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

Dairy Sheep Genetics
Any ewe can be milked, however, there are significant differences in personality, letdown,
udder conformation, lactation length, and other factors that impact sheep dairy profitability. We
have chosen to select for a combination of milk components and production, as well as conformation.
In 1998, we culled our ewe flock heavily based on udder conformation and milking
“attitude”. Each ewe’s udder was rated on a 1-5 scale based on teat placement, strength of fore
and rear udder attachment, tightness of fit, “meatiness” and willingness to “let-down” with
minimal manipulation.
In 2000 we began unofficial DHI testing through AgSource Cooperative Services. They
provide calibrated meters each month that allows us to estimate the production of each ewe in the
milking flock. In addition, we receive a monthly status report for each ewe on pounds of milk
produced, percent and pounds of butterfat and protein, and somatic cell counts. Using a combination
of the age-factor production factors noted by David Thomas 1 , a standardized 180-day
lactation and weighting for estimated pounds of milk and of butterfat produced, we have developed
a rank-ordering scale for all ewes. Ewes are kept, culled or sold as brood ewes based on
those rankings.
It is uncertain if the culling strategy has had any impact on milk production. In fact, we were
somewhat disappointed in the lack of change in production in 2001. Our total number of ewes
milked in 2000 was 164: in 2001, 202 ewes. We have typically left the lambs with the ewes for
anywhere from 30 to 50 days. While this results in growthy, healthy lambs, it doesn’t put the
majority of the ewes’ milk in the bulk tank. The older ewes are synchronized using teaser rams
to lamb within a 3-week period beginning about February 1. We’ve typically begun milking
about March 10-15, which means that many ewes may have already passed their peak production
by the time the first DHI test was performed.
As of the September, 2001 test, 171 ewes were still being milked with 52 milking under 1
pound per day. Fifty-one of the ewes are still milking between 2 and 3.5 pounds per day. Several
of these ewes lambed January 28-Feb. 9 (11), while most lambed February 12-26 (23), and
the remainder lambed in early to mid-March (15). These earliest lambing ewes are still averaging
2.3 pounds of milk per day. The highest producing ewe for this test (3.1 pounds) also had the
highest butterfat (8.2%) and is 22% East Fresian. This group of ewes averages 57% East Fresian
genetics. Most of these ewes will milk over 210 days, perhaps 220 before drying off. Their
estimated milk production for the season is between 675 and 750 pounds, including the amount
their lambs took. A few may go over 900 pounds.
Our ewe flock average percentage of East Fresian was 45.1% in 2000 and 50.7% in 2001. In
2001, we will be milking a larger proportion of the flock twice a day further into the fall than in
2000. Fewer ewes have been dried off by the August test date than in previous years. The dairy
genetics, coupled with close attention to nutrition, appears to extend the milking season. Late
season milk has higher cheese yield due to the increased butterfat and protein content; a higher
quality product. From our perspective, it seems that one needs to consider making a commitment
to milking an extended season in order to realize the production benefits from an investment
in East Fresian genetics. Chart 1 compares 2000 and 2001 flock averages for overall
production.
1 Thomas, David. Opportunities for Genetic Improvement of Dairy Sheep in North America. Proceedings of
the Great Lakes Dairy Sheep Symposium. 1996.