Ever wonder what the odds are that the heifers you’re raising will complete their first or second lactation? Researchers in Spain have recently completed a study that looks at the associations between different aspects of heifer development and dairy cow survivability to second lactation.
This research published in the February Journal of Dairy Science looks at a data set of 7,768 Holstein heifers born between 2004 and 2006. Researchers looked at growth rates from birth until first calving; age and body weight at insemination; and incidence of diarrhea, navel infections, and bovine respiratory disease (BRD) to see if there were any potential associations between these factors and the odds of completing the first lactation.
Heifers in the data set were raised at a contract heifer operation and returned to the herd of origin prior to calving. There were 133 herds included in the data set.
In total, 655 (8.4 percent) of the heifers did not complete the first lactation and 31.5 percent of these left the herd within the first 50 days in milk. Also, 4.5 percent of heifers aborted and were rebred.
“Incidence of diarrhea or navel infection was not associated with the chances of finishing the first lactation,” they said.
Heifers that completed the first lactation calved at an earlier age than those that did not. A higher growth rate between 12 days of age and 65 days of age was also a factor in heifers that reached second lactation.
Researchers also note that as conception rate decreased, chances of leaving the herd before completing the first lactation increased. The number of AI services needed per conception was negatively associated with surviving to the second lactation. Heifers that experienced an abortion were 2.73 times more likely to exit the herd before completing the first lactation.
Heifers that experienced four or more BRD cases before calving had 1.87 greater odds of not completing the first lactation than those that never experienced BRD.
Researchers concluded, “these results show potential to forecast future heifer success in finishing the first lactation based on average daily gain early in life, incidence of BRD, reproductive performance (conception and abortion rates), and age at first calving.”