| Popis: |
Practical use is made of an increase in the ovulation rate of gilts over the first few oestrous cycles. In large herds it may well be easier to increase the interval between entry into the herd and first service in order to improve the size of the first litter. The present study considers existing herd records, taken from the Easicare management system, in which the relationship between age at first litter and reproductive parameters in the first parity are examined. A total of 3778 gilt litters were involved, mostly Large White or Landrace, from 14 nucleus or multiplication herds. Average age at first litter ranged from 342 to 376 days across herds and total numbers born per litter from 9.03 to 11.27. Within herd variation in age at first service ranged from a standard deviation of 19 days to 40 days, that of litter size being more consistent, ranging from 2.45 to 3.21. The within herd regressions between these traits were generally small, averaging 0.007 piglets per day, and insignificant (p>0.05). |
