RESUMEN
We aimed to evaluate the effect of dietary calcium (Ca)-octanoate supplementation on concentrations of ghrelin, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and insulin in plasma and milk of beef cattle during late gestation and early postpartum. Twelve Japanese Black cattle were offered concentrate without (CON, n = 6) or with Ca-octanoate supplementation at 1.5% of dietary dry matter (OCT, n = 6). Blood samples were collected at -60, -30, and -7 d relative to the expected parturition date and daily from d 0 to 3 after parturition. Milk samples were collected daily postpartum. Compared to the CON group, concentrations of acylated ghrelin increased in plasma as parturition approached in the OCT group (P = 0.02). However, concentrations of GH, IGF-1, and insulin in plasma and milk were not affected by treatment groups throughout the study. Additionally, we showed for the first time that bovine colostrum and transition milk contain acylated ghrelin at a significantly higher concentration than plasma (P = 0.01). Interestingly, concentrations of acylated ghrelin in milk were negatively correlated with those in plasma postpartum (r = -0.50, P < 0.01). Feeding Ca-octanoate increased concentrations of total cholesterol (T-cho) in plasma and milk (P < 0.05), tended to increase those of glucose in plasma at postpartum and milk (P < 0.1). We conclude that feeding Ca-octanoate in late gestation and early postpartum may contribute to increased concentrations of glucose and T-cho in plasma and milk without affecting concentrations of ghrelin, GH, IGF-1, and insulin in plasma and milk.
RESUMEN
We aimed to determine the effects of nutritional status on concentrations of somatotropic axis hormones (growth hormone (GH) and insulin-like growth factor 1 (IGF-1)), insulin and metabolites (glucose, total protein and nonesterified fatty acids (NEFA)) in the plasma and colostrum in late antepartum cows. Eight pregnant Japanese Black cows were randomly assigned to two experimental groups (n = 4 per group). Control cows (CON) received 100% of their nutritional requirements until parturition, whereas restricted group cows (RES) received 60% of their nutritional requirements. Blood samples were taken during the antepartum period, and blood and colostrum samples were collected on days 0, 1, and 3 after calving. Compared to the CON group, the RES group had higher concentrations of GH and NEFA in plasma, but significantly lower concentrations of glucose and insulin in plasma. The concentrations of GH in plasma after calving were significantly higher, but total plasma protein was significantly lower in RES than in CON cows. Compared to the CON group, the RES group had significantly higher concentrations of GH in colostrum, but significantly lower total concentrations of protein in colostrum. Concentrations of IGF-1 were not different between the two groups. These findings suggest that maternal nutritional status during late gestation influences concentrations of GH and total protein in the blood and colostrum of Japanese Black cows.