The Relation of Certain Semen-quality Tests to Breeding Efficiency and Characteristics of Semen from Low-fertility Bulls Before and After Hormone Injection

Summary Laboratory tests for semen quality including concentration, motility, fructolysis index, percentage dead sperm, and percentage abnormal sperm were investigated for their relationship to breeding efficiency. The two latter tests were most closely correlated to fertility, as measured by 30-60 day non-returns. A deficiency of follicle-stimulating hormone appears as one of the factors involved in the production of low-quality semen by certain related bulls. The luteinizing hormone and testosterone appeared to be secreted in normal amounts in these bulls. Factors other than the above are indicated to have been involved in poor-quality semen production by three inbred Holstein bulls.