| Semen preservation technology is very important for boar artificial insemination, while the quality of boar semen diluents determines the effect of preservation. Boar semen is easily contaminated by microorganisms during the process of collecting and diluting. The microorgansisms could use the nutrients in the boar semen for maintaining its growth and reproduction and eventually decrease the sperm molity. Therefore, adding antibiotics into the boar semen was the conventional method to inhibit the growth of microorganisms. However,because of lacking the scientific program of adding antibiotics in the production practice, led to the problem of bacteria resistance become increasingly prominent. To solve the current problem, this study was first to investigate the effect of methionine iodine solution through the test of in vitro bactericidal on the semen preservation. Then identify the bacterial species in the fresh boar semen. Next explore the effects of methionine iodine on bacteria composition and the quality of porcine sperm preservation at room temperature. Finally,methionine iodine and conventional antibiotics were separately added to the diluent to compare their effects on the semen preservation. This study was to find the antibiotics replace for the semen diluent and provide a theoretical support for Chinese self-developed sperm diluent. The following are the main results in this study:1. The results showed that 1:5000 dilution of methionine iodine solution for E.coli sterilization rate could reach 100% in 1 min; 1:10000 dilution of methionine iodine solution for E.coli sterilization rate could reach 100% in 10 min; 1:20000 dilution of methionine iodine solution for E.coli sterilization rate could just reach 81.71% in 10 min. 1:5000 dilution of methionine iodine solution for Salmonella sterilization rate could reach 100% in 1 min;1:10000 dilution of methionine iodine solution for Salmonella sterilization rate could reach100% in 5 min; 1:20000 dilution of methionine iodine solution for Salmonella sterilization rate could just reach 89.32% in 10 min. 1:5000 dilution of methionine iodine solution for staphylococcus aureus sterilization rate can reach 100% in 5 min; 1:10000 dilution of methionine iodine solution for staphylococcus aureus sterilization rate could reach 100% in10 min; 1:20000 dilution of methionine iodine solution for staphylococcus aureus sterilization rate could just reach 78.39% in 10 min. Therefore, 1:5000 and 1:10000 dilution of methionineiodine solution could inhibit the growth of bacteria, while 1:20000 dilution of methionine iodine solution had no effect on the inhibition of bacteria growth.2. There were seven predominant genera in the fresh boar semen. Halomonas were the most predominant genus and were accounted for 62.21%. Acinetobacter were the next genus and were accounted for 11.71%. The genera Campylobacter, Prevotella, Streptococcus,Bacteroides and Staphylococcus were accounted for 8.64%, 8.55%, 4.45%, 2.38% and 1.83%,respectively.3. With the increasing concentrations of methionine iodine solution added into the semen dilution, the bacteria in the boar semen was inhibited by the methionine iodine solution.However, the effect of semen preservation, the sperm motility, membrane integrity, acrosome integrity in the methionine iodine solution at concentration of 200 and 400 ? L/L were significantly lower than the control group(P < 0.05). However, the effect of preservation was constntly increasing at 25, 50, 100 ?L/L, and reached the top at 100 ?L/L. The sperm motility,membrane integrity and acrosome integrity were significantly better than the control group(P< 0.05). Therefore, 100 ?L/L of methionine iodine effectively inhibited the growth of bacteria in the semen, and significantly improved the normal temperature preservation effect of semen.4. From 1 to 6 days, the sperm motility in the methionine iodine group were higher than the sulfanilamide group, and there were significant differences between 5 d and 6 d(P < 0.05).From 1 to 6 days, the sperm motility in the sulfanilamide group were higher than the penicillin group, and there were significant differences between 3 d and 6 d(P < 0.05). On 1d and 2 d, the membrane integrity in methionine iodine group were lower than the sulfanilamide group, while the differences were not significant(P > 0.05). From 3 to 6 days,the membrane integrity in the methionine iodine group were better than the sulfanilamide group, and there were significant differences between 5 d and 6 d(P < 0.05). From 1 to 6days, the membrane integrity in the sulfanilamide group were better than the penicillin group,and there were significant differences between 4 d, 5 d and 6 d(P < 0.05). On 2 d and 3 d, the acrosome integrity in the methionine iodine group were lower than sulfanilamide group, and there weren’t significant differences in the two groups(P > 0.05). On 1 d, 4 d, 5 d and 6 d, the acrosome integrity in the methionine iodine group were better than the sulfanilamide group,and there were significant differences between 5 d and 6 d(P < 0.05). From 2 to 6 days, the acrosome integrity in the sulfanilamide group were better than the penicillin group, and there were significantly differences between 3 d, 5 d and 6 d(P < 0.05). Therefore, the effect of methionine iodine on semen preservation was the best, sulfanilamide was secondary,penicillin was poor. |
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