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Journal of Animal Science Abstract - Animal Genetics and Genomics

Genetic variance and covariance and breed differences for feed intake and average daily gain to improve feed efficiency in growing cattle

 

This article in JAS

  1. Vol. 95 No. 4, p. 1444-1450
     
    Received: Nov 30, 2016
    Accepted: Jan 29, 2017
    Published: April 13, 2017


    1 Corresponding author(s): retallickk@gmail.com
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doi:10.2527/jas.2016.1260
  1. K. J. Retallick 1*,
  2. J. M. Bormann*,
  3. R. L. Weaber*,
  4. M. D. MacNeil*†,
  5. H. L. Bradford*,
  6. H. C. Freetly,
  7. K. E. Hales,
  8. D. W. Moser*,
  9. W. M. Snelling,
  10. R. M. Thallman and
  11. L. A. Kuehn
  1. * Department of Animal Science, Kansas State University, Manhattan 66502
     Delta G, Miles City, MT 59301 and University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
     Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68166

Abstract

Feed costs are a major economic expense in finishing and developing cattle; however, collection of feed intake data is costly. Examining relationships among measures of growth and intake, including breed differences, could facilitate selection for efficient cattle. Objectives of this study were to estimate genetic parameters for growth and intake traits and compare indices for feed efficiency to accelerate selection response. On-test ADFI and on-test ADG (TESTADG) and postweaning ADG (PWADG) records for 5,606 finishing steers and growing heifers were collected at the U.S. Meat Animal Research Center in Clay Center, NE. On-test ADFI and ADG data were recorded over testing periods that ranged from 62 to 148 d. Individual quadratic regressions were fitted for BW on time, and TESTADG was predicted from the resulting equations. We included PWADG in the model to improve estimates of growth and intake parameters; PWADG was derived by dividing gain from weaning weight to yearling weight by the number of days between the weights. Genetic parameters were estimated using multiple-trait REML animal models with TESTADG, ADFI, and PWADG for both sexes as dependent variables. Fixed contemporary groups were cohorts of calves simultaneously tested, and covariates included age on test, age of dam, direct and maternal heterosis, and breed composition. Genetic correlations (SE) between steer TESTADG and ADFI, PWADG and ADFI, and TESTADG and PWADG were 0.33 (0.10), 0.59 (0.06), and 0.50 (0.09), respectively, and corresponding estimates for heifers were 0.66 (0.073), 0.77 (0.05), and 0.88 (0.05), respectively. Indices combining EBV for ADFI with EBV for ADG were developed and evaluated. Greater improvement in feed efficiency can be expected using an unrestricted index versus a restricted index. Heterosis significantly affected each trait contributing to greater ADFI and TESTADG. Breed additive effects were estimated for ADFI, TESTADG, and the efficiency indices.

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