Application Of Tea Powder With Different Sizes In Duck Feed

This study was aimed to investigate the component changes of tea powders with different sizes and its effect on growth performance, carcass traits, lipid metabolism, antioxidant capacity and meat quality of Cherry Valley meat-type ducks in order to explore the methods to decrease fat deposition and improve meat quality, and provide some references for application of tea powders. The study included4trials as follows:Trial1was conducted to evaluate the component changes of tea powders with different sizes during storage. Oolong tea leaves was ground to three sizes (16mesh,400mesh and800mesh) and stored at room temperature. Samples were taken after30,60and90days. The results showed that specific surface area of tea powders increased as its size decreased, whereas surface area mean diameter and volume averaging diameter presented the opposite pattern. Compared with the original tea leaf, all tea powders had higher tea polyphenols (TP) content during3months of storage (P<0.01), and they had lower caffeine content after30and60days but not thereafter (P<0.05); reduced moisture content was observed in400-mesh tea powder after30days and in400-and800-mesh tea powders after90days (P<0.01), but there was no difference among groups after60days; free amino acid content of400-and800-mesh tea powders decreased (P<0.05) after30and60days but not thereafter.Trial2was conducted to determine the effects of tea powders with different sizes on growth performance and carcass traits of ducks. A total of36016-day-old Cherry Valley ducks were randomly allocated to4groups with6replicates, and fed a basal diet with or without1%tea powder (16-mesh,400-mesh or800-mesh). The results showed that ADG of ducks was reduced only by800-mesh tea powder (P<0.05), while there was no difference in ADFI or F/G. Increased dressing percentage and decreased abdominal fat percentage were found in ducks fed400-mesh tea powder at28d of age (P<0.05), which also had19%lower abdominal fat percentage at42d of age (P>0.05). Tea powders did not affect percentage of breast or leg muscle (P>0.05). Trial3was conducted to determine the effects of tea powders with different sizes on lipid metabolism of ducks, and materials and methods were the same as those in Trial2. The results showed that fat deposition was reduced by dietary tea powder supplementation. Compared with the control group,400-mesh tea powder reduced intramuscular fat width of ducks by9.4%(P>0.05) and23.2%(P=0.051) at28and42d of age, and800-mesh tea powder decreased42-d subcutaneous fat thickness (P<0.05). Tea powders did not affect ether extract content in breast muscle or liver or28-d serum lipid level (P>0.05). Dietary400-mesh tea powder reduced42-d serum TG level and increased28-d serum HL activity (P<0.05), moreover, it promoted serum glucagon and leptin level by10.4%and35.6%, respectively (P>0.05).Trial4was conducted to determine the effects of tea powders with different sizes on antioxidant capacity and meat quality of ducks, and materials and methods were the same as those in Trial2. The results showed that tea powders did not affect muscular VE content or T-AOC in serum, liver, breast muscle or leg muscle (P>0.05). Drip loss of48h and serum MDA content were reduced by16-and400-mesh tea powder, respectively (P<0.05). Both400-and800-mesh tea powders elevated serum SOD activity and reduced drip loss of24and48h in breast muscle (P<0.05). Shear force of breast muscle tended to be decreased by tea powders, but pH of breast muscle, pressure loss, cooking loss, meat color or leg muscle quality was not affected (P>0.05). In conclusion,400-mesh tea powder was most effective in promoting antioxidant capacity and meat quality of ducks.