[Jacob-list] Effects of co-twin gender in sheep

[Laura C Frazier]

This is not specifically related to Jacobs, but interesting none-the- 
less.

Laura C Frazier
FarmGirl Arts
(336) 971-3834
Kernersville, NC
http://farmgirlreneweables.blogspot.com/
http://www.etsy.com/shop/FarmGirlArts

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From: Susan Schoenian [mailto:sschoen at umd.edu]
Sent: Monday, November 22, 2010 9:30 AM
To: shepherdsnotebook at umd.edu
Subject: [Shepherd's Notebook] Effects of co-twin sex

Data analyzed at the University of Wyoming suggests that producers  
should select female replacements from same sex litters, as ewe  
productivity tends to be affected by the sex of the co-twin.

The uterine environment for developing fetuses is influenced by sex  
of the co-twin and the effects vary by species. Although  
freemartinsim is rare in prolific species, such as sheep,  effects of  
co-sibling sex on  development have been reported in numerous  
species, including humans.

Nine years of lambing records from the University of Wyoming's  
Suffolk, Hampshire, Columbia, and Rambouillet purebred flocks were  
analyzed to determine if the sex of the co-twin had any effect on the  
number of offspring, flock longevity, and age at first lambing of ewe  
lambs retained for breeding.
Ewes born as singles had fewer lambs during their productive lifetime  
than ewes born co-twin with ewes, but did not differ from ewes born  
co-twin with rams.  Among the twin-born ewe lambs, the presence of a  
male co-twin tended to decrease the number of lambs born, but it did  
not affect longevity.  Nor did it affect age at first lambing.

Ewes born co-twin to a ram produce approximately 10 percent fewer  
lambs during their productive lifetime thans ewes born co-twin to a ewe.

Source:  Effect of Sex of Co-Twin and Breed on Ewe Flock  
Productivity, 2010 Proceedings of the U.S. Sheep Research and Outreach.

Topic originally suggested by Kelly Cole.

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Posted By Susan Schoenian to Shepherd's Notebook at 11/22/2010  
09:30:00 AM






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