The effects of dietary phytase activity on the concentration of Coenzyme Q10 in the liver of young turkeys and broilers

Coenzyme Q (2,3-dimethoxy, 5-methyl, 6-polyisoprene parabenzoquinone, ubiquinone) is the lipid soluble compound present in endomembranes of cells as well as in the mitochondria. It is involved in the mitochondrial respiratory chain, accepts and transports electrons to oxygen and at the same time the proton gradient promotes ATP synthesis. The presence of high concentrations of coenzyme Q in all membranes enhances the antioxidant status of these membranes either by direct reaction with free radicals or by regeneration of tocopherols and ascorbate (Surai et al., 2004). A protective effect of coenzyme Q against lipid peroxidation was shown in fatty acid emulsions. Coenzyme Q protects effectively not only membrane phospholipids from oxidation but also mitochondrial and membrane proteins from free-radical-induced oxidative damage and is continuously regenerated by an intracellular reduction system in animals tissues (Geng et al., 2004). Dietary phytase improves not only phytate P utilisation but also the utilisation of other dietary nutrients including minerals, proteins, starch and energy (Ravindran et al., 2001). The improvements seen with the use of phytases may be a function of improved health and could also be reflected in improved antioxidant status within the bird. However, there is no existing information about the effect of dietary phytase on the antioxidant status of commercially reared birds. There are at least two possibilities where the oxidative stress on the birds may be altered by the presence of phytase in the diets. The increased utilisation of nutrients may enhance the antioxidant status of the birds, however, the increased availability and uptake of metal ions may also increase the oxidative stress on the bird. Exogenous phytase supplementation in poultry feed, low in available P, may trigger coenzyme Q synthesis, thereby reducing oxidative stress and improve performance. Nine hundred and sixty birds (480 chickens and 480 turkeys) were randomly assigned to 64 floor pens in a split plot design. Low P maize-based diets, otherwise nutritionally adequate, were offered to chickens and turkeys, respectively. Each of the basal diets was split into 4 batches, with one of the diets being used as a control without enzyme. An evolved E. coli phytase was added (250, 500 and 2500 U/kg) to each of the diets for chickens and turkeys. The concentration of coenzyme Q10 in the liver of the birds was determined by HPLC at 28 and 35 d of age, using four birds per treatment at each time period. It is clear that, irrespective of age, the concentration of coenzyme Q in the liver of chicks was higher than for turkeys at the same age (P < 0.001; Table). At d 28, supplementation of broiler diets with phytase increased the concentration of coenzyme Q in the liver. This was not the case with turkeys where the concentration of coenzyme Q remained constant. However, at d 35 the coenzyme Q concentration in the livers of broilers remained constant while that for turkeys tended to increase with increasing content of phytase. It is clear that the addition of phytase to diets marginal in P for broilers and turkeys enhances