Although milk production has almost doubled in the past 50 years, reproduction remains a significant challenge for producers. The performance of average Canadian herds is still unsatisfactory, with a gestation rate of 17.6%.

The transition period is challenging for the dairy cow since the cow needs to adapt very quickly to the calving process, the sudden change from a non-lactating to a lactating stage and to the preparation for the next breeding period.

The transition period is challenging for the dairy cow since the cow needs to adapt very quickly to the calving process, the sudden change from a non-lactating to a lactating stage and to the preparation for the next breeding period.

Although some dairy herds do have excellent reproductive performance, the average Canadian herd is still showing unsatisfactory performance with an insemination rate of 44.1 percent, pregnancy rate of 17.6 percent and conception rate of 40.5 percent; those performances were shown to be similar in other countries.

Dairy cows are very susceptible to heat stress and will adapt by reducing their milk production. Only half of that milk reduction is explained by a lower dry matter intake; other metabolic changes are involved, including a shift in the use of glucose by the mammary gland to other tissues, reducing its availability for milk production, a reduction in rumination and nutrient absorption, and an increase in maintenance needs to dissipate heat.

Although some dairy herds do have excellent reproductive performance, the average Canadian herd is still showing unsatisfactory performance with an insemination rate of 44.1 percent, pregnancy rate of 17.6 percent and conception rate of 40.5 percent; those performances were shown to be similar in other countries.

Dairy cows are very susceptible to heat stress and will adapt by reducing their milk production.

The transition period is a very challenging period for the dairy cow. Her metabolism needs to adapt rapidly from a non-lactating to a lactating stage, and the reproductive system is preparing new ova for the next breeding period.

Even if cows consume an increased amount of dry matter, meeting the early lactation nutrient needs of high-producing dairy cows is a big challenge. The transition period is, more than ever, a critical period.