Revised quantitative insulin sensitivity check index: Associations with the metabolic status of cows during early lactation

Abstract

© 2019, University of Zagreb, Facultty of Veterinary Medicine. All rights reserved. The revised quantitative insulin sensitivity check index (RQUICKI) is the most commonly used indicator of insulin resistance in dairy cows. The aim of this study was to examine the characteristics of metabolic status in cows with different RQUICKI index values during early lactation. The experiment included 40 Holstein-Friesian cows in the first week of lactation. The cows were classified into four groups according to quartile (Q 1 to 4) values of RQUICKI indexes: Q1 = 0.35-0.41 (most insulin resistant), Q2 = 0.42-0.52, Q3 = 0.53-0.67, Q4 = 0.68-0.77 (most insulin sensitive). Metabolic parameters were significantly different in early lactation cows, classified according to the values of the RQUICKI index. The cows that were the most resistant to insulin (Q1) had higher levels of non-esterified fatty acid (NEFA), cortisol, somatotropic hormone (STH), beta-hydroxybutyrate (BHB), total bilirubin, aspartate aminotransferase (AST), malondialdehyde (MDA) and body condition score (BCS) in comparison to the cows that were the least resistant to insulin (Q4). The cows also had lower levels of insulin-like growth factor I (IGF-I), triiodothyronine (T3), thyroxine (T4), albumin, cholesterol, triglycerides, Ca and P as well as a tendency towards lower insulin and glucose concentrations. Metabolic parameters were strongly regressed by RQUICKI in the most insulin resistant cows (Q1) in relation to the cows in the other groups, Q2-4. The cows with a higher number of metabolic abnormalities in their metabolic profiles had lower RQUICKI values: 0.56 ± 0.045 (no abnormalities); 0.52 ± 0.041 (1 abnormality); 0.47 ± 0.042 (2 abnormalities) and 0.4 ± 0.043 (≥3 abnormalities). We concluded that the RQUICKI index could be applied in order to accurately identify metabolic status in cows during early lactation. However, the kinetics of insulin sensitivity should be further studied using more animals per group, as well as in other breeds of cows.