JWSS - Journal of Water and Soil Science

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A 46-day feeding trial was conducted with rainbow trout (Oncorhynchus mykiss) 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.

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Variability of seed storage protein electrophoretic patterns revealed by SDS-Polyacrylamide gel electrophoresis and their possible relations with some morphological and phenological characteristics were studied using 193 accessions from Iran Mungbean (Vigna radiata L. Wilczek) Collection. Seed protein electrophoresis revealed six different patterns that were different in two albumin and four globulin subunits with molecular weights of 23500-34000. Pattern types 1 and 2 had a considerable frequency but pattern types 3, 4, 5 and 6 had low frequencies and probably had developed recently in mungbean evolution process. Cluster analysis of countries and cities using the frequencies of albumin and globulin subunits showed no relation between geographical diversity and similarity distances. The correlations of morphological traits and albumin and globulin subunits indicated a relationship between G1 and G2 subunits with 1000 seed weight and days to beginning of maturity. Therefore, selection based on protein patterns at preliminary stages of breeding programs might be effective in increasing seed yield together with earliness.

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This study was conducted to evaluate the capability of reversed-phase high performance liquid chromatography (RP-HPLC) of wheat (Triticum aestivum L.) storage proteins, and their genetic variability in different winter and spring isolines, cultivars and landraces. Gliadin proteins were extracted from the flour of five randomly selected seeds of each genotype. In this method, Nucleosil C18 300 A column (250×4.6 mm ID), equipped with a guard column and acetonitrile containing TFA as mobile phase was used.

All selected conditions for RP-HPLC such as suitable velocity and resolution were sufficient to achieve the objectives of this study. Under these conditions, the number of gliadin components by RP-HPLC analysis was more than electrophoresis subunits. In addition, quantitative results of RP-HPLC facilitated the data analysis. Also gliadin analysis by RP-HPLC had a high potential in detecting rye (Secale cereale L.) genes, so that the presence of ω-secalins in the genome of Falat variety was easily detected. Therefore, it was concluded that RP-HPLC analysis of gliadin proteins is as efficient as electrophoresis, and could even replace it in some cases. The result of cluster analysis for gliadin polypeptides indicated the gradual increase of genetic variation from isolines to landraces. Generally speaking, among the landraces, Ali Abad, Aghda, Sefid Bafghi, Ghermez Bafghi, Shahdas and Sorkheh had greater genetic variations.

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An important and fundamental step in breeding honeybees is the separation of honeybee populations in Iran. During the years 1992-1996, several research works were directed towards the investigation of genetic populations of the Iranian honeybee (Apis mellifera L.), using biochemical methods. For this purpose, samples of worker bees were taken from 251 colonies of 115 apiaries in 84 cities in 21 provinces. The biochemical studies were conducted on thoracic proteins of worker bees using the horizontal electrophoresis.

The thoracic proteins of worker bees from the north and east populations isolated by electrophoretic techniques lacked a protein band having molecular weight of about 100,000 daltons. The results obtained from morphological and biochemical techniques and segregation of populations, indicate that breeding centers can be established in northern as well as western and central regions of Iran to improve genetic potentials of Iranian honeybee population. 

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The objectives of this study include the determination of the growth potential of Naeini lambs when fed with diets varying in energy and protein concentrations and also an investigation of the influence of level of energy and/or protein intake on carcass characteristics and composition. Ninety Naeini weather lambs (initial live weight 29.89 ± 2.9 kg) were used in a 92-day feeding experiment. Animals were blocked to each of nine dietary treatments. Diets contained either 2, 2.25 or 2.5 Mcal ME/Kg DM and 11.7, 13.2 or 14.7% CP diets were fed in a 3 × 3 factorial arrangement in randomized complete blocks.

Lambs fed with high energy diets consumed significantly more feed (P<0.05) than lambs given the medium (ME) or low energy (LE) diets. The average final body weight and daily weight gain for lambs fed with HE, ME and LE diets were 41.4, 38.3, 34.5 Kg and 162, 124, 74 g/d, respectively, which were significantly different (P<0.05). Feed conversion ratio in HE group was significantly lower (8.3) than ME (10.4) or LE (14.3) groups. Energetic efficiencies and protein efficiencies were better for HE than for ME and LE diets. Increasing dietary energy significantly (P<0.05) improved energy and protein efficiencies of the diets. Dressing percentage, lean meat and eye muscle depth were significantly (P<0.05) improved with increasing levels of energy in the diet, but also increased dissectible fat. No significant changes were observed in bone percentage and body ash due to any changes in dietary energy. As the protein level of rations increased, feed conversion ratio and carcass meat percentage increased, but carcass protein percentage decreased.

