INSULIN RESISTANCE IN COWS DURING DRY PERIOD AND EARLY LACTATION

Insulin resistance is pathophisiological term defined as change in insulin responsiveness (insulin response to glucose) or insulin sensitivity (tissue response to insulin) or both. The aim of this study was to investigate insulin resistance in dairy cows during dry period and early lactation, and determine influence of insulin, glucose and NEFA to RQUICKI index of insulin resistance. Cows in early lactation showed lower concentration of glucose and insulin and higher concentration of NEFA compared to cows in dry period. Insulin:glucose index are 2.5 in dry period and 2.05 in early lactation. RQUICKI index was lower during early lactation. Determination of RQUICKI value using a concentration of glucose, insulin and NEFA was correct in 78.9% in dry period and 84.5% in early lactation. During dry period insulin and glucose showed significant influence to RQUICKI value (negative correlation), but there was found absence of NEFA influences. However, NEFA only showed significant influences to RQUICKI in early lactation (negative correlation). Insulin and glucose determined RQUICKI in 56% from 78.9% of whole model, but in early lactation NEFA determined 32% from 84.5%. Higher glucose concentration means higher insulin response in dry period with consequently poor insulin binding and glucose transport. In this condition it is need higher concentration of insulin to neutralize same concentration of glucose. Therefore, found higher insulin:glucose ration was found in dry period in relation to early lactation. Insulin resistance is more intense in early lactation compared to dry period. Based on metabolic change insulin resistance in dry period is consequence of decreased insulin sensitivity of peripheral tissue with compensatory increased insulin:glucose ration. During early lactation there is decrease insulin and glucose concentration with lower insulin response to glucose. Absence of insulin increases lipid mobilization which determined insulin resistance level