Effects of Diet and Stress Mimicked by Corticosterone Administration on Early Postmortem Muscle Metabolism of Broiler Chickens

Abstract

Three experiments were conducted to evaluate the effects of preslaughter physiological states mimicked by long- or short-term administration of corticosterone (CORT) and dietary energy sources on muscle glycogen contents and meat quality of broiler chickens. In experiment 1, the broilers were fed a high lipid diet (LD) or a normal diet (ND) that differed in carbohydrate (3.8%) and lipid (2.5%) contents from 21 d of age. From 28 d of age onwards, 50% of the chickens in each dietary treatment were subjected to CORT treatment (30 mg/kg of diet). At 7 and 11 d after CORT supplementation, musculus pectoralis major was sampled before and immediately after slaughter and analyzed for glycogen, pH, and R-value. In experiment 2, broilers, fed with the LD or ND diet from 21 d of age were subjected to 1 single s.c. injection of CORT (4 mg/kg of BW) for 3 h to mimicked acute stress at 46 d of age. In experiment 3, broiler chickens were supplied with water supplemented with glucose (30 g/L) for 1 wk before slaughter and were then subjected to the same CORT treatment as experiment 2. Blood and muscle samples were respectively obtained before and immediately after slaughter and analyzed for plasma glucose, urate and lactic acid, and muscle variables. Plasma concentrations of glucose and urate were significantly increased by acute CORT administration, whereas the lactic acid was not changed. Neither dietary energy source nor water glucose supplementation had any influence on the plasma variables. Dietary energy source or water glucose supplementation could not alter glycogen stores in musculus pectoralis major. Breast muscle glycogen stores were increased by stress mimicked by long-term CORT administration rather than by acute treatment. Preslaughter stress reactions had no relation to the depletion of breast muscle glycogen during the initial postmortem period. The initial breast muscle pH was significantly decreased by long-term CORT administration. The result suggests that short-term upregulation of circulating CORT is not involved in the elevated drip loss induced by preslaughter stress.

Hormones and Metabolism in Poultry

“…• Increasing circulating concentrations of glucose (Lin et al, 2007;Jiang et al, 2008;Yuan et al, 2008;Zhao et al, 2009) although depressed circulating concentrations of glucose have also been reported (Gao et al, 2008) • Increasing circulating concentrations of insulin (Jiang et al, 2008;Yuan et al, 2008;Zhao et al, 2009 • Increased breast muscle glycogen (Lin et al, 2007) but lower levels have also been reported (Gao et al, 2008). Despite the marked effects on glucose metabolism, circulating concentrations of lactate are unchanged in chickens receiving glucocorticoid administration (Lin et al, 2007).…”

“…Despite the marked effects on glucose metabolism, circulating concentrations of lactate are unchanged in chickens receiving glucocorticoid administration (Lin et al, 2007). There is a growing viewpoint that corticosterone acts via induction of insulin resistance.…”

“…• Decreasing circulating concentrations of total amino-acids (Gao et al, 2008) and increased concentrations of urate (Lin et al, 2007). These are indicative of both increases in deamidation of amino-acids and consequently of gluconeogenesis (Lin et al, 2007) • Increasing gluconeogenesis by perfused liver (Kobayashi et al, 1989) • Reductions in super-oxide dismutase activity (Lin et al, 2009).…”

“…These are indicative of both increases in deamidation of amino-acids and consequently of gluconeogenesis (Lin et al, 2007) • Increasing gluconeogenesis by perfused liver (Kobayashi et al, 1989) • Reductions in super-oxide dismutase activity (Lin et al, 2009). …”

“…• Decreased skeletal muscle weight (Yuan et al, 2008;Song et al, 2011) • Increased protein degradation as indicated by increases in the concentrations of 3-methyl histidine in both pectoralis and femoris muscles (Dong et al, 2007) • Increases muscle proteolysis (Gao et al, 2008) • Reduced skeletal protein synthesis as indicated by the RNA:protein ratio (Dong et al, 2007) Decreasing the growth of the small intestine in chickens although the effect is of a small magnitude than that with overall growth as weight of the small intestine relative to body weight is increased (Hu et al, 2010) • Increases expression of myostatin (Song et al, 2011).…”