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

dairy cattle industry and is certainly not backed up by government funding as the French system
is. Alternative solutions have to be found and a Group Breeding Scheme could very well be what
the industry needs.
Group Breeding Scheme
A Group Breeding Scheme is a group of producers with a common selection goal where
breeding stock is selected and shared among the members of the group. By increasing the number
of animals in the selection pool, using EPDs and sharing the best rams, the group of producers
increases the rate of genetic gain over purchasing sheep from outside flocks or from selecting
solely within their own flock.
A Group Breeding Scheme uses a team of common sires over a group of flocks in order to
create genetic links between member flocks. With genetic links between flocks, it becomes
possible to compare animals between flocks regardless of the environmental differences between
flocks, management, nutrition or other non-genetic effects, and EPDs can be calculated. An EPD
is an estimate of the genetic value of an animal calculated from performance information from
all relatives of that individual and is the most accurate estimate of genetic value possible. An
EPD calculation for a prospective ewe or ram replacement would use the milk yields (or any
other trait) of the individual’s dam, maternal grand-dam, paternal grand-dam, full-sisters, halfsisters,
and any other female relatives with milk production records. Rams with the highest EPD
become reference rams and are used on a certain percentage of ewes (generally the ones with the
highest EPDs) of each member flock either with natural mating or, better yet, with artificial
insemination. The conditions of use of the rams and rewards to the owner of the rams (payment,
time of use, cost, etc…) need to be sorted out by the group of producers.
EPD calculations require relatively sophisticated statistical techniques and fairly large computing
resources. EPDs are currently calculated by the National Sheep Improvement Program
(US) and by the Record of Performance Program (Canada) on a few meat breeds. It would be up
to a group of sheep dairy producers to form an association and to work with NSIP (or another
entity) for the calculation of milk production EPD
A Sire Reference Scheme is not a new concept since most selection schemes use the similar
principles of a nucleus population and diffusion of genetic improvement throughout the base
population. New Zealand, however was the pioneer in the use of group breeding schemes in
sheep and achieved rather good results on meat and wool breeds. Some similar breeding programs
are being developed in other countries (Spain for instance) on commercial dairy sheep
operations.
How does a Group Breeding Scheme work?
First step. A group of producers with a set of common goals get together with the purpose
of genetically improving their flock. By-laws should be clearly defined to which all members
should abide. Rewards to the producers of the best rams used by the group should be spelled out
to eliminate all possible controversies. Selection criteria should be well chosen and agreed upon
by all members. Generally, in dairy sheep production, milk yield is the primary selection criterion.
However, since practically all sheep milk is transformed into cheese, fat and protein percentages
are extremely important for cheese yield and high quality products. In North America a
good level of production has been obtained by crossbreeding with the East Friesian. However,
this higher level of production has resulted in lower fat and protein percentages in the milk
because of the negative correlation between production and components. It would seem essential
that fat and protein content should be included as selection criteria as soon as possible.