ASSOCIATION BETWEEN THE LACTOGENIC HORMONES AND MILK COMPONENTS IN MITHUN (Bos frontalis)

To find out the association between major plasma lactogenic hormones and milk constituents in mithun, milk samples were collected from 11 mithun cows of 2-6 parity from the day of calving till dry off. Various milk constituents were estimated as per standard method. Serum growth hormone (GH), prolactin, cortisol and thyroid hormones (triiodothyronine, T3 and thyroxine, T4) were estimated by commercially available ELISA kits. A significant positive correlation (P<0.01) was found between total milk yield and lactogenic hormones except for T4, which was negatively (P<0.01) correlated with milk yield. Milk protein content was found to be negatively correlated with cortisol (P<0.01), prolactin (P<0.05) and T4 (P<0.05). Milk fat content was negatively (P<0.01) correlated with lactogenic hormones except T4. Milk solid not fat (SNF) was positively correlated with lactogenic hormones where as milk total solids were negatively (P<0.01) correlated with the lactogenic hormones. In conclusions, this study confirmed the positive effect of lactogenic hormones (GH, prolactin, cortisol) on milk yield and negative effect on milk fat and protein content in mithun.