The denominator
is the farrowing interval for a sow that is successfully
mated as soon as she comes into estrus after weaning.
A herd
LSY of 2.43 may suggest that the calculation for LSY is biased
upwards since this is achieved only with a near perfect record
for each sow in the breeding herd.
Gilts were entered into the
breeding herd after being mated, hence non-productive day accumulation
does not occur until after the sows have weaned
their first litter.