Of the 19th pre-pubescent gilts, 14 (73.68%) manifested estrus and in anestrus gilts, from 17 animals, 13 (76.47%) manifested estrus after P.G. 600 treatment. The result presented in table 1 shows that PG 600 can be used in treatment anestrous gilts since the majority of the treated animals (76.47%) manifested heats after administration. The differences between estrus manifestations in pre-pubescent gilts and anestrous gilts are not significant, showing the P.G. 600 is efficient in both, from a total of 36 gilts treated 27 manifested estrus (75.00%). In table 2, we presented the estrus manifestation day of the treated animals, during the 8-day observation period, following the P.G. 600