| With the improvement of social and economic level,people have higher requirements for pork quality.At the same time,in order to increase the development and utilization of Shaziling pig germplasm resources,Xiangtan Livestock Breeding Station plans to cultivate a new breed(Xiangling Swine)with excellent meat quality and good growth performance.Xiangling Swine is bred by crossing American Berkshire pig and Shaziling pig,selecting black ideal offspring to form breeding base group,and then cross-fixed,locked breeding.It is planned to be bred through subculture of five generations,and has been cultivated to the second generation.The purpose of this study was to measure the production performance of Xiangling Swine,fit the growth curve,calculate the economic weight Value of main target traits and formulate a comprehensive selection index to guide the breeding work of Xiangling Swine.The number of alive born piglets(10.41±2.53)of Xiangling sows at or beyond second parity was higher than that of primiparous sows(9.26±1.16),and the total number born(11.37±2.53)was significantly higher than that of primiparous sows(9.85±1.26).The litter weight of alive born piglets(1.09±0.16 kg)at or beyond second parity was much larger than that of Shaziling pigs and much smaller than that of Berkshire pigs.The meat color grade score and the marble grade score of Xiangling Swine were not as good as those of Shaziling pig,the meat color grade score was slightly better than that of Berkshire pigs,and the marble grade score was slightly worse than that of Berkshire pigs.In terms of carcass traits,the slaughter rate(74.0±3.0%)and carcass lean meat rate(44.1±3.4%)of Xiangling Swine in the second generation were very close to those of the first generation,and the carcass traits were stable.Compared with Shaziling pigs,the carcass lean meat rate of Xiangling Swine was significantly improved,but there was still a large gap with Berkshire pigs.By measuring the weight and backfat thickness of Xiangling boar and sows at different ages,the growth curves of weight and age were fitted by three animal growth models,namely,Logistic model,Gompertz model and Saturation model.The R~2of the three models was above 0.99.Finally,combined with the actual situation,it was concluded that the optimal growth model of weight and age of boar was Logistic model,and the optimal growth model of sows was Gompertz model.The growth law of backfat thickness and body weight was fitted by linear model,and the results were ideal.When formulating the correction formula,combined with the actual situation,the Saturation model was used to formulate the correction formula of the day of Xiangling Swine grown to 50 kg.The correction formula of the backfat when grown to 50 kg was formulated according to the linear model fitting results.When formulating the comprehensive selection index formula,the main target traits selected were the day of Xiangling Swine grown to 50 kg,the backfat when grown to 50 kg,and the number of alive born piglets.First calculate the economic weight value of the three target traits,which are:-11.94、-27.69 and 3.20.Then,the comprehensive selection index formula was formulated according to the population average phenotypic value,heritability and the economic weight value of the target traits.The comprehensive selection index formula can be used to scientifically evaluate the breeding value of breeding pigs under the target traits,thus effectively guiding the selection of breeding pigs and accelerating the breeding process of Xiangling Swine.In summary,through the test,the production performance of Xiangling Swine II generation breeding herd has reached the expected breeding goal,and the results of this test also provide theoretical guidance for its subsequent breeding. |
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