Improvement of Prolificacy of Israeli and U.S. Sheep Breeds through
Inclusion of the F Gene of the Booroola Merino - Stage II

BARD Project No. IS-1817-90C*; Duration: 3 years; Budget: $270.000
* Continuation of US-1153-86
 

Gootwine E. Bet Dagan  ARO
Thomas D.L. Madison WI U Wisconsin
Braw-Tal R. Bet Dagan  ARO
Bor A. Bet Dagan  ARO
Dziuk P.J. Urbana IL U Illinois
 

ABSTRACT

The purposes of this project were: 1) to introduce the FecB gene to the Awassi and Assaf breeds in Israel and the Rambouillet breed in the U.S.A. aiming in the long run to establish Awassi, Assaf and Rambouillet nucclei breeding flocks homozygous for the F gene in which the contribution of the Booroola Merino genetic background will be less than 10%; (In the U.S., Booroola crosses with Suffolk and Targhee were also studied. 2) to evaluate the effect of the FecB gene and different proportions of Booroola Merino genetic background on lamb survival, growth, milk production and wool production in Booroola crosses with the native breeds; 3) to reveal the specific effect of the FecB gene on ovarian development, follicle stimulating hormone (FSH) and inhibin secretion in prepubertal ewe lambs and in adult ewes in order to define physiological criteria for distinguishing carriers of the FecB allele from non-carriers and 4) to identify genetic markers linked to the FecB gene to assist in selection of genotypes within the Booroola crosses.

Introgression of the Booroola gene reached the stage of the third backcross in the Awassi, Assaf and the Rambouillet crosses. In all cases the Booroola crosses were superior in prolificacy. However, they were inferior in comparison to the local breeds in production due to Booroola Merino genes other than the FecB. It is expected that the beneficial economic contribution of the Booroola gene will increase along with the upgrading to the local breeds. FSH plasma levels and induced ovulation rate of 5 month old  FecB carriers among the crossbreeds. The OarAE101 marker can assist in detecting FecB carriers among Booroola-Awassi crosses. However, this marker is informative only in some of the families.