HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Morrow, R. E. Articles by Butts, W. T. Search for Related Content PubMed Articles by Morrow, R. E. Articles by Butts, W. T.

Effect of Age on Estimates of Bovine Growth-curve Parameters¹

University of Tennessee, Knoxville 37916 and and U.S. Department of Agriculture, Knoxville, Tennessee

Abstract

Estimates of mature weight (A) and rate of maturing (K) determined by asymptotic regression were studied to determine the optimum age range over which estimate of growth curve parameters can be estimated. Quarterly weights of 102 Angus cows at the Plateau Experiment Station were used. The weight-age paremeters were estimated at various ages; all available weights from birth to the specified age were used. The mean estimates of mature weight (A) were 503, 465, 473, 481, 485, 484, and 482 kg for ages 2.5 through 8.5 years, respectively. Mean estimates of rate of maturing (K) were .069, .073, .069, .065, .061 and .061 for ages 2.5 through 8.5 years, respectively. Mean estimate of A and K in which lifetime weights were used, were 497 kg and .056, respectively. Correlations among estimates of A at the various ages were low until cows were 4.5 years old, at which time the correlations tended to stabilize. The same trend was shown among estimates of K; however, correlations among these estimates tended to stabilize at slightly later ages than those among estimates of A.

The least-squares analyses of estimates of A and K showed a significant age-reproductive status interaction. The fact that the cow-within-reproductive status component was highly significant indicated significant independent variation available for use in selection programs. The least-squares means of A and K at the various ages with reproductive status held constant indicated a stronger trend with respect to stabilization of estimates at 4.5 years of age with a decline in K as age increased.

¹ Published with the approval of the Dean of the University of Tennessee Agricultural Experiment Station.

² Present address Department of Animal Science, University of Missouri, Columbia, MO.

³ Department of Animal Science, University of Tennessee, Knoxville.

⁴ ARS, USDA, The University of Tennessee, Knoxville.

This article has been cited by other articles:

				B. A. Sandelin, A. H. Brown Jr., M. A. Brown, Z. B. Johnson, D. W. Kellogg, and A. M. Stelzleni Genotype x environmental interaction for mature size and rate of maturing for Angus, Brahman, and reciprocal-cross cows grazing bermudagrass or endophyte infected fescue J Anim Sci, December 1, 2002; 80(12): 3073 - 3076. [Abstract] [Full Text] [PDF]

				J. A. Arango, L. V. Cundiff, and L. D. Van Vleck 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 J Anim Sci, December 1, 2002; 80(12): 3123 - 3132. [Abstract] [Full Text] [PDF]

				J. A. McCracken, E. E. Custer, and J. C. Lamsa Luteolysis: A Neuroendocrine-Mediated Event Physiol Rev, April 1, 1999; 79(2): 263 - 323. [Abstract] [Full Text] [PDF]