In connection with the global demand for safe human food and the production of environmentally friendly aquaculture products, acidifiers are natural organic acids and salts that have received considerable attention as animal-feed additives. The current study was designed to evaluate the effects of potassium diformate (KDF) on the growth performance and immunity of cultured Oreochromis niloticus (O. niloticus). Four iso-nitrogenous and iso-caloric rations containing graded levels of KDF, including 0% (control basal diet), 0.1%, 0.2% and 0.3%, were fed separately to four equal fish groups (30 fish/group with an initial body weight of 53.49 ± 6.15 g) for sixty days. At the end of the experimental period, the fish groups fed on 0.2% and 0.3% KDF exhibited significant improvements in their feed intake, live weight gain, specific growth rate, feed conversion ratio and protein efficiency ratio, with concomitant improvement of their apparent protein digestibility (p < 0.05). Dietary supplementation of 0.3% KDF appeared to stimulate the beneficial intestinal flora; a proliferation was observed of indigenous probionts (Eubiosis) associated with the relative activation of cellular and humeral innate immunity (phagocytic activity/index, nitroblue tetrazolium reduction test and serum/gut mucous lysozyme activity). The cumulative mortality of the fish groups fed on KDF and challenged orally with Aeromonas hydrophila was lower than that of the control group. The resistance against diseases increased with dietary KDF in a dose-dependent manner. Thus, we conclude that the use of acidifiers can be an efficient tool to achieve sustainable, economical and safe fish production.

Our trial was conducted to study the effects of formic acid (FA) and potassium di-formate (KDF) in broiler ration on performance, carcass traits, blood biochemical, intestinal microbial load, histological picture of intestine and immune parameters of broilers. In this study 360 one-day-old broiler chicks were divided to 3 groups with 3 replicates of 40 chicks each. The trial continued for 35 days. The control group was fed only basal diet (G1). Group 2 (G2) were fed basal diet supplemented with FA (5 g/kg diet), and group 3 (G3) received basal diet supplemented with KDF (5 g/kg diet). The results showed that both FA and KDF significantly increased body weight gain (BWG), dressing percentage of broilers and significantly decreased feed conversion ratio (FCR) (P < 0.05). The highest percent of breast and thigh was observed in G3. The improvement in villus height was observed in G2 and G3 compared with the control one, and the highest was in G3. The results evidence that the using of FA or KDF in broiler feeds have significant effects on performance, immune parameters, and gut health without having any significant effects on blood biochemical. However, KDF is more effective than FA as little amount of FA reaches the small intestine due to metabolism and absorption, whereas KDF permits a proportion of FA to pass through the fore-gut intact and enter the small intestinal tract. In addition, FA has a strong odor and corrosiveness to gastrointestinal tract which limits its use.

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Sixty days feeding trial was carried out to investigate the supplemental effects of dietary phytobiotic mixture composed of Spirulina platensis powder (SP) and Garlic powder (GP) on the growth performance, intestinal morphometry, and immune responses of Nile tilapia Oreochromis niloticus. A total of 240 cultured O. niloticus (41.4 ± 0.09 g) were randomly divided into four experimental groups (three replicate/group), fed on basal diets contain 0% (control), 1% (SP), 0.5% (GP), or a combination of both (SP + GP). Fish group fed on phytobiotic mixture showed significant improvements in its feed intake, live weight gain, specific growth rate, feed conversion ratio and protein efficiency ratio (p<0.05), associated with a healthy gut, compared to non-supplemented control. Dietary supplementation of phytobiotics appeared to stimulate the humoral and cellular innate immunity. Fish group that were fed on phytobiotic mixture revealed up-regulation in some immune related genes; TNF-α and liver hepcidin as well as it exhibited the least cumulative mortality % upon A. hydrophila infection. So we can conclude that dietary supplementation of garlic and Spirulina have been improved the growth performance, gut health, immune status and disease resistance in Nile tilapia.

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Highlights Nucleotides are an integral part of the genetic information in each cell. Nucleotides are naturally present in all feeds of animal and vegetable origin but lower concentrations. Dietary nucleotides improve the intestinal barrier function and intestinal histomorphology which positively reflected on the growth performance of C.perfringens infected chickens.

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