Two different hormones were administered on the fifth day after the first insemination to evaluate their influence on serum progesterone concentrations and on reproductive efficiency, in multiparous sows between the third and the sixth parturition. The reproductive performance was evaluated in 103 sows distributed into three groups: 1-Control (n=35); 2-GnRH, 50m g of GnRH-analogue, administered IM on the fifth day after the first insemination (n=34); and 3-hCG, 500 IU of hCG administered IM in the fifth day after the first insemination (n=34). No effect (P>0.05) of hormone treatments on farrowing rate, litter size, live born and litter weight was observed. Five sows of each group were blood sampled on days 3, 5, 8, 12, 21, 28, after the first insemination, to evaluate serum progesterone concentrations (ng/ml). Serum progesterone concentrations were not affected (P>0.05) by hormone treatments.
sow; GnRH; hCG; progesterone; pregnancy
