Supplementing molasses to transition dairy cows to improve behaviour, metabolic status, and productivity

处于从干期到哺乳期过渡阶段的奶牛有患产后疾病的风险，如亚临床酮症（SCK），这不仅减少了产奶量，而且进一步增加了它们患其他健康和生殖疾病的风险。亚临床酮症通常与哺乳期早期营养摄入不足有关，并影响许多奶牛，估计发病率为40%。通过增加饲粮淀粉含量来增加饲粮营养密度是不可取的，因为这可能导致另一种常见疾病——亚急性瘤胃酸中毒（SARA），影响多达30%的泌乳奶牛，在泌乳早期发病率最高。通过以糖蜜为基础的液体饲料提供补充糖，有可能将哺乳期早期SCK和SARA的风险降至最低。在产犊之前，通过饲喂低营养密度的原料（如稻草）来控制能量摄入，也被证明可以降低SCK的风险。不幸的是，高秸秆饲料可能很容易分类，导致奶牛消耗比预期更多的能量。使用糖蜜为基础的液体饲料可以减少这些饲料的分选。因此，本研究的目的是确定以糖蜜为基础的液体饲料补充对过渡奶牛的行为、能量平衡和产奶量的影响。在两项研究中，我们将研究在奶牛产犊之前和产犊之后饲喂这种补充剂的预期益处。我们预测，产犊前在干奶牛总混合日粮中添加糖蜜基液体饲料，可减少分选活动，增加采食量、反刍时间和瘤胃稳定性，从而改善产犊后奶牛的代谢状态和产量。我们还预测，产犊后向泌乳奶牛补充基于糖蜜的液体饲料将改善它们的能量平衡和反刍活动，从而提高产奶量和效率，并减少产后健康障碍的发生率。有了这些结果，奶牛的健康、福利和效率的改善将有助于加拿大乳制品生产商提高利润，同时也增加了消费者对这一农业部门的信心。

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.