BACKGROUND: The use of natural immune stimulants is one of the most effective methods for strengthening immunity and preventing diseases in fish. OBJECTIVES: Due to the abundance of red algae (Laurencia caspica) in the Caspian Sea, the aim of this study was to investigate the effect of this algae on growth performance and blood indices of rainbow trout. METHODS: The present study was performed on 750 randomly selected rainbow trout (Oncorhynchus mykiss) in 5 experimental treatments including an algal extract-free diet (control), and diets supplemented with 0.5, 1, 1.5, and 2% of algal hydroalcoholic extract. During the experimental period, fish were sampled to measure growth performance and blood indices every two week for 8 weeks. RESULTS: Growth indices were not affected by the algal extract at the end of eight weeks of feeding. There were no significant differences in fish survival at different treatments. Total counts of red blood cells, white blood cells, hematocrit percentage, hemoglobin concentration and neutrophil and monocyte percentages were affected by algal extract with significant increases compared to the control group (p < /em><0.05). Results of serum biochemistry showed that significantly increased total protein, albumin and globulin and also significantly reduced ALT, AST and ALP compared to the control in rainbow trout. CONCLUSIONS: Based on the results of this study oral use of red algae (L. caspica) as an immune stimulant in rainbow trout (O. mykiss) was recommended.

BACKGROUND: Balance in the amount of minerals in the aquatic animal’s diet is very important. Phosphorus is one of the most important minerals in fish and aquatic animal’s nutrition. Phosphorus is important not only for the proper growth and fish health, but also for excessive phosphorus excretion that may cause water pollution and algal bloom. OBJECTIVE: In this study the effects of adding monoammonium phosphate in the diet of fish (Cyprinus carpio Koi) and its comparison with monocalcium phosphate were investigated. METHODS: 650 koi fish weighing 17 g were distributed in 15 tanks (5 treatments - each in three replicates) and mono-ammonium phosphate-fed diets at three levels (0.75, 1.5 and 3% of the diet), monocalcium phosphate in one level (3% of the diet) and a control group (no phosphorus supplementation) were fed for 8 weeks. RESULTS: Growth indices and feed conversion ratio in fish fed 3% monoammonium phosphate showed the best results. The control group showed the lowest weight gain and the highest feed conversion ratio. Blood phosphorus was also significantly correlated with increasing monoammonium phosphate. The highest level of calcium in the blood was observed in the group fed monocalcium phosphate (3%). CONCLUSIONS: Considering the improvement of growth and nutrition indices, adding 1.5 to 3% monoammonium phosphate in the diet of koi fish was suggested.

Objective: Selenium (Se), as the form of selenite, is commonly supplemented in poultry diet, which has low bioavailability and high toxicity. Here, we compared the effects of the supplemen¬tation of the diet with Se nanoparticles (nano-Se) on the growth, sexual behavior, and reproduc¬tive performance (gonad size, sperm quality traits, and plasma testosterone levels for males and egg production for females) of Japanese quail (Coturnix coturnix japonica). Materials and Methods: Quail chicks (n = 300) aging 14 days were divided into three groups: Group 1 (basal diet and Se at 0.2 mg/kg ration), Group 2 (basal diet and nano-Se at 0.2 mg/kg ration), and Group 3 (basal diet and nano-Se at 0.1 mg/kg ration). Several parameters relating to body weight and egg were measured. Sexual behaviors of the birds were observed by continuous visual scanning. The sperm viability, sperm morphology, and concentration of spermatozoa were determined after staining and microscopic examination. The plasma testosterone levels were determined by indirect enzyme immunoassay assay. The Se concentrations in the testicular, ovar¬ian, and ration samples were measured by flame emission atomic absorption spectrophotometer. Results: The type or concentration of nano-Se administration had no impact on body weight, feed efficiency, egg production, or egg weight. However, the total feed intake throughout the experi¬ment was reduced in Group 2 at 0.2 mg/kg. Nano-Se supplementation significantly increased the sexual behavior. In general, the deposition of Se in the testicular and ovarian tissues increased with increasing supplement concentration. At the same supplement concentration, the tissue deposition of nano-Se was more enhanced than that of inorganic Se. Nano-Se supplementation improved the testicular functions by enhancing plasma testosterone level and sperm quality traits (sperm count, motility, and viability). This improvement was found more prominent with the lower supplement concentration (when comparing 0.1 vs. 0.2 mg/kg diet). Conclusion: It is concluded that the use of nano-Se (at 0.1 mg/kg) in the ration of Japanese quail improves several reproductive performance parameters. [J Adv Vet Anim Res 2020; 7(4.000): 597-607]