Effects of supplemental feed and fertilizer on growth and survival of Macrobrachium rosenbergii (de Man) post larvae in pond nursery system

The study was conducted to compare the performance of different nursing practices of giant freshwater prawn (Macrobrachium rosenbergii) post-larvae (PL). Three treatments such as only fertilizers (T1), fertilizers with 5% supplementary feed (local feed) (T2), and 10% commercial feed (T3) were applied in the nursing system of prawn PLs in earthen pond. An earthen pond (315m²) was divided into nine equal small ponds by fine meshed nylon nets. Feeds were used once daily on a tray placed near the pond bottom. There was a significant difference (p<0.05) in some water quality parameters like pH and total alkalinity, but all measured water quality parameters viz. water temperature, transparency, dissolved oxygen and ammonia-nitrogen were within the acceptable range for nursing of prawn PL. The results showed that the mean final lengths of prawn post-larvae were 6.3±0.07 cm, 7.12±0.22 cm and 8.17±0.16 cm in T1, T2 and T3, respectively. There were significant difference (p<0.05) in mean final length of prawn PL among the treatments. Significantly higher (p<0.05) average daily weight gain was observed in T3 (0.071 ±0.007 g) than in T2 (0.052±0.006 g) and T1 (0.031 ±0.002 g). The specific growth rate (SGR) of T3 (8.81±0.26) was found significantly higher (p<0.05) than T2 (8.35±0.22) and T1 (7.42±0.11). Survival rate (%) was also significantly higher (p<0.05) in T3 (66.24±1.58) than in T2 (60.52±1.64) and T1 (53.86±2.71). Therefore, it may be concluded that the growth and survival in prawn nursery was better in commercial feed than only fertilizers and fertilizers with local feeds.

Comparative effect of Pediococcus acidilactici and Lactococcus lactis on growth performance, survival and enzyme activity of western white leg shrimp (Litopenaeus vannamei)

This study was done in Shahid Kiani Marine Aquaculture Development Center, Choebde, Abadan in order to evaluate the effects of Pediiococcus acidilactici, Lactococcus lactis and vitamin C on growth performance, survival, enzymatic activities and immune responses of L. vannamei during three months. Treatments were included control group, Pediiococcus and Lactococcus treatments which fed with diet containing 1×10P9P cfu gP_1P bacteria and vitamin C. At the end of the experiment, the growth factors, immune parameters, digestive enzymes, intestinal, histology of intestine, carcasses and microbial flora (bacterial total count and lactic acid count) were evaluated. The results indicated that administration of lactobacillus had significant effects on the growth factors as the highest weight, increase specific growth rate, relative growth rate, feed conversion ratio and protein efficiency in the shrimps received pediococcus and then Lactococcus (P<0.05). The best immune function was also observed in the shrimps fed by probiotics, so that proteins and hemoglobin̛ hemolymph, phenoloxidase activity and challenged with V. parahaemolyticus showed a statistical difference comparing to the control group and the group received vitamin C (P<0.05). Some digestive enzymes, in pediococcus treatment showed a significant increase when compared to other treatments (P<0.05). Significant changes in bacterial intestinal flora were observed in probiotic groups compared with control and vitamin C groups (P < 0.05). Histological results showed the positive effects of probiotics in the gut (P < 0.05). While these supplements cannot caused to significant impacts on the shrimp carcass composition (P ˃ 0.05). As a result pediococcus group had the best performance among treatments.