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A glasshouse study was conducted to measure the effects of salinity and drought stresses on growth and chemical and biochemical composition of 4 onion cultivars. The cultivars were Dessex, Texas Early Grano (Texas), Dehydrator, and PX492. Salinity treatments included control, 45mM NaCl, 45mM NaCl + 5mM CaCl2 and drought treatments were control (maintaining soil moisture at field capacity) and irrigation when 50% of available water was used. Four weeks after the treatments, the plants were harvested and root and shoot dry weights (RDW, SDW), Na⁺, K⁺, Ca²⁺, total protein, reduced sugars, as well as free proline contents were measured in both roots and shoots.

 Results showed that NaCl and drought treatments significantly reduced SDW and RDW. The Texas cultivar and the Dessex cultivar produced the highest and the lowest amounts of SDW, respectively. NaCl significantly increased Na⁺ uptake but reduced K⁺ uptake in shoots and roots and also reduced Ca²⁺ uptake in roots. NaCl+CaCl₂ significantly alleviated the deleterious effects of NaCl such that SDW significantly increased in two cultivars and increased RDW and the K⁺ contents while causing decreased Na⁺ and sugar contents in shoots and roots of all cultivars. All stresses increased total protein contents of shoots in Texas only but decreased or had no effect on others. Root total protein increased under salinity stress, while drought had no effect. Changes in proline and sugars in both shoots and roots did not follow any particular pattern. Out of the biochemical compositions measured, shoot total protein in plants under the stresses showed a positive significant correlation with SDW, which may be used to screen onion cultivars for drought and salinity stresses.

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An experiment was carried out to determine the effects of different levels of lysine and protein on the performance of 240 Hy-Line W36 layers. Ten experimental diets were tested in a 2×5 factorial arrangement with a completely randomized design. Two basal diets (13 and 14% protein) were tested at different levels (10 and 20% lower than NRC, NRC and 10 and 20% above NRC recommendations). Dietary lysine levels were 0.56, 0.62, 0.69, 0.76 and 0.83%. During the three months of experimental period, egg production, egg weight, egg output, feed intake and conversion and lysine and protein intake were determined.

 The results indicated that 0.76% lysine and more (10 and 20% above NRC recommendation) with 13% dietary protein led to significantly (P<0.05) higher egg production, egg output and better feed conversion, but there was no significant difference regarding egg weight. The difference in performance with different levels of lysine was lower in the 14% dietary protein than that in the 13% one. In the 14% dietary protein, the lowest level (0.56%) of lysine led to significantly (P<0.05) lower egg production and egg output and higher feed conversion. The best performance with the 14% dietary protein belonged to 0.62% dietary lysine (10% below NRC recommendation). The 14% dietary protein had significantly (P<0.05) higher egg production, egg output and feed intake than the 13% dietary protein, regardless of dietary lysine but there was no significant difference regarding egg weight and feed conversion. The best and most economical performance belonged to the 0.76% lysine and 13% protein diet. The results of this experiment indicated that reducing dietary protein and addition of lysine to the diets of post peak laying hens can obtain an equal performance to the higher dietary protein, thus reducing production costs.

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A Complete Randomized Block design was used to study the total protein efficiency (TPE) in Iranian Kilka and Peruvian Anchovy fish meals. Six isoenergetic (3200 kcal ME/kg) and isonitrogenous (18.5% CP) diets based on corn with six samples of fish meal (No. 1, 5, 6 steam processed, 2, 4 flame processed Kilka fish meal and No. 3 Peruvian Anchovy fish meal) were formulated and fed to Lohman male chicks from 7 to 42 days of age. Feed consumption and weight gain were measured weekly. Total protein efficiency and feed conversion (FC) were calculated and statistically analyzed.

