Blood concentrations of thyroid hormones and lipids and histological changes in the liver in dairy cows in post-parturient period

Radojica Djokovic

doi:10.2298/vetgl0906285d

Abstract

The triiodthyronine (T3), thyroxine (T4), glucose, free fatty acids (FFA), triacylglycerols (TAG) and total cholesterol concentrations were estimated in the blood serum and content of lipids in the liver in healthy (n=10) and ketotic (n=10) dairy cows in the post parturient period. Samples of liver and blood tissues were taken from all the cows. Pathohistoligical examination of liver tissues showed statistically significant higher (p<0.01) lipid infiltration in ketotic cows compared to healthy ones. Biochemical examination of blood serum showed significantly higher values (p<0.01) of free fatty acids in ketotic cows such as significantly lower concentrations of glucose (p<0.01), triacylglycerols (p<0.01), total cholesterol (p<0.05), triiodthyronine (p<0.05) and thyroxine (p<0.05) compared to values of these parameters in the blood serum in healthy cows. Significant increase of concentration of free fatty acids, such as positive correlation (r=0.51; p<0.05) between the free fatty acids in blood and the content of lipids in liver in ketotic cows compared to healthy ones, as well as pathohistological report, shows that during intensive lipomobilisation newly synthesized triacylglycerols accumulated in the hepatocytes. In ketotic cows hypo thyroidal status is established and it can be a significant factor in the development of fatty liver. .

Highlights

The triiodthyronine (T3), thyroxine (T4), glucose, free fatty acids (FFA), triacylglycerols (TAG) and total cholesterol concentrations were estimated in the blood serum and content of lipids in the liver in healthy (n=10) and ketotic (n=10) dairy cows in the postparturient period
Fatty liver and ketosis present the most frequent disturbances occuring in dairy cows, resulting in significant economical losses due to a decrease in milk production (10-15%) high expenses of therapeutic treatment, emergency slaughter and deaths
Under the conditions of a negative energy balance and of high lipomobilisation, the concentrations of thyroid hormones were reduced in blood of dairy cows in the postparturient period, with pronouncedly declined triiodthyronine in blood shortly before and after calving (Blum et al, 1983; Gerloff et al, 1986; Nikoli} et al, 1997; Reist et al, 2002; Pezzzy et al, 2003)