فاطمه شیرمحمد

The current study was aimed to investigate the effect of 1-OH-D3 on ileal digestibility of dietary calcium and phosphorus and turkey performance. A total of 225 one-day- old male bronze strain turkey with a mean body weight of 65 g were allocated to 3 treatments with 5 replications (each, 15 birds) for 8 weeks, under a completed randomized design. Diets were adjusted separately for two periods 1-4 and 5-8 weeks of age. The experimental treatments, for the first period were consisted: 1) control, containing D3 (4500 IU/kg) 2) 1-OH-D3 (0.14 gr/kg without D3) 3) 1-OH-D3 (0.07 gr/kg) + D3 (2250 IU/kg) and for the second period of experiment were consisted: 1) control, containing D3 (3500 IU/kg) 2) 1-OH-D3 (0.12 gr/kg) 3) 1-OH-D3 (0.06 gr/kg) + D3 (1750 IU/kg) in the diet. The results showed that no significant differences exist among treatments in turkeys’ body weight, feed intake and feed conversion ratio. However, the use of 1-OH-D3 in treatments 2 and 3 increased the ileal digestibility of calcium and phosphorus and the levels of calcium and phosphorus in plasma and bone, also decreased the activity of alkaline phosphatase in plasma, in compared to the control group (P<0.05). Our findings imply that inclusion 1-OH-D3 to the diet did not affect on growth performance in turkeys. However, it caused to increase absorption and accumulation of calcium and phosphorus in bone. In conclusion, 1-OH-D3 can be used to improve the quality of the turkey bone, alone or in combination with D3

Coccidiosis is a serious problem in the poultry industry, and medication is required continuously. There are several approaches to the control of coccidiosis. Several drugs have been used in the control of coccidiosis. The ionophore antibiotics such as lasalocid, maduramicin, monensin, narasin, and salinomycin are extensively used in poultry feed for the prevention or treatment of coccidiosis induced by Eimeria species. Unfortunately, the toxic effects of ionophores cause concern because of their narrow safety margin. Ionophores’ toxicity could be probably due to oxidative damage. Therefore, it can be prevented by the supplementation of antioxidants in the diet. It has been reported that 60 or 120 mg/kg of salinomycin caused some pathological changes in the liver, heart, kidney, and muscles, such as degeneration or necrosis of these tissues. However, administration of salinomycin with vitamin E or selenium showed that vitamin E decreases the pathological changes.  The present study aimed to investigate the effects of salinomycin administration in combination with some natural antioxidants on reducing salinomycin toxicity in laying chickens.
A total number of 400 day-old hy-line w36 chicks were used in a completely randomized design with five treatments and four replications for 35 days. Treatments were included: 1) control diet, 2) negative control diet containing 0.05% salinomycin sodium, 3) negative control + garlic powder (15 g/kg of diet), 4) negative control + selenium (450 mg/kg of diet) + vitamin E (2 g/kg of diet), and 5) negative control + zinc-methionine (160 mg/kg of diet). Body weight gain, feed intake, and body weight uniformity were measured weekly. Blood samples were taken to evaluate the levels of antioxidant enzymes, liver enzymes, electrolytes, and malondialdehyde levels at the end of the experimental period.
The results showed that the salinomycin diet (T2) decreased body weight and feed intake compared with the control diet in the total experimental period (P<0.05). But the addition of supplemental Zn-methionine to the diet (T5) led to improved body weight and feed intake (P<0.05). Significant differences were observed among various treatments for the relative weight of visceral organs (liver, heart, kidney, gizzard, proventriculus, intestine, and bursa of Fabricius), but there were no significant differences for spleen and lungs. Also, salinomycin increased the activity of liver enzymes including alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and serum malondialdehyde (MDA) in the negative control group and control group, and decreased the level of serum antioxidant enzymes compared to the control group (P<0.05), but the addition of vitamin E + selenium to the diet, eliminated the negative effects of salinomycin on these parameters (P<0.05). Vitamin E plays important roles in various biochemical and physiological processes, including antioxidation. The protective effect of vitamin E against the alterations induced by salinomycin on these estimated parameters in this study could be attributed to the role of vitamin E as a fat-soluble antioxidant, which protects the biological membranes from oxidative damage and decreases osmotic fragility of erythrocytes. Selenium also exerts its protective effect against oxidative damage by a decline in free radicals and increasing the synthesis of glutathione peroxidase, which catalyze the breakdown of toxic hydrogen peroxide and lipid hydroperoxides. Salinomycin decreased serum chlorine and increased serum potassium compared to the control group (P<0.05), and only the use of vitamin E + selenium adjusted these changes (P<0.05). The T2 group reduced the serum level of chlorine and increased the serum level of potassium (P<0.05). But there is no significant effect on the level of blood calcium. Although all treatments with antioxidants changed the levels of these electrolytes. The changes in electrolyte balance can result in metabolic alkalosis and acidosis. However, the T4 group only reduced the serum levels of potassium and calcium and increased the serum level of chlorine significantly, compared to the T2 group (P<0.05). However, there were no significant differences in the serum sodium and creatinine levels among various treatments.
Salinomycin administration in the diet of laying chicken induces undesirable effects on some estimated parameters probably due to oxidative damage. But, the supplementation of pullet diets with vitamin E and selenium can reduce the possible side effects of salinomycin.