The highest TPE values in fish meals obtained over the period of 7-28 days and significantly differed (P< 5%) among Kilka and Peruvian fish meals. With the exception of sample No. 5, the highest values of TPE obtained in the case of steam processed and the lowest obtained the case of flame processed Kilka fish meals. The TPE value of Peruvian fish meal was approximately equal to the average of the two types of processed Kilka fish meals. The orthogonal and nonorthogonal comparison of TPE and feed conversion (FC) in Kilka fish meals, regardless of the type of processing, with the same values in Peruvian Anchovy fish meal did not show any significant differences (P> 5%). With the exception of sample No. 5, the highest final weight of chicks obtained with steam processed Kilka fish meal. In general, TPE values in Kilka fish meals were variable when compared to Peruvian fish meal and TPE of steam processed Kilka fish meal was better.

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In order to study the effects of different protein feeds on honey bees (Apis mellifera L), experiments were conducted in a completely randomized block design with 15 treatments and 4 replicates. The nutritional effects of different treatments on caged bees were studied through recording half-life time (50% mortality). Pollen substitutes were soybean flour, soybean meal, bread yeast, wheat gluten, soybean flour + soybean meal, soybean flour + bread yeast, soybean flour + wheat gluten, soybean meal + wheat gluten, and wheat gluten + bread yeast. Pollen supplements were wheat gluten + pollen , soybean flour + pollen, soybean meal + pollen, bread yeast + pollen and two controls as pollen and honey. The nutritional effects of different protein sources provided by pollen substitutes and supplements were recorded on the amount of carcass protein and fatbody of honey bee workers in experimental colonies. The wheat gluten supplement and the soybean substitute showed the longest (60.58 days) and the shortest (10.53 days) half-life time of worker bees, respectively. The amount of food consumption in different treatments was not significantly different (P>0.05). The greatest DM of worker bees (dry matter of carcass) was related to soybean (34%) and the least related to yeast supplement (31.54%), which were significantly different (P<0.05). The highest carcass protein belonged to wheat gluten supplement (22.57%) and the lowest was related to yeast supplement (20.01%). The greatest carcass fat was related to soybean supplement (4.75%) and the lowest to wheat gluten supplement (3.84%). Results of the present experiments showed that soybean flour, soybean meal, wheat gluten and bread yeast can be used in pollen supplement and substitute cakes.

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Effect of supplemental phytase on phosphorus and protein utilization and performance of broiler chickens fed on eight different wheat varieties were evaluated. The phytate contents of wheat varieties were determined. In a completely randomized design with a 8*3 factorial arrangement, 384 day-old commercial male brioler chicks (HubbardPeterson) were divided into 96 groups, four chicks per group. Each of the 24 experimental diets (eight varieties) and three levels of phytase (zero, 500 and 1000 FTU/Kg) were given to four replicates for a period of 21 days. At 21 days of age, chickens of each replicate were weighed and killed by cervical dislocation. Ileal contents were collected and analyzed for P, N, phytate and chromic oxide. Left tibia of two birds in each replicate were removed, pooled and stored at -20^oC for bone ash determination. There was a significant (P<0.03) difference in phytate contents between different wheat varieties. Effect of wheat varieties on body weight, feed conversion ratio and bone ash was significant (P<0.05). Added phytase improved body weight, feed consumption, feed conversion ratio and bone ash significantly (P<0.05). Phytase added at 500 FTU/Kg, improved protein digestibility significantly (P<0.01), but increasing the supplement to 1000 FTU/Kg had no further effect. Difference between enzyme levels (500 and 1000 FTU/Kg) was not significant regarding body weight, feed consumption, feed conversion ratio and bone ash. Overall addition of phytase to the diets containing wheat caused an improvement in performance, protein digestibility, and phytase phosphorus utilization in broiler chickens, and can, therefore, be used in diets to reduce feed cost and environmental problems.

