Regulation of Bovine Adipose Tissue Metabolism During Lactation. 2. Lipolysis Response to Milk Production and Energy Intake

Abstract

Lipolytic adaptations of bovine adipose tissue during late pregnancy, lactation, and dry period were studied in Holsteins. Treatment groups consisted of first lactation daughters of high or low bulls based on Predicted Difference for milk. Heifers were fed either a 60% concentrate, 40% hay diet or a 40% concentrate, 60% hay diet from 0 to 140 d lactation. Feeding a low energy diet for the first 140 d of lactation did not affect adipose tissue lipolytic rates measured in vitro. Epinephrine and norepinephrine responsiveness of bovine adipose tissue increased prior to parturition, increased further in early lactation, then remained elevated during lactation and into the dry period. This responsiveness was unaffected by feeding low energy diets. Basal glycerol release in high genetic merit heifers was 64, 17, 40, 23, 20, and 42% greater than in low genetic merit heifers at -30, -15, 30, 60, 180, and 349 d about parturition. Response to norepinephrine was 15, 20, 18, and 15% greater in high genetic than low genetic merit heifers and response to epinephrine was 12, 20, 14, and 50% greater in high genetic than low genetic merit heifers at 30, 60, 180, and 349 d postpartum. The lack of a dietary energy restriction effect on lipolysis in early lactation suggested that these rates were near the physiological maximum for those animals. Rates of lipolysis were positively related with milk fat production. This study indicates a genetic component in adrenergic regulation of lipolysis in adipose tissue, independent of energy balance, in supporting lactation.

Expression of NGF, BDNF and their receptors in subcutaneous adipose tissue of lactating cows

“…Similarly, a large body of research has been devoted to the study of fat metabolism and its implication on physiological regulation during health and disease conditions in dairy cows (McNamara and Hillers, 1986;Graugnard et al, 2012 andSgorlon et al, 2015).…”

“…Research in Veterinary Science 102 (2015) 196-199 Six mid lactation cows (180 ± 20 days in milking, DIM) from a commercial farm were selected. Biopsies of scAT were collected from the dorsal pelvic region as described by McNamara and Hillers (1986), using a 20 gauge biopsy needle. Tissue samples were divided in two aliquots, one immediately frozen at −80°C and the second fixed in 10% (w/v) neutral formalin for 24 h at room temperature.…”

Variation in fat mobilization during early lactation differently affects feed intake, body condition, and lipid and glucose metabolism in high-yielding dairy cows

“…Therefore, the transition period and the earlylactation period are characterized by the mobilization of body reserves of different tissues, in particular fat tissue (Ingvartsen and Andersen, 2000;Drackley et al, 2001), to cover the energy demand, and include various metabolic and endocrine adaptations. It seems that cows with high genetic merit for milk production mobilize more body reserves than cows with lower genetic merit (McNamara and Hillers, 1986;Pryce et al, 2001), to bridge the gap between energy intake and energy output. High rates of fat mobilization lead to markedly increased plasma concentrations of NEFA and, in consequence, the accumulation of triglycerides (TAG) in the liver (Bobe et al, 2004;Overton and Waldron;2004).…”

Proliferation and apoptosis in subcutaneous adipose tissue of lactating cows with different genetic merit for milk yield

“…The energy deficit during early lactation in high yielding dairy cows is accompanied by fat mobilization from AT. In a condition of negative energy balance (NEB), reduced lipogenesis and increased lipolysis is described in discrete AT depots (McNamara and Hillers, 1986). When the energy balance reaches positive values, the energy is stored in AT depots, which are increasingly refilled by means of lipogenesis and by adipogenesis, thus preparing the organism for the upcoming energy deficit in the subsequent lactation (Hausman et al, 2001;McNamara, 1995).…”