Improving animal health, resilience, and efficiency through diet formulation is a critical area of investigation for livestock. Improving health and resilience through nutrition will reduce the need for pharmaceuticals, such as antibiotics, while also improving the health and longevity of dairy cattle. Specific interest lies in investigating nutrients or feed additives and how they may improve resilience as well as diet formulations of macronutrients, such as starch. We investigated whether rumen protected niacin (RPN) altered inflammation, improved animal health, or improved milk production. In late-lactation cows, RPN reduced milk SCS prior to intramammary challenges and reduced or blunted the inflammatory response after the intramammary challenges. These data also indicate that some epigenetic programming may be occurring as the inflammatory response was blunted well after RPN supplementation had ceased. When we translated this approach of supplementing RPN to dairy cows on a farm in Michigan we observed that RPN did not alter inflammation or health. The incidence of mastitis or culling was not different across the treatments. We observed an increase in peak milk yield and more persistent lactation for cows supplemented with RPN. Primiparous and 2nd parity cows supplemented with RPN had 639 kg and 712 kg more milk over the course of their lactation. This, again, indicates some kind of programming affect as the vast majority of the increase in milk yield occurred after RPN supplementation had ended. Additionally, we demonstrated that β-caryophyllene (BCP) has promise as an anti-inflammatory feed additive for dairy cattle. Our results suggest that BCP reduced cytokine secretion and alters immune cell migration capacity, but in vivo investigation is necessary. We also investigated the role of dietary starch in inflammation. Upon review of the data, we observed that dietary starch alone does not consistently modulate inflammation. Under challenge scenarios, where starch is abruptly added to the diet, then inflammation occurs. The data suggest that diet adaptation and feeding management play a role in diet-derived inflammation. We fed increasing levels of starch and different corn silage varieties to lactating dairy cattle and found that inflammatory biomarkers were similar for each treatment group. Furthermore, additional starch increased feed efficiency, energy-corrected milk yield, and milk protein yield. The α-amylase enhanced silage increased digestibility and reduced milk urea nitrogen but it did not affect milk production. In summation, nutrition can modulate the inflammatory status of dairy cattle and it should continue to be investigated across a variety of life cycle stages and under a variety of stressor scenarios.
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