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In order to investigate the effects of mineral compounds as complementary nutrients for silkworm, Bombyx mori, an experiment was performed in CRD with five treatments including: 1%, 5% and10% concentrations of multi-mineral mixtures (nitrogen, phosphorus and potassium) with normal and distilled water treatments as controls. The larvae were fed by mulberry leaves from Shien Ichenoise variety up to the fourth instar. From the beginning of the fourth instar, the supplementary leaves were used once a day. The supplementation of the leaves was done by spraying the solution on them. The amount of total protein and uric acid in haemolymph of a 6-day 5^th instar larva was measured. The value of total protein compared to controls had significantly increased in all mineral treatments. The larvae's weight on the third day of the fifth instar had significant difference from controls, but the weight of silk gland did not show such a difference. However, uric acid of insect's blood demonstrated little differences but it showed no statistical significant differences from that in controlled insects. Despite this, the weight of cocoon, cocoon shell and pupa also had significant differences compared to controls, where this enhancement was higher in females than in males. Due to increase of the number of eggs, statistically there was a significant difference between the 10% treatment and others. The compounds had decreased the hatching percentage.

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This experiment was conducted to investigate the effects of intensity of restricted early feed and increased nutrient density after restriction period on performance and compensatory growth in broilers. Two hundred and eighty-eight broiler (Lohman) chicks in a completely randomized design in a 2*3 factorial arrangement of treatments were employed. Birds were fully fed from 7 to 13d or 100% of adlibitum intake on a daily basis. The diets were diluted at 25% and 50% levels with rice hulls. After the restriction period, birds were fed with a diet, formulated to meet all their nutrient needs, according to the NRC (1994) or 10% of protein, methionine and lysine above NRC in the realimentation diet from 13 to 21d. Body weight, feed intake, daily gain and feed conversion were determined weekly and selected carcass characteristics (liver, intestine and abdominal fat pad) were measured at 49 days of age. Feed restriction significantly (P<0.01) decreased body weight gain and feed conversion during the restriction period. Birds were able to fully recover body weight depression up to 49d. The intensity of restriction had no effect on body weight, feed intake, daily gain and feed efficiency at 49d (p>0.05). Increased nutrient density had no effect on growth rate, feed intake and feed efficiency for fully-fed birds and restricted birds at 49d. The results from this experiment showed that broiler chicks may be expected to gain weight similar to chicks with fully feeding even after restricted early feed if fed with NRC diets. The effect may be due to compensatory growth.

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In a completely randomized design with a factorial arrangement (3× 5× 3), three fistulated sheep with an average body weight of 47.5 ± 2.5 kg were used to determine the effect of cutting and growing stages (no bloom , early bloom and full bloom) on chemical composition and In situ degradability of alfalfa (Medicago sativa). Nylon bags (50 µm pore size) were filled with 3.5 g of each sample and suspended in the rumen before morning feeding and incubated for seven different times (0, 2, 4, 8, 16, 24 and 48 h). The results showed that alfalfa at no bloom stage had the highest crude protein and the lowest crude fiber content. The third – cut alfalfa had the highest degradability of dry matter and organic matter. Extent of degradability depended on crude fiber and solubility. During growth stage, the protein, soluble material and degradability levels decreased while crude fiber, neutral detergent insoluble crude protein (NDICP), and acid detergent insoluble crude protein (ADICP) increased. The amount of ADICP was an estimate of unavailable crude protein in the rumen. Although the rate of organic matter degradation was maximum in full bloom, no significant difference was observed between the three stages of growth. Effective degradability (ED) of crude protein was significantly different among stages the growth (p<0.05). Effective dry matter degradability (EDDM) with a passage rate of 6%/h was significantly higher in the third cutting of alfalfa. The results of this study showed that first cutting and full bloom alfalfa had the lowest and fifth cutting and no bloom had the highest CP levels. The effect of cutting and growing stages on degradability parameters was variable and did not allow any firm conclusions to be made.

