Effects of glucose-glycine melanoidins on apparent digestibility coefficients of minerals in the rainbow trout Oncorhynchus mykiss

MÁRQUEZ, LORENZO; HERNÁNDEZ, ADRIÁN J.; PATRICIO DANTAGNAN; SERRANO, XAVIER; MORALES, GABRIEL A.

Congreso; 18th International Symposium on Fish Nutrition and Feeding; 2018

ISFNF

Thermal treatments of animal feeds and dietary raw materials can lead to the formation of molecules affecting digestive,absorptive and/or metabolic processes in animals. Melanoidins are non-enzymatic browning products with an effect on theabsorption and retention of minerals in mammals, probably due to their negative charge, but no comparable data areavailable for cultured fish. Thus, the present work is aimed at exploring the effects of glucose-glycine melanoidins onapparent digestibility of minerals in the rainbow trout.Melanoidins were produced from a solution of glucose 1M, glycine 1M, and NaHCO3 0.1 M, heated to 103°C for 24 hours,were isolated by acidification and included at 0.0% or 1.2% in a basal diet prepared without heated ingredients. The two dietswere isonitrogenous (~50%), isoenergetic (23.5 MJ/kg) and included 0.75% Cr2O3. Each diet was supplied to three tanks with25 juvenile trouts (24 g) for 17 days. Settled feces were collected daily for days 11-17th, freezed at -20°C, lyophilized andstored at -80°C. Diets and feces were analyzed for chromium and minerals, apparent coefficients of digestibility (ADC?s) werecalculated according to the inert-marker procedure and subjected to t-tests.ADC?s of Na, K, Ca, Mg, Cu, and Mn showed no statistical differences between diets. ADC?s of Zn and Fe were statisticallyhigher in the presence of melanoidins: 28.6 ± 0.7% vs. 23.2 ± 1.0% for Zn (p=0.007), 12.6 ± 1.7% vs. -11.2 ± 1.3% for Fe(p<0.001) (mean ± sem). The improvement of iron absorption in rats in the presence of bread crust high molecular weightbrowning products previously obtained in rats and is in keeping with the results herein reported. On the other hand, copperabsorption in rats was also improved in the presence of glucose-Lys or glucose-Met melanoidins, but this variable remainedstatistically unchanged in the present experiment. It can be concluded, that sugar-animo acid melanodins can increase thedigestibility of some cationic minerals in the rainbow trout, but mechanisms and the metabolic fate of these mineralswarrant further research.