In order to investigate the possibility of replacing antibiotics with a mixture of several plant extracts (Immunopropophyte), an experiment using 300 Ross 308 broilers in a completely randomized design with 3 treatments and 4 replications and 25 broilers per replication was performed for 42 days. Experimental diets were: basal diet, basal diet containing 0.02% of the antibiotic virginiamycin, and diets containing 0.1% of water-soluble immunopropophyte solution. The results showed that the difference in body weight and conversion ratio between the experimental groups in the periods of 22 to 42 and 1 to 42 days was significant so that the use of antibiotics and immunopropophytes improved these parameters compared to the control group (P<0.05). Feed intake did not show a significant difference between experimental treatments. Stimulation of the immune system by the treatments was evaluated in two stages and it was found that the antibody titer against SRBC and Newcastle in the treatments with antibiotics and immunopropophytes were higher than the control treatment (P<0.05). The use of antibiotics and immunopropophytes caused a significant reduction in abdominal fat compared to the control treatment (P<0.05). Immunopropophyte significantly decreased the bacterial population of E. coli and salmonella in ileocaecal part of broilers’ intestine (P<0.05). The results of this study showed that immunopropophytes can be used as an alternative to antibiotics in the diet of broilers without adversely affecting performance.

Using 36 Hubbard grandparent roosters at 45 weeks of age, the present study investigated the effects of supplementing vitamin E and soybean lecithin in the roosters' diet on their semen quality. The experiment was conducted in a completely randomized design with four treatments including basal diet, basal diet supplemented with vitamin E (300 mg/kg), basal diet supplemented with lecithin (1%), and basal diet supplemented with lecithin & vitamin E. Roosters were fed their diets for 60 days and semen collection was performed on days 0, 20, 40 and 60 of the experiment. The results showed that the treatment containing vitamin E + lecithin significantly improved total sperm motility and sperm concentration (P<0.05). The semen volume and sperm kinematic values were not affected by experimental diets (P>0.05). Although experimental treatments had no effect on abnormal morphology of sperm and DNA fragmentation, but membrane integrity and sperm viability were significantly increased in roosters fed diet supplemented with soybean lecithin and vitamin E (P<0.05). Malondialdehyde (MDA) concentration was also shown to be significantly lower in treatment containing vitamin E and soybean lecithin (P<0.05). The interaction effects of time× diet on total and progressive motility, sperm concentration, viability, membrane integrity and MDA content were significant (P<0.05) and these traits improved in the last days of the experiment due to diet supplemented with vitamin E+ soybean lecithin. Overall, it was concluded that supplementing aged roosters' diet with vitamin E and lecithin appears to improve sperm quality traits.