Effect of two green algae species (Chlorella sp. & Scenedesmus obliquus) enriched with B group vitamins on food chain of Rutilus frisii kutum (Kamensky, 1901) fry

The Effect of two freshwater green algae species Chlorella sp. & Scenedesmus obliquus enriched (from the beginning of culture and after 96 hours) with different dosages of B group vitamins (0, 0.5, 1, and 2 ml of enriching solution per each liter of algae medium) on fecundity of Daphnia magna and growth of Rutilus frisii kutum fry were investigated in a research from spring, 2008 to autumn, 2009. First, each of the green algae species were cultured purely and massively in the Zander (Z-8+N) medium and then the nutritional value (the amount of protein, lipid, and carbohydrate) of enriched algae were meausered. In this study, enriching of Chlorella sp. & S. obliquus with a suitable mix of B group vitamins significantly improved their nutritive value. So the highest amount of nutritional value of Chlorella sp. was obtained because of enriching with dosage 0.5 ml.l-1 (366.654Kcal) and for Scenedesmus obliquus with dosage of 1 ml.l-1 (376.95Kcal). The acquired amount from control group showed an increase of respectively 42% and 11%. According to the results, increased dosages of enriching solution caused Daphnia fecundity to increase (at both stages : enrichment from the beginning of culture and after 96 hours). So the highest average of D. magna reproduction rate was obtained through being fed with Chlorella sp. and S. obliquus enriched with dosage of 2 ml enriching solution per liter of algae medium. The average fecundity of D. magna fed with Chlorella sp. enriched with dosage of 2 ml.l-1 enriching solution from the beginning of culture and after 96 hours was obtained respectively 2.128 ± 0.375 and 2.1 ± 0.69 and the average fecundity of D. magna fed with S. obliquus enriched with dosage of 2 ml enriching solution from the beginning of culture and after 96 hours was obtained respectively 2.128 ± 0.375 and 2.1 ± 0.69 which showed respectively an increase of 61 ٪, 91٪, 77 ٪, and 83٪ in proportion to the acquired amount from control group. When enriching solution was added to either algae culture medium from the beginning of culture, showed statistically significant differences (P<0.05) between dosages of 0 and 2 ml.l-1, 1 and 2 ml.l-1, and 0.5 and 2 ml enriching solution per each liter of Chlorella sp. culture medium and between dosages of 0 and 1 ml.l-1, and 0 and 2 ml enriching solution per each liter of S. obliquus culture medium. The highest average of body weight gain percentage and specific growth rate of kutum fry was obtained respectively 21.19%, 26.63%, 1.92, and 2.34 from the beginning of culture and after 96 hours with dosage of 1 ml B group vitamins per each liter of Chlorella sp. culture medium, which showed respectively an increase of 50%, 70%, 46%, and 62% in proportion to the acquired amount from control group. In the cases which Chlorella sp. were grown in the medium containing vitamin, from point of view of the average percentage of weight and specific growth rate of kutum fry significant differences were observed on the basis of the result of One-way ANOVA between dosages of 0 and 1, 1 and 2 , 0.5 and 1 ml B group vitamins per each liter. The highest average of body weight gain percentage and specific growth rate of kutum fry was obtained respectively 32.02%, 29.42%, 2.78, and 2.34 from the beginning of culture and after 96 hours with dosage of 2 ml B group vitamins per each liter of S. obliquus culture medium, which showed respectively an increase of 32%, 19%, 28%, and 17% in proportion to the acquired amount from control group. In the cases which S. obliquus were grown in the medium containing vitamin, from point of view of the average percentage of weight and specific growth rate of kutum fry significant differences were observed on the basis of the result of One-way ANOVA between dosages of 0 and 1, 0 and 2. According to the results of the present research we can say that considerable enhancement in the quality of the food of D. magna can be made by manipulation of the nutritional value of fresh water unicellular green algae with suitable mixture of B group vitamins, so that both the fecundity of D. magna will increase and the nutritional requirements of the kutum fry will be filled in this way.

