|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2002
Publication Date: 12/1/2002
Citation: Arango, J.A., Cundiff, L.V., Van Vleck, L.D. 2002. Breed comparisons of Angus, Charolais, Hereford, Jersey, Limousin, Simmental and South Devon for weight, weight adjusted for body condition score, height and body condition score of cows. Journal of Animal Science. 80:3123-3132. Interpretive Summary: Breed means and differences for weight (CW, n = 19,851), height (CH, n = 14,553) and condition scores (CS, n = 19,536) recorded in four seasons per year were evaluated for 881 cows ranging from 2 through 7 yr of age from Cycle I of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center. Significant effects of heterosis were found in Hereford-Angus crosses for weight, height and condition score at different ages. Significant differences were found among crosses by 7 sire breeds representing diverse biological types for cow weights, height and condition scores. Differences generally were maintained across ages, through maturity, with few interchanges in ranking at different ages. Those estimates can be used to synchronize breeding systems with environmental, managerial and market requirements to optimize beef production under conditions similar to those from this experiment. Cow weight reflects differences in size associated not only with skeletal size and lean growth, but also with fatness, which is associated indirectly and negatively with milk production. Therefore, adjustment for condition score caused some differences in estimates of breed differences for weight and their significance. However, ranking of breed groups was generally the same for actual weight and for weight adjusted for condition score. Those results indicate that a portion of the breed differences in weight was due to differences in condition, but that those differences were of moderate to small magnitude. Differences among breed groups for height followed closely differences for weight.
Technical Abstract: Breed means and differences for weight (CW, n = 19,851, height (CH, n = 14,553) and condition scores (CS, n = 19,536) recorded in 4 seasons/year were evaluated for 881 cows at 2 through 7 yr of age from Cycle I of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center. Cows were Herefords and Angus and topcrosses from mating of Hereford, Angus South Devon, Jersey, Simmental, Limousin, and Charolais sires to Hereford and Angus dams. Model included cow age and season of measurement and their interactions, year of birth, pregnancy-lactation (PL) code and breed-group as fixed effects for CW and CS. Analyses of weight adjusted for condition score included CS as covariate. Model for CH excluded PL. Random effects were genetic and permanent environmental effects. Analyses were by REML. Differences due to sire breeds were significant for all traits across ages, with few interchanges in ranking through maturity: Jersey (lightest and shortest), Hereford-Angus (and reciprocal), Limousin, South Devon, Simmental and Charolais (heaviest and talliest). The exception was for F1 Limousin cows, which were heavier than South Devon F1 cows after 5 yr. Cows sired by breeds of British origin tended to be lighter than breeds of continental European origin. Adjustment for condition score changed estimates of breed differences. Rankings of breed groups were similar for actual weight and weight adjusted for condition score. Results indicated that part of the differences in weight due to condition were of small magnitude. Differences tended to increase when adjusted for condition score, especially in contrasts of continental and British breeds. Differences among breed-groups for height followed differences for weight closely.