Influence of prepartum body condition score change on reproduction in multiparous beef cows calving in moderate body condition.

Abstract

Multiparous, spring-calving beef cows (n = 250) were used to determine whether large changes in body energy reserves during mid- to late gestation influenced subsequent reproductive performance of cows calving in moderate body condition. In three states, cows were blocked by BW and body condition score (BCS; 1 = emaciated to 9 = obese) then allotted to receive either a high or low plane of nutrition from late summer to early winter over a 3-yr period. This generated an array of BCS by the beginning of the last trimester of pregnancy when cows were grouped by BCS as follows: Group 1, BCS < or = 4; Group 2, BCS of 5 or 6; and Group 3, BCS > or = 7. Each group was managed so that individual cows would calve with a BCS of 5 to 6. At the time of group assignment, mean BW and BCS differed (P < .01) among groups and were 480 kg and 3.6, 541 kg and 5.5, and 594 kg and 7.1 for Groups 1 to 3, respectively. Within 28 d before calving, BW and BCS were similar (P > .20) among groups averaging 555 kg and 5.1. Prepartum BCS changes averaged 1.4, -.4, and -2.0 units for Groups 1 to 3, respectively (P < .01). Cows were managed as a single group after calving in each state. Location effect was significant for the prepartum and postpartum BW and BCS changes but not for postpartum reproductive performance. Significant location x BCS group interactions were found for the 90-d prepartum BW, BCS at calving, and prepartum changes in BW, but were caused by differences in magnitude among locations. The percentage of cows with luteal activity at the start of a subsequent breeding season was not affected (P > .20) by either location or BCS group, and averaged 66%. Mean pregnancy rates at 20, 40, and 60 d of a subsequent breeding season were 55, 76, and 89% for Group 1; 51, 67, and 82% for Group 2; and 64, 79, and 89% for Group 3 (P > .30). Mean days to conception were 89, 87, and 85 for Groups 1 to 3, respectively (P = .70). Neither calf birth weight (x = 38.6 kg) nor adjusted 205-d weight (x = 223.6 kg) were affected by prepartum BW and BCS changes. We conclude that reproductive performance of cows calving in moderate body condition is not influenced by large changes in body energy reserves during the last trimester of pregnancy.

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

“…Vieira et al (2006) determined in primiparous Nelore cows, an average body weight of 436.0 kg at a date close to calving, during four years of observations. Morrison et al (1999), in a study with multiparous cows presenting moderate body condition score (3-3.5), observed that moderate loss of body reserves in the final third of gestation did not influence subsequent reproductive performance, if forage availability was not limiting to consumption post-calving. In the present experiment, cows grazing on natural pastures pre-calving lost an average of 0.31 points of body condition score until calving.…”

A Perspective on the Impact of Reproductive Technologies on Food Production in Africa

“…The maintenance of body energy reserves is considered to be the basis of any reproductive management strategy (Houghton et al 1990;Morrison et al 1999;Flores et al 2008). It is well known that the Gonadotropin releasing hormone (GnRH) pulse generator system and subsequent secretion of GnRH from the hypothalamus are inhibited by under nutrition.…”

Desempenho reprodutivo pós-parto de vacas de corte submetidas a indução/sincronização de cio

“…A diferença de peso entre os dois grupos de vacas (Tabela 2) reduziu do acasalamento até o desmame, comprovando que as vacas em anestro profundo apresentaram ganho compensatório nesse período, promovendo equilíbrio no desempenho reprodutivo de ambos os grupos (Morrison et al,1999;Jaume & Moraes, 2002;Pimentel et al, 2005). Vacas em anestro superficial demonstraram tendência a desempenho reprodutivo melhor (Tabela 3), evidenciando que este grupo de vacas parece responder com maior eficiência ao protocolo de indução/sincronização de cio.…”

“…Os resultados obtidos confirmam que a produção de leite não influencia a condição reprodutiva nem a fertilidade pós-parto de vacas de corte com condição corporal moderada conforme observado por Pimentel et al (2005) e Brauner et al (2006. O equilíbrio entre as vacas de nível superior e inferior de produção de leite está relacionada ao fato de essas vacas apresentarem condição corporal moderada durante todo o período pós-parto, uma vez que a condição corporal é um fator marcante em relação ao desempenho produtivo e reprodutivo pós-parto em vacas (Spitzer et al, 1995;Morrison et al, 1999;Wettemann et al, 2003;Hess et al, 2005). A taxa de gestação não ocasionou diferença (P>0,05) nas variáveis de produção estudadas (Tabela 2).…”