Study On The Effect Of Different Parities On Litter Traits Of Sows

The study chosed 2312 litters of Landrace X Yorkshire sow,and nine litter traits were tested and analysised. The litter traits including litter size (LS),number born alive (NBA),birth weight (BW),litter birth weight (LBW),weaning weight (WW),litter size at weaning (LWW),weaning weight of litter (WL)and litter livability (LL),and abnormal litter(AL). The results showed the litter livability and birth weight in different parities were not significant (P>0. 05). NBA in different parities was significant (P<0. 05) and average alive litter size reached the highest value in the 4th parity( 11.04),the lowest value in the 7th parity (10. 12),higher in the 6th and the third parity,and Lower in the first and second parity. LBW and LSW in different parities were very significant(P<0. 01). Their means had the highest value in the sixth parity and the lowest in the first,higher in the 5th,and lower in the second. The WWL and WW in different parities were also very significant (P<0. 01),and their means had the highest value in the 5th parity,the lowest value in the first parity. The LS and AL were very significant(P<0. 01),too. The results alsoshowed that there were the lower average litter in the first and second parity,the most average abnormal litter in the seventh parity. The actual herd parity structure is in accordance with ideal herd parity structure. Around 40% of sows in a herd should be between parities third to 5th,as this is the most productive period in a sow' s life. Often low farrowing rates can also be attributed to less than ideal herd structure when the herd is too young or too old.