Effect of treatment with Prolan or with a GnRH superactive analog on the sexual function of sows after weaning

On a large, closed pig farm using artificial insemination (AI), 29 sows were treated with Prolan S-öl injection (Bayer, FRG) and 31 sows with a GnRH superactive analog (Ovurelin, D-Phe6-GnRH-EA, Reanal, Hungary) 48 h after weaning. The effect of treatment on the sows' sexual function was monitored by serum progesterone radioimmunoassay (RIA). The conception rate in the control group (36 sows) was 69.4%. In the groups treated with Prolan and Ovurelin it was 79.3 and 71%, respectively. The use of Prolan S-öl injection markedly reduced the number of acyclic sows and of those having an irregular oestrous cycle. Treatment with the GnRH analog inhibited the manifestation of weaning-induced heat; subsequently, however, it induced a regular cycle in 30 out of the 31 sows treated.