From a metabolic standpoint, the start of lactation is the most challenging period in a dairy cow’s life cycle. Increased energy demands are often met by mobilizing fat reserves. This can result in Hyperketonemia, or ketosis, which is defined by elevated ketone bodies in the blood.
Ketosis and subclinical ketosis negatively impact milk production, animal health, and profitability. Research has shown that ketosis affects 40 to 60% of dairy cows, at an average cost of $289 per case. Cows with ketosis produce less milk, are more likely to develop a displaced abomasum, and are more likely to be culled from the herd. Ketosis in fresh cows can be seasonal and impacted by herd management changes.
Source:uwex.edu