The aim of this study was to investigate the effect of adding cottonseed meal and a mixture of organic acids to the diet on growth parameters, economic justification, and nitrogen and phosphorus retentions in rainbow trout. For this purpose, six triplicate treatments consisting of six diets were considered in a 3 × 2 factorial design, where two levels of cottonseed meal (0% and 15%) and three levels of organic acid mixture (a mixture of lactic acid, citric acid, and potassium sorbate in equal proportions) at 0%, 0.5%, and 1% were added to the diets. A total of 270 rainbow trout with an average weight of 14.0 ± 0.35 g were stocked in 18 aquaria containing 40 L of water, with a density of 15 fish per aquarium. The above diets were offered to the fish for 8 weeks at a daily rate of 3 to 4 % of biomass. The aquariums were equipped with a semi-closed system including aeration, physical filter, biological filter, and UV filter, with a daily water exchange of 30% during the experimental period. After the feeding trial, sampling of the fish muscle was conducted. The results of this study showed that adding cottonseed meal to the diet had no significant effect on final weight, fish production per unit volume of water, or feed cost; however, it significantly reduced the growth rate and increased feed conversion ratio. Additionally, adding organic acids to the diet had no significant effect on fish growth parameters. The addition of cottonseed meal to the diet did not significantly affect the phosphorus and nitrogen content in the fish muscle; however, adding organic acids to the diet significantly increased the phosphorus content in the fish muscle. Overall, the results indicated that cottonseed meal could be used at a level of 15% in rainbow trout diet. Although this amount of cottonseed meal significantly reduces growth and increases feed conversion ratio, it does not have a significant economic impact on trout production. Furthermore, adding organic acids at levels of 0.5% to 1% to the trout diet, while having no positive effect on growth, efficiency, or feed cost, does increase the phosphorus content in the fish muscle.
Hoseini S M, Kashiri H, Aghaeimoghddam A, Gharavi B. The effect of partial replacement of soybean meal with cottonseed meal and addition of organic acids to the diet on growth indicators, phosphorus and nitrogen retention in rainbow trout muscle. JAIR 2024; 12 (2) :61-70 URL: http://jair.gonbad.ac.ir/article-1-901-en.html