Influence of niacin application on inflammatory parameters, non-esterified fatty acids and functional status of liver in cows during early lactation
Metabolic stress in periparturient period in cows is characterized by reduced food intake, negative energy balance, increased lipolysis, ketogenesis, insulin resistance and inflammation. Central metabolic organ in early lactation is liver. Lipid peroxidation and ketogenesis can trigger inflammatory response. Niacin has anti-lipolytic action and potential anti-inflammatory effect. The aim of this study was to determine influence of niacin application on inflammatory response and functional status of liver (expressed with liver functional index, LFI) in cows in early lactation. 30 Holstein-Friesian cows were included in the experiment. Niacin was aplicated to 15 cows two weeks before and two weeks after calving and 15 cows were included in negative control group. Blood samples were taken by venipuncture of v. coccigea before morning feeding, in the moment of calving and then at first and second week after calving. Reduction of TNF-α, haptoglobin, total bilirubin and NEFA concentration, but increase of albumin and cholesterol parameters was caused by niacin application. Fibrinogen concentration was unchanged. Increased values of albumin, cholesterol and reduced value of bilirubin followed by increase of LFI was noted after niacin application. That indicates improved liver hepatocytes function. Positive correlations between TNF-α and fibrinogen, NEFA, haptoglobin and negative with albumin were noted. That proves significance of albumin as a negative protein of acut phase and role of lipolysis in inflammation development in cows in early lactation. Negative correlation between LFI and TNF-α, haptoglobin and NEFA was noted. Correlation between LFI and NEFA and correlation of LFI and haptoglobin was controlled by TNF-α. This indicates that niacin can have dominant anti-inflammatory effect in liver protection. Besides anti-lipolytic effect, niacin has showed anti-inflammatory action that can be significant in hepoatocyte protection in early lactation in dairy cows. Significant influence of niacin on TNF-α was noted. This cytokine controls correlations of LFI, lipolysis and inflammatory response.