Effects of recombinant ovine placental lactogen and recombinant ovine growth hormone on growth of lambs and milk production of ewes

The somatogenic and galactopoietic effects of recombinant ovine placental l actogen (oPL) were compared with the effects of recombinant ovine growth ho rmone (oGH) in post-weaned growing lambs and in lactating ewes. In two expe riments that each lasted 35 days, 7-month-old lambs were given daily subcut aneous injections (0.1 mg/kg live weight) of oPL or oGH, and their daily gr owth rates were compared with those of non-treated control lambs. Ovine CH and oPL had similar profound (P < 0.01) growth-stimulating effects, enhanci ng lamb growth by 10 to 25%, In two other experiments. lactating ewes were injected with oGH or oPL (0.1 mg/kg live weight/day) for 14 days in mid-lac tation. Treatment with oGH increased (P < 0.001) daily milk production by u p to 55% over control ewes. Ovine pi, increased (P < 0.01) milk production by up to 25%. In all experiments, treatment of lambs or lactating ewes with oGH, but not with oPL increased (P < 0.05) serum insulin-like growth facto r-I concentrations. It is concluded that oPL and oGH have similar somatogen ic effects in lambs. Both hormones exhibited galactopoietic effects, but oG H was considerably more potent than oPL. (C) 2001 Elsevier Science B.V. All rights reserved.