ABSTRACT
INTRODUCTION Fully fertile bulls are critical in herd fertility management, especially where farmers are trying to achieve high pregnancy rates in restricted breeding periods. A sensible working definition of a fully fertile bull is a bull that can achieve a 90% pregnancy rate in a group of 50 normal cyclic females in a nine-week mating period. Various surveys worldwide have shown that 20-30% of bulls are found to be subfertile or infertile in routine breeding soundness examinations. Although subfertile bulls will achieve pregnancies, they contribute to fertility
inefficiency in herds and thus should be identified and replaced or treated. Bull breeding soundness examinations carried out prior to breeding will help identify most subfertile and infertile bulls and should be a routine part of herd management.
