Document Detail


Adaptability of pregnant Merino ewes to the cold desert climate in Nevada.
MedLine Citation:
PMID:  19933439     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Grazing ability is difficult to record in animals under free-ranging conditions without sophisticated methods. Alternatively, grazing ability may be indirectly inferred from changes in BW and production characteristics during the grazing period. The present study investigated the effect of grazing on resource-limited rangelands on BW, wool characteristics, and offspring weaning weights in nine hundred five 5/8, 7/8, and fullblood Merino ewes of 2 to 7 yr of age during a grazing period of approximately 2.5 mo (between January and March). A total of 469 ewes gave birth to a single lamb, 248 to twin lambs, and 188 did not give birth. Body weights were measured and wool samples taken before and after the ewes were allowed to graze freely on the rangelands; absolute change in BW and change in BW as a percentage of initial BW were estimated. On average, grazing on resource-poor rangelands resulted in BW loss, a reduction in fiber diameter and its CV, and increased staple length. Animals with finer wool at the start of the grazing period lost phenotypically (r = -0.07, P < 0.05) and genetically (r = -0.23, P < 0.05) less BW during the grazing period and had a greater probability to carry 1 lamb (or 2) to term (P < 0.05). Animals that lost less BW produced more greasy fleece (r = 0.09, P < 0.01). Body weight change did not significantly influence offspring weaning weights. Change in BW was moderately heritable at h(2) = 0.29; fiber diameter was strongly heritable at h(2) = 0.51. Animals with the least inclusion of Merino genetics lost more BW (P < 0.01) during the grazing period and had a more uniform fiber diameter (P < 0.05) but shorter staples (P < 0.05) and less fleece (P < 0.0001) than animals with a greater level of Merino genetics. Our results indicate that animals with finer wool appeared to be better adapted to the cold Nevada desert. Thus, selection for finer wool may positively influence adaptability to resource-limited cold climate conditions; alternatively, BW change may be selected for directly. Because nutritional deficiencies during pregnancy can have adverse consequences for the offspring, indirect selection for grazing ability would foremost result in healthier ewes that can produce lambs and wool without compromising their welfare.
Authors:
W M Rauw; D S Thain; M B Teglas; T Wuliji; M A Sandstrom; L Gomez-Raya
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-11-20
Journal Detail:
Title:  Journal of animal science     Volume:  88     ISSN:  1525-3163     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-02-26     Completed Date:  2010-05-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  860-70     Citation Subset:  IM    
Affiliation:
Department of Animal Biotechnology, University of Nevada, Reno 89557, USA. wrauw@cabnr.unr.edu
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MeSH Terms
Descriptor/Qualifier:
Acclimatization / genetics*
Animals
Birth Weight / genetics,  physiology
Body Weight / genetics,  physiology
Cold Temperature
Desert Climate*
Feeding Behavior / physiology
Female
Nevada
Phenotype
Pregnancy
Pregnancy, Animal / genetics*,  physiology
Quantitative Trait, Heritable
Sheep / genetics*,  growth & development,  physiology
Weaning
Wool / growth & development

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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