FoCus - Food Chain Plus. Verbund Fütterung und Tiergesundheit (TP B) (Kuh)
Contact: Prof. Dr. Cornelia C. Metges
Funding: Bundesministerium für Bildung und Forschung
Phytochemicals that have potential benefits for the health of humans and animals are commercially available, but their effectiveness in vivo is largely unknown. Additionally, the increase in public concern with the use of pharmaceuticals in animal production requires a closer examination of the use of phytochemicals as alternatives to pharmaceuticals. Flavonoids are polyphenolic substances found in all higher plants. Some flavonoids have hepatoprotective potential, and in studies with rodents and pigs quercetin was shown to be one of the most potent flavonoid. For ruminants, and especially for dairy cows, information on the metabolic effects of flavonoids is extremely scarce. Thus the objectives of this study were to investigate bioavailability, metabolization and effects of quercetin, rutin, and green tea catechine on performance, metabolism, and anti-oxidative status of dairy cows in different lactation stages. It was shown that quercetin aglycone and green tea catechine are bioavailable after intraduodenal administration but not so rutin. In contrast, intraruminal administration of quercetin aglycone resulted in an absolute bioavailability of 0.1% whereas bioavailability was improved to 0.5% when quercetin was administered in form of rutin suggesting some rumen protection. Intraruminal administration of green tea catechine resulted in complete degradation by rumen microbes and almost none of the catechins administered were detected in plasma. After a 4-week intraduodenal administration of quercetin aglycone in dairy cows in established lactation milk protein level was increased, and we obtained some indications of a slightly improved insulin sensitivity and insulin secretion. When quercetin aglycone was administered via duodenum from 3 weeks prior to 3 weeks after calving no quercetin effects were observed on metabolic state, energy metabolism and fat oxidation. However, in quercetin-treated transition cows a certain liver protection was seen in terms of lower increases of liver enzyme activities in plasma (indices of hepatocyte destruction) and liver fat. A 2-weeks oral administration of rutin in mid-lactation dairy cows did not lead to effects on heat production, methane emission, and performance. Taken together, our results suggest positive health effects of quercetin especially for metabolically challenged cows but further studies are necessary.