The purpose of this trial was to investigate the effects of adding Spiralina platensis algae in layer diets on the performance, intestinal microflora and morphology, and some blood parameters. The recent trend in the feed business is currently directed toward the use of natural ingredients as alternativest antibiotics, synthetic colors, and other chemicals. Spirulina platensis algae is one of the high quality natural feed additives that can be used in animal and poultry nutrition. There are two different species of spirulina: Spirulina maxima and spirulina platensis, with varying distribution throughout the world (Oliveira et al, 1999). Spirulina maxima, contains high levels of vitamin B1, vitamin B2 and β- carotene, and up to 71% crude protein with sufficient concentrations of all essential amino acids except for the sulfur-containing ones (Becker, 2004). Spirulina platensis dried supplement has an excellent nutritional profile. It has increased level of protein with values ranged between 55- 65% and includes all of the essential amino acids, high carotenoids, and rich in minerals and vitamins (Ross and Dominy, 1990). Spirulina contains up to 20 percent of phycocyanin, a water-soluble blue pigment and green pigment chlorophyll a, and relatively high content of vitamin B12 (Ciferri and Tiboni, 1985). Spirulina platensis is the source of essential fatty acid, γ-linolenic acid (Abd El-Baky et al, 2003). Spirulina platensis also has minerals, magnesium, manganese, iron, calcium, chromium, copper, phosphorus, potassium, sodium and zinc (Belay, 1997). The available energy content of Spirulina platensis has been determined to be 2.50-3.29 kcal/gr and its phosphorous availability is 41% (Yoshida and Hoshii, 1980).Verma et al (2004) reported that Spirulina platensis inclusion in broiler diet at 1 percent showed profound antioxidant effects in term of increased activity of erythrocyte antioxidant enzymes and decreased serum lipid peroxidation. Hens fed with diets supplemented with varying levels of Spirulina platensis tended to decrease the cholesterol content in the egg yolk of hens (Sakaida, 2003). The addition of 1.5 to 12% of spirulina platensis into the diets for broilers can replace other protein sources given to broiler, especially soybean meal, as the former shows satisfactory growth rates and feed efficiency (Nikodemusz et al, 2010).

A total of 192 LSL hens aged from 26 to 37 weeks were used in a completely randomized design with 4 treatments and 4 replicates and 12 hens per replicate. The treatments consisted of feeding a corn-soybean meal control diet alone or supplemented with 1.5, 3 or 4.5% Spirulina platensis. Cages were ventilated in a way that daily temperature was maintained between 21˚C and 23˚C. Each cage was equipped with feeder and drinker. Feed and water were provided ad libitum. A standard LSL diet was fed, containing (calculated): 17.6% CP, 0.42% Met, 0.82 Lys, 4.1% Ca, 0.6 Available P, and 2770 kcal ME/kg. During the experimental period, a 16-hour lighting schedule was applied. Performance including feed intake, feed conversion ratio, egg production, and egg mass weekly were calculated over the period. After feeding the experimental diets for 12 weeks blood parameters included cholesterol, triglycerides, HDL, and LDL were analyzed. In addition, villi height, crypt depth, villi height to crypt depth ratio, epithelium width and villi surface and also intestinal microflora (coliform, lactobacillus and total bacterial population) were measured. Statistical analysis used in this study was performed in completely randomized design using GLM procedure with SAS software and comparison of means by fisher's protected LSD test. A P-value of less than 0.05 was considered significant, unless otherwise stated.

The results showed that experimental treatments had no significant effect on feed intake, feed conversion ratio, egg production and egg mass. According to the present study, Zahroojian et al (2013) reported that egg qualitative and performance traits of laying hens were not affected by diets containing spirulina platensis. In contrast, Shanmugapriya et al (2015) reported that body weight gain and feed conversion ratio increased significantly by adding 1% spirulina platensis to the broiler diet compared to the control treatment. The reason for this discrepant is likely due to the inclusion of different levels of spirulina platensis and the age of the birds used (Bonos et al, 2016). Addition of spirulina platensis to the laying hens diet had no significant effect on cholesterol, triglyceride and LDL, but HDL levels was decreased significantly in third and fourth treatments (p < 0.05). Shanmugapriya et al (2015) reported that in broiler fed 1.5% spirulina platensis and saccharomyces cerevisiae, serum cholesterol and triglyceride levels decreased but HDL levels increased compared to the control treatment. These results are inconsistent with the findings of the present study which may be due to the use of low levels of algae. In addition, the condition of cultivation and processing of algae that are effective in their composition may be another reason for this inconsistency (Gutierrez–Salmean et al, 2015). Experimental treatments had no significant effect on villi height, villi height to crypt depth ratio, villi surface and epithelium width, but the crypt depth was significantly increased in the fourth treatment (p < 0.05). The use of red seaweed algae in brown luhman laying hens diet increased the villi height and crypt depth compared to the control treatment (Kulshreshtha et al, 2014). Also, the use of different levels of spirulina platensis had no significant effect on coliforms, lactobacillus and total bacterial population.

The present findings show that, supplementation of Spiralina platensis by 4.5% in the diet, had no effect on performance of laying hens and high levels of that are likely to needed.

