Somatotropina bovina: efeitos no metabolismo hepático de neonatos e desempenho produtivo e reprodutivo de vacas leiteiras

Abstract

The supplementation of cows with bovine somatotropin during the peripartum period has been associated with possible positive effects on physiological adaptations and hepatic function. The objective of this study was to investigate the effect of different d oses of rbST in the prepartum period in dairy cows on productive and reproductive efficiency at subsequent lactation, as well as its effect on the hepatic metabolism of progeny at birth through the expression of genes related to GH IGF I axis,gluconeogenes is, insulin signaling, glucose uptake and oxidative stress. For this study, 152 Holstein cows were used and divided in three groups: animals that received 2 doses of rbST ( rbST2 ) (n = 60), at days 28 and 14 related to calving, animals that received 3 do se s of rbST (rbST3 ) (n = 46), at days 42, 28 and 14 related to calving, and control gr oup, with no rbST application (GC ) (n = 46). Treated groups received 500 mg of rbST (Lactotropin ® Elanco Saúde Animal , São Paulo, São Paulo) in each injection. Data of body condition score data (BCS), interval between calving to conception (ICC), milk production in days 14, 21, 28, 35, 42, 56, 70, and 84 of lactation and total milk production (TMP) were evaluated. A subset of twenty calves were evaluated, identified acc or ding to their dams: newborns rbST2 (NrbST2) (n = 9), newborns rbST3 (NrbST3) (n = 7) and newborns rbST (NGC ) (n = 4). Calves were submitted to liver biopsy at birth, to evaluate the expression pattern of genes related to GH IGF I axis,gluconeogenesis, in sulin signaling, glucose uptake and oxidative stress . Cows from rbST2 had greate r milk production than CG and rbST3 at 35 th day of lactation. No difference was found in the total milk yield, ICC and BCS between groups. Among the markers on neonatal hepatic metabolism, the expression of IGF I, SLC2A2 and CAT were higherin N rbST I I and N rbST3 compared to NCG. The expression of GHR1A tended to be higher in NrbST3 compared to NCG. The expression of PC was higher in NrbST2 compared to NCG. The pre partum rbST treatment induced an increase in milk production in some moments during lactation. There was no interaction between rbST and dairy cows reproductive efficiency. In addition, maternal treatment with rbST affected the ne onatal hepatic metabolism, and these changes can positively impact the newborn metabolism.