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United States Department of Agriculture

Agricultural Research Service

Title: Chapter 6, Use of Prolific Breeds in Different Countries-North America

Authors
item Young, Lawrence
item Fahmy, Mohamed - AGRIC. & AGRI-FOOD CANADA
item Torres-Hernandez, G - MEXICO

Submitted to: Prolific Sheep
Publication Type: Book / Chapter
Publication Acceptance Date: October 27, 1995
Publication Date: N/A

Technical Abstract: The prolific breeds available in the United States are Finnsheep, Romanov, Booroola Merino, St. Croix and Barbados Blackbelly. The Finnsheep can be used in crossbreeding programs to increase the reproduction of crossbred ewes. Research has shown that for every 1% Finnsheep breeding in the crossbred ewe, number of lambs born will increase by 1%. Purebred Romanov ewes produce .2 to .5 more lambs than purebred Finnsheep ewes depending on ewe age. In contrast to the multigenic fecundity of the Finnsheep and Romanov, the increased litter size of the Booroola Merino is the result of a major gene which has an additive effect if 1.5 eggs on ovulation rate. Lamb survival and mothering ability of Finnsheep and Romanov crossbred ewes is excellent, but these traits are relatively poor in Booroola Merino crossbred ewes. Fleece weight is reduced by crossing with Finnsheep and Romanov and increased by crossing with Booroola Merino. The St. Croix and Barbados Blackbelly are hair breeds of sheep and intermediate in prolificacy between our domestic breeds and breeds like the Finnsheep, Romanov, and Booroola Merino. They have proven to have an advantage in productivity under some hot, humid conditions. However, crosses of these breeds with wool breeds result in progeny with fleeces containing both hair and wool. Animals with higher percentages of St. Croix or Barbados Blackbelly have variation in wool cover on the body. These breeds also tend to be slower growing than many of our better domestic breeds.

Last Modified: 12/26/2014
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