1 JULY 1999
DIETARY METHIONINE REQUIREMENT OF JUVENILE ARCTIC CHARR SALVELINUS ALPINUS (L.)
L. Simmons, R.D. Moccia, D.P. Bureau, J.G. Sivak, K. Herbert-1999
Aquaculture Nutrition, 5 : 93-100
Abstract :
The dietary methionine requirement of juvenile Arctic charr Salvelinus alpinus (L.) was assessed by feeding diets supplemented with graded levels of DL-methionine (9, 12, 15, 18, 21 and 24 g/kg dietary protein) for 16 weeks at 12 C. All diets contained 400 g/kg protein, 170 g/kg lipid, 66 g/kg ash and an estimated 17.5 MJ digestible energy (DE)/kg. When live-weight gain was examined using quadratic regression, the estimate of methionine requirement for optimal growth was 17.6 g/kg of dietary protein (DP) or 7 g/kg of the diet. Requirements estimated on the basis of carcass protein and energy gains were 18.8 and 17.9 g/kg DP, respectively. Plasma methionine concentrations and ocular focal length variability measurements did not provide a sensitive measure of requirement, because each responded in a linear fashion to increasing dietary methionine levels. Based on the prevalence of cataracts, the methionine level required to prevent lens pathology (26.7 g/kg DP) appears to be higher than that required for maximum growth.
(Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada, N1G 2W1, e-mail of R.D. Moccia : rmoccia@aps.uoguelph.ca)