| Small Meishan Pig is an excellent provincial pig strain which has the high litter、good meat quality、strong adaptability、good combining ability in China.It shows very obvious heterosis.The meat quality is also very good in its hybrid.In this study,Xiao Meishan pig was bred in Xiao Meishan national conservation farm of Jiangsu agricultural and forestry Polytechnic College,and the basic group was established.The new lean meat line of Xiao Meishan pig was bred by the method of group successive generation breeding.The breeding results of Xiao Meishan pig were evaluated from the aspects of growth performance,reproduction performance and slaughter performance.The main results were as follows:1、The results of breeding showed that there was no significant difference in body weight and length between generations(P>0.05),but the body size index of Xiao Meishan pig was also slightly increased,regardless of the general trend of body weight and back fat thickness.The feed conversion ratio decreased from 3.96:1 in the first generation to 3.76:1 in the fourth generation.2、There was no significant difference in body weight,back fat thickness and body size between different generations of Xiao Meishan pig(P>0.05).In general,with the increase of generations,all indexes were increased except back fat thickness(back fat thickness was the opposite,and gradually decreased with the increase of generations).The reproductive performance of Xiao Meishan pig did not fluctuate much,and there was no significant difference(P>0.05)between the total number of litter,the number of live litter and the litter weight of each generation,which slightly improved.The breeding of Xiao Meishan pig kept the high reproductive characteristics well.The slaughter rate,carcass lean rate,fat thickness and eye muscle area of four generations of finishing pigs were 69.17±0.30,48.09±0.32,3.27 ±0.03,27.51 ± 0.30,respectively,significantly higher than those of the first and second generations(P<0.05).3、The results showed that IGF2 RN and OB genes had significant effect on reducing backfat thickness and increasing eye muscle area(P<0.05).The fixed effects of BLUP predicted target traits W180 and BF180 were 9.13631 and 0.12336,respectively,which were higher than those of sows(0.45991 and 0.03638).Therefore,increasing the selection intensity of boars can improve the genetic progress.4、The fitting results of Gompertz model for the growth curve of each generation of pigs show that the fitting degree R2 is above 0.99,which shows that the Gompertz model is accurate and reliable for fitting the weight growth process of Xiao Meishan pigs.5、The fitting results of multiple regression equations of body weight at 120 days and 180 days showed that y=7.359+0.571fwl20-0.435xw120 was the best regression equation for predicting body weight at 120 days according to abdominal circumference and chest circumference,while y=85.438+0.843tc180+4.372gw180-2.203xw180 was the best regression equation for predicting body weight at 180 days through body length,tube circumference and chest circumference.The optimal regression equation for predicting lean meat ratio of fattening pigs was y=34.585+0.7981ion-2.568bf. |
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