| Etong two-end-black pig is a new pig breed through crossbreeding of Chinese local breed Tongcheng pig and Large White pig.Etong two-end-black pig is characterized by two-end black hairs,high resistance to porcine reproductive and respiratory syndrome virus,and good meat quality Furthermore,Etong two-end-black pig presents effective improvements in growth rate,lean meat percentage and body form.Concerning Etong two-end-black pig as a new pig breed,the training system of boars and semen dilution is different from other pig breeds,it is necessary to develop a method to train Etong two-end-black boar.This thesis focuses on studying the training system of Etong two-end-black boars and the semen dilution method.The training style of Etong two-end-black boars,the selection of diluters,the dilution ratio of diluters will affect the pregnancy rate of the artificially inseminated sows.These results provided basic data for artificial insemination and selective breeding of Etong two-end-black pigs.The main result is as follows:1.The establishment of training processes.Twenty Etong two-end-black boars were selected as trainees.training was conducted by adopting five training methods including manual stimulation,hormone,learning,manual back raising,and narrowing of activity space.With practical application,efforts were made to develop training processes covering five aspects: pre-training preparatory work,vigorously driving the pigs,observation,selection of training method,and tail-in work at the end of training.Boar sexual desire is divided into three types,and different training methods are selected according to different types.2.The selection of semen diluters.Four types of commercial diluters were used to dilute the semens from ten Etong two-end-black boars,average original semen activity≥0.85,the average density was 100-140 million/m L,each group of semens underwent sperm motility test once,with the 24 h test interval,each sample was tested three times.Under the condition that the ratio of semen to diluter was 1:1,the preservation effects in different preservation times after dilution were studied,and the preservation effects were evaluated through the semen motility test.On the 1st day,the motilities of semen sperm preserved by four types of diluters had no significant difference(P>0.05),both sperm motility were above 0.92.On the 2nd-5th days following semen dilution,the sperm motility following dilution by diluter A and diluter B ranged from 0.89 to 0.74,while that in the case of dilution by diluter C and diluter D ranged from 0.85 to0.55,the semen sperm motility with the addition of diluter A and diluter B was significantly higher than that in the case of groups C and D(P≤0.05).On the 5th day following semen dilution,the semen sperm motility following dilution by diluter A and diluter B was above 0.74,significantly higher than that in the case of groups C and D(P≤0.05),and the sperm motility in the case of diluter A and diluter B had no significant difference(P>0.05).The sperm motility in the case of diluter C and diluter D had a significant difference(P≤0.05).This shows that both diluter A and diluter B are suitable for preserving the semen from Etong two-end-black boars.3.The selection of the optimal dilution ratio.In this experiment,under the same environment,the semens from five Etong two-end-black boars were collected and diluted by the chosen diluter A and diluter B,average density was 100-140 million/m L,the dilution ratio of semens to diluters was 1:0.5,1:1,1:2,1:3,respectively.Semens were preserved in 17℃ incubators,each group of semens underwent sperm motility test once,with the test interval being 24 h.Each sample was tested three times for three consecutive days.with the increase of preservation time,the sperm motility based on different dilution ratios in the case of diluter A and diluter B gradually decreased.on the 1st,2nd,and 3rd days,the sperm motility in the case of dilution ratio 1:1 was 0.98,0.86 and 0.83,all of which were higher than the post-dilution sperm motility 1:0.5,1:2,1:3.On the 1st,2nd and 3rd days,the semen sperm motility based on dilution ratio 1:3 was relatively low,namely,0.93,0.76 and 0.73,which decreased by about 10% compared with that in the case of 1:1.According to the analysis incorporating the two-factor method based on different diluters and different dilution ratios,the semen motility in the case of preservation by diluters based on different dilution ratios had significant difference(P≤0.05),while the semen sperm motility with preservation by diluter A and diluter B had no significant difference(P>0.05).Therefore,when the semens collected from Etong two-end-black boars were diluted and preserved by diluter A and diluter B,the optimal semen dilution ratio was 1:1.4.Artificial insemination test.The semen was diluted with diluent A and B respectively,the ratio of semen to diluent was 1:1,artificial insemination was performed,and the method of deep insemination was used,and pregnancy test was performed 25 days after artificial insemination.The results showed that the conception rate was 93.02%with diluent A and 91.18% with diluent B.There was no significant difference in conception rate between the two diluents,therefore,diluent a or diluent B should be used in sperm dilution and artificial insemination in 1:1 ratio during the breeding of Etong two-end-black pig.As indicated by the study,the method most suitable for training Etong two-end-black boars is learning,the optimal diluter for normal temperature dilution and preservation of boar semen is diluter A,and the optimal ratio of semen to diluter is 1:1,this has laid a foundation for continuous selective breeding and artificial insemination of Etong two-end-black boars. |
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