Effects of Subclinical Ketosis and Subclinical Hypocalcemia on Some Biochemical Parameters and Reproduction in Cows

The purpose of the study was to evaluate the effects of Subclinical Hypocalcemia (SCH) and Subclinical Ketosis (SCK) diagnosed on the 10^th day of lactation on reproductive performance.

The study used 120 clinically healthy Holstein cows aged 2 to 6 years who had just given birth and had no puerperal illness. Blood samples were collected on the 10^th and 30^th postpartum days and centrifuged at 3000 rpm for 15 minutes. The serum was removed and stored at -80°C until analysis. β-hydroxybutyrate (BHB), Non-esterified fatty acids (NEFA), glucose, cholesterol, triglycerides, aspartate aminotransferase (AST), alanine aminotransferase (ALT), calcium (Ca), phosphorus (P) and magnesium (Mg) levels were measured. Cows with serum BHB levels >1.2 mmol/L were rated as SCK (n=10), those with serum BHB levels <1.2 mmol/L were rated as normal (n=50), those with serum total Ca levels <8.6 mg/dL were rated as SCH (n=30) and those with serum total Ca levels >8.6 mg/dL were rated as normal. Progesterone levels were evaluated using blood samples collected on the 30^th day after parturition. To assess the reproductive performance of the animals in the study, the calving to first estrus, calving to first insemination and calving to conception periods for each animal were measured in days and the number of inseminations per pregnancy was estimated.

In this study, no significant changes were observed in the biochemical parameters of cows with SCH. Calving to first estrus and calving to first insemination times were found to be higher in cows with SCH than in normal cows. There was no difference in other biochemical markers between normal and SCK cows, however NEFA and BHB levels were higher. While progesterone levels were higher in SCK-affected cows, there was no difference in reproductive parameters between these cows and non-ketotic cows.