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A 3×4 factorial experiment was conducted for 45 days to determine the effects of diets containing different levels of protein and fat on growth of fingerlings Beluga (Huso huso L.1758). Twelve different diets were formulated with 3 levels of protein (45,50 and 55) and 4 levels of oil including fish oil and sunflower oil (0.5 ,4 , 8 and 12). 1260 Beluga fingerlings with an initial body weight (IBW) of 2.2 gram, after adaptation to the experimental conditions, were selected and stocked randomly into 36 fiberglass tanks (100 water volume) at 35 fish per tank, and fed on experimental diets for 45 days. Two ways analysis of variance showed that the percentage of body weight increase (%BWI), specific growth rate (SGR),protein efficiency ratio (PER), food concumpsion ratio, and productive protein value (PPV) content were significantly (P<0.05) affected by different protein and fat levels. Fishes fed on diets No.3 (containing 45% protein and 14 % lipid) and No.8 (containing 50% protein and 17 % lipid) showed the highest increase in body weight percentage, the best specific growth rate, protein efficiency ratio, and lowest food concumption ratio. Besides, the highest productive protein value was observed in diet No.2 (45% protein and 10.5% lipid) and diet No.3 (45% protein and 14 % lipid).Comparison of chemical composition of examined fish corps indicated a significant difference in their protein and lipid contents (P<0.05). However, the composition of the diet, revealed no significant changes on the dry matter and ash content of the body. Based on the findings of the present study 45-50% dietary crude protein is recommended for the optimum growth of Beluga fingerling. Moreover, the rate of needed lipid for optimum growth of fingerling range is from 14 to17 percents.

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In order to determine the effects of fetal growth rate on plasma concentrations of glucose, triglyceride, total protein, and urea in ewes, this experiment was conducted at Animal Research Station of Tehran University Agricultural College. Sixteen pregnant Varamini ewes were allocated to 4 groups (n=4). During the breeding season, ewes of group 1 were mated by Varamini ram, animals in groups 2, 3 and 4 were mated by Moghani, Afshari and Shall rams, respectively. Because of the different genetic capacities of sires, fetal growth rate was expected to be different in various groups. Ewes in all groups were fed the same ration, so it was expected that differences in fetal growth rates would affect the mobilization of maternal fat and protein storage and blood levels of their metabolites. Blood samples were collected from jugular veins of ewes during the last 8 weeks of pregnancy and first week after lambing. Plasma levels of glucose, cholestrol, and triglycerid were not different among 4 groups. Total plasma protein in ewes carrying heavier fetuses was lower than in ewes with lighter fetuses (p<0.05). Conversely, plasma urea concentrations in ewes with heavier fetuses were higher than in ewes with lighter fetuses.

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This study was conducted to evaluate the effects of different levels of energy and protein on the performance of male broiler breeder chicks. Three hundred and sixty day-old Arian male broiler breeder chicks were used in a 2×3 factorial experiment with two levels of metabolizable energy (3050 and 3200 Kcal/Kg) and three levels of protein and sulfur amino acids (110% NRC, NRC and 90% NRC) in a completely randomized design with four replicates per treatment. Results obtained from the whole of the experiment’s period (0-49 days of age) indicated that level of dietary energy had a significant effect on body weight and daily gain (P<0.05). Increasing of the energy levels from 3050 to 3200 kcal/kg increased body weight (2216g vs 2314g) and daily gain (45.2 vs. 47.2 g per day). Dietary energy level had no effect on feed intake, feed conversion and carcass components. Increasing of dietary protein significantly increased body weight and daily gain and decreased feed conversion and percentage of abdominal fat pad (P<0.05). The results of this study indicated that we can fed Arian male broiler breeder chicks by using diets containing 3200 Kcal ME/kg and protein and sulfur amino acid levels according to NRC recommendation or 10% higher during 0-21, 21-42 and 42-49 days of age and achieve suitable growth rate and body weight.

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This study was conducted to evaluate the effects of four levels of irrigation (irrigation of plants after I₁ = 40, I₂ =60, I₃ = 80 , and I₄ = 100mm of evaporation from class A pan) and four plant densities(D₁ = 30, D₂ = 40, D₃ = 50 and D₄ = 60 plants/m²) on the seed yield and seed quality in three soybean cultivars(V₁=Hobit, V₂=Williams and V₃=Hill) in a split factorial design, based on the completely randomized blocks, with three replication for two years(2001 and 2002). The Irrigation treatments were assigned to the main plots, and the plant densities and cultivars to the sub plots. Results indicated that soybean seed yield was influenced by the different irrigation and plant density levels in the both years. Irrigation levels I₂ produced the highest and I₄ the lowest seed yield. It was also revealed that the plant density D₃ produced the highest and D₁ the lowest seed yields. Among the cultivars under investigation, V₂ produced the highest and V₃ the lowest seed yield . Seed oil and its protein contents both were affected significantly by the irrigation levels, plant densities and cultivars in both years. The plants receiving I₁ treatment had the highest and those having I₄, the lowest percentages of seed oil. Changes in the plant densities also affected seed oil and protein content. The plant density of D₁ caused the seeds to have the highest oil and lowest protein percentages. However, D₄ decreased oil and increased protein percentages. The highest water use efficiency was obtained from I₃ and that of the lowest value from I₁. The results also indicated that D₄ had the highest and D₁ the lowest water use efficiencies. Therefore, it could be concluded that the water use efficiency can be increased by increasing the plant density per unit area. The highest efficiency for biological and grain yield belonged to V₂ and V₁ respectively where as the lowest efficiency for those two mentioned characters belonged to V₁ and V₃, respectively. However, the treatment I₂V₂D₂ is recommended for higer the seed yield production per unit area.

