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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Genetics and Animal Breeding » Research » Publications at this Location » Publication #134497
Title: MODELS WITH CYTOPLASMIC EFFECTS FOR THREE DUAL PURPOSE BREEDS OF SHEEP

Author
item Van Vleck, Lloyd
item Snowder, Gary
item Hanford, Kathryn

Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: 1/4/2002
Publication Date: 7/1/2002
Citation: Van Vleck, L.D., Snowder, G.D., Hanford, K.J. 2002. Models with cytoplasmic effects for three dual purpose breeds of sheep. Proceedings of the 7th World Congress of Genetics Applied in Livestock Production. CD-ROM Communication No. 17-13. Montpellier, France.

Interpretive Summary: Studies of lactation performance of dairy cattle and weights of beef cattle with models that account for relationships among animals and records on which prior selection has been based have shown that cytoplasmic non nuclear effects accounted for negligible fractions of phenotypic variance. More recently, interactions of the mitochondrial and nuclear genomes have been identified. The main objective of this study was to estimate the importance of cytoplasmic line and cytoplasmic line by genotype (sire) effects on representative traits (birth weight, 120-d weaning weight, fleece weight, and litter size born) for Columbia, Rambouillet, and Targhee breeds of dual-purpose sheep. Records were available from 1950 through 1998 from the United States Sheep Experiment Station (USSES) near Dubois, ID. As an example of number of records available, for birth weight, records were from 24,741 Columbia, 35,604 Rambouillet, and 33,944 Targhee lambs. No evidence was found for cytoplasmic influence on the four representative traits. Dominance genetic effects were found for birth weight and less convincingly for fleece weight. The models in common use for genetic evaluation seem satisfactory except for birth weight. Why random effects of dam by year and dam by number born accounted for about 10% of phenotypic variation for birth weight when added to the usual model require further study.

Technical Abstract: Studies of lactation performance of dairy cattle and weights of beef cattle with models that account for relationships among animals and records on which prior selection has been based have shown that cytoplasmic non nuclear effects accounted for negligible fractions of phenotypic variance. More recently, interactions of the mitochondrial and nuclear genomes have been identified. The main objective of this study was to estimate the importance of cytoplasmic line and cytoplasmic line by genotype (sire) effects on representative traits (birth weight, 120-d weaning weight, fleece weight, and litter size born) for Columbia, Rambouillet, and Targhee breeds of dual-purpose sheep. Records were available from 1950 through 1998 from the United States Sheep Experiment Station (USSES) near Dubois, ID. As an example of number of records available, for birth weight, records were from 24,741 Columbia, 35,604 Rambouillet, and 33,944 Targhee lambs. No evidence was found for cytoplasmic influence on the four representative traits. Dominance genetic effects were found for birth weight and less convincingly for fleece weight. The models in common use for genetic evaluation seem satisfactory except for birth weight. Why random effects of dam by year and dam by number born accounted for about 10% of phenotypic variation for birth weight when added to the usual model require further study.