Dietary supplementation of chitosan affects milk performance, markers of inflammatory response and antioxidant status in dairy cows

High-yielding cows produce a lot of free radicals in the body due to high levels of metabolism during lactation, causing oxidative stress and susceptibility to diseases. The influence and mechanism of chitosan (CHI) on antioxidant status and inflammatory response of dairy cows is unclear. This study investigated the effect of dietary supplementation of CHI on promoting milk production and antioxidant status, and reducing markers of inflammatory response of dairy cows. Forty multiple Holstein dairy cows (200 +/- 15 days in milk, 34.8 +/- 4.95 kg/d of milk yield) were randomly assigned to five treatments (n = 8): control (CON; without CHI addition), supplementation of CHI (mg/kg dietary DMI) with 500 (C500), 1000 (C1000), 1500 (C1500), or 2000 (C2000). The experiment period included 2 weeks for adaptation and 8 weeks for data and sample collection. Blood samples were collected on the 60th day to separate peripheral blood mononuclear cells. The results indicated that supplementation of CHI to the diet linearly increased the milk yield (P < 0.01), energy-corrected milk yield (P = 0.01), milk protein yield (P = 0.03) and lactose yield (P < 0.01) of dairy cows, quadratically increased the proportion of lactose (P = 0.03) and milk urea (P = 0.01), and linearly reduced somatic cell score (P < 0.01) in milk. With the increase of CHI, glutathione peroxidase (P = 0.03) and superoxide dismutase (P = 0.01) activity showed a quadratic increase, while CHI quadratically increased reactive oxygen species (P < 0.01) activity, and linearly reduced malondialdehyde (P = 0.01) and nitric oxide (P < 0.01) content in serum. The supplementation of CHI to the diet suppressed the activity and expression level of gene and protein of inducible nitric oxide synthase, and linearly decreased interleukin-1 content (P = 0.02) and gene expression (P = 0.02). The supplementation of CHI linearly increased the proportion of CD4+ (P < 0.01) and CD3+ (P = 0.03) T lymphocytes. The supplementation of CHI linearly down-regulated the expression of nuclear factor-kappa Bp65 gene (P = 0.01) and phosphorylation level (P = 0.01) in peripheral blood mononuclear cells and linearly inhibited the activity of inducible nitric oxide synthase (P < 0.01) and the production of nitric oxide (P = 0.01). The results suggested that the supplementation of CHI to the diet of dairy cows can improve the milk performance, antioxidant function and reduce pro-inflammatory mediators, which may be related to its inhibition of nuclear factor-kappa B pathway.

Automated summary

This study found that dietary supplementation of CHI can significantly improve milk production, antioxidant function, and inhibit inflammatory response in dairy cows. This may be related to the inhibition of the nuclear factor-kappa B pathway by CHI.