engleski

Paraoxonase activity and lipid levels in the serum of dairy cows with liver hypertrophy

Oxidative stress could contribute to certain disorders in dairy cattle such as reproductive ones, liver diseases and infection. A major role in the development of oxidative stress is a negative energy balance which often occurs in late pregnancy and early lactation. Maternal metabolic accommodation for glucose and amino-acid requirements causes adipose fat mobilisation with a consequence of lipids accumulation in the liver and development of liver hypertrophy and fatty liver syndrome during lactation. Taking into account the antioxidative properties of paraoxonase, we used serum paraoxonase activity to monitor antioxidative capacity in dairy cows with liver hypertrophy. The relation between paraoxonase activity and HDL-cholesterol concentration was also compared. The study was carried out on 18 clinical healthy non-pregnant Holstein dairy cows in the middle lactation and 18 cows in the same reproduction period with clinical confirmed liver hypertrophy. The serum paraoxonase activity was determined by the method of hydrolysing of paraoxon, while glucose, triglyceride, cholesterol and HDL-cholesterol concentrations were measured by the enzymatic kit methods. A significantly lower paraoxonase activity (p<0.01) was found in cows with liver hypertrophy compared to clinical healthy cows. The serum glucose, triglyceride and cholesterol concentration were also markedly reduced in cows with hypertrophic liver (p<0.001, p<0.001 and p<0.05, respectively), while the serum HDL-cholesterol concentration showed no significant change. Paraoxonase/HDL-cholesterol ratio in liver hypertrophy was significantly lower (p<0.05) as well. A lower paraoxonase activity contribute to the reduction of the antioxidative capacity in cows with liver hypertrophy. Furthermore, results indicate the involvement of paraoxonase in hepatocellular oxidative stress.

paraoxonase; lipid levels; liver hypertrophy; dairy cows

nije evidentirano