Grants and Contributions:

Grant or Award spanning more than one fiscal year (2017-2018 to 2019-2020).

Dairy cows undergoing the transition from the dry period to lactation are at risk for developing post-partum diseases, such as subclinical ketosis (SCK), which not only reduce milk production, but further increase their risk of developing other health and reproductive disorders. Subclinical ketosis is often related to inadequate nutrient intake during early lactation and impacts many cows, with an estimated incidence >40%. Increasing dietary nutrient density, by increasing dietary starch content, is undesirable as that may lead to another prevalent condition, subacute ruminal acidosis (SARA), which impacts up to 30% of lactating cows, with highest incidence in early lactation. Provision of supplementary sugar, through a molasses-based liquid feed, has potential to minimize the risk of both SCK and SARA in early lactation. Controlling energy intake prior to calving, by feeding ingredients with low nutrient density (e.g. straw), has also been shown to reduce the risk of SCK. Unfortunately, high-straw diets may be easily sorted, leading to cows consuming more energy than expected. Sorting of these diets may be reduced by using a molasses-based liquid feed. Thus, the objective of this research is to determine the effect of molasses-based liquid feed supplementation on the behaviour, energy balance, and milk production of transition dairy cows. In two studies, we will examine the expected benefits of feeding such a supplement to dairy cows prior to and after calving. We predict that pre-calving supplementation of molasses-based liquid feed in the total mixed ration of dry cows should reduce sorting activity, while increasing feed intake, rumination time, and rumen stability, resulting in improved metabolic status and production of cows after calving. We also predict that post-calving supplementation of a molasses-based liquid feed to lactating cows will improve their energy balance and rumination activity, resulting in improved milk production and efficiency, and a reduction in incidence of post-partum health disorders. With these results, improvements in health, welfare, and efficiency of dairy cows will help Canadian dairy producers be more profitable, while also increasing consumer confidence in this agricultural sector.