The objective of the present study was to determine metabolic status in late pregnant (n = 15) and puerperal (n = 15) Simmental dairy cows. The various blood metabolites and serum enzyme activities were determined by photometric methods. The early lactation cows had the indicative values of the beta-hydroxybutyrate (BHB) (> 1.20 mmol/l) but did not display any clinical signs, which means that they had a typical subclinical condition. The lipomobilization markers, serum BHB and non-esterified fatty acids (NEFA) concentrations, were markedly enhanced (P<0.05) in early lactation cows. Liver steatosis compromised hepatocyte metabolism, leading to significantly weaker (P<0.05) circulating concentrations of glucose, triglyceride (TG) and urea, and induced some cellular lesions as evidenced by significant increases (P<0.05) in the serum bilirubin concentrations and theaspartate transaminase (AST) enzyme activities in early lactation cows. On the basis biochemistry estimation, early lactation cows had metabolic disturbances which were associated with ketosis, and some degree of hepatic lesions, probably due to fat infiltration. [Projekat Ministarstva nauke Republike Srbije, br. TR31001]

The objective of the present study was to investigate nutritional and metabolic status in Simmental cows during early and mid-lactation. Fifteen early lactation cows and 15 mid lactation cows were chosen for the analysis. Blood samples were collected to measure beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), glucose and the activity of aspartate transaminase (AST). Blood metabolites, milk yield, dry matter intake (DMI) and energy balance (EB) were recorded. Correlation analysis showed that DMI was significantly negatively correlated with NEFA, BHB and AST, and positively with glucose and TG. EB was significantly negatively correlated with NEFA, BHB and AST, and positively with glucose. Early lactation as compared to mid lactation cows were found to have significantly higher blood serum concentrations of NEFA, BHB and AST activities and lower blood serum concentrations of glucose and TG, but not significant. These metabolic changes were in correlation with DMI and EB, but not with milk yield. Suggest that they can serve as useful indicators of the nutritional and metabolic status of dairy cows during lactation.

No abstract

Insulin resistance is a phenomenon which accompanies the ongoing metabolic adaptation in cows during early lactation. The aim of our study was to determine the linear correlations of HOMA (Homeostatic Model Assessment), QUICKI (Quantitative Insulin Sensitivity Check Index) and RQUICKI (Revised Quantitative Insulin Sensitivity Check Index) indexes of insulin resistance with the metabolic status of cows (concentration of hormones, metabolites and body condition score). The experiment included 40 Holstein-Frisian cows in the fi rst week after calving. Indexes of insulin resistance valued: 18.68±5.43 (HOMA), 0.39±0.06 (QUICKI) and 0.45±0.06 (RQUICKI). Linear correlations were examined by testing the coeffi cient of correlation (r), determination (r 2 ,%) and regression parameter beta (b) in linear equation. A negative correlation was found between HOMA and IGF-I (insulin growth factor I) (r=-0.51, r²=25.0, b=-1.1257, p<0.01). HOMA showed a positive correlation with BHB (betahidroxybutyrate) (r=0.48, r²=23.2, b=0.0234, p<0.01). A positive correlation was found between QUICKI and IGF-I (r=0.30, r²=10.0 b=46.7900, p<0.05) and cholesterol (r=0.44, r²=18.3, b=1.9021, p<0.01). In contrast, QUICKI and BHB (r=0.51, r²=27.1, b=-1.7241, p<0.01), just like QUICKI and BCS (r=0.46, r²=20.9, b=-2.424, p<0.01), showed a negative correlation. RQUICKI showed positive correlations with IGF-I (r=0.48, r²=22.8, b=28.1230, p<0.01), T4 (r=0.47, r²=22.1, b=87.142, p<0.01) and triglycerides (r=0.36, r²=13, b=0.0407, p<0.05) but negative correlations with cortisol (r=-0.36, r²=13.0, b=-9.0332, p<0.05), STH (somatotropic hormone) (r=-0.42, r²=17.3, b=-5.4976, p<0.01), BHB (r=-0.62, r²=38.3, b=-1.1872, p<0.01), total bilirubin (r=-0.58, r²=33.7, b=-7.131, p<0.01) and BCS (body condition score) (r=-0.6, r²=36.4, b=-1.8347, p<0.01). In conclusion, indexes of insulin resistance may be used to evaluate the metabolic status of cows in early lactation. RQUICKI might be the most appropriate predictor of metabolic status due to its linear relationship with most of the parameters included in homeorhetic process.

Insulin resistance is a state in which the biological effect of insulin is reduced when its concentration decreases or when a compensatory mechanism increases its concentration. Insulin resistance is characterized by reduced insulin response to glucose, i.e. decreased pancreatic beta cell function (insulin hyporesponsiveness) and/or reduced sensitivity of glucose to insulin (reduced intake of glucose by peripheral tissues under the influence of insulin-eng. insulin sensitivity). Methods for estimating insulin resistance include direct methods (hyperinsulinaemic-euglycaemic clamp, golden standard), indirect methods (intravenous glucose tolerance test) and surrogate methods (indices calculated from basal concentrations of insulin, glucose, NEFA and BHB-HOMA, QUICKI, RQUICKI and RQUICKI-BHB). Surrogate indices show correlations with direct and indirect test results but they are inconsistent. Inconsistency occurs because the dependence of glucose concentrations on the degree of hepatic gluconeogenesis should be kept in mind when evaluating insulin resistance in ruminants. Therefore, the hyperinsulinaemic-euglicaemic clamp method is particularly suitable as it excludes gluconeogenesis in hepatocytes from analysis. Our results have shown a correlation between HOMA, QUICKI and RQUICKI indices and metabolic profile parameters. The correlation between dynamic and basal responses of NEFA, BHB, insulin, glucose and inorganic phosphorus is significantly dependent on RQUICKI-BHB index values in