Dairy Sheep Symposium - the Department of Animal Sciences ...

Based on the unexpected results of having lactating ewes respond as well as non-lactating
ewes to the protocol, we will again tinker with the system in 2002. Having used the light treatment
for the past three years, we now have a good segment of our flock on a Fall lambing schedule.
These ewes lamb sometime in the Fall, lactate for several months under 20-hour days in the
milking barn, and leave the milking barn sometimes between February and June. We know we
can expect about 68 percent of these ewes to breed back in April, May or June, and lamb again in
the Fall. Those that don’t breed for Fall lambing then breed back in the early Fall, so we don’t
miss a year of production on those ewes.
Practically, this means we can now hold back fewer ewes from Fall breeding for a separate
light control group. In fact, we’ll probably hold back no more than 100 production ewes for a
February light control group this year. Production ewes that end their lactations in January and
February will be folded into that group and they will all go out in early April for breeding in May
and June. Ewes that end their lactations April through June will simply be folded into the light
control breeding groups.
Also for 2002 the only Elite Group light control ewes will be replacements that were not
quite old enough to breed in the fall. We will not plan to keep replacements from this group, so
they will be exposed to a number of rams. Hopefully our results using this method will be better
than the Elite Group results have been in the past. However, since the group will only consist of
replacements that were not ready to breed in the Fall, any ewe that conceives will be a bonus.
Conclusion:
Despite some drawbacks, the use of light control in our operation has been a great success for
us, and we believe any producer who is contemplating year-round production should strongly
consider trying it. Most importantly, it has meant we no longer have to ration orders to important
customers in the Fall, something we had to do as recently as 1998. And, since we can now spread
our lambing over the whole year, our labor and our facilities are much more efficiently utilized.
We also believe our protocol and/or variants of it should be studied more extensively in a
more scientific manner to see if our results can be improved on.