| In this paper, a comparative study on reproductive traits, growth performance and carcass performance in American Yorkshire, Landrace, Red Duroc and White Duroc were made. The study included 3 parts:The first experiment:The comparative analysis of reproductive traits in American Yorkshire, Landrace, Red Duroc and White Duroc.This experiment is designed to investigating the differences of the litter size among the four varieties of breeding pigs, and the influence of the parities in Yorkshire’s litter size.199 litter of American Yorkshire,200 litter of Landrace,200 litter of Red Duroc and 191 litter of White Duroc were selected to make a comparison. The result shows that:(1) The litter size of Landrace, Yorkshire, White Duroc and Red Duroc are performanced from highly to low, and it’s same to the alive litter size.Variance Analysis shows that, the difference between Landrace’s litter size and other three varieties of breeding pigs are very significant (P<0.01), the difference between Yorkshire and White Duroc is significant (P<0.05),the difference between Red Duroc and other varieties of breeding pigs are very significant (P<0.01).(2) The litter size and alive litter size of Yorkshire pigs are larger from lth to 6th tires, which began to rise from 1th to the 3th tire until it reach to the peak of calving (11.86,10.96), it shows a declining trend from 4th tire and the 7th tire began to decrease significantly. Variance Analysis shows that, the litter size and alive litter size of Yorkshire pigs in 3th(12.13,10.96) and 7th (9.83,10.10)has very significant difference(P<0.01),the 8th has very significant difference with other varieties of breeding pigs (P<0.01).there are no other significant difference between other combinations (P>0.05)(3) In the peak of farrowing (3th parity),the litter size and alive litter size of Yorkshire, Landrace, White Duroc and Red Duroc performanced from high to low, and Red Duroc is significantly less than three other varieties. Variance Analysis shows that, the difference of litter size and alive litter size between Red Duroc and three other varieties are very significant (P<0.01).while the difference between White Duroc and Red Duroc is not significant (P> 0.05).(4) Piglets’ birth weight of four varieties was descending as Landrace, Red Duroc, White Duroc and Yorkshire. While 28-day-old weaning weight is descending as Landrace, Yorkshire, Red Duroc and White Duroc. Variance Analysis shows that, the birth weight of Landrace and Yorkshire is very significant difference (P<0.01), the difference between Red Duroc and Yorkshire was significant difference (P<0.05), while the difference between other combinations are not significant (P> 0.05).To the 28-day-old weaning weight, the difference between Landrace, Red Duroc and White Duroc are very significant (P<0.01), the difference between Yorkshire and Red Duroc is significant (P<0.05), the difference between Yorkshire and White Duroc is not significant (P> 0.05), the difference between Red Duroc and White Duroc is not significant (P> 0.05).The second experiment:The comparative analysis of growth performance among American Yorkshire, Landrace, Red Duroc and White Duroc.This study is designed to investigating the difference of piglet birth weight, weaning weight at 28 days, and up to 100kg weight correction day old among four varieties of American breeding pigs.200 of Yorkshire, Landrace, Red Duroc,White Duroc in three growth stages was selected to measuring and analyzing their differences. The result shows that:(1) To up to 100kg weight correction day old:it is descending as White Duroc, Yorkshire, Red Duroc and Landrace. Landrace is significantly less than White Duroc (P<0.01),there are no significant differences among other varieties (P>0.05).(2)The average daily gain from weaning is descending as Landrace, Red Duroc, Yorkshire, and White Duroc. Variance Analysis shows that, the average daily gain between Yorkshire and Landrace is significant (P<0.05), the difference of average daily gain between Landrace and Red Duroc, White Duroc are very significant (P <0.01), there are no other significant difference among other combinations (P>0.05).The third experiment:The comparative analysis of carcass performance among American Yorkshire, Landrace, Red Duroc and White Duroc.This study is designed to investigating the differences of two important indicators in the carcass performance among four varieties of American breeding pigs.200 of each varieties was selected to measuring and analyzing the differences between correction back-fat thickness and correction eye muscle area of up to 100kg in weight.The result shows that:The correction back-fat thickness of up to 100kg in weight of Landrace is significantly thicker than three other varieties. Variance Analysis shows that, Landrace has significant difference with three other varieties (P<0.01).the difference among other combinations are not significant (P> 0.05).The correction eye muscle area of up to 100kg in weight of four varieties descending as Landrace, Red Duroc, White Duroc and Yorkshire, but it’s not significantly (P>0.05)In conclusion, the Landrace’s reproductive traits is the best among the four varieties of American breeding pigs for it has bigger litter size and piglets birth weight. Moreover, the Landrace has a biggest average daily gain and lowest up to 100kg weight correction day old, it’s growth performance is the best. The Yorkshire’s carcass performance is the best, it has a lower up to 100kg back-fat thickness than Landrace and Red Duroc, it’s correction eye muscle area of up to 100kg is the biggest. |
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