ABSTRACT
This study was carried out on ten Egyptian female multi parous buffaloes suffering from prolonged postpartum period with no estrous signs and low serum progesterone level. Animals were randomly divided into two groups. Females in both groups were injected subcutaneously with 500 mg recombinant bovine somatotropin "rbST",one group received a single intramuscular dose of PMSG [2000 i.u.] 7 days later. Blood samples were collected one week before treatment and for four consecutive weeks after treatment. The levels of progesterone, insulin-like growth factor- 1[IGF-1] and total cholesterol were analysed. Injection of rbST with or without PMSG elevated serum level of IGF-1 for the first two weeks post-injection then declined during the 3rd and 4th weeks compared to pretreatment levels. Both serum progesterone and total cholesterol levels increased throughout the 4 weeks post-injection as compared with their corresponding control values before treatments. In addition, rbST increased milk yield significantly as well as motivated the females to resume cyclic activity of the ovaries [4 / 5 in animals treated with rbST plus PMSG and 3/5 in those treated with rbST alone]. The conception percent improved