Effect of increasing body condition on key regulators of fat metabolism in subcutaneous adipose tissue depot and circulation of nonlactating dairy cows

Abstract

In response to negative energy balance, overconditioned cows mobilize more body fat than thin cows and subsequently are prone to develop metabolic disorders. Changes in adipose tissue (AT) metabolism are barely investigated in overconditioned cows. Therefore, the objective was to investigate the effect of increasing body condition on key regulator proteins of fat metabolism in subcutaneous AT and circulation of dairy cows. Nonlactating, nonpregnant dairy cows (n=8) investigated in the current study served as a model to elucidate the changes in the course of overcondition independent from physiological changes related to gestation, parturition, and lactation. Cows were fed diets with increasing portions of concentrate during the first 6wk of the experiment until 60% were reached, which was maintained for 9wk. Biopsy samples from AT of the subcutaneous tailhead region were collected every 8wk, whereas blood was sampled monthly. Within the experimental period cows had an average BW gain of 243±33.3 kg. Leptin and insulin concentrations were increased until wk 12. Based on serum concentrations of glucose, insulin, and nonesterified fatty acids, the surrogate indices for insulin sensitivity were calculated. High-concentrate feeding led to decreased quantitative insulin sensitivity check index and homeostasis model assessment due to high insulin and glucose concentrations indicating decreased insulin sensitivity. Adiponectin, an adipokine-promoting insulin sensitivity, decreased in subcutaneous AT, but remained unchanged in the circulation. The high-concentrate diet affected key enzymes reflecting AT metabolism such as AMP-activated protein kinase and hormone-sensitive lipase, both represented as the proportion of the phosphorylated protein to total protein, as well as fatty acid synthase. The extent of phosphorylation of AMP-activated protein kinase and the protein expression of fatty acid synthase were inversely regulated throughout the experimental period, whereas the extent of phosphorylation of hormone-sensitive lipase was consistently decreasing by the high-concentrate diet. Overcondition in nonpregnant, nonlactating dairy cows changed the expression of key regulator proteins of AT metabolism and circulation accompanied by impaired insulin sensitivity, which might increase the risk for metabolic disorders.

Methionine supply during the periparturient period enhances insulin signaling, amino acid transporters, and mechanistic target of rapamycin pathway proteins in adipose tissue of Holstein cows

“…The greater overall abundance of LIPE in Met-fed cows particularly after calving is noteworthy and would suggest a more pronounced degree of lipolysis (Khan et al, 2013;Locher et al, 2015). Whether differences in abundance of LIPE are a reflection of insulin sensitivity status is unclear.…”

Relationship between the pre- and postpartum body condition scores and periparturient indices and fertility in high-yielding dairy cows

“…Jankowska and Sawa (14) also reported a positive correlation between an excessively good body condition (reserve fat) towards the end of lactation and in the dry period and the length of the period of insemination services. For cows with BCS >3.5 during the transition from late gestation to early lactation, considerable amounts of adipose tissue are mobilised, resulting in elevated plasma nonesterified fatty acids (NEFA) supporting increased energy requirements in dairy cows and at the same time negative energy balance (NEB) (19). Circulating NEFA can be oxidised in the hepatocytes or exported as constituents of very low density lipoproteins (VLDL).…”

“…Circulating NEFA can be oxidised in the hepatocytes or exported as constituents of very low density lipoproteins (VLDL). However, postpartum release of NEFA from adipose tissue mostly exceeds the needs and oxidation capabilities of the liver (19) and causes formation of ketone bodies including β-hydroxybutyrate (BHBA) and reesterification to triglycerides (TG). The latter are stored in hepatocytes and implicate the development of fatty liver, reduced metabolic function, health status, productivity, and reproductive performance, as well as incidence and severity of metabolic disorders and infectious diseases (2).…”

Metabolic profiles of cow's blood; a review

“…56 Over-conditioning in non-pregnant, non-lactating dairy cows changed the expression of key protein regulators of adipose tissue metabolism while impairing insulin sensitivity. 57 Roche et al 58 reported a greater BCS loss in early lactation with increasing calving BCS, and a decreasing rate of BCS gain post-nadir with increasing nadir BCS. Chmielewski 59 reported that the contents of NEFA and BHBA were highest in cows characterized by the strongest lipolysis in the first period of lactation (condition BCS > 4).…”

“…There is a nonlinear association between BCS and the incidence of milk fever as a result of both attenuated post‐calving DMI (in cows with BCS > 3.5) and increased milk production supported by catabolism of tissue reserves . Over‐conditioning in non‐pregnant, non‐lactating dairy cows changed the expression of key protein regulators of adipose tissue metabolism while impairing insulin sensitivity . Roche et al .…”