جستجوی مقالات مرتبط با کلیدواژه « growth » در نشریات گروه « محیط زیست »

Water quality management in culture ponds is the most important factor in the proper growth of shrimp and achieving proper production, which can help to improve the quality of the conditions of the pool floor and achieve the desired production. Poor quality water causes stress and illness. Today, ozone technology can be used in areas with viruses, bacteria, and fungi. Due to the high oxidation potential, ozone oxidizes the cellular components of the bacterial cell wall to reduce the number of inactive microorganisms. In this study, chronic ozone concentrations (0.02, 0.04, 0.06 mg/l) were applied serially to western white-leg shrimp for 60 days two hours after each diet. During the experiment, quality factors were measured, and at the end, growth factors and Body composition were performed. The results showed that salinity and temperature were in the optimal range of western white-leg shrimp and there was no significant difference between treatments (p>0.05). With increasing ozone concentration between treatments, dissolved oxygen, pH and nitrate increased and total ammonia, suspended solids, and nitrite decreased. Also, according to Body composition, there was a significant difference between the treatments in protein and ash levels with a decreasing trend and fat and moisture with an increasing trend concerning ozone concentration. The results of growth factors showed a significant difference between ozone levels, indicating the optimal level of growth factors in concentrations of 0.02 and 0.04, respectively.

Heavy metals are especially important because of the toxic effects of the environment, the accumulation of biodiversity in various aquatic species and the creation of biological magnification in food chains. The present study was conducted to compare the toxicity of heavy metals of cadmium and lead in different concentrations (500, 250, 100, 50, 5 μg/L) on microorganism growth of Isochrysis galbana during 15 days in F2 culture media. The results showed that the effect of two metals on growth of I. galbana was dependent on two factors of time and concentration. Observations showed that concentrations of 500 micrograms per liter of cadmium on day 4 significantly inhibited the growth of I. galbana. The highest growth rate was obtained at a concentration of 5 μg/L for both tested metals. In this experiment, the highest content of chlorophyll a for cadmium and lead was 5 g/L and the lowest content of chlorophyll was in two concentrations of 250 and 500 μg/L. Also, by studying the effect of cadmium and lead on the amount of alfalfa protein, low concentrations increased protein levels and high concentrations reduced the amount of microalgae protein.

The aim of this study was to investigate the effect of replacing fish meal with plant protein sources on growth performance, digestive enzymes activity and also introducing a diet suitable for cultured Asian sea bass species in terms of biological efficiency. A total of 600 juveniles with an average weight of 54±2.5 gr were distributed in 15 tanks (500 liters) with a density of 40 pieces in each tank and were fed with prepared diets for 60 days. The composition of plant proteins (soybean meal, wheat gluten and corn gluten) was used at two levels of 35 and 70% to replace fish meal and the growth performance and activity of digestive enzymes were examined.The results showed that T1 (fish meal) and T2 (35% replacement) had the best performance in specific growth factor, weight gain percentage, relative growth rate, weight gain. Also, replacement of 70% fish meal with plant protein sources led to a significant reduction in specific growth rate, daily weight gain and relative growth rate compared to T1 (P<0.05).The results of gastrointestinal enzymes activity showed that the T4 (commercial 1) in alkaline phosphatase, lipase, α-amylase and the T2 in trypsin activity had a significant difference compared to other treatments (P<0.05). It can be inferred that Asian sea bass can easily have good growth performance by replacing 35% fish meal with plant protein sources.

