Glucose uptake in tissues is mediated by insulin receptor (INSR) and glucose transporter 4 (GLUT4). The aim of this study was to examine the effect of body condition during the dry period on adipose tissue mRNA and protein expression of INSR and GLUT4, and on the dynamics of glucose and insulin following the i.v. glucose tolerance test in Holstein cows 21 d before (d -21) and after (d 21) calving. Cows were grouped as body condition score (BCS) ≤3.0 (thin, T; n = 14), BCS = 3.25 to 3.5 (optimal, O; n = 14), and BCS ≥3.75 (overconditioned, OC; n = 14). Blood was analyzed for glucose, insulin, fatty acids, and β-hydroxybutyrate concentrations. Adipose tissue was analyzed for INSR and GLUT4 mRNA and protein concentrations. During the glucose tolerance test 0.15 g/kg of body weight glucose was infused; blood was collected at -5, 5, 10, 20, 30, 40, 50, and 60 min, and analyzed for glucose and insulin. On d -21 the area under the curve (AUC) of glucose was smallest in group T (1,512 ± 33.9 mg/dL × min) and largest in group OC (1,783 ± 33.9 mg/dL × min), and different between all groups. Basal insulin on d -21 was lowest in group T (13.9 ± 2.32 µU/mL), which was different from group OC (24.9 ± 2.32 µU/mL. On d -21 the smallest AUC 5-60 of insulin in group T (5,308 ± 1,214 µU/mL × min) differed from the largest AUC in group OC (10,867 ± 1,215 µU/mL × min). Time to reach basal concentration of insulin in group OC (113 ± 14.1 min) was longer compared with group T (45 ± 14.1). The INSR mRNA abundance on d 21 was higher compared with d -21 in groups T (d -21: 3.3 ± 0.44; d 21: 5.9 ± 0.44) and O (d -21: 3.7 ± 0.45; d 21: 4.7 ± 0.45). The extent of INSR protein expression on d -21 was highest in group T (7.3 ± 0.74 ng/mL), differing from group O (4.6 ± 0.73 ng/mL), which had the lowest expression. The amount of GLUT4 protein on d -21 was lowest in group OC (1.2 ± 0.14 ng/mL), different from group O (1.8 ± 0.14 ng/mL), which had the highest amount, and from group T (1.5 ± 0.14 ng/mL). From d -21 to 21, a decrease occurred in the GLUT4 protein levels in both groups T (d -21: 1.5 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL) and O (d -21: 1.8 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL). These results demonstrate that in obese cows adipose tissue insulin resistance develops prepartum and is related to reduced GLUT4 protein synthesis. Regarding glucose metabolism, body condition did not affect adipose tissue insulin resistance postpartum.

Adipose tissue plays an important role in a cow's ability to adapt to the metabolic demands of lactation, because of its central involvement in energy metabolism and immunity. High adiposity and adipose tissue resistance to insulin are associated with excessive lipid mobilization. We hypothesized that the response to a glucose challenge differs between cows of different body condition 21 d before and after calving and that the responses are explainable by gene expression in subcutaneous adipose tissue (SAT). In addition, we aimed to investigate insulin resistance with gene expression in SAT and lipid mobilization around parturition. Multiparous Holstein cows were grouped according to body conditions score (BCS) 4 wk before calving, as follows: BCS ≤ 3.0 = thin (T, n = 14); BCS 3.25 to 3.5 = optimal (O, n = 14); BCS ≥ 3.75 = over-conditioned (OC, n = 14). We collected SAT on d −21 and d 21 relative to calving. A reverse-transcriptase quantitative (RT-q) PCR was used to measure gene expression related to lipid metabolism. One hour after the collection of adipose tissue, an intravenous glucose tolerance test was carried out, with administration of 0.15 g of glucose per kg of body weight (with a 40% glucose solution). Once weekly from the first week before calving to the third week after calving, a blood sample was taken. The transition to lactation was associated with intensified release of energy stored in adipose tissue, a decrease in the lipogenic genes lipoprotein lipase (LPL) and diacylglycerol O-acyltransferase 2 (DGAT2), and an increase in the lipolytic gene hormone-sensitive lipase (LIPE). On d −21, compared with T cows, OC cows had lower mRNA abundance of LPL and DGAT2, and the latency of fatty acid response after glucose infusion was also longer (8.5 vs. 23.3 min) in OC cows. Cows with higher insulin area under the curve on d −21 had concurrently lower LPL and DGAT2 gene expression and greater concentration of fatty acids on d −7, d 7, and d 14.In conclusion, high adiposity prepartum lowers the whole-body lipid metabolism response to insulin and causes reduced expression of lipogenic genes in SAT 3 weeks before calving. In addition, more pronounced insulin release after glucose infusion on d −21 is related to higher lipid mobilization around calving, indicating an insulin-resistant state, and is associated with lower expression of lipogenic genes in SAT.

This work examined the effects of precalving administration of continuous-release monensin capsule on postcalving milk fatty acid (FA) profile and on the accuracy of FA as a biomarker in the early identification of cows with elevated blood plasma nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) concentrations. Approximately 3 wk before expected calving, 203 multiparous Estonian Holstein cows were randomly divided into control (CO; n = 116) and experimental (MO; n = 87) groups, and a continuous-release capsule of monensin was administered to the MO cows. Blood samples were taken daily in the first 4 d postpartum, then on the sixth or seventh day in milk, twice in the second week, and thenceforth once per week until the end of the sixth week. Milk samples were taken once from 4 to 7 d in milk, twice in the second week, and thenceforth once per week. Blood samples were analyzed for NEFA and BHB, and milk was analyzed for FA concentrations. Cows with postpartum BHB concentrations ≥1.2 mmol/L at least once during the 6 wk were classified as hyperketonemic (HYK), and cows with NEFA concentrations ≥1.0 mmol/L as having elevated concentration of NEFA (NEFA H ). The ability of FA to predict NEFA H and HYK cows was studied with logistic regression and receiver operating characteristic curve analysis and the identification accuracy was estimated by area under the receiver operating characteristic curve. For these analyses, we used FA measured on the ninth day after calving. Monensin administration affected FA mobilization and metabolism of the animals as blood NEFA were lower in the MO group on wk 1 and wk 3, and BHB values were considerably lower from wk 1 to wk 4 compared with the CO group. The FA dynamics were generally similar for MO and CO groups. Monensin ad-ministration resulted in higher concentrations of C15:0, C16:0, iso C17:0, anteiso C15:0, anteiso C17:0, total trans monounsaturated FA, and C18:2 cis-9,trans-11, and lower proportions of C18:0, C18:1 cis-9, and most of the iso FA. The identification accuracy of NEFA H and HYK cows was higher in the CO compared with the MO group and for the identification of HYK compared with NEFA H cows (0.75-0.77 vs. 0.78-0.80 in the CO group, and 0.61-0.66 vs. 0.68-0.75 in the MO group for NEFA H vs. HYK, respectively). For all FA, the threshold values to identify NEFA H and HYK cows were different in the CO and MO groups. Results suggest that specific threshold values for the identification of NEFA H and HYK cows could be applicable only within similar feeding conditions and rumen environment.

No abstract

No abstract