6 September 1996

Persistency goal

DAIRY cow breeders in Canada seek high yielding cows with more persistent lactations in preference to high peak yields.

Kevin Wade, Macdonald College, Sainte-Anne-de-Bellevue, Quebec, expects persistency of daughters lactations to be included in bull proofs within two years.

"Cow lactation persistency is a measure of the slope of the lactation curve," he says. "Breeders are trying to produce animals that have more persistent lactations and are, therefore, easier to manage." Flatter, longer lactation curves would benefit herds fed one total mixed ration or those working with longer calving intervals.

But he warns that cows with more persistent lactations may show reduced fertility. &#42