A study was conducted to determine the effect of sources and levels of zinc on tissue zinc concentration and the carcass quality of broilers. A total of 6,000 1-day-old unsexed broiler chicks were allotted randomly to four floor pens with 1,500 birds per pen. A corn-wheat-soybean meal basal diet (Control) was formulated, and 40 ppm inorganic zinc (40 IZ), 40 ppm organic zinc (40 OZ), and 80 ppm organic zinc (80 OZ) were added to the basal diet to form four dietary treatments. During the 4-wk experimental period, feed and water were provided ad libitum. At the end of the feeding trial, five birds from each pen were randomly selected as five replicates, slaughtered and carcass evaluation was performed. Results showed that zinc supplementations have no effect on zinc content in thigh muscle but a significant increase was found in skins from broilers in 80 OZ (P50:05). The epidermis thickness of tibia and back skin were not affected by the zinc supplementations. However, significant increases of tibia and back skin dermis thickness were found (P50:05) by zinc supplementation and organic zinc was more effective than inorganic zinc in this respect (P50:05). The collagen contents of breast and thigh muscle were not affected by dietary zinc supplementation, but organic zinc increased the collagen contents in the back skin of broilers (P50:05). Shear force values of back skin and breast muscle were not affected by zinc supplementation. It is concluded that dietary organic zinc is more effective in increasing the skin zinc concentration, and improving skin quality of broilers than inorganic zinc.

Hydrolytic enzymes such as cellulase and hemicellulase have been attracted in lignocellulose based biorefinery. Especially, mannanase has been a growing interest in industrial applications due to its importance in the bioconversion. In this study, an extracellular endo-β-1,4-D-mannanase was produced by Streptomyces sp. CS147 (Mn147) and purified 8.5-fold with a 43.4% yield using Sephadex G-50 column. The characterization of Mn147 was performed, and the results were as follows: molecular weight of ∼25 kDa with an optimum temperature of 50°C and pH of 11.0. The effect of metal ions and various reagents on Mn147 was strongly activated by Ca(+2) but inhibited by Mg(+2) , Fe(+2) , hydrogen peroxide, EDTA and EGTA. Km and Vmax values of Mn147 were 0.13 mg/mL and 294 μmol/min mg, respectively, when different concentrations (3.1 to 50 mg/mL) of locust bean gum galactomannan were used as substrate. In enzymatic hydrolysis of heterogeneous substrate (spent coffee grounds), Mn147 shows a similar conversion compared to commercial enzymes. In addition, lignocellulosic biomass can be hydrolyzed to oligosaccharides (reducing sugars), which can be further utilized for the production of biomaterials. These results showed that Mn147 is attractive in quest of potential bioindustrial applications.