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 Vesely, J. A. Articles by Winter, K. A. Search for Related Content PubMed PubMed Citation Articles by Vesely, J. A. Articles by Winter, K. A.

Evaluation of Cow Reproduction in the Pureline Foundation Phase of the Canadian National Dairy Cattle Breeding Project

Agriculture Canada Research Station, Lethbridge, Alberta, T1J 4B1

A. J. Mc Allister, A. J. Lee and T. R. Batra

Agriculture Canada Animal Research Centre¹, Ottawa, Ontario K1A 0C6

J. F. P. Darisse

Agricultural Canada Experimental Farm, Normandin, Quebec G0W 2E0

G. L. Roy

Agriculture Canada Research Station, Lennoxville, Quebec J1M 1Z3

K. A. Winter

Agriculture Cnanda Research Station, Charlottetown, Prince Edward Island C1A 7M8

ABSTRACT

Five reproduction traits—number of inseminations per cow, days to first estrus, days open, calving interval, and culling rate for infertility—were studied on dairy cows from a long-term breeding project of the Agriculture Canada Research Branch. Five experimental farms maintained either Holstein line, Ayrshire line, or both. Traits were analyzed within each line by a model in which station, year, sire group (paternal parentage), and bull (cow's mate) were considered. Variation these factors caused was small; most represented less than 1% of the total sum of squares. Holstein cows at Lethbridge, Lennoxville, and Ottawa had 1.9, 2.3, and 2.0 inseminations per cow, 55.1, 63.9, and 51.2 days to first estrus, and 109.9, 125.2, and 112.4 days open. The same traits of Ayrshire cows at Charlotte-town, Normandin, and Ottawa were 2.3, 2.2, and 2.0; 53.3, 61.4, and 53.0 days; and 105.2, 129.2, and 114.5 days. All three traits were derived from records of all cows, including those that did not complete calving intervals. Calving interval at all five stations varied from 376.1 to 412.4 days. Intensity of culling for infertility differed between stations, e.g., 5% in one and 31% in another. About 24% of all disposed cows were culled in both lines for infertility.

¹ ARC Contribution 1061.