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

Background and History:
Most sheep producers are aware that while most breeds of sheep are seasonal breeders, there
is a continuum in different breeds and individuals within breeds ranging from very short breeding
seasons to practically year round breeding. Our East Friesian flock is somewhere in the
middle of that continuum with a natural breeding season that ranges from mid-August to mid-
February. Therefore, we can easily extend our lambing period from early January to mid -June.
Historically, however, under natural conditions, we could expect only between 15 to 25 percent
of ewes exposed to rams between March and June to lamb in the Fall.
Because of this, in our early years, we experienced chronic shortages of fresh milk from
September though December, and surplus production in April though June or July. Not only did
this cause chaos in our marketing efforts, it also caused our lambing and milking barns to be
over-taxed for part of the year and under-utilized in another part of the year.
In the past, we experimented with hormone treatments to increase Fall lambing. While
hormone treatments did improve the out of season lambing numbers over natural breeding, the
results varied from year to year, ranging from 30 percent to 70 percent success rates. Additionally,
hormones are costly in terms of both money and labor. The cost is about eight dollars per
ewe, and the treatment regimen requires each ewe treated to be handled individually twice. And,
most importantly, the use of hormones did not fit philosophically into our otherwise organic
management of the farm.
Protocol:
This was not a scientific experiment. We made no effort to compare one protocol with another,
to maintain control groups or to compare light control with a number of other methods in
the same year to evaluate results. We haven’t even done our project exactly the same way each
year. We simply chose a protocol we thought might work, and we tried it. However, because we
do have good records going back a number of years we were able to compare our results using
the light control with results from hormone treatment and natural breeding.
We discovered a number of different light treatment protocols when we first started looking
into trying it for our farm. However, many of the protocols were developed by researchers who
needed lambs all year around for their research, and most involved year-long schedules that
required climate-controlled buildings where day could be turned to night and night into day.
These protocols worked very well, but are not practical for most farms.
We settled on a protocol that only required lengthening day lengths, which is much easier
than shortening day lengths. Simply put, we started groups under lights the first week of January,
and kept them under 20-hour days for 60 days. We were advised by some that a 16-hour day
would work, and by others that 24 hours of light would work. Some said the dark period had to
be complete and total darkness, meaning even a streetlight within 50 yards of the building would
compromise the results, others disagreed. We decided to keep the lights on from 4 AM until
midnight and made every effort to keep the dark period from midnight until 4 AM as dark as
possible. Since the barn we use is far from other light sources, this has not proved difficult.
After 60 days under the lights, the ewes were moved outside into normal day lengths. Rams
were introduced about four weeks later and the ewes started cycling within a week or so. We
have found that some ewes will start cycling right away, and some will cycle as much as six to
eight weeks later.