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At this study, the effects of adding Iranian acorn flour on growth performance, carcass composition and resistance to salinity stress of common carp were investigated. Experimental diets included: 1) without acorn and not autoclaved diet; 2) without acorn and autoclaved diet for 2 minutes; 3) without acorn and autoclaved diet for 10 minutes; 4) with 10 percent acorn and not autoclaved diet; 5) with 10 percent acorn and autoclaved diet for 2 minutes; 6) with 10 percent acorn and autoclaved diet for 10 minutes. After 6 weeks results showed that weight and total length in the treatment 2 were higher than the rest. This increase was significantly higher than all treatments except 4 (p<0.05). Autoclaving reduced carcass protein and increased its moisture contents significantly and this effect intensified with an increase in the duration of autoclaving. Short-term autoclaving caused a significant increase in carcass fat while long-term autoclaving resulted its significant reduction. Adding acorn flour into the diet reduced amounts of carcass protein and fat and increased its moisture content significantly. Accordingly, although there was no significant difference between fish weights of treatments 1 and 4, replacement of wheat flour with acorn flour at 10% of diet was undesirable. In not autoclaved or short-term autoclaved diets, oak acorn flour reduced carcass ash significantly. In salinity stress test, the highest and lowest survival time were observed in the treatment 2 and treatments 1 and 6, respectively. When autoclaving (heat) was used in food production, the addition of oak acorn flour to the diet significantly reduced survival time at the salinity stress. Overall, considering the growth performance, carcass composition and resistance of carp to stress, it is recommended to study oak acorn flour consumption at levels less than 10% of the diet.
 

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Peeled oak acorn was soaked in tap water for 24 or 48 h. The 24 h soaked acorn was fermented by baking yeast for 24 h. The effect of four diets including treatments 1: diet without acorn, 2: diet containing not soaked and fermented acorn, 3: diet containing 48 h soaked acorn, and 4: diet containing 24 h soaked and 24 h fermented acorn was determined on common carp with an initial weight of 8 g for 61 days. The phenolic compounds in the acorn were significantly reduced by soaking and fermentation (P<0.05). Diet had no significant effect on total length, feed intake, carcass moisture and survival rate (P>0.05). Treatment 3 significantly increased weight and specific growth rate in comparison with treatments 2 and 4. The condition factor in treatment 3 was significantly higher than treatment 4. The best feed conversion ratio and protein and lipid efficiency rates were observed in treatment 3, which were significantly different from treatment 2. There was no significant difference in protein retention between the treatments fed with acorn, but treatment 4 compared to treatment 1 had significantly less protein retention. The highest lipid retention was observed in treatment 1, which had a significant difference with treatments 3 and 4. Acorn led to a significant reduction in carcass crude protein, crude fat and ash. There was no significant difference in terms of carcass ash between treatments fed with acorn. The negative effects of treatments 3 and 4 were higher on the percentage of carcass lipid and carcass protein, respectively. Soaked acorn for 48 h did not have a negative effect on growth and feed consumption and can be used up to 5% of diet, but the study of other soaking and fermentation methods is recommended to improve the carcass quality.

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In this study, the effects of dietary extruded oak acorn flour on growth performance and carcass composition of common carp were studied. Four diets were investigated in a completely randomized design included 1- extruded wheat flour (17%), 2- non-extruded wheat flour (5%) and extruded wheat flour (12%), 3- non-extruded acorn flour (5%) and extruded wheat flour (12%), and 4- extruded acorn flour (5%) and extruded wheat flour (12%). The culture was started in round tanks with a volume of 250 liters and a density of 15 fish in each tank with an initial weight of 5.4 g in three replicates. After 4 weeks, no significant difference was observed in the weight and total length of fish, but after 8 weeks, the highest weight and total length were observed in the fish fed diet 4. Extrusion of acorn flour had a significant positive effect on the weight and total length of fish, but extrusion of wheat flour did not have such an effect. Diets had no significant effect on the condition factor, specific growth rate, feed intake, feed conversion ratio, protein efficiency ratio, lipid efficiency ratio, protein retention, carcass moisture content and survival rate. Extrusion of wheat flour and acorn flour had significant positive effects on lipid retention and these effects were much greater when the extruded acorn flour was consumed. The levels of carcass protein and ash were significantly reduced by feeding on non-extruded acorn flour. Consumption of non-extruded wheat flour or acorn flour caused a significant reduction in carcass lipid and this reduction was more severe when using non-extruded acorn flour. Overall after peeling the oak acorn, its flour can be used instead of wheat flour at the level of 5% of the extruded diet for common carp.