| In this study,according to the test record of reproductive and growth performance from2014 to 2018 of a national core breeding farm,we studied the effects of different breeds,parities and delivery seasons on the reproductive performance of American sows by SAS,and the differences of different breeds and genders on growth performance were compared.The phenotypic value,the estimated breeding value and comprehensive index of traits were calculated by using the BLUP analysis function of GBS software.At the same time,WOMBAT was used to estimate the heritability and genetic correlation,so as to provide the scientific basis for the field to develop a new breeding program.The results were as follow:1.Comparison of reproductive performance among different American breeds,the pig breeds can significantly(P<0.05)affect the reproductive performance of sows.The total number born(TNB),the number of newborn alive(NBA),healthy litter size(HLS)and total litter weight at birth(LWB)of Landrace sows were significantly higher than those of Yorkshire and Duroc sows.The initial weight of Duroc piglets was higher than that of Landrace and Yorkshire,and the difference was significant(P<0.05).2.Comparison of reproductive performance of different parities of American sows: the effect of parities on reproductive performance was significant(P<0.05).The litter size and litter weight at birth of first parity were significantly(P<0.05)lower than that of 2nd?3rd?4th?5th?6th parity.The TNB and NBA increased from 1st to 4th or 5th parity,then decreased.The TNB in 6th parity were the highest of Landrace and Yorkshire,and Duroc was the highest in5 th parity.But the number of stillborn(NSB)and weak piglets in 5th and 6th were higher among six parities.3.Comparison of reproductive traits of American sows in different delivery seasons:when sows of different breeds give birth in winter,the TNB was the best,which was significantly higher than that in spring,summer and autumn(P < 0.05);The TNB in summer was very low,and the NSB and weak piglets were more than other seasons;the TNB of Landrace sows is the lowest in spring.4.The effect of breed and sex on the growth traits of American reserve pigs: the AGE100 kg and BF 100 kg of Duroc were significantly lower than that of Yorkshire and Landrace(P < 0.05),and there was no significant difference(P >0.05)between Yorkshire and Landrace.There was no significant difference(P >0.05)in AGE 100 kg between the boars and sows in Landrace and Duroc,but the difference in Yorkshire was significant(P < 0.05).The BF 100 kg of sows was significantly(P < 0.05)higher than that of boars in Yorkshire,Landrace and Duroc(P < 0.05).5.Progress in genetic breeding: in general,the TNB of Landrace,Yorkshire and Duroc respectively increased by 1.03,1.67 and 0.74 from 2014 to 2018,but the phenotypic values of100 kg AGE and 100 kg BF increased in varying degrees,indicating that the growth rate of reserve pigs was gradually decreasing.6.The heritability and genetic correlation of reproductive traits: the estimated heritability of reproductive traits of large white pigs was 0.088-0.196,that of Landrace pigs was 0.111-0.190,and that of Duroc pigs was 0.094-0.242.The genetic correlation between TNB and NBA,HLS,NBA and HLS,HLS and LWB were higher and positive.There was a negative correlation between birth LWB,BWB and TNB,NBA.7.The heritability and genetic correlation of growth trait: the heritability of AGE 100 kg of Landrace,Yorkshire and Duroc was 0.351,0.326 and 0.331,and the heritability of BF100 kg was 0.426,0.403 and 0.445.The genetic correlation and phenotypic correlation between AGE 100 kg and BF 100 kg thickness were positive. |
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