Effect of growth hormone on milk yield and reproductive performance of subfertile Holstein cows during extended lactations

Abstract

The objective of this study was to determine the effects of the administration of recombinant bovine somatotropin (rbST) throughout lactation to high-yielding subfertile (conception > 270 days postpartum) Holstein cows undergoing extended lactations (≥480 d) on milk production and reproductive performance. The study used two large adjacent commercial herds with similar management in a hot area of northern Mexico (25° N). Cows in one herd (n=2341) received a 500-mg dose of rbST every 14 d until dried off, starting 60 days postpartum. The other herd served as control (n=984). Across parity, rbST-treated cows produced 20% greater milk yield than control cows in 305-d lactations. Across parities, milk yield from 305 d postpartum to the end of lactation was 2734 kg higher in rbST-treated cows than control cows. Across parities rbST-treated cows produced 4777 more kg of milk during the entire lactation (mean 605 d) than the control group (mean 572 d). Conception rates (CR) at first service were only 3.2% and 5.9% (p<0.05) for control and rbST-treated cows, respectively. Overall CR was 43.5% and 61.6% (p<0.05) for control and treated cows, respectively. Control cows required 2.4 more (p<0.01) services per conception than rbST-treated cows. It was concluded that in this hot environment, the use of rbST suits dairy producers because it substantially improves both milk yield and reproductive performance in subfertile high-yielding Holstein cows. By markedly increasing lactation length and lactation persistency farm efficiency is greatly improved due to extended herd life.

Effect of two formulations of recombinant bovine somatotropin on milk production and body condition of cattle under intensive management in Peru

“…In this sense, the growth stage of primiparous cows would reduce the increases in milk production induced by rbST. In primiparous and multiparous cows, no significant differences were found between evaluated rbST, which is similar to that indicated by Posada et al ( 2008 ), Barrios ( 2015 ), and Flores et al ( 2019 ). On the other hand, Almeida and Viechnieski ( 2011 ) reported significant differences between rbST, where cows injected with VEL-rbST produced 1.6 kg/day more milk than those treated with ZSO-rbST, while De Morais et al ( 2017 ) reported differences between ZSO-rbST and VEL-rbST, being higher for primiparous (+ 2 kg/day) and multiparous cows (+ 1.3 kg/day) treated with ZSO-rbST.…”

Effect of reproductive indices and bovine somatotropin on milk yield in Holstein cows experiencing climatic sub-fertility

“…These results demonstrated a clear evidence that the administration of rbST aiming to enhance milk synthesis (Bauman, 1999) and persistence of lactation (Bauman, 1992), also benefited the reproduction performance of sub-fertile cows with extended lactations. These results reaffirmed the marked improvement in reproductive performance with extended lactations and the use of rbST throughout lactation (Flores et al, 2019). Also, these results are in line with other reports where rbST has had a positive impact on fertility of Holstein cows (Santos…”

Milk Production and Reproductive Performance of Retained and Culled Cows in a Large Holstein Herd in Egypt

“…Kalantari and Cabrera (2015) proposed that the relationship between infertility level and farm economics may not be linear and many aspects are included when estimating the losses. Moreover, the increase in NSPC and DO which result in longer calving intervals may lead to prolonged lactations as it is a herd management approach followed in the intensive dairy system in hot regions (Flores et al, 2019). The reason is that the hot climate adversely affects the conception rate and more services are needed for conception (Mellado et al, 2016).…”