The relationship between body condition score, thyroxin, and health condition and serum energy indices, insulin like growth factor-1, and lipids profile over the transition period in Holstein dairy cows.

Background: Lipid mobilization increases significantly in cows around the time of calving; a correlation between excessive blood NEFA concentrations, oxidative stress, and impaired health status in transition dairy cattle was observed. Aims: The relationship between serum thyroxin (T4) values and energy indices and lipid profile in all cows, non-fat cows (NFCs), fat cows (FCs), healthy, and diseased animals were estimated in the present study.
Methods: Blood samples were obtained from fifty multiparous cows on -14, +10, +20, and +30 days relative to parturition. They had similar diets and were kept under the same management conditions.
Results: NEFA and BHBA values increased significantly on the 10th day of calving. Inversely, glucose, T4, triglyceride, LDL-C, and VLDL-C decreased significantly ten days after calving. There was a significant negative correlation between serum T4 and NEFA for all cows and FCs. Serum T4 and BHBA values had a significant negative correlation in NFCs, FCs, healthy, and diseased cows. In addition, serum T4 and fructosamine had a significant negative relationship in FCs and a significant positive correlation in diseased cows. Serum T4 values had a significant negative correlation with cholesterol, HDL-C, and a positive correlation with triglyceride and VLDL-C for all cows, NFCs, FCs, and healthy cows.
Conclusion: The data emphasized the effects of negative energy balance during the transition period on serum lipids profile and thyroid function. In addition, the correlation between T4 and energy and lipids indices may indicate a possible effect of health and body condition status on thyroid responses.