Relationships between milk yield and fertility in dairy cattle

In three studies of 51,618 Holstein, 6,630 Jersey, and 1,524 Guernsey records, correlation was .07 between 120-day milk yield and number of services required for probable conception, independent of days postpartum. The partial regression coefficient for Holsteins was .014 +/- .001 more services for each additional 100 kg of 120-day milk. For Jerseys and Guernseys, .028 +/- .008 more services were required for each additional 100 kg of 120-day milk.