Manipulating dry cow diets to ensure consistency in feed intake across the transition period

在奶牛从干乳期过渡到哺乳期的过程中，乳制品生产商不断面临着确保奶牛持续的饲料摄入量的挑战，以减少产后疾病并促进生产。奶牛在产犊后死于一种或多种代谢性疾病的风险更高，产奶量低，繁殖性能降低，其他疾病的风险增加，生产效率降低，因此利润较低。亚临床酮病(SCK)是一种影响许多奶牛的健康状况，估计发病率为40%，与此时期的低饲料摄入量有关。同样，亚急性瘤胃酸中毒(SARA)，通常与营养摄入不平衡(可能是由于饲料分选)有关，影响高达30%的哺乳期奶牛，在哺乳期早期发病率最高。在整个过渡期，在数量和一致性(即减少分选)方面提高采食量的一个潜在方法是使干牛和鲜牛的口粮在物理成分上看起来相似。这项研究的目的是确定是否可以改善产犊前的饲料摄入量，是否可以阻止饲料分选，以及在产犊后保持采食量的一致性，方法是饲喂在物理特性上更类似于哺乳期奶牛饲料的干奶牛日粮。在两项研究中，我们将测试具有成本效益的方法，使干奶牛日粮在物理上与哺乳日粮更相似，特别是通过改变饲料(秸秆)颗粒长度和添加水。我们预测，这些日粮调整不仅将减少干奶期的分选和改善采食量，而且还将在哺乳早期改善营养物质的摄入量和能量平衡。从这些结果来看，奶牛健康、福利和效率的改善不仅将使加拿大乳制品生产商更有利可图，还将增加消费者对这一农业部门的信心。

Dairy producers are continually challenged with ensuring consistent feed intake in their cows as they transition from the dry period to lactation, to reduce post-partum diseases and promote production. Cows that succumb to one or more metabolic diseases after calving are at higher risk of low milk production, reduced reproductive performance, increased risk of other disease, and lower efficiency of production, and thus are less profitable. Subclinical ketosis (SCK), related to low feed intake during this time period, is one health condition that impacts many cows, with an estimated incidence of >40%. Similarly, subacute ruminal acidosis (SARA), often related to imbalanced nutrient intake (possibly due to feed sorting) impacts up to 30% of lactating cows, with highest incidence in early lactation. A potential method of improving intake, both in terms of amount and consistency (i.e. reduced sorting) across the transition period would be to make the dry and fresh cow rations appear similar, in physical composition. The objective of this research is to determine if pre-calving feed intake can be improved, feed sorting can be discouraged, as well as consistency in intake maintained after calving, by feeding dry cow diets that more closely resemble lactating cow diets in terms of physical characteristics. In two studies we will test cost-effective methods of making dry cow rations more similar in physical resemblance to lactating diets, specifically by changing forage (straw) particle length and through the addition of water. We predict that these ration modifications will not only reduce sorting and improve intake during the dry period, but carry over to improve nutrient intake and energy balance in early lactation. From these results, improvements in health, welfare, and efficiency of dairy cows will not only allow Canadian dairy producers to be more profitable, but also increase consumer confidence in this agricultural sector.