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 Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bar-Anan, R. Articles by Osterkorn, K. Search for Related Content PubMed PubMed Citation Articles by Bar-Anan, R. Articles by Osterkorn, K.

Prediction of Annualized Lactation Yield from Partial Lactations¹

Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel

G. R. Wiggans

Animal Improvement Programs Laboratory, Agricultural Research Service, United State Department of Agriculture, Beltsville, MD 20705

K. Osterkorn

Institiut fuer Tierzucht and Tierhygiene, 8000 Munich 22, Veterinaerstrasse 13 West Germany

ABSTRACT

Extension factors for annualized lactation yields [365 (total lactation yield)/-days between calvings] were computed by generating 747,904 partial lactations from complete lactation records of 105,379 Israeli-Holstein cows with one to three lactations. Factors included in the model were last test yield, days pregnant, days in milk, farm type, calving season, and days remaining in the lactation. Both linear and quadratic effects were assumed for the first three factors. Primiparous and multiparous cows were analyzed separately for milk, fat, and economically fat-corrected milk [.67 (milk) + 10 (fat)] yields.

Adjusted coefficients of determination computed for this model were .04 higher for fat and .01 higher for milk and economically fat-corrected milk than for an alternate model in which remaining yield was predicted as a linear function of last test yield and remaining days in milk. Correlations between actual and predicted lactations for partial lactations of less than 4 mo in milk computed by the first model were .03 higher for fat but were nearly identical to those computed by the second model for milk. Although last test yields was the most important factor in predicting annualized yields, inclusion of other factors increased accuracy of annualized fat yield prediction.

¹ Supported by the United States-Israel Binational Agricultural Research and Development Fund, Project Number US-3334-81, and by the Schaumann Foundation, West Germany. This manuscript is Contribution Number 1441-E, 1985 series, from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.