SEMEN COLLECTION, SEMEN PRODUCTION AND FERTILITY RATES IN POLLED VS HORNED BULLS IN NORWAY

A comparison of polled and horned bulls with respect to semen collecti on, semen production and fertility rates was performed. Data on 548 No rwegian Cattle bulls were analysed, including a total of 21 500 semen collections. The causes of slaughter were summarized and compared for polled and horned individuals, totalling 520 bulls. Finally the non-re turn rates for polled and horned bulls were compared, including 130 82 0 first inseminations. The polled bulls had significantly shorter prot rusion (p < 0.001) and weaker thrust (p < 0.001) than horned ones. The re was also a significant difference in post-thaw motility, the polled bulls having 0.49% higher motility than horned ones (p < 0.01). There was, on the other hand, no significant difference in libido, semen vo lume, sperm concentration, prefreeze velocity and motility, post-thaw velocity and number of discarded ejaculates. More polled bulls were sl aughtered because of problems with the semen collection than was the c ase for horned ones. There was no significant difference in non-return rates for polled and horned bulls.