Campus Units

Animal Science

Document Type

Article

Publication Version

Published Version

Publication Date

1991

Journal or Book Title

Journal of Animal Science

Volume

69

Issue

8

First Page

3190

Last Page

3201

DOI

/1991.6983190x

Abstract

Lamb weaning weights at 30 +/- 14, 60 +/- 28, and 90 +/- 28 d were used to evaluate the effect of birth weight on the linear adjustment of weaning weight to a constant age and the effect of deviations from target dates on the accuracy of linear age adjustment. The data consisted of 13,501 birth weights, 3,721 30-d records, 10,988 60-d records, and 3,285 90-d records from the National Sheep Improvement Program data base for the Dorset, Polypay, Rambouillet, Columbia, Hampshire and Suffolk breeds. The effect of using constant vs actual birth weights in a standard linear age adjustment was evaluated using various sex, type-of-birth, and breed type constants. Product moment and rank correlations indicated that a constant birth weight should be used when the actual birth weight is not known, but the choice of constant makes little difference in average bias or maximum adjustment error. The linear age adjustment procedure and the optimal age range for recording weaning weight were examined using a model including effects for contemporary group, sex, type of birth and rearing, age of dam, and breed. The linear age adjustment did not remove the effect of age for the small breed type (Dorset, Polypay, and Rambouillet breeds) at 30 d and the large breed type (Columbia, Hampshire, and Suffolk breeds) at 60 d for age ranges greater than +/- 7 d (P less than .01) but was adequate for all lambs weaned at 30 +/- 7 d, 60 +/- 7 d, and 90 +/- 28 d of age.

Comments

This is an article from Journal of Animal Science 69 (1991): 3190, doi:/1991.6983190x. Posted with permission.

Copyright Owner

American Society of Animal Science

Language

en

File Format

application/pdf

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