Investigations of the use of rumen-protected niacin for modulating muscle fiber type composition and improvement of oxidative metabolism in skeletal muscle of high-yielding dairy cows during the periparturient phase

• Applicant: Professor Dr. Klaus Eder
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 260518511

For high yielding dairy cows, the periparturient phase represents a stressful condition which is associated with a high metabolic demand. The excess flow of non-esterified fatty acids (NEFA) to the liver due to intensive mobilisation of body fat leads to a severe metabolic burden of the liver and commonly to an impairment of liver function resulting in fatty liver and ketosis. Balancing the release and the consumption of NEFA could offer possibilities to improve the metabolic problems present in high yielding dairy cows. Based on own studies performed with obese rats, sheep and pigs, the planned project aims to investigate the hypothesis that high doses of rumen-protected niacin during the periparturient phase are able to cause a shift from fast twitch glycolytic fibers (type II fibers) to slow twitch oxidative fibers (type I fibers). This muscle fiber type switching is expected to be accompanied by an improved vascularisation and an increased blood flow through the skeletal muscle of dairy cows. These events in turn might be associated with an increased uptake of NEFA into the skeletal muscle, reduced plasma concentrations of NEFA, a reduced flow of NEFA to the liver and a diminished load of the liver with NEFA. These changes might lead to a reduced triacylglycerol content in the liver and a reduced formation of ketone bodies which in turn might be beneficial for liver function and overall health of dairy cows. In order to investigate this hypothesis, an experiment with 30 high yielding dairy cows is planned which are allotted to two groups, a control group and a group supplemented with a high dose of rumen-protected niacin. In order to investigate alterations in the skeletal muscle, the fiber type distribution (type I vs. type II fibers) and the vascularisation will be determined in biopsies of three different muscles. To assess the capacity of fatty acid utilisation, key regulators of muscle phenotype and muscle fiber type switching, and besides, genes involved in fatty acid uptake and ß-oxidation on mRNA and protein levels will be considered. Concentrations of NEFA and ß-hydroxy butyric acid in plasma, liver concentrations of triacylglycerols and the expression of genes involved in ketogenesis in the liver will be determined in order to prove the reduction of the burden of the liver by supplementation of niacin.

• DFG Programme: Research Grants