A comparative study on effects of Immunoster and Immunowall as immunostimulants on some hematological, biochemical and growth indices of farmed great sturgeon juveniles (Huso huso)

Prebiotics are non-digestible food ingredients that profitably affect the host by selectively stimulating the growth and /or activation of one or a limited number of bacteria in the intestine that can enhance host health status. Immunoster (IS) and Immunowall (IW) are prebiotics and immunostimulants derived from the outer cell wall of brewers yeast, Saccharomyces cerevisiae. These substances contain MOS and �-glucans. After a four-week acclimatization period to rearing conditions and basal diet, 450 farmed great sturgeon juveniles weighing 95.58 ± 9.38 g were randomly distributed into 15 fiberglass tanks (2 × 2 × 0.53 m) in five treatments (Control, IS 1%, IW 1%, IS 3%, and IW 3%) in three replicates (completely randomized design) and kept at a density of 30 fish per tank for a period of 8 weeks at water temperature 20.55 ± 5.11ºC, dissolved oxygen 6.73 ± 0.35 mg L-1 and pH 7.92 ± 0.09. IS and IW were added at two levels of 1% and 3% to the basal diet in place of cellulose, except the control. At the beginning, in the middle and at the end of the trial, carcass analysis was done to determine the moisture, protein, fat, ash, and total carbohydrate. Also, blood samples were collected to measure hematological, biochemical and immune indices. At the end of the trial, final weight, final length, body weight increase (BWI), specific growth rate (SGR), average daily growth (ADG), protein efficiency ratio (PER), feed conversion ratio (FCR), and condition factor (CF) in fish fed on IS and IW in both levels 1% and 3% showed some differences. These differences were significant in IS 3% and IW 1% and 3% compared with the control (P<0.05). HSI showed no significant difference (P>0.05) and survival rate was 100% in all treatments. Crude protein of carcass in fish fed on IS and IW at 1% and 3% showed an increase in comparison with the control. There was significant difference between IS 3% and the control in crude protein of carcass (P<0.05). Fish fed on IS and IW at 1% and 3% showed various results in hematological and biochemical factors. It was observed significant difference in MCV between IW 1% and IS 3% compared with the control (P<0.05). Although there was an increase in values of hematocrit, hemoglobin (except IS 1%), WBC (except IW 3%), MCH, neutrophil, total protein, albumin (except IS 3%), K+, and lysozyme in fish fed on IS and IW compared with the control, it was no significant (P>0.05). The maximum count of WBC and the highest value of Ca2+ were seen in IW 1%. The maximum count of lymphocyte, the highest values of total protein, albumin and IgM were recorded in IW 3%. IS 1% had the maximum count of neutrophil and the highest concentration of lysozyme. Based on obtained results, it can be declared that IS and IW at two levels of 1% and 3% can enhance growth performance and feed efficiency and also improve some hematological, biochemical, and immune indices in farmed great sturgeon juveniles.

Effects of Zataria multiflora Boiss essential oil and nisin on the growth of Staphylococcus aureus in light salted silver carp fillet (Hypophthalmichthys molitrix)

There is an increasing demand in developing newer and safer methods in preserving food products.Among which herbal additives seem to attract evermore attention recently.the major advantage of herbal additives is due to their favorable aroma besides their antimicrobial effects and less expensive than chemical additives. Zataria multiflora Boiss is a native Iranian herb which is used vastly as a food preserver essential oils and also medical usage. Metabolites of harmless bacteria, such as Nisin are also known to be safe preservatives that have antimicrobial activity. However to establish the usefulness of natural antimicrobial preservatives, they must be evaluated alone and in combination with other preservation factors to determine whether there are synergistic effects in rigid media . In this study were evaluated the effects of different concentrations of Zataria multiflora (EO 0, 0.005, 0.015, 0.045, 0.135, 0.405 ,0.810 %) and Nisin(0, 0.15, 0.25, 0.75 μg/ml) and Storage time (up to 21 days) on growth of Staphylococcus aureus ATCC 6538 in a food model system(light salted fish of silver carp, Hypophthalmichthys molitrix). The results on growth of S. aureus were evaluated using SPSS 15.0 statistical software (SPSS 15.0 for windows, SPSS Inc.) and analyzed the logarithm of total count of the bacteria by Tukey Test. Results were considered statistically significant when P≤0.05. The growth of Staphylococcus aureus was affected significantly(P<0.05) by EO and Nisin and also combinations of EO and Nisin. Samples treated with 0.135, 0.405 and 0.810% of thyme essential oil showed a significant decrease on the growth of the bacteria compared with an treated samples(P<0.05). No significant difference was seen on the growth of S.aureus in samples treated with lower concentrations of Z.multiflora(below 0.045%) and untreated group(P>0.05). The most inhibitory effects were seen in samples treated with 0.405% and 0.810% of thyme essential oil until 9 and 12 days after storage,respectively. Also there was significant inhibtory effect(P<0.05) in different concentration of nisin on the organism compared with an treated samples. The synergism effects of the Eo and nisin on the growth rate of the bacteria was significant (P<0.05) compared with untreated samples and samples treated with the Eo or nisin, only. Synergismic effects was observed at concentration of 0.405 and 0.810% of Z. multiflora essential oil with 0.25 μg/ml Nisin, respectively until 15 days after storage. As expected it is preferred to apply the least possible amounts of additives in food preserving that not only are effective and safe but are economically justifiable.

