Final answer:
It would take approximately 64 days from the observation of lameness in a bull to find abnormal sperm in the ejaculate due to the spermatogenesis cycle, plus additional time for sperm to mature in the epididymis.
Step-by-step explanation:
If lameness is observed in a bull, it would take approximately 64 days from the injury or onset of lameness to observe abnormal sperm in the ejaculate. This is due to the spermatogenesis cycle, which takes about 64 days to produce mature sperm. Given this cycle, if an issue occurs such as an injury or other health problem, the effects on sperm would not be immediate but will manifest approximately two months later. It is also important to consider the time it takes for sperm to mature in the epididymis, which is on average 12 days. Given these time frames, a problem with lameness and sperm quality will exhibit a delay from the time of the initial issue to the presence of abnormal sperm.