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 Miller, R. H. Articles by Hooven, N. W. Search for Related Content PubMed Articles by Miller, R. H. Articles by Hooven, N. W., Jr.

Factors Affecting Whole- and Part-Lactation Milk Yield and Fat Percentage in a Herd of Holstein Cattle

Animal Husbandry Research Division, USDA, Beltsville, Maryland 20705

ABSTRACT

Relationships among milk and fat-corrected milk yield, fat percentage, weight change, body weight, and days open were studied in 1,004 lactations collected over a 14-year period in a herd of Holstein cattle. Least-squares analyses of 31 to 60-day, 121 to 150-day, and of 181 to 210-day part lactations and total lactation were performed on an intra-sire basis. The regressions of milk and fat-corrected milk on weight change were consistently large, negative, and linear. The regressions of yield on average lactation body weight were significant and curvilinear; production increased up to average or above-average weight, then declined. Effects of the number of days open were small, accounting for less than 2% of the variance in all cases. Years and age were the factors most closely associated with variation in fat percentage.