[Results of impregnating cows and heifers on consolidated farms and the methods for synchronizing their estrus]. / Prouchvane na rezultatite po zaplozhdane na kravite i iunitsite v uedrenite fermi i metodi za sinkhronizirane na estrusa im.

Studied were the conception rate, milk productivity, calving period, and age at first conception with 3265 cows of 12 herds and 3 breed groups--Bulgarian Red Cattle (BRC), Holstein-Friesian Cattle (HFC), and HFC X BRC. The effect was followed up of the enzyme preparations Cytochrome 'C' and Beta-glucuronidase on the conception rate of cows. Tested was the action of prostaglandin F2 alpha and its analogues Equimate, Luteolysine, and Panazelen on the synchronization of the estrus and the conception. It was found that there was a considerable delay in the calving of the heifers (29 months). The calving period of the cows was prolonged and ranged in days from 369.17 +/- 3.17 up to 381.26 +/- 8.61 for BRC, 378.09 +/- 3.56 to 393.21 +/- 14.85--for HFC, and 339.75 +/- 6.56 to 390.42 +/- 3.51--for HFC X BRC. The use of Beta-glucuronidase and Cytochrome 'C' in the artificial insemination of the cows with deep-frozen semen raised the conception rate at first insemination by about 8-10 per cent.