Pregnancy and Bovine Somatotropin in Nonlactating Dairy Cows: I. Ovarian, Conceptus, and Insulin-Like Growth Factor System Responses

Abstract

Nonlactating dairy cows were used to examine effects of bovine somatotropin (bST) on components of the insulin-like growth factor (IGF) system. Estrus was synchronized in cows with a Presynch + Ovsynch protocol and timed AI (TAI; n = 55) or not TAI (cycling, C; n = 23) on d 0 (time of synchronized ovulation). On d 0 and 11, cows received bST (500 mg) or no bST, and were sacrificed on d 17. Pregnancy rates were less in bST cows (27.2%, 9 of 33) than in controls (63.6%; 14 of 22). In contrast, conceptuses were larger in bST-treated cows (39.2 +/- 4.8 cm) than in controls (20 +/- 4.3 cm). Total interferon-tau in uterine luminal flushings (ULF) was greater in bST-treated cows (7.15 > 2.36 microg). Number of class 2 follicles (6 to 9 mm) was less in bST-C cows on d 7 and 16. On d 17, corpus luteum (CL) weight tended to be greater in bST-treated cows. Concentrations of progesterone were greater after d 10 in C than in pregnant (P) cows. In the ULF, IGF-binding protein-3 was greater in bST-P cows than in pregnant cows. A tendency for an increase in IGF-I hormone concentrations in the ULF was detected on d 17 in bST-treated and cyclic cows. Endometrial mRNA for IGF-I, IGF-II, IGFBP-2, and IGFBP-3 increased in bST-C, but not in bST-P cows. Treatment with bST increased plasma concentrations of insulin, IGF-I, and growth hormone (GH). In conclusion, bST may have hyperstimulated plasma IGF-I and insulin to cause asynchrony between conceptus and uterus that was detrimental to pregnancy.

Superovulatory response and embryo quality of Holstein heifers treated with one or two injections of somatotropin

“…Administration of rbST in cattle has shown to increase serum concentrations of IGF-I and insulin (Bilby et al, 2004;Rivera et al, 2010). Hence, the administration of a higher dose of rbST led us to suggest that higher serum concentration of IGF-I and insulin may have occurred, but a final conclusion from our study cannot be drawn because analyses of these metabolites were not performed.…”

Maternal embryokines that regulate development of the bovine preimplantation embryo

“…Endometrial expression of IGF1 was not regulated by somatotropin in 2 experiments (59,60). In a third study, expression of IGF1 as well as IGFBP2 and IGFBP3 was increased in endometrium of cyclic but not pregnant animals at day 17 after estrus (55).…”

“…The extent to which changes in circulating concentrations of IGF1 modify local amounts in oviductal or uterine fluids is not well established. There were nonsignificant increases in amounts of IGF1 in uterine lumen of cows in response to administration of bovine somatotropin (54,55).…”

“…Expression peaks around estrus and declines thereafter (56,57). IGF1 is also expressed in the uterine endometrium (55,59,60). There is little variation in expression between days 5 and 16 after estrus in cyclic or pregnant cows (61).…”

Somatotropina: Aspectos Relacionados à Sua Aplicação em Vacas Leiteiras

“…Esse consumo aumentado apresenta-se de seis a oito semanas após a administração do medicamento e varia dependendo da resposta da produção de leite, do método de administração e da densidade de energia na dieta, daí a necessidade de se maximizar o consumo de ração durante o tratamento com BSTr (Costa, 2008). O uso de BSTr pode causar efeitos sobre a reprodução das vacas leiteiras com redução significativa nas taxas de gestação nas vacas leiteiras (Bilby et al, 2004). No entanto, há relatos de que o uso de BSTr aos 150 dias de lactação não influencia no intervalo partoconcepção, no número de serviços por concepção e na taxa de gestação (Rennó et al, 2006).…”