The effect of subclinical and clinical ketosis on metabolic disease, milk yield and reproductive parameters in dairy cows

Negative energy balance (NEB) is a physiological state that arises during the transition from pregnancy to lactation in dairy cows. This transition period is associated with a decline in dry matter intake and an increased demand for energy sources for milk production. Ketosis, a metabolic disorder, often emerges shortly after calving and is characterized by reduced glucose levels, depleted liver glycogen, and elevated ketone body concentrations. The study aimed to investigate the impacts of ketosis on milk yield, reproductive parameters, and postpartum metabolic diseases in cows with subclinical and clinical ketosis. The study involved 267 healthy pregnant Holstein dairy cows in the second and third lactation periods. Groups were formed based on postpartum third-day beta-hydroxybutyrate (BHBA) levels. The groups included control (BHBA < 1,2 mmol/dL), subclinical ketosis (BHBA = 1,2-2,4 mmol/dL), and clinical ketosis (BHBA > 2,4 mmol/dL) groups. Results indicated that higher body condition scores (BCS) during calving were associated with an increased risk of postpartum ketosis (p<0,001). Subclinical ketosis led to a higher number of inseminations per pregnancy (p<0,01), extended service periods (p<0,001), and decreased pregnancy rates at first insemination (p>0,05). It was observed that the clinical ketosis group had a longer time to reach peak milk yield (p<0,001) and a higher peak milk yield (p<0,01). The incidence of septic metritis was found to be higher in cows with clinical ketosis (p<0,01). Consequently, the study revealed that ketosis has negative effects on reproductive parameters, milk yield, and the incidence of metabolic diseases. Additionally, the importance of BCS in assessing and managing the risk of ketosis in dairy cows during their transition period was emphasized. It is believed that further evaluation of the study with more animal material and additional parameters could yield more meaningful results. Keywords: BHBA, negative energy balance, cattle, milk yield