Interrelationship among methionine, choline, and betaine in channel catfish Ictalurus punctatus

Abstract

The present research was conducted to evaluate if there is an interrelationship between methionine and choline as well as between betaine and choline in feed formulations for channel catfish. A semi- purified basal diet was formulated to contain 28-g crude protein/100-g diet. DL-methionine was added to the basal diet to produce deplete, sufficient, and replete levels of miethionine (0.35%, 0.39%, and 0.43%); choline chloride (200, 400, and 600-mg choline/kg diet) was added to the basal diet to produce low, median, and high levels of choline; and free base betaine (0 and 1,000-mg betaine/kg diet) was added to the basal diet to produce sufficient and replete levels of betaine in eight experimental diets. Each diet was randomly fed to triplicate groups of fish (15 fish/each group) over a 13-wk growth trial. Added choline in the diets containing 0.35% (deplete) methionine had a significant linear effect on weight gain and feed consumption. There were no significant differences in weight gain, FCR, survival, HIS, and liver lipid between diet 3 (deplete methionine and high choline) and diet 6 (sufficient methionine and median choline). Both added choline and betaine in the diets containing 0.39% (sufficient) methionine had significant effects on weight gain, feed consumption, and FCR. There were no significant differences in the measured parameters between diet 7 (low choline and excess betaine) and diet 6 (median chotine and no betaine). Methionine had no significant linear effect on weight gain and feed consumption when choline was low. Therefore, in the absence of sufficient methionine, choline or betaine cap spare a portion of methionine requirement of channel catfish. In the absence of sufficient choline, methionine cannot spare choline requirement of channel catfish. Further, in the absence of sufficient choline, betaine can spare at least a portion of choline requirement of channel catfish. © Copyright by the World Aquaculture Society 2005.