No synergistic effects by the dietary supplementation of ascorbic
acid, α-tocopheryl acetate and selenium on the growth performance and
challenge test of Edwardsiella tarda in fingerling Nile tilapia, Oreochromis
niloticus L.
Kang-Woong Kim, Xiaojie Wang, Se-Min Choi, Gun-Jun Park,
Ja-Wan Koo, Sungchul C. Bai-2003
Aquaculture
Research, 34(12):
1053
Abstract:
To
investigate the potential synergistic effects of dietary ascorbic acid (AA),
α-tocopheryl acetate (TA) and selenium (Se) supplementation above
minimum requirement levels on the growth performance and disease challenge
of fingerling Nile tilapia, Oreochromis niloticus L., five
experimental diets were formulated: control (150 mg AA, 100 mg TA
and 0.2 mg Se per kg diet), excessive ascorbic acid (eAA) (2000 mg
AA, 100 mg TA and 0.2 mg Se per kg diet), excessive α-tocopheryl
acetate (eTA) (150 mg AA, 240 mg TA and 0.2 mg Se per kg
diet), excessive selenium (eSe) (150 mg AA, 100 mg TA and 0.5 mg
Se per kg diet) and excessive all (eALL) (2000 mg AA, 240 mg TA
and 0.5 mg Se per kg diet). Experimental fish averaging 2.9 were
randomly distributed in each aquarium as a group of 40 fish with total
weight 116ą2.9 g (meanąSD). Each diet was fed on a dry-matter basis
to fish in three randomly selected aquaria at a rate of 4-8% of total body
weight daily. After 10 weeks of the feeding trial, fish fed eAA, eTA and
eALL diets had significantly higher weight gain, feed efficiency ratio,
protein efficiency ratio and specific growth rate than fish fed eSe and
control diets (P<0.05). There was no significant difference among
fish fed five experimental diets in cumulative mortalities when fish were
challenged with Edwardsiella tarda at the end of the experimental
period. These results indicate that sufficient supplementation of dietary AA
or TA had positive effects on growth performance, but there was no
synergistic effect of excessive dietary AA, TA and Se supplementation on
growth performance and disease resistance to E. tarda in fingerling
Nile tilapia.
(Department of Aquaculture, Feeds &
Foods Nutrition Research Center, Pukyong National University, 599-1 Daeyeon
Dong, Busan 608-737, Korea. E-mail of Sungchul C. Bai: scbai@mail.pknu.ac.kr)