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An experiment was conducted with the male Ross broiler chicks from 1 to 42 days of age to test the effects of different dietary protein and lysine levels on performance, carcass characteristics, and N excretion. Treatment diets consisted of three levels of supplemental lysine in starter and grower period (0, 0.15, and 0.30 %) and the two levels of protein (20.84, 17.84 in starter, and 18.12, 16.12% in grower period) with 2900 Kcal ME/kg diet. The results indicated that the Reducing dietary protein decreased significantly the weight gain in starter, grower, and total period up to 6, 4.6, and 5.6%respectively (P<0.05). It also decreased the feed consumption in starter period (P<0.05). Decreasing dietary protein had no significant effect on gain to feed ratio and breast meat yield, but increased abdominal fat percentage significantly (P<0.05). Increasing dietary lysine increased the feed consumption in starter and weight gain, gain to feed ratio in grower and total period of the experiment (P<0.05). Increasing lysine in diet caused a significant increase in breast meat and tight yield, and percentage. Adding supplemental lysine reduced the N excretion in starter period significantly (P<0.059). N excretion reduced significantly by decreasing dietary protein (P <0.05). Dietary treatments had not significant effect on mortality percentage. The results of the present experiment indicated that with providing limiting amino acids and adding supplemental lysine to diet, the crude protein could be reduced up to 3 and 2 percent in starter and grower periods respectively. Reducing the crude protein had not adverse effect on the feed efficiency.

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Using a deterministic model for dairy herd according to milk pricing system in Iran, the economic weights of milk production, fat percentage, protein percentage and herd life with minimized cost were identified, while restricted total input and total costs were variable in animal unit. By data simulation and the data obtained from 3 different dairy herds in Iran, the sensitivity of economic values with the assumption of 20% change in forage and concentrate price, forage to concentrate ratio, feed-cost, non-feed cost, base price of milk, free-market price of milk, average milk production, fat percentage, protein percentage and herd life were estimated. In the base condition, the economic weights of milk production, fat and protein percentage and herd life in three herds were -0.55, -0.24, -0.54 -34, -20, -11 -34, -37, -33 -0.37, 0.67, -0.39, respectively. The effect of change in different factors of production system on economic weights of three farms was variable. The economic weights of milk production, fat percentage, protein percentage and herd life had the most sensitivity to change in the average milk productoin, base price of milk and herd life, respectively.

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Proteolytic enzymes play important roles in food and drug industries. Actinidin, the most abundant protein of kiwifruit is a cystein protease (EC 3.4.22.14). In the present study, protein contents and levels of actinidin in kiwifruit cultivars were assayed and the enzyme was purified by a simple procedure. Actinidin was purified using two steps: (1)) precipitation by ammonium sulfate and (2) ion-exchange chromatography on diethylaminoethyl Sepharose. Molecular mass and proteolytic activity of the purified enzyme were determined by SDS-PAGE and casein digestion test, respectively. Protein content of the cultivars was compared by three different methods, namely, Bradford, UV and Lowry methods. The yield and degree of enzyme purity were 65 and 95 percents, respectively. Molecular mass of the purified enzymes were estimated 29 KDa in reducing SDS-PAGE. Results of the protein assays showed that protein and actinidin contents of kiwifruit were overestimated using UV or Lowry methods for assay. It was concluded that Bradford method is more accurate than UV or Lowry methods for measurement of protein level in kiwifruit.