The study reported in this Research Communication was carried out to examine how parity and milking time affected donkey milk yield under a typical Chinese production system. Eighteen Jiangyue breed donkeys with good health condition, aged between 6 and 9 years, and with parities 3 and 4, were selected. Milk production was measured commencing from the fourth week post-foaling, with a total data collection of 170 d in milk (lactation length). Mean milk yield of the donkeys used in this study was 3·0 kg/donkey/d. Results showed milk yield decreased with days in milk from 3·3 kg/donkey/d at the start of the study, to 2·2 kg/donkey/d by the end of the 170 d. Parity 3 donkeys produced 22% more milk than parity 4 donkeys (3·3 kg/donkey/d vs 2·7 kg/donkey/d). The information provided by this study should aid producers in estimating the expected milk yields from individual donkey, and better predict milk yield over the course of a production cycle.

Objective: The present study evaluated the preservation of ram semen at 0°C using soybean lecithin with a Tris-fructose extender.Methods: Semen was collected by artificial vagina ejaculation from six rams with proven fertility. High quality ejaculates were diluted by soybean lecithin (0.25%, 0.5%, 0.75%, 1.0%, 1.25%) using Tris-fructose extender and control (Tris-fructose egg yolk extender), respectively. The ejaculates were diluted to a concentration of 5×10⁸ sperm/mL, followed by cooling to 0°C in 90 min and maintaining the temperature for 12 days. The diluted semen samples were examined and recorded for sperm progressive motility, acrosome integrity at 0, 24, 72, 144, 216, 288 h, respectively. Two hundred and twenty-three ewes were inseminated for 216 h with optimal soybean lecithin concentrated semen or control via trans-cervical insemination.Results: The results showed that there were no differences in sperm progressive motility at 0, 24, 72, and 144 h (p>0.05). After 216 h, the sperm progressive motility in the control group and 0.5% concentration groups was significantly higher when compared to 0.25% concentration (p<0.05). The 0.5% concentration group demonstrated the highest survival rate and had no difference with the control group (p>0.05). At 216 h, the sperm progressive motility of all groups was still above 50%. The acrosome integrity of all groups was decreased with prolongation of storage time, but there was no difference at each time point (p>0.05). There was no significant difference in the lambing rate and pregnancy rate between the 0.5% concentration group and the control group (p>0.05).Conclusion: These results suggest that ram sperm is capable of fertilization after preservation at 0°C with 0.5% of soybean lecithin in Tris-based extender substituted for egg yolk and produce normal offspring after insemination.

No abstract

The present study investigated the effects of various concentrations of trehalose in Tris-fructose egg yolk diluent on ram semen preservation at 0 ℃. Semen was collected by artificial vagina ejaculation from six rams of proven fertility. Highquality ejaculates were diluted with 0 (control), 5, 10, 15, and 20 mM trehalose of Tris-fructose egg yolk extender and control (tris-fructose egg yolk extender without trehalose), respectively. Then, the ejaculates were diluted to a concentration of 5×10 8 sperm/mL, cooled to 0 ℃ for 90 min, and maintained at that temperature for twelve days. The diluted semen samples were examined, and their sperm progressive motility, membrane functionality, and acrosome integrity recorded at 0, 24, 72, 144, 216, and 288 h. Two hundred ninety-six ewes were transcervically inseminated with the 216-h control (without trehalose) or the optimal trehalose concentration group semen, and the pregnancy and lambing rates were measured. No significant differences were established in the sperm progressive motility and membrane functionality among the control and 5, 10, 15, and 20 mM groups. The sperm samples of trehalose addition groups had no significant difference in the acrosome integrity of sperm, but they were, nonetheless, significantly higher than those in the control. No significant difference was detected in the lambing and pregnancy rates between the 5 mM and control groups. These results suggest that ram sperm is capable of fertilization after cooling and preservation at 0 ℃ by the use of 5 mM trehalose for Tris-fructose egg yolk diluent. Under these conditions, ram sperm can be more effectively preserved than under other four concentrations of diluents.