The objective of this study was to investigate the effects of different levels (0%, 0.3%, 0.6% and 0.9%) of blue-green algae (Spirulina platensis) on performance, egg quality, ovarian parameters and immune system of LSL laying hens at 26-37 wk. of age. One hundred and ninety-two hens were used in a completely randomized design with four treatments and four replications. The effect of algae on daily feed intake, feed conversion ratio, broken eggs percent and egg weight was not significant, but the egg mass improved using 0.6% algae compared with control group (P<0.05). Also, egg production of hens fed the diet with 0.6% and 0.9% Spirulina/kg were higher than treatment 2 (P<0.05). Eggshell breaking strength, eggshell relative weight, eggshell thickness, albumen height and haugh unit were not affected by treatments. However, increasing the dietary levels of Spirulina caused the improvements in eggshell weight and egg yolk color. None of the treatments had significant effects on white and red blood cells, platelets, heterophiles/lymphocytes ratio and concentration of hemoglobin. Dietary treatments did not have significant effects on humoral immunity against SRBC and cell mediated immunity response against PHA injection. But the treatments had a significant effect on the antibody titer in vaccinated birds against Newcastle. In addition, there were no influences of the experimental diets on ovarian different follicles, relative weight of bursa, spleen and carcass. In conclusion, inclusion of 0.6% Spirulina platensis algae in diet increased egg mass, egg yolk color and antibody titer against Newcastle vaccine.

A 360 Ross 308 broilers were used in a completely randomized design with 6 treatments and 4 replicates with the objective of comparing the effects of different sources of zinc on growth performance and some liver enzymes. The experimental treatments were: 1) negative control (non-supplemented), 2) positive control with 80mg/kg zinc sulfate, 3) hydroxychloride Zn (80mg/kg), 4) zinc sulfate (60mg/kg) + Zn-Met (20mg/kg), 5) zinc sulfate (40mg/kg) + zinc oxide (40mg/kg) and 6) zinc sulfate (30mg/kg) + zinc oxide (30mg/kg) + Zn-Met (20mg/kg). After 42 days, relative weight of bursa of Fabricius  (except for treatment 4) and thymus (except for treatment 3) were decreased significantly compared with the  negative control group (P<0.05). The hydroxychloride Zn source improved feed intake, compared to positive control group and daily weight gain compared to treatments 1, 2 and 4 (P<0.05). The inclusion of zinc oxide in treatments 5 and 6 increased alkaline phosphatase activity in plasma compared to treatments 3 and 4 (P<0.05). But, there were no differences in plasma AST, ALT, and LDH levels among the zinc different sources. These findings show that hydroxychloride Zn have comparable effects with zinc of inorganic and combination of organic with inorganic sources in broiler chickens.

The aim of this trail was to evaluate the effects of the use of Mn, Zn and Cu from different sources (inorganic, organic and hydroxy) in the diet on egg and eggshell quality of aged laying hens. A total of 240 Hy-Line w36 Leghorn, from 55 to 65 weeks of age, were used. The experiment carried out in a completely randomized design, with four treatments, four replicates, each containing 15 hens. The experimental treatments included: 1. The control diet, consisted of sulphate source of Mn, Zn and Cu, 2. The diet consisted of Mn, Zn or Cu-Methionine chelate, 3. The diet consisted of Mn, Zn or Cu Hydroxy, and 4. The diet consisted of Mn, Zn and Cu Hydroxy, only 70% level relative to treatment 3. In the most of experimental weeks, the Mn, Zn and Cu hydroxy and chelate forms increased egg weight and improved significantly feed conversion ratio in the 62, 64 and 65 weeks of age, compared with the sulphate group of these elements (P<0.05). But there was no difference between 70% hydroxy and sulphate groups. Also, there were no differences in feed intake, eggshell thickness, strength and weight, yolk index, Haugh unit, yolk color and shape index of egg and blood alkaline phosphatase, cereluplasmin, Zn, Cu and Ca levels among the treatments. The chelate source only increased blood Mn level significantly (P<0.05). There was the significant increase in eggshell and yolk Mn and yolk Zn levels and also significant decrease in the levels of Mn, Zn, Fe and Cu of excreta using hydroxy and chelate forms compared with the sulphate and 70% hydroxy forms (P<0.05). These results indicated that the Mn, Zn and Cu hydroxy and chelate forms in the diet improved the performance of aged laying hens.

