A Field Study To Compare Post-Thaw Sperm Progressive Motility And Pregnancy Rate Using Brahman Bull Semen Frozen In Milk Based Extender Containing Egg Yolk Or Soybean Lipids Extract

Abstract

The objective of this study was to compare post-thaw sperm progressive motility and pregnancy rate using Brahman bull semen frozen in milk based extender containing egg yolk or soybean lipids extract. Three semen ejaculates from two Brahman bulls were divided into three aliquots for dilution with one of three milk-based semen extenders: complete egg yolk (CE), processed egg yolk (PE) or soybean extract (SE) before freezing. Mean post-thaw progressive motility was not different between soybean extract and processed egg yolk treatments, except for two time points (0.5 and 1 h) when soybean extract was superior to processed egg yolk (P <0.01). Post-thaw progressive motility was consistently lower in frozen semen in complete egg yolk during the 2.5-h incubation period compared to processed egg yolk and soybean extract (P<0.05). Pregnancy rate was not significantly different among extenders, with values of 35.7, 40.1 and 40.6 % for complete egg yolk, processed egg yolk and soybean extract, respectively. In conclusion, the use of semen extenders containing processed egg yolk or soybean extract resulted in higher post-thaw sperm progressive motility than complete egg yolk based extender. Pregnancy rates using Brahman bull frozen semen containing complete egg yolk, processed egg yolk or soybean extract, did not differ. Procedures to obtain the processed egg yolk seem to diminish the detrimental compounds of egg yolk. The use of soybean extract represents a promising alternative for milk-based bull semen extender and provides additional benefits reducing the potential risk for microbial contamination.