Reproductive Performance of Gyr Cows: The Effect of Weaning Age of Calves and Postpartum Energy Intake

Abstract

Two nutritional levels following parturition and five weaning ages for the calf were evaluated to study their effect of reproduction in Gyr cows in the savannas of West Central Brazil (Campos Cerrados). Early weaning of calves reduced postpartum weight losses and shortened the postpartum interval to conception. Energy level did not affect cow weight at weaning or conception, the number of days from parturition to first estrus or the number of matings/conception; however, the postpartum period to conception was reduced (116 vs 160 d; P less than .05) for cows on the higher energy diet. Weaning age significantly affected postpartum weight loss in cows. Six months after calving, cows that nursed calves for 1 mo were 89 kg heavier than those that nursed calves for 6 mo (384 vs 295 kg; P less than .05). Cows that were nursed for 1 mo returned to estrus at an average of 40 d postpartum, which was 23 d earlier (P less than .05) than the average of the other groups nursed for longer periods of time. There was no significant difference in the postpartum period to conception among cows that had their calves weaned at 1 mo, 3 mo and cows which were nursed twice daily beginning 30 d after parturition (57, 94 and 97 d, respectively), but was less (P less than .05) for cows nursed for 5 or 6 mo (212 and 231 d, respectively). The results show that Gyr cattle are genetically capable of responding reproductively to improve nutrition and reduced lactation stress achieved through early weaning or controlled nursing.

Desempenho produtivo de vacas de quatro grupos genéticos submetidas a diferentes manejos alimentares desmamadas aos 42 ou 63 dias pós-parto

“…O desmame aos 90 dias ou menos de idade tem resultado no aumento da taxa de reprodução, conforme constatado por vários autores (Moore & Rocha, 1983;Lobato & Barcellos, 1992;Moojen et al, 1994;Moletta & Perotto, 1997;Restle et al, 2001).…”

Complementary use of neotropical savanna and grass-legume pastures for early weaning and effects on growth and metabolic status of weaners and inter-calving intervals of dams

“…Early weaning is known to enhance reproductive performance of underfed beef cows (Moore and da Rocha 1983;Holroyd et al 1990;Schlink et al 1994;Coppo et al 2002;Arthington et al 2004), an effect shown also in Table 6 that demonstrates the trade-offs between weaning age and LWs of calves, LWs of their dams and intercalving intervals. Moore and da Rocha (1983) investigated the effects of 2 levels of nutrition and 5 weaning ages in Zebu Gyr breed cows fed hay of B. decumbens in the Brazilian Cerrados and found that, irrespective of the cows' nutritional level, early weaning of calves improved cow weights at different stages throughout the reproductive cycle and subsequent reproductive performance.…”

“…Weights of cows at weaning were 313 kg and 325 kg on low and high supplementary energy treatments, respectively, and the authors suggested that Zebu cows rarely conceive if suckling cows weigh less than 300 kg. Weights of cows at weaning decreased linearly from 352 kg, when calves were weaned at 1 month of age, to 294 kg if calves were weaned at 6 months of age, with LW losses during lactation increasing from 21 to 102 kg for the respective weaning ages (Moore and da Rocha 1983). Mukasa-Mugerwa (1989) reviewed the literature regarding reproduction of Zebu cattle in the tropics, and noted that tropical cattle dependent on natural pastures most often calve in alternate years, but animals with access to good quality sown pastures have improved reproductive performance.…”

“…Moore and da Rocha (1983) investigated the effects of 2 levels of nutrition and 5 weaning ages in Zebu Gyr breed cows fed hay of B. decumbens in the Brazilian Cerrados and found that, irrespective of the cows' nutritional level, early weaning of calves improved cow weights at different stages throughout the reproductive cycle and subsequent reproductive performance. Weights of cows at weaning were 313 kg and 325 kg on low and high supplementary energy treatments, respectively, and the authors suggested that Zebu cows rarely conceive if suckling cows weigh less than 300 kg.…”

“…Early weaning has rarely been investigated in the neotropics (Moore and da Rocha 1983;Betancourt-López et al 2012) and, as elsewhere, the practice has generally been coupled with regular supplementation of cows and calves with different combinations of concentrates and/or other feedstuffs in different settings. However, to the authors' knowledge, raising early weaned beef calves exclusively on sown pastures in the neotropics has not been investigated.…”