Fertility of Bull Semen Frozen with β-Amylase, β-Glucuronidase, and Catalase

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Abstract
Capacitase, a product combining .beta.-amylase and .beta.-glucuronidase, was compatible with survival of bull spermatozoa frozen in whole milk-glycerol extender at final concentrations per ml of 0, 5, 10 and 20 .mu.g of .beta.-amylase combined with 0, 75, 150 and 300 units of .beta.-glucuronidase, respectively. Bull semen was frozen in whole milk-glycerol extender containing the 3 lower concentrations of enzymes tested in the previous trial and used to inseminate 9057 first-service cows within 4 mo. of freezing. The 60- to 90-day percent nonreturns were 74.6, 75.6 and 75.0. The same treatments plus a 4th one containing 10 .mu.g of catalase per ml were fertility tested in another trial. Insemination of 16,842 cows resulted in 75.6, 74.1, 74.6 and 74.2% non-returns. In this trial semen was held immersed in liquid N and distributed for immediate use each month for 6 mo. There was no change in fertility during 6 mo. of continuous storage at -196.degree. C. Under the conditions tested neither catalase nor .beta.-amylase with .beta.-glucuronidase enhanced fertility of frozen bull semen.