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Evaluation of Cow Type Classification Score and Its Relationship to Cow Productivity^1,2

Oklahoma State University, Stillwater 74074 and U.S. Department of Agriculture, El Reno, Oklahoma 73036

Abstract

Classification and productivity records from 220 spring-calving Angus cows raised under range conditions were studied. The cows were classified during the spring and fall of 1964 and 1965 by official breed association classifiers and performance was measured on their calves produced from 1964 to 1969.

Analyses of variance indicated that classifiers were not a significant source of variation in total classification scores. However, significant (P <.01) interactions of classifiers with both cows and seasons indicated the classifiers were not consistent in their scoring. Scores given by the same classifier on the same cows at different classification times were more highly repeatable on older cows. Agreement in scores was higher among different classifiers who scored cows at the same time than between the same classifier's scores at different times.

Correlation coefficients between type classification scores and measures of cow productivity were of low magnitude. A slight negative association was indicated between type classification scores and cow productivity as measured by calf weaning weight. Spring classification scores had virtually no association with cow productivity; however, fall classification scores had significant negative correlations with cow productivity as measured by MPWW for cows 2 and 3 years of age at first classification. Fatter cows received higher type classification scores (P <.01) but weaned lighter (P <.10), lower scoring (P<.05) calves. Total type classification score was of little value in predicting future producing ability as measured by MPWW. Although of limited value, a heifer's 18-month adjusted weight was the most accurate estimator of most probable weaning weight for heifers prior to calving. A more reliable predictor of future producing ability was the weaning weight of the cow's first calf.

¹ Journal Article 2153 of the Oklahoma Agricultural Experiment Station, Stillwater. Research conducted by the Department of Animal Sciences and Industry in cooperation with the Animal Science Research Division, A.R.S., U.S.D.A. as a part of Regional Project NC—1, Improvement of Beef Cattle Through Breeding Methods.

² Research supported in part by a grant from the American Angus Association, St. Joseph, Missouri.

³ Present address: Population Genetics Institute, Life Sciences Building, Purdue University, Lafayette, Indiana.

⁴ Present address: Biometrical Services, A.R.S., U.S.D.A., Beltsville, Maryland.

⁵ Superintendent, Ft. Reno Livestock Research Station, Animal Sciences Research Division, A.R.S., U.S.D.A., El Reno, Oklahoma.