted BW at 120 days (123 vs. 136 kg) and adjusted BW at 205 days (weaning; 174 vs. 188 kg) compared to calves from cows fed LFA. There was a period effect (P<0.01) for average daily gain (ADG). The ADG was greater during birth to 120 days compared to 121 days until weaning (0.777 vs. 0.608 kg/day). Calf carcass ultrasound measurements were not influenced (P≥0.13) by maternal nutrition, except for a trend on marbling (P=0.10) where calves born from cows fed HFA had greater ADG compared to calves born from cows fed LFA (2.53% vs. 2.30). In conclusion, the high forage allowance provides better body condition for the cows at calving and does not affect the reproduction, production and composition of milk. Also, the high forage allowance in maternal nutrition promotes heavier calves from birth to weaning.
The objective was to evaluate the impact of two forage allowances on the Nellore cow/calf pair's performance during the pregnancy and lactation phases. Seventy-two male pregnant Nellore cows were used [body weight (BW) = 444 ± 42 kg and body condition score (BCS) = 3.66 ± 0.28] were kept on Urochloa brizantha cv. Marandu, under two forage allowances [low (LFA): 2.81 and high (HFA): 7.58 dry matter (DM)/kg BW] from the middle to third of pregnancy (d-151) until calving season (d0) and under the same conditions in the lactation phase (d1 to d240). The experimental design was in a randomized block (blocked by initial BW; 6 cows/paddock, 6 paddocks/treatment), containing 6 blocks, and the experimental unit was the animal (paddock). The grazing method used was continuous with fixed load, the forage mass was estimated using the double sampling method, and the qualitative characteristics were performed using simulated grazing. As expected, there was a difference (P<0.01) between forage allowance, influencing the quantitative and qualitative characteristics of the pasture (P≤0.05). The forage mass showed variations, in the pregnancy phase, from 5022 to 3478 kg DM/ha with a reduction of 31.9% for LFA and from 5193 to 7188 kg DM/ha with an increase of 40.7% for HFA. There was an interaction between forage allowance × period (P<0.01) for BW and BCS. Since cows kept in HFA had higher BW (+ 43kg) and BCS (+0.40 points, P<0.01) during the pregnancy phase. During lactation, the BW was the same for cows kept on LFA and HFA (on average 422 kg), while the BCS at weaning was greater for cows kept on HFA (+0.20 points, P<0.01). The pregnancy rate in the subsequent breeding season was not affected by the forage allowance during pregnancy, with an average of 66% (P=0.90). There was an interaction between forage allowance × period (P≤0.03) for the rib eye area (REA; cm² and cm²/100 kg BW), marbling, subcutaneous fat thickness (SFT; mm and mm/100kg BW). The REA in cows fed LFA decreased by 12.1% in the pregnancy phase and remained at an average of 52.2 cm² in lactation. On the other hand, cows fed HFA maintained an average of 57.4 cm² of REA during pregnancy and a reduction of 9.09% in REA during lactation. The REA in cm²/100kg of BW showed a reduction of 6.60 and 6.85%, respectively, for LFA and HFA in the pregnancy phase. Cows fed LFA maintained an average of 12.1 cm²/100 kg of BW, and the cows fed HFA showed a 9.98% reduction in lactation. Marbling decreased 10.4% in the LFA and remained at an average of 3.83% in the HFA in the pregnancy phase and increased 21.3 and 12.6% in lactation in the LFA and HFA, respectively. Cows fed LFA showed a reduction in SFT and SFT/100kg BW by 10.5 and 14.6%, respectively, during pregnancy, and the averages of 3.19 mm and0.77 mm/100 kg of BW during lactation. However, cows fed HFA maintained an average of 3.91 mm in SFT and0.86 mm in SFT/100 kg BW during pregnancy, whereas in lactation, there was a 13.4% reduction in SFT and a 7.05 % in SFT/100 kg of BW. The forage allowance did not affect (P>0.21) milk production and milk composition in any evaluated period of lactation (30,120 and 210 days postpartum). Calves born from cows fed HFA had greater BW (P<0.01) at birth (34.9 vs. 39.1 kg), adjusted BW at 120 days (123 vs. 136 kg) and adjusted BW at 205 days (weaning; 174 vs. 188 kg) compared to calves from cows fed LFA. There was a period effect (P<0.01) for average daily gain (ADG). The ADG was greater during birth to 120 days compared to 121 days until weaning (0.777 vs. 0.608 kg/day). Calf carcass ultrasound measurements were not influenced (P≥0.13) by maternal nutrition, except for a trend on marbling (P=0.10) where calves born from cows fed HFA had greater ADG compared to calves born from cows fed LFA (2.53% vs. 2.30). In conclusion, the high forage allowance provides better body condition for the cows at calving and does not affect the reproduction, production and composition of milk. Also, the high forage allowance in maternal nutrition promotes heavier calves from birth to weaning.
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Palavras-chave
Desempenho, Nelore, Oferta de forragem, Programação fetal