Study on effects of extracted probiotics from microbial flora of digestive system on growth indices in beluga (Huso huso) and Persian sturgeon (Acipenser persicus)

Isolation of Lactic Acid Bacteria (LAB) was carried out from gastro intestinal tract of beluga and Persian sturgeon at international sturgeon research institute and PCR has been used for bacteria Identification. Two species of LAB including Enterococcus seriolicida and Leuconostoc mesenteroides were isolated from Gastrointestinal tract (GI) of persian sturgeon in this study and the counts of Leu. mesenteroides (4.63×102 CFU/gr of GI) was significantly higher than other species. Lactobacillus curvatus, Lactococcus raffinolactis, Lactococcus lactis and Streptococcus sp. were also isolated from GI of beluga and maximum counts was belonged to Lb. curvatus (4.63×102 CFU/gr of GI) in this species. Dominant species were lyophilized and adding to the water since start of mix feeding of sturgeon with different counts including 2×109, 5×109 and 9×109 CFU/gr of live food, 4 times a day. The results revealed that the maximum and minimum growth rate and protease, amylase, and lipase activity in beluga was gained by using of Lb. curvatus with total viable count of 9×10 9 CFU/gr of live food and Leu. mesenteroides with total viable count of 9×109 CFU/gr of live food. According to the results of this study, the maximum and minimum growth rate and protease, amylase, and lipase activity in Persian sturgeon was gained by using of Leu. mesenteroides with total viable count of 2×10 9 CFU/gr of live food and Lb. curvatus with total viable count of 9×109 CFU/gr of live food. Histological study showed that gastrointestinal development was same during larva rearing in control and other treatments but the size of liver was bigger in treatments that received nonspecific LAB in both species. According to the results, positive effects of using dominant specific LAB bacteria for larviculture of sturgeon has been proved in this study.

Effects of Artemia enriched with unsaturated fatty acids and vitamin C on growth, survival and resistance Salmo trutta caspius larvae

This experiment was conducted to investigate the effect of using n-3 HUFA and Vitamin C enriched Artemia urmiana Nauplii Five difference treament were tested: for Caspian salmon (Salmo trutta caspius) larvae compare with artificial food in five treatment: (1) Artificial food, (2) Newly hatched Artemia (3) n-3 HUFA enriched Artemia (4) n-3 HUFA + 10% Ascorbyl Palmitate enriched Artemia (5) n-3 HUFA+20% Ascorbyl palmitate enriched Artemia during 15 days then all treatment were fed with artificial food during 20 days. In days of 15, larvae fed with newly hatched Artemia didn’t show significant difference of growth rate and survival compared to larvae fed with n-3 HUFA and Vitamn C enriched live food (p<0.05), However all treatment which fed live food have better growth rate and survival compred to larvae fed artificial food. Larvae fed with enriched Artemia with n-3 HUFA + 20% Ascorbyl palmitate has best result of temperature resistance at 26'C and 28'C. There is not significant difference between treatment (1) and (2), (3) and in this manner between (2), (3) and (4), (5) (P>0.05). In days of 35, larvae fed n-3 HUFA + 10% and 20% Ascorbyl pamlitate show better wet weight and dry weight compared to other treatment (P<0.05). Larvae fed n-3 HUFA Artemia showed significant difference compared to treatment (1) and (2), However there is not significant difference between treatment (1) and (2). Larvae fed artificial food show less and significant difference of survival compared to other treatment (P<0.05). Larvae fed artificial food show least of temperature resistance at 26'C and 28'C , However, there is not significant difference between all treatment (P<0.05).

