Chilled Storage of Ram Semen Improves with the Addition of Egg Yolk and Glycerol to Milk-Based Extenders

and uncapacitated spermatozoa (US) (·10 6 spermatozoa ⁄ AI dose) were used to assess the semen quality at 0, 12, 24, 48 and 72 h of preservation. UHT-based extenders yielded better (p < 0.05) SM and MI than INRA-96 � -based extenders (59.7% vs 57.9%; 60.2% vs 55.8%, respectively) but similar numbers of US (64.2% vs 62.3 · 10 6 sperm ⁄ AI dose, respectively) along the preservation time. Egg yolk–glycerol or just egg yolk as additives improved (p < 0.05) the results compared with the base extenders without additives or just with glycerol. The sperm parameters assessed decline slowly from 0 to 48 h, with a sharp decline (p < 0.05) at 72 h of preservation. In conclusion, UHT and INRA-96 � were similar as base extenders, and the addition of 5% egg yolk plus 2% glycerol or just 5% egg yolk improved the quality of ram semen preserved at 5� C, at least for 48 h. The combination of egg yolk–glycerol might provide extra protection in case of fluctuation of temperatures below 5� C, commonly seen under field conditions.