Journal of Animal Science, Vol 74, Issue 3 522-528, Copyright © 1996 by American Society of Animal Science

JOURNAL ARTICLE

Genetic trend and environmental effects in a population of cattle selected for twinning

L. D. Van Vleck and K. E. Gregory
Roman L. Hruska U.S. Meat Animal Research Center, USDA, ARS, Lincoln, NE 68583-0908, USA.

A selection experiment was established in 1981 to increase twinning rate in cattle. Results reported are through 1993 calf crops. Estimates of genetic parameters for a two-trait twinning and ovulation rate model with genetic groups were as follows: heritabilities of .03 for twinning and .07 for ovulation rates with a genetic correlation of nearly 1.00 and fractional permanent environmental variances of .06 for twinning and .05 for ovulation rate. Corresponding estimates when group effects were ignored were as follows: heritabilities of .08 and .08 and fractional permanent environmental variances of .02 and .04 for twinning and ovulation rates, respectively. Twinning rate (percentage) in the project at the U.S. Meat Animal Research Center has increased in all cows born in the project by year of calving from 3.4% in 1982 to 28.5% in 1993, a phenotypic increase of 25.1%. The estimated genetic change in twinning of cows by year of calving using the groups model has been 15.2%. The increase in average genetic value by year of birth has been 18.2% in twinning and 15.0% in ovulation rate from 1980 through 1991. Solutions for seven selected groups of foundation animals ranged from -6.0 to 33.1% and influenced genetic trend.

This article has been cited by other articles:

				K. M. Cammack, M. G. Thomas, and R. M. Enns Review: Reproductive Traits and Their Heritabilities in Beef Cattle Professional Animal Scientist, October 1, 2009; 25(5): 517 - 528. [Abstract] [PDF]

				N. Ghavi Hossein-Zadeh, A. Nejati-Javaremi, S. R. Miraei-Ashtiani, and H. Kohram Estimation of variance components and genetic trends for twinning rate in Holstein dairy cattle of Iran J Dairy Sci, July 1, 2009; 92(7): 3411 - 3421. [Abstract] [Full Text] [PDF]

				M. F. Allan, L. A. Kuehn, R. A. Cushman, W. M. Snelling, S. E. Echternkamp, and R. M. Thallman Confirmation of quantitative trait loci using a low-density single nucleotide polymorphism map for twinning and ovulation rate on bovine chromosome 5 J Anim Sci, January 1, 2009; 87(1): 46 - 56. [Abstract] [Full Text] [PDF]

				M. F. Allan, R. M. Thallman, R. A. Cushman, S. E. Echternkamp, S. N. White, L. A. Kuehn, E. Casas, and T. P. L. Smith Association of a single nucleotide polymorphism in SPP1 with growth traits and twinning in a cattle population selected for twinning rate J Anim Sci, February 1, 2007; 85(2): 341 - 347. [Abstract] [Full Text] [PDF]

				R. A. Cushman, M. F. Allan, G. D. Snowder, R. M. Thallman, and S. E. Echternkamp Evaluation of ovulation rate and ovarian phenotype in puberal heifers from a cattle population selected for increased ovulation rate J Anim Sci, August 1, 2005; 83(8): 1839 - 1844. [Abstract] [Full Text] [PDF]