Effects of two beta-adrenergic agonists on adipose tissue, plasma hormones and metabolites of Moghani ewes

The effects of different levels of dietary terbutaline (T) and metaproterenol (MP) on adipocyte size, plasma hormones and metabolites in Moghani ewes (a native fat-tailed breed) were examined. MP and T were administered at 0, 5 (low dose), 10 (middle dose) and 20 (high dose) mg/kgDM in a concentrate diet. Plasma concentrations of insulin, T4, triglyceride, cholesterol, high and low density of lipoprotein (HDL and LDL) were measured on days 60 and 90 of fattening period. Adipose tissue samples of fat-tail were taken after slaughtering the animals. Both beta agonists decreased the diameter of fat-tail adipocyte (P < 0.01). Plasma concentration of insulin was decreased in ewes receiving low dose of MP on days 60 and 90, likewise middle dose of T, low and high doses of MP on day 90 decreased plasma insulin (P < 0.05). T4 plasma concentration was increased on day 60 by middle dose of both beta agonists (P < 0.05), but this effect was not observed on day 90. Treatment of ewes with low and high doses of T and high dose of MP decreased the plasma concentration of triglycerides on day 90 (P < 0.05). Three levels of MP decreased cholesterol plasma concentration on day 60 (P < 0.05). This effect was not statistically different on day 90. Low dose of MP decreased plasma HDL on days 60 and 90, likewise middle dose of T and middle and high doses of MP decreased plasma HDL on day 90 (P < 0.05). Three levels of T and MP on day 60, and low dose of MP on day 90 decreased plasma LDL (P < 0.05). It is concluded that the measured repartitioning effects of T and MP were within the range of effects observed for thin-tailed sheep and other animals, but their effects on size of fat-tail adipocyte are particularly seen in Moghani ewes.