Sheep graze near a mountain
lake at the U.S. Sheep Experiment Station in southwestern Montana. Click the
image for more information about it.
To Boost Flock Fertility, First Find Superior
Studs By Erin
Peabody August 23, 2005
Sheep producers expect a lot from the rams in their flocks. Many
depend on just one of these male sheep to mate with every 20 of their ewes. So
if the males aren't up to the task, new rams--often costing upwards of
$500--must be brought in.
To help producers get more breeding for their buck, animal scientists
with the Agricultural Research Service in
Dubois, Idaho, have determined the simplest and most effective way to increase
these rams' reproductive potential.
Instead of trying to find the source of trouble--males with
languishing libidos--the researchers discovered it's easier to just identify
the best breeders, or the sheep that are most sexually active.
Lewis of the agency's
Sheep Experiment Station in Dubois, recently completed their most extensive
study on the problem of low sexual performance in rams.
Using about 1,000 ewes and 15 rams, the two researchers wanted to find
out which of the tests currently used by the industry is most accurate for
predicting mating performance. They even used the latest molecular genetics
technology--including a sheep "paternity test"--to confirm which rams had
impregnated the most ewes and sired the most lambs.
The researchers confirmed that serving-capacity tests, which have been
used for at least three decades, are a simple and effective way to identify
promising performers. For these tests, producers document how many times a ram
attempts to mate when exposed to female sheep in estrous.
For a relatively small investment in time and money, this approach
allows producers to spot which of their animals are "high-performance" rams.
Stellflug and Lewis calculate that producers could cut the number of rams
needed by half, if they were to identify the most promising breeders through
screening techniques such as the serving-capacity test.
The Dubois researchers are now conducting experiments to further
streamline the serving-capacity test for easier use by breeders who raise and
sell rams to sheep producers.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.