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 Google Scholar Google Scholar Articles by Wilcox, C. J. Articles by Bartlett, J. W. Search for Related Content PubMed Articles by Wilcox, C. J. Articles by Bartlett, J. W.

Effects of Season, Age, and Stage of Lactation upon Type Ratings of Holstein Cows¹

New Jersey Agricultural Experiment Station, Sussex

ABSTRACT

Spring and fall type ratings by official inspectors from 1945 to 1957 were coded to maintain equal intervals (1.0) between ratings. Lactation numbers represented age, with scores grouped into first, second, and third through fifth (mature) lactation. Each lactation was divided (a) parturition to 60 days, (b) 61 to 240 days, and (c) 241 days to next parturition. Only cows with five or more ratings were included. Least squares analyses using dummy variables measured the various environmental effects independent of each other on 918 ratings of 113 cows. With the confounding of the other measured effects removed, and using coded values, over-all ratings in fall were lower than those in spring by 0.09 (P<0.08); first and second lactation scores were lower than mature scores by 0.52 and 0.29 (P<0.01), respectively. Early and mid-lactation scores were similar, but late-lactation scores were 0.15 lower (P<0.01). Subratings for fall, and for first and second lactations, generally were lower than their counterparts. Scores in late lactation were higher, except for dairy character, which scored 0.19 lower (P<0.01) than in mid-lactation. Application of adjustment factors increased repeatability only slightly. Adjustments for the significant influences, in studies with limited numbers of observations per cow, would yield more accurate type estimates.

¹ Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers University, the State University of New Jersey, Department of Dairy Science, New Brunswick. This investigation was supported in part by funds provided by the Charles H. Hood Dairy Foundation, Boston, Massachusetts, and through cooperation of the Holstein-Friesian Association of America.