The current experiment was conducted to investigate the effects of zinc different sources, inorganic, organic and hydroxy, in the diet on performance and egg quality of aged laying hen. A total of 288 hy-line W-36 hens, from 65 to 73 weeks of age were used. The study carried out in a completely randomly design, with 6 treatments, 4 replicates, each contains 12 hens. The treatments consisted of: 1- zero level mg/kg of zinc supplementation (control) 2- control+ 70 mg/kg of zinc as zinc sulphate (inorganic source) 3- control+ 70 mg/kg of zinc as zinc-methionine complex (organic source), and treatments 4, 5 and 6 consisted of control diets supplemented with 50, 70 or 90 mg/kg of zinc as zinc chloride hydroxide, respectively. All experimental treatments decreased feed conversion ratio and increased eggshell strength (during experiment), egg weight (8th week), yolk index and haugh unit (6th and 8th weeks) compared to the control group. The zinc organic and hydroxy sources increased significantly (P<0.05) percentage of eggshell, levels of blood and tibia zinc, blood albumin and antibody titer against Newcastle disease compared to control group. The zinc sulphate only increased blood zinc level. There were no differences in feed intake, production, specific gravity, eggshell thickness and shape index of egg due to supplementation with zinc. The results of this study suggest that 50 mg/kg zinc hydroxyl source can be a replacement for 70 mg/kg zinc sulphate or complex of zinc-methionine in aged laying hen diet.

In order to study the effect of manganese sources in the form of sulphate, hydroxychloride and methionine- chelated manganese organic complex on egg quality of aged laying hens, an experiment was conducted using 384 Hy-line W-36 laying hens at 65 week of age for 8 weeks in completely randomized design with 6 treatments, 4 replications and 16 hens in each replication. The experimental treatments included control (with no Mn supplementation), control plus 50, 70 and 90 mg of Mn as hydroxychloride per kg of diet, control plus 70 mg of manganese as manganese-methionine organic complex per kg of diet and 70 mg of manganese as manganese sulphate per kg of diet. The results showed that the different manganese sources had no significant effect on body weight, feed intake, egg production rate, yolk index, specific gravity and Haugh unit of egg. All treatments had better feed conversion ratio in weeks 6, 8 and in the entire experimental period when compared to control group (P<0.05). All treatments increased egg weight at 8th week and entire experimental period and eggshell thickness, eggshell percentage and eggshell breaking strength during different weeks of experiment when compared to control group (P<0.05). The increase in eggshell strength with 90 mg/kg of manganese hydroxychloride in comparison to 70 mg/kg of manganese sulphate was significant (P<0.05), however no significant difference was observed between 50 mg/kg manganese hydroxychloride and 70 mg/kg manganese-methionine organic complex. The use of manganese organic source or manganese hydroxychloride increased blood and tibia manganese concentrations (P<0.05) in comparison to control group. Generally, the results showed that 50 mg/kg of manganese hydroxychloride can be replaced for 70 mg/kg of manganese-methionine organic complex or manganese sulphate in the diet of aged laying hens.

This study was conducted to investigate the effect of Protexin probiotic and aquablend antibody on the intestinal histology characteristics of broilers. In this experiment 320 day-old male broiler chicks of the Ross 308, with 5 treatments and 4 replications in a completely randomized design were distributed in experimental units (cages). The treatments include: control (C), Protexin(P1), Protexin(P2) with double there commended dose, Aquablend(A1) and Aquablend(A2) Aquablend twice there commended amount. The results showed that consumption of different dose of Protexin probiotic and aquablend antibody had significant effect on width of duodenal villus, height of epithelial tissue of the duodenum, depth of jejunum crypt, length of ileal villus, height of the ileum epithelial tissue and length of villus to depth of duodenal crypt of broilers(p<0.05). According to results of this research, it seems that the using of Protexin probiotic and aquablend antibody was effective in improving performanceof broilers.

Effects of dietary rosemary (Rosmarinus officinalis) essential oil were evaluated on the semen quality of broiler breeder rooster using sixteen 24-wk Ross 308 male birds. Experimental groups were consisting of four treatments (0, 50, 100 and 200 mg rosemary essential oil/kg of feed) with four replicates per each group. Semen samples were collected on days 0, 14, 28, 42 and 56 of experiment. Results showed that 100mg rosemary significantly improved several traits of sperm such as Amplitude of Lateral Head Displacement (ALH), Average Path Velocity (VAP), and Straight Line Velocity (VSL) on days 42 and 56, and sperm Membrane Integrity (MI), sperm viability, Linearity (LIN) and Total Motility (TM) on day 56 (P

