title: Evaluation of Optimum Dietary Threonine Requirement by Plasma Free Threonine and Ammonia Concentrations in Surgically Modified Rainbow Trout, Oncorhynchus mykiss.
abstract: This study was carried out to evaluate the dietary threonine requirement by measuring the plasma free threonine and ammonia concentrations in rainbow trout, Oncorhynchus mykiss after dorsal aorta cannulation. A total of 70 fish (average initial weight 506±8.2 g) were randomly distributed into each of the 14 net cages (5 fish/cage). After 48 hours (h) of feed deprivation, each group was intubated at 1% body weight with one of the seven L-amino acid based diets containing graded levels of threonine (0.42%, 0.72%, 0.92%, 1.12%, 1.32%, 1.52%, or 1.82% of diet, dry matter basis). Blood samples were taken at 0, 5, and 24 h after intubation. Post-prandial plasma free threonine concentrations (PPthr) of fish 5 h after intubation with diets containing 1.32% or more threonine were significantly higher than those of fish intubated with diets containing 1.12% or less threonine (p<0.05). Post-absorptive free threonine concentrations (PAthr) after 24 h of intubation of the fish with diets containing 0.92% or more threonine were significantly higher than those of fish intubated with diets containing 0.72% or less threonine. Post-prandial plasma ammonia concentrations (PPA, 5 h after intubation) were not significantly different among fish intubated with diets containing 1.12% or less threonine, except the PPA of fish intubated with diet containing 0.42% threonine. Broken-line model analyses of PPthr, PAthr, and PPA indicated that the dietary threonine requirement of rainbow trout should be between 0.95% (2.71) and 1.07% (3.06) of diet (% of dietary protein on a dry matter basis).
authors: Woosung Feed Co., Ltd, Daejeon 306-785, Korea .
authors: Hyeonho
authors: H
authors: Yun
authors: Woosung Feed Co., Ltd, Daejeon 306-785, Korea .
authors: Gunjun
authors: G
authors: Park
authors: Aqua leader, Co., Ltd, Sacheon 664-914, Korea .
authors: Imho
authors: I
authors: Ok
authors: Woosung Feed Co., Ltd, Daejeon 306-785, Korea .
authors: Kumar
authors: K
authors: Katya
authors: Department of Animal Science, University of California, Davis, CA 95616-8521, USA .
authors: Silas
authors: S
authors: Hung
authors: Woosung Feed Co., Ltd, Daejeon 306-785, Korea .
authors: Sungchul C
authors: SC
authors: Bai
keywords: Dorsal Aorta Cannulation; Plasma; Rainbow Trout; Threonine
references: Br J Nutr. 2003 Nov;90(5):865-76
references: 14667180
references: J Nutr. 1979 Oct;109(10):1710-4
references: 490209
references: J Nutr. 1981 Jan;111(1):46-52
references: 6778981
references: J Nutr. 1960 Nov;72:340-6
references: 13710939
references: J Nutr. 1997 Jun;127(6):1166-75
references: 9187632
references: J Nutr. 1995 Apr;125(4):964-9
references: 7722700