Distribution and growth biology of rock oyster Saccostrea cucullata in the Oman Sea

Distribution and growth biology of rock oyster (Saccostrea cucullata) in the northern shores of Oman sea have been struied. During this one-year study, samples have been taken monthly from ten different stations. quantity of vertical distribution of this species was obseredl in the mid - intertidal zone. After determining the spread pattern, the following subjects were studied: - Growth parameters - Distionction of the "cohorts" - Determination of "spawning Season" - Condition of the "Gonado Somatic Index" - Sex ratio - Length of the species during the first year of maturation. - Identification and determination of percentage of "Biofouler Organisms." Results obtained from the above - mentioned studies show that considering a growth factor (k) of 0.52, the value of "Loo " for this species is equal to 114 (mm).Five to six different age groups were observed among the samples taken. In the areas where this study was conducted, this species grows 24 to 30 (mm) in the first year of its life this growth rate is lower in the higher - aged grpups relative to the lewer - aged groups, so that the longest size classes grow between 4 to 6 (mm) per year. • The maxinum Value of the "Condition Index" is in the pozm area and the minimum value of it belongs to Darak and Tang areas. Along with the increase in the growth of gonads the above mentioned condition index increases gradually simultaneous with the onset of spawning. Also, study of the influence of environmental factors on the maturation process suggests that the most important factors affecting maturation and spawing are temperature and salinity. The study of GSI shows that this species has a coordinated bimodal spawing trend, with its spring peak in june and its autumn peak, being still higher than the spring peak, in september. The recruitment curve confirms the above spawning peaks with its peaks occuring after a delay of one month or maximum two months in comparison to the spawning peaks. The results of calcuation of "Sex Ratio" of this species in each area show that sex ratio is 1:1. Among the first size classes that reach maturity, nearly 67% of the samples are male and the remaining 33% are female. with the increase in the shell size, the percentage of males decreases and the percentage of females increases. , The above facts prove the protandrous nature of this species the diagram showing the sizes of the first samples which reach maturity suggests that more than 50% of the samples mature after their length exceeds 36 (mm). The shortest mature sample was found to have a length of 22(mm). After studying "Biofouler Organism" nine different invertebrate groups were indentified. Barnacles and Tunicates have the highest and lowest percentages respectively. According to zonal observations, Barnacles and polychacta do the greatest damage to this species.

Growth rates of juvenile Nile perch, Lates niloticus L. in lakes Victoria, Kyoga and Nabugabo

The growth rates of Nile perch, Lates niloticus L. of 20 cm to 40 cm total length were estimated in lakes Victoria and Kyoga in 1991 and 1992 and Nabugabo in 1992 and 1993 by tagging. Fish grew faster in Lake Kyoga (mean growth rate 28.7 ± 1.3 cm S.E. per year, N = 49) than in Lake Victoria (18.9 ± 1.4 cm per year, N = 20) and Lake Nabugabo (19.0 ± 0.7 cm per year, N = 43). There were significant differences in growth rates between the lakes (F2 109 = 24.037, P < 0.001). Growth rates in Lake Kyoga were significantly higher than those of lak'es Victoria and Nabugabo (p < 0.001) but those of lakes Victoria and Nabugabo were not significantly different from each other (p = > 0.05). The faster growth rates in Lake Kyoga were attributed to improvement in food supply due to increases in stocks of haplochromine prey. Growth rates in Lake Kyoga were significantly higher, but those of lakes Victoria and Nabugabo were within the ranges of those reported in several native habitats of Nile perch.