The current study was aimed to investigate the effect of Primalac probiotic, Fermacto prebiotic and their composition on growth performance, carcass quality and decreased requirements of protein and energy in broilers diets. A number of 720 one day male and female Cobb 500 chicks were allocated to 6 treatments with 4 replications and 30 chicks for each replication, under a completed randomized design. Treatments were consisted of A: control (without the additives); B: control+ recommended level of Primalac in each growth stage; C: control+ recommended level of Fermacto in each growth stage; D: control+ 50% of recommended level of Primalac+ 50 % of recommended level of Fermacto in each growth stage; E: control+0.5% lower protein+50 kcal/kg lower ME+ 50% of recommended level of Primalac and Fermacto in each growth stage; and F: control+1% lower protein+100 kcal/kg lower ME+ 50% of recommended level of Primalac and Fermacto in each growth stage. No significant difference did exist (P>0.05) among various treatment for body weight gain, feed intake, feed conversion ratio, carcass relative weight, and percentage of carcass, leg, breast, heart, small intestine, abdominal fat, spleen and bursa of fabricius. Treatments E and F, in spite of lower level of dietary protein and energy, had similar performance with other treatments. Therefore the influence of probiotics and prebiotics appears when the diet nutrient content or its availability is restricted.

In order to investigate the effect of phytase and copper supplementaion on growth and carcass composition of common carp (Cyprinus carpio L.), in a completely randomized design with 3 ×2 factorial arrangement with three replicates the experimental diets including three levels of phytase 0, 500 and 1000 (FYT) kg-1 and two levels of copper 0 and 15 mg/kg were tested. Diets contained 0.72 percent total phosphorus. One hundred and forty four carps with a mean weight of 207±23 g were selected and allocated in eighteen cages (8 fish per cage). The experiment was carried out for 8 weeks and 2 weeks for acclimatization. Phytase supplementation caused no significant differences in weight gain (WG), feed conversion ratio (FCR), carcass index (CI), protein efficiency ratio (PER), liver, carcass and blood composition but increased apparent phosphorous digestibility (APD) significantly (P<0.04). Copper supplementation also caused no significant differences in WG, FCR, CI, PER, APD, liver copper, carcass composition, cholesterol (Ch), triglycride (TG), phosphorus of serum but decreased liver fat significantly (P<0.004) and increased high density lipoprotein (HDL) of serum (P<0.02). Interactions between phytase and copper on WG (P<0.01), FCR (P<0.04), PER (P<0.03), liver copper (P<0.02) and TG of serum (P<0.001) were significant. This experiment suggests the presence of antagonistic effect between phytase and supplemental copper. Phytase enzyme improved some parameters of growth and carcass composition of common carp without supplemental copper but addition of copper to the diets with phytase enzyme impaired the improved performance of carp.

A 46-day feeding trial was conducted with rainbow trout (Oncorhynchus mykiss</em>) to examine the effects of partial substitution of plant protein sources with fish meal in diets. Three different sources of plant protein including soybean, sunflower and cottonseed meals were substituted by fish meal at four levels of 10, 20, 30 and 40 percentages. Each diet was assigned to triplicate groups of fish in a completely randomized design as a 3×4 factorial arrangement, with a control diet. Seven hundred and eighty fish were used in this trial. Twenty fish were randomly assigned to each of 39 pens and were acclimated in these pens to the experimental conditions two weeks before treatments began. This substitution caused no significant differences in all the criteria measured with control diet. Fish fed diets of 30 and 40 percent soybean meal substitution showed greater weight gain and better growth performance, lower FCR and higher PER values in comparison with the fish receiving other diets, although the differences were not significant. Irrespective of substitution levels, comparison of fish fed by three different sources of plant protein in their diets showed that the fish fed diet containing sunflower meal had significantly (p<0.0l) lower final mean weight and growth performance, higher FCR and lower PER than the fish receiving soybean and cottonseed meal diets. Relative liver weight of fish receiving soybean meal diets was significantly (p<0.0l) higher than those fed with cottonseed meal diets, but the difference was not significant when compared with the fish fed with the sunflower meal diets. Partial replacement of cottonseed meal resulted in a higher energy availability to fish and also better performance of fish. However, diets containing soybean meal showed not much effects on performance of rainbow trout. These results indicate that cottonseed and soybean meals can be recommended as a suitable and fish meal-sparing ingredient in diets for rainbow trout.