195 Sperm motion characteristics of ram semen liquid-stored in a milk egg yolk extender at four temperatures

Abstract

Abstract Varying temperatures have been used for liquid storage of ram semen and that of other species. This study evaluated motility characteristics of ram semen stored at 5, 10, 15, and 20°C for up to 96 h. Two ejaculates were collected and pooled from each of 6 rams using an artificial vagina and evaluated for motility and concentration. Samples were extended in ultra-high temperature pasteurized skim milk and egg yolk (10% v/v) containing penicillin and streptomycin, diluted to 250 million sperm/mL, and packaged in 0.5 mL straws. Semen was held at 32°C during processing, and straws placed in 500 mL jars for storage at 5°C (refrigerator), 10 and 15°C (refrigerated water bath) and 20°C (air conditioned room temperature). Cooling rates were 0.04, 0.25, 0.44, and 0.02 °C/min, and final temperatures reached after 672, 83, 36, and 567 min in the four storage environments, respectively, with cooling rates faster in a liquid than air environment. Straws from individual rams were removed at 6, 24, 48, 72 and 96 h of storage and analyzed with a computer-assisted sperm analyzer after warming to 36°C. Data were analyzed for the effect of storage time, temperature, and their interaction on sperm motion characteristics. Sperm motion characteristics were not affected over time during storage at 5 and 10°C. At 15°C motility parameters decreased in a curvilinear (P < 0.05) relationship with time (progressive motility: 52.6 to 29.7%; rapid motility: 36.5 to 16.5%), and at 20°C in linear (P < 0.001) relationship (progressive motility: 51.9 to 13.1%; rapid motility: 36.1 to 6.3%). Circular motility decreased (P < 0.05) with increasing temperatures after 72 and 96 h of storage, while local motility was not affected by storage temperature and time. Results suggest storage at 10°C may be a viable alternative to storage at 5°C as retention of motility was similar.