Periparturient concentrations of insulin glucagon and ketone bodies in dairy cows fed two different levels of nutrition and varying concentrate/roughage ratios.

High producing multiparous dairy cows were fed either diets differing in energy content or diets with identical energy and protein content but differing in roughage content at the end of the dry period and beginning of lactation. Basal insulin and ketone bodies were analysed every week from 3 weeks before to 7 weeks after calving. Pancreatic glucagon was estimated 3 weeks before, 1-3 days after, and 3 weeks after calving. Before calving the feeding regimen had a very strong influence on the basal insulin level. High amounts of concentrate increased basal insulin levels until one week before calving and caused an interruption in the physiological decreasing course. After calving the insulin levels were low in all groups of cows. Before calving there were small variations in the glucagon levels, and no influence of feeding was observed. After calving there was a strong increase, especially in the cows fed the highest amounts of concentrate. Feeding high amounts of concentrate resulted in varying and in many cases increased levels of ketone bodies in plasma. Hyperketonemic cows had lower insulin and higher glucagon levels than normal cows. The influence of non-structural carbohydrates in the feed on pancreatic hormones is a cause of ketogenesis is discussed.