|Zhang, Yao-bei-ping - Anhui Agricultural University|
|Zhou, Yi-bin - Anhui Agricultural University|
|Sang, Ba-yi - Anhui Agricultural University|
|Wan, Xiao-chun - Anhui Agricultural University|
|Yang, Yan-ou - Anhui Agricultural University|
|Zhang, Jian-li - Anhui Agricultural University|
Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2014
Publication Date: 10/11/2014
Citation: Zhang, Y., Zhou, Y., Sang, B., Wan, X., Yang, Y., Zhang, J., Welker, T.L., Liu, K. 2014. Effects of dietary Chinese tea on growth performance, disease resistance, and fresh fatty acid profile of Channel catfish (Ictalurus punctatus). Aquaculture. 23:683–698.
Interpretive Summary: Aquaculture remains a growing, vibrant and important production sector for high-protein food. If becomes the fastest growing food-producing sector, accounting for nearly 50% of the world's consumable fish. Yet, the current practice of high-density cultivation and over-nutrition can lead to fatty liver and suppressed fish immunity, while the substitution of fish meal and fish oil in feed can cause decreased unsaturated fatty acids and impaired flavor of fish fresh. In order to solve these problems, certain feed additives, including tea and Chinese herbs, have been investigated. Tea (Camellia sinensis) is cultivated all over the world and contains bio-active polyphenols. Several recent studies have investigated the effect of Chinese tea on grow performance, feed efficiency, immunity, and resistance to disease infection of such fish as Nile tilapia and olive flounders. There is lack of information on use of Chinese tea as a feed additive for channel catfish (Ictalurus punctatus). Therefore, in this study, six types of Chinese tea (green or fermented) were used as feed additive at four levels (0, 1, 2 and 4% w/w) for channel catfish. The objectives were: (1) to compare their effects on growth performance, body composition, fatty acid profile and resistance to Aeromonas hydrophila of channel catfish fingerlings, and (2) to determine which tea types are most effective and the optimal inclusion level, with respect to enhancing growth performance, achieving ideal body composition, improving fatty acid profile and increasing resistance to A. hydrophila. Results show that low inclusion levels of tea tended to enhance body weight and feed efficiency while high inclusion levels tended to reduce body weight. Tea addition decreased saturated fatty acids and increased unsaturated fatty acids in the fish fresh. It also decreased the mortality of catfish challenged with A.hydrophila.
Technical Abstract: Six types of Chinese tea were incorporated into diets at 4 different levels ((0, 1, 2, and 4% w/w) in order to determine their effects on the growth performance, fatty acid composition of muscle lipids and resistance to Aeromonas hydrophila of channel catfish (Ictalurus punctatus) fingerlings. Each diet was fed to the test fish in triplicate tanks for 8 weeks. Results show that the 1% tea diet was significantly (P < 0.01) better than diets with other inclusion levels as well as the control diet with regards to weight gain (WG) and the feed conversion rate (FCR) of fish; while the 4% tea diet increased feed intake (P < 0.01) and FCR (P < 0.01) but decreased WG (P < 0.05). In addition, 2% and 4% tea diets resulted in significant decrease in muscle lipid content and saturated fatty acids and a significant increase in unsaturated fatty acids. The hepatosomatic index decreased significantly in fish fed the 4% tea diet. The mortality of the catfish challenged with A. hydrophila decreased with an increasing addition of tea to the diet. A diet supplemented with dragon well tea (one of the six types), which contained the highest levels of catechins, was found to perform best with regards to growth, FCR and increased content of unsaturated fatty acids. It is concluded that diets supplemented with a low dose of Chinese tea could increase growth performance, enhance the fish quality and resistance against A. hydrophila.