Compromised liver functions during the breeding period of clinically healthy Holstein cows

The sub-clinical carry-over effects of post-partum (PP) conditions and the problems independent of parturition may affect the cows' performance during the breeding period.

It was hypothesized that some mid-lactation cows may have compromised liver functions and calculating liver activity index (LAI; -1.5 to +1.5) may be helpful in detecting such conditions.

Plasma lipid and protein profiles, retinol and ceruloplasmin were measured in 37 Holstein cows on days 60, 90, and 120 PP. Liver activity index was calculated using the measures of cholesterol, albumin and retinol. The results were interpreted using some health and performance indices.

The mean LAI was 0.00 ± 0.61. Sixteen cows (45.7%) were LAI‾ and 19 cows (54.3%) were LAI⁺. In LAI⁺ cows the concentrations of cholesterol and albumin were unchanged, but in LAI‾ cows both of them increased through the study (P<0.05). Greater concentrations of low density lipoproteins (LDL) (P<0.01) and lower concentrations of γ- and total globulins (P<0.05; day 60) were detected in LAI⁺ cows. Ceruloplasmin was not different between the LAI groups with the highest level on day 90. Cholesterol had the strongest and the most repeated correlations with LAI during the study. The correlation of albumin with LAI faded on day 120 and vitamin A had a relationship only on day 60 PP. Triglycerides (TGs), very low density lipoproteins (VLDL) (day 60) and LDL (days 60 and 90) had positive correlations with LAI. All globulin fractions showed negative correlations with LAI on day 60. Seventy percent of the cows without endometritis (day 30 PP) and 33% of the infected cows were LAI⁺ during the breeding period. About 79% of the cows with body condition score (BCS) loss ≤0.75 (day 60) and 38% of the cows with BCS loss >0.75 were LAI⁺ during the breeding period.

Compromised liver functions may exist in dairy cows during the breeding period and may be detected by calculating LAI. The relationship of LAI during the progressed lactation with herd's performance needs to be investigated.