Pre- and post-calving forage systems and reproductive performance of primiparous cows

Abstract

-During pre and post calving periods, it was evaluated the influence of the following forage systems on reproductive performance of primiparous cows: natural pasture during pre and post-calving periods; natural pastures during pre-calving period and improved pastures during post-calving period; improved pastures during pre-calving and natural pasture during post-calving; improved pasture during pre-and post-calving periods. The lowest body weights and body condition scores were observed on cows kept on natural pastures pre-calving (384.3 kg and 3.31; 391.4 kg and 3.60), followed by those on improved pastures during pre-calving and on natural pasture during post-calving period (424.4 kg and 3.60), finally, cows on improved pasture during pre-and post-calving period (421.2 kg and 3.59). Cows on improved pastures pre and post-calving showed higher body weight and body condition score in the beginning of the breeding season (442.1 kg and 3.76), higher pregnancy rate (82.3%) and they conceived earlier. Natural system during pre-calving and improved on post-calving and that with improved pasture in pre-calving and natural in post-calving did not differ on weight at the beginning of breeding season (417.2 and 409.8 kg) and on pregnancy rate (65.8 and 62.8%), respectively. However, cows on natural pasture in pre-calving and on improved pasture in post-calving conceived earlier. Cows on natural pastures showed lower weight in the beginning of breeding season (391.2 kg), the lowest pregnancy rate (52.7%), and they conceived later. Cows maintained on improved pastures pre-and post-calving improved weight and body condition score at calving and beginning of the breeding season making high reproductive performance possible.Key Words: body condition, Brangus, improved pastures, natural pastures, pregnancy rate, weights Sistemas forrageiros pré e pós-parto e desempenho reprodutivo de vacas primíparasRESUMO -Durante os períodos pré e pós-parto, foi avaliada a influência de sistemas forrageiros no desempenho reprodutivo de vacas primíparas: pastagem natural nos períodos pré e pós-parto; pastagem natural no pré-parto e pastagem melhorada no pós-parto; pastagem melhorada no pré-parto e pastagem natural no pós-parto; pastagem melhorada nos períodos pré e pós-parto. Os menores pesos e condições corporais foram observados nas vacas mantidas em pastagem natural no pré-parto, (384,3 kg e 3,31; 391,4 kg e 3,60), seguidas daquelas em pastagem melhorada no pré-parto e natural no pós-parto (424,4 kg e 3,60); e, por ultimo, das vacas em pastagem melhorada no pré e pós-parto (421,2 kg e 3,59). As vacas em pastagem melhorada no pré e pós-parto tiveram maior peso e condição corporal ao início do acasalamento (442,1 kg e 3,76), maior taxa de prenhez (82,3%) e emprenharam mais cedo. Os sistemas com pastagem natural no pré-parto e melhorada no pós-parto e aquele com pastagem melhorada no pré-parto e natural no pós-parto não diferiram quanto a peso ao início do acasalamento (417,2 e 409,8 kg) e taxa de prenhez (65,8 e 62,8%), respectivame...

Energy-protein supplementation before and after parturition of Nellore primiparous cows in the Brazilian tropical savannah

“…Providing the protein-energy supplementation during the pre and postpartum period produces interesting results, which lead to the reduction of the calving interval in up to 27 days. Similar result in a study evaluating the use of improved versus natural pastures was reported (Lobato et al, 2010). By providing better pre and postpartum nutritional level, PREPOST allowed to reach a calving interval shorter than those considered the ideal calving interval (365 days) to obtain one calf/cow/year.…”

Natural and improved pastures on growth and reproductive performance of Hereford heifers

“…However, if this continues throughout the years, heifer frame and weight may increase due to selection of larger animals, which may result in late sexual maturity and higher maintenance requirements of the breeding herd caused by the larger mature size (Jenkins & Willians, 1994;Cundiff et al, 1998), affecting fist-calf cow reproduction, as observed by Olson (1994) and recently by Lobato et al (2010) and Tanure et al (2011). Although all heifers were born in the same season of 90 days in 2006, weight groups may have been confused with age in days, as the precise date of birth of the heifers was no available.…”

Precocidade De Parto Na Estação De Parição Sobre a Eficiência Produtiva De Vacas Primíparas Aos 24 Meses De Idade

“…Porém, de nada vale esta prenhez precoce das novilhas se as mesmas não repetirem cria, sendo perdida toda a alimentação diferenciada para acelerar o processo de puberdade e acasalamento (27) , bem como sendo descartados por infertilidade animais geneticamente superiores em rebanhos que trabalham com melhoramento genético (29) . Isso é determinado, provavelmente, pelo maior tempo de recuperação das vacas, com maiores pesos, condições corporais e, consequentemente, melhor resposta reprodutiva (9) .…”

“…A prenhez de primíparas pode ser melhorada, através da utilização de pastagens cultivadas de ciclo hibernal no pós-parto (9) , ajuste de carga animal (7) , utilização de desmame precoce (8) , utilização de suplementação estratégica no pré e pós-parto (6) . Além destes fatos, melhores escores de condição corporal e a idade são fatores a influenciar a prenhez de primíparas (10) .…”