To purpose fish meal reduaction in Huso huso diet, a combinaton of plant and animal proteins (corn gluten: 35%, wheat gluten: 19.34%, processed soy meal: 3%, poultry by product: 20%, meat and bone meal: 8%, blood meal: 4.3%) similar in chemical composition and amino acid profile was subsutsted Anchovy fish meal at 0, 20, 40, 60 and 80% and named of treatment 1 (FM), treatment 2 (MPP20), treatment 3 (MPP40), Treatment 4 (MPP60) and treatment 5 (MPP80). All diets had the same protein and energy levels (44% and 4365 kcal / kg). Huso huso (average weight, 167 ± 6.5 gr) were fed saturarated and growth indices, hematology and enzyme liver were studied. The results showed that growth indices were not affected by different diets (P> 0.05). There was no significant difference in white blood cell count, red blood cell, hemoglobin, hematocrit, mean hemoglobin concentration (MCHC), monocyte and eosinophil in fish compared to fish fed on fish meal (FM) diet (P>0.05), but mean erythrocyte volume (MCV) in diets fed with diets (MPP20, MPP40, MPP60 and MPP80) and mean hemoglobin weight in one erythrocyte (MCH) of MPP60 and MPP80 compared to (FM) were significantly Decreased (P<0.05). Increasing mixture of animal protein instead of fish meal significantly increased the activity of liver AST and ALT enzymes compared to fish fed a diet based on fish meal (P<0.05). The results of this experiment showed that there was possibility of replace 40% fish meal by mixture of animal and plant proteins without adversely affect on hematological parameters and and liver enzym in growing Huso huso.

This study was carried out to investigate population dynamic of Caspian roach (R. caspicus) on the south east Caspian Sea in 2018 (In the 6 months of the catch season). A total of 215 samples were collected using beach siene (Total length with 0.01 accuracy and total weight with accuracy of 0.001 were measured). The length of samples range from 16.74 to 30.03 cm and weighing from 52 to 346 gr. The age of the specimens was ranges from 3+ to 7+. Length-weight relationship was W=0.009L3.09, indicating positive allometric growth for population. After fitting the regression using least square method, the relationship was W=0.009L3.42. The Von Bertalanfy growth equation as, Lt=37.1033(1-EXP (-0.19(t+0.40)) . Natural mortality using Pauly's experimental equation calculated as 0.445. The highest condition factor and growth rate was 0.42 and 0.44 respectively, for population in the south east Caspian Sea. Overall, the Caspian roach stocks in the southeastern part of the Caspian Sea appear to be in serious danger and require effective management strategies to maintain their reserves.

Recently, the use of Acidifier (a group of organic acids) has been increased in aquaculture. The purpose of this study is to evaluate the effects of Acidifier (sodium diformate and Formic acid) on the growth performance, nutrition indices, and Digestive enzymes activity of the juvenile Huso huso. A total of 420 juvenile Huso huso (30.55 ± 1.72 g) was randomly divided into seven experimental treatments (Three replicates each). All groups were fed with the experimental diet for 60 days. The Bioassay conducted on the first day and after 30 and 60 days and then growth parameters were investigated. The experimental diets contain 0.05, 0.1 and 0.15 % sodium diformate (NDF) and 0.05, 0.1 and 0.15 % Formic acid (Formi). diet control was without any acidifier. Results show that all growth and Intestinal enzymes (trypsin, chymotrypsin and alkaline phosphatase) are affected by acidifier and in these two parameters  groups that fed 0.1 % supplemented food by NDF and citric acid compared to the control group. The best FCR and SGR observed in the groups fed with 0.1 % supplemented food by NDF)0.5±00), (0.5±0.005) (p < 0.05) at day 30 respectively. Although the best FCR and SGR observed in the groups fed with 0.1 % supplemented food by Formic acid (0.81±0.001), (2.7±0.005) (p < 0.05) at day 60 respectively. Intestinal enzymes (trypsin, chymotrypsin and alkaline phosphatase) are affected by acidifier. The highest activity of trypsin and chymotrypsin was significant in groups 0.1 % supplemented food by NDF (P˂0.05) in  the first 30 days. Alkaline phosphatase activity increased with increasing acidifier diets in groups, but this increase was not significant compared to the control (p>0.05). It can be concluded that the addition of  0.1% of NDF to beluga diets improves growth parameters and decreases FCR, increases digestive enzyme activity. Moreover, these results indicated that 0.1 % of NDF and citric acid in the diet could be a useful food supplement preferably at 30 days and can be used to improve the growth parameters in juvenile Huso huso.