Hyperglycaemia in transition dairy cows: Effects of lactational stage and conjugated linoleic acid supplementation on glucose metabolism and turnover

Abstract

Supplementing conjugated linoleic acid (CLA) is supposed to spare glucose due to the milk fat-depressing effect of the trans-10, cis-12 CLA isomer, and allows repartitioning nutrients despite an energy deficiency in early lactation. However, there is still a lack of knowledge in terms of the dynamic pattern of the glucose turnover in transition dairy cows. We hypothesized that dairy cows supplemented with CLA have an altered rate of glucose turnover and insulin sensitivity during early lactation. We conducted three consecutive hyperglycaemic clamps (HGC) in weeks -2, +2 and +4 relative to parturition in Holstein cows supplemented daily either with 70 g of lipid-encapsulated CLA (6.8 g trans-10, cis-12 and 6.6 g of the cis-9, trans-11 CLA isomer; CLA; n = 11) or with 56 g of control fat (CON; n = 11). From week -3 up to week +4 relative to parturition, milk yield and dry matter intake (DMI) were recorded daily, while body weight (BW) and milk composition were obtained once weekly. Blood samples were taken once weekly and every 30 min during the HGC. Plasma was analysed for concentrations of glucose, fatty acids (FFA), beta-hydroxybutyrate (BHB), insulin, triglycerides and cholesterol. The CLA supplementation did not affect performance and metabolic parameters except for BHB and cholesterol. Furthermore, insulin concentrations and insulin sensitivity were affected by treatment. During the HGC in early lactation, insulin response was lower and decrease in FFA and BHB greater compared with the HGC in week -2 although glucose target concentration achieved during the steady-state period was similar for all three HGC. Our findings in terms of insulin and cholesterol suggest that body reserves are preserved through CLA feeding without restraining animal's performance. Furthermore, CLA effects on cholesterol and triglyceride concentrations indicated beneficial effects on hepatic lipid export contributing to an improved efficiency of prevailing metabolites in circulation.

Inflammatory and metabolic responses to an intramammary lipopolysaccharide challenge in early lactating cows supplemented with conjugated linoleic acid

“…The induction of the diverse local and systemic responses during an intramammary LPS challenge was shown to be influenced by the metabolic status of the dairy cow (Vernay et al., ). Although we did not observe a milk fat depressing effect in CLA‐fed cows, the supplementation of CLA has the potential to improve the metabolic status (Baumgard, Corl, Dwyer, & Bauman, ; Benninghoff, Metzger‐Petersen, Tröscher, & Südekum, ; Galamb et al., ) and in particular modulate the repartitioning of nutrients such as glucose in early lactation (Grossen‐Rösti et al., ; Harvatine, Perfield, & Bauman, ). We assumed that besides supporting other tissues, the “improved” glucose availability benefits the immune response during an inflammatory process.…”

“…The supplementation of dairy cows with the trans ‐10, cis ‐12 isomer of conjugated linoleic acid (CLA) causing a milk fat depression was shown to allow nutrient repartitioning despite an energy deficiency in early lactation (De Veth et al., ) and also to spare glucose (Grossen‐Rösti, Kessler, Tröscher, Bruckmaier, & Gross, ). The “abundant” nutrients, in particular glucose, might improve the metabolic status, benefit the immune system and thus reduce the risk of infectious diseases such as mastitis.…”

Invited review: Metabolic challenges and adaptation during different functional stages of the mammary gland in dairy cows: Perspectives for sustainable milk production

“…Glucose infusions in transition dairy cows before and after calving revealed differences in the endocrine response (Sartin et al, 1985;Grossen-Rösti et al, 2018). Glucose clearance rate was higher in early lactation than in late gestation accompanied by a shortterm increase of milk production on the infusion day (Grossen-Rösti et al, 2018). However, administered glucose was not fully converted into additional milk synthesis.…”

“…The question of whether glucose in early lactation is limiting for milk synthesis was addressed by different approaches. Infusing glucose in early lactation temporarily increased milk yield (Brown and Allen, 2013;Grossen-Rösti et al, 2018), although some authors argued that import capacities via GLUT and sodium-dependent glucose transporters into the mammary gland are limited (Zhao and Keat-ing, 2007b). In mid-to late-lactating cows, we could show that the expression of glucose transporters in the mammary gland seems to not be affected by a shortage of glucose forced by insulin infusion, whereas enzymes and milk components directly depending on glucose as precursor were immediately downregulated (Gross et al, 2015b).…”

“…During LPS-induced mastitis in combination with hypoglycemia, mammary gland metabolism was more aligned to save glucose for the immune system compared with the situation in which glucose availability was not limited (Vernay et al, 2012). Glucose infusions in transition dairy cows before and after calving revealed differences in the endocrine response (Sartin et al, 1985;Grossen-Rösti et al, 2018). Glucose clearance rate was higher in early lactation than in late gestation accompanied by a shortterm increase of milk production on the infusion day (Grossen-Rösti et al, 2018).…”