| The extension and application of new techniques of artificial insemination (AI) are very necessary for pig production, since they can improve the genetic potentialities in a great degree and reproductive efficiency of the excellent boars. In this study, systematical studies were performed to compare the results of various mating models, semen diluents and antibiotics added in boar semen, the times of AI per sow, the sperm concentration of diluted boar semen, as well as the application of oxytocin. The aims of this study is to make use of new techniques of AI and improve the reproduction performance of sows.1. The study on mating models. Five models of mating, thrice artificial insemination (AI+AI+AI), natural service (NS) in combination with artificial insemination (NS+AI, NS+AI+AI, NS+NS+AT) and thrice natural service (NS+NS+NS) were studied in this study. The results showed that the farrowing rate and litter size were not significantly different between the thrice NS group and the other ones. The number of piglets born alive (NBA) per litter was also not significantly different among five models. The additional 3.7 piglets per sow per year were produced by the use of AI new techniques as comparison to previous years without use of AI techniques.2. The study on oxytocin injection and thereafter insemination. In test 1, two artificial insemination models, NS+AI+AI and AI+AI+AI in combination with oxytocin injection before the first insemination, were used. The results showed that the farrowing rate and NBA per litter were not significantly different between two groups (P > 0.05) . In test 2, AI in combination with or without oxytocin injection was performed. Comparison of these two treatments showed that the farrowing rate and NBA per litter were also not significantly different between oxytocin injection before insemination and the control (P >0.05) . 3. The study on insemination times and oxytocin administration models. Experiments were performed to compare the results of twice inseminations and thrice insemination. The results indicated that the farrowing rate and NBA per litter were not significantly different between two times of AI and three times of AI (P＞0.05). In another experiment, addition of oxytocin in semen or muscular injection of sows before AI was performed. The similar results were observed between two groups of oxytocin administration. These results indicated that the mating model of twice insemination in combination with oxytocin injection is worth spreading and applying in swine production.4. The study on different antibiotics added in boar semen. Penicillin, streptomycin and expensive ceftiofur were selected to add in boar semen in the experiment. The result showed that penicillin and streptomycin effectively inhibited bacteria propagation in semen, altogether with good effects on the storage of diluted boar semen.5. The study on different diluents of boar semen. Semen from five boars was diluted by BTS of IMV, our BTS and Modena each, and packed and stored in the same conditions. Within these three controls, BTS of IMV was most helpful for semen storage since it maintained the semen activity for the longest time, and next dominant diluents was Modena. BTS diluents could be only used for short-period storage of diluted boar semen. After diluted semen by BTS and stored it under 17℃for 24 hours, no significant differences of farrowing rate and NBA per litter were observed when compared with using fresh semen (P＞0.05).6. The study on the sperm numbers of AI. The effects of semen with three different sperm concentrations, which were 5×10~7/ml, 4×10~7/ml and 3×10~7/ml respectively, were analyzed in this study. Result showed that the farrowing rate, the total number born (TNB) per litter and NBA per litter didn't differ significantly within each other. The sperm concentration of 4×10~7/ml was the best and most suitable control for practical use, as in this case the diluted boar semen could be stored for the longest period.
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