Evaluation of serum analytes in pregnant and non-pregnant dairy cows as indicators of pregnancy

This study was conducted to reveal the dynamics of haematological indicators in pregnant and nonpregnant dairy cows. Sixty multiparous healthy dairy cows were divided into four groups based on the length of time they had been pregnant, namely first, second and third trimesters, and non-pregnant (n=15 each). Blood was collected from each animal, and serum was harvested and stored at -20 degrees C for biochemical profiling. Concentrations of serum total oxidants (TOC), ceruloplasmin oxidase (CpO) and triiodothyronine (T-3) were higher (P <0.05) during the third trimester compared with non-pregnant cows. Serum arylesterase (Ary) concentration was lower (P <0.05) during the second and the third trimesters compared with the non-pregnant cows. The concentration of serum total homocysteine (tHcy) was higher (P <0.05) the third trimester compared with the first and the second trimesters. The concentrations of serum total antioxidants (TAC), paraoxonase 1 (PON1), thyroxine (T-4), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not different in the pregnant and the non-pregnant cows. Thus, TOC, Ary, CpO, tHcy and T3 could be taken as biological markers to assess the progression of pregnancy and to develop management tools to improve health status during late gestation in dairy cows.