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 Tucker, W. L. Articles by Farthing, B. R. Search for Related Content PubMed Articles by Tucker, W. L. Articles by Farthing, B. R.

Genetic Improvement in Production Attributable to Sires Used in Artificial Insemination in North Carolina¹

Department of Animal Industry, North Carolina State College, Raleigh

ABSTRACT

The genetic advantage attributable to the sires used in artificial insemination in North Carolina was evaluated. The effect of season of calving on production was pronounced. Cows freshening during the months of December through May produced 21 lb. of fat and 595 lb. of milk more than cows freshening in June through November. The performance of artificially sired animals was evaluated by using the first-lactation contemporary comparison, and also by using all lactations of the naturally sired progeny as contemporaries. The 305-day, 2 x, M.E. lactations of the artificially sired progeny were 15.7 lb. of fat and 366 lb. of milk above those of the naturally sired progeny. The use of the records of all contemporaries imposed a negative bias on the comparisons, presumably due to the selection of the older animals on the basis of previous performance.

¹ Contribution from the North Carolina Agricultural Experiment Station and published with the approval of the Director of Research as Paper No. 1136 of the Journal Series.

² Present address: Station Statistician, Louisiana State University, Baton Rouge.