Fixed-time artificial insemination in beef cattle.
BACKGROUND
The study was designed to test the effect of fixed-time artificial insemination (fixed-AI) after the slightly modified Ovsynch protocol on the pregnancy rate in beef cattle in Finnish field conditions. The modification was aimed to optimize the number of offsprings per AI dose.


METHODS
Ninety Charolais cows and heifers were entered into the program an average of 1.8 times. Thus, 164 animal cases were included. Animals were administered 10-12 microg of buserelin. Seven days later animals without a corpus luteum (CL) were rejected (20.7%) while the remaining 130 cases with a CL were administered prostaglandin F2alpha, followed 48 h later with a second injection of buserelin (8-10 microg). Fixed-AI was performed 16-20 hours after the last injection.


RESULTS
The pregnancy rate was 51.5% (67/130). The pregnancy rate after a short interval (50-70 d) from calving to entering the program was significantly higher than that after a long interval (>70 d).


CONCLUSIONS
This protocol seems to give acceptable pregnancy results in beef herds and its effect on saving labour is notable.
Taponen
Juhani
J
Department of Clinical Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, Paroninkuja 20, 04920 Saarentaus, Finland. juhani.taponen@helsinki.fi
D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D005387:Finland; D007315:Insemination, Artificial / Q000662:veterinary*; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D012621:Seasons