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

The rams are put under the same light treatment protocol, but in a completely different
building. We feel it is important for the ewes to be out of sight and smell of the rams until they
are exposed to them at the end of the protocol. This way we also take advantage of the “ram
effect” that has been well documented.
Lights Used:
We have used three different barns with somewhat different light levels successfully, so it
seems that varying brightness levels of light in the barns can produce good results. We have not
tried changing the light intensity to compare results. It is possible different light levels would
produce better results than we have experienced. A research project comparing light levels
would probably produce some useful information on this subject.
In all of our barns we have 100-watt metal halide fixtures. This type of fixture is relatively
expensive to buy and install, but they are very energy efficient, providing about 450 watts of
light per 100 watts of electricity used. Although the lights are installed a bit differently in each
barn, on average they are about 14 feet above the barn floor and are spaced about 25 feet apart.
At night, the barns are not extremely bright inside, but there is enough light to read a book or
newspaper without much strain.
Results:
We are now into our third year of light treatment, and because we have done things a bit
differently every year, it will be most straightforward if each year’s results are presented independently.
We started cautiously in 1999, because we had no idea how the system would work.
Ewes selected for the light control group were held back from breeding during the normal Fall
season, so if the light treatment protocol didn’t work, we would have lost production of those
ewes for the season.
In discussing our results, it is necessary to digress a bit to explain one aspect of the way we
manage our flock. For the past five years, our flock has been divided into two groups, the “Elite
Group” and the “Production Group”. The Elite Group consists of our highest milk-producing
ewes. This group is blood tested three times a year to screen for disease, and it is the source of all
replacement stock for our use or for sale. The two groups are kept separate in every phase of the
operation. No replacement stock is kept from the Production Group.
Practically, this means during breeding ewes in the Production Group can be exposed to a
number of rams simultaneously, because it is not important for us to know the sire of lambs from
that group. Of course the opposite is true for the Elite Group. Ewes from the Elite Group can
only be exposed to one ram at a time, because it is critical to our selection program to know the
sire of replacement stock. This turns out to be important for the light control protocol because, as
you will see later, we have had different success rates in the two groups.
In 1999 we started only one group of 50 ewes in the first week of January. In the first week
of March the group was turned out to a winter paddock, and five weeks later, the rams were
introduced. These ewes were all from our production group, so we were able to put a number of
rams in the group. Within six weeks, 87 percent of the ewes had been marked, and 62 percent of
those ewes eventually lambed sometime in the fall, which we defined as September 1 st through
December 31 st .