Aspects of the biology of the Lake Tanganyika sardine, Limnothrissa miodon (Boulenger), in Lake Kariba

Juveniles of limnothrissa miodon (Boulenger) were introduced into the man-made Lake Kariba in 1967-1968. Thirty months of night-fishing for this species from Sinazongwe, near the centre of the Kariba North bank, from 1971 to 1974 are described. Biological studies were carried out on samples of the catch during most of these months. Limnological studies were carried out over a period of four months in 1973. Limnothrissa is breeding successfully and its number have greatly increased. It has reached an equilibrium level of population size at a lower density than that of Lake Tanganyika sardines, but nevertheless is an important factor in the ecology of Lake Kariba. The growth rate, size at maturity and maximum size are all less than those of Lake Tanganyika Limnothrissa. A marked disruption in the orderly progression of length frequency modes occurs in September, for which the present body of evidence cannot supply an explanation.

Effect of water temperature on the growth performance and digestive enzyme activities of Chinese longsnout catfish (Leiocassis longirostris Gunther)

The present study was carried out to investigate the influence of water temperature on the growth performance and digestive enzyme (pepsin, trypsin and lipase) activities of Chinese longsnout catfish. Triplicate groups of Chinese longsnout catfish (35.6 +/- 0.48 g, mean +/- SE) were reared at different water temperatures (20, 24, 28 and 32 degrees C). The feeding rate (FR), specific growth rate (SGR) and feed efficiency ratio (FER) were significantly affected by water temperatures and regression relationships between water temperature and FI, SGR as well as FER were expressed as FR=-0.016T2+0.91T-10.88 (n=12, R2=0.8752), SGR=-0.026T2+1.39T-17.29 (n=12, R2=0.7599) and FER=-0.013T2+0.70T-8.43 (n=12, R2=0.7272). Based on these, the optimum temperatures for FR, SGR and FER were 27.66, 26.69 and 26.44 degrees C respectively. The specific activities of digestive enzymes at 24 or 28 degrees C were significantly higher than that at 20 or 32 degrees C. In addition, there was a significant linear regression between FR or SGR and specific activities of pepsin and lipase, which indicated that pepsin and lipase played important roles in regulating growth through nutrient digestion in Chinese longsnout catfish.

A one-year investigation of the relationship between serum GH levels and the growth of F-4 transgenic and non-transgenic common carp Cyprinus carpio

It has been demonstrated that growth hormone (GH) transgenic fish often posses a trait for fast growth. Here, we investigated the growth of F-4 'all-fish' GH transgenic carp Cyprinus carpio and their serum GH levels for a year. The results showed that F-4 all-fish GH transgenic carp were significantly larger in body mass (c. two-fold, P < 0 center dot 001) and body length (c. 1 center dot 3 fold, P < 0 center dot 001), compared with the non-transgenic group. The discrepancy of serum GH levels between the transgenic carp group and control group is 54 fold, when the water temperature was 12-34 degrees C. When the water temperature decreased to 3 center dot 5 degrees C in January, the discrepancy was 256 fold. The serum GH level of the transgenic group was relatively constant, while that of control varied greatly based on month and water temperature. The changes of growth rates between the transgenic group and the control group were similar for a year. Taken together, the results indicated that F-4 all-fish GH transgenic carp had not only higher and constant serum GH levels but also a significant fast-growing effect, compared with the control. To our knowledge, this is the first report on a one-year investigation of growth trait and serum growth hormone level in F-4 all-fish GH transgenic carp.

RESPONSES OF Elodea nuttallii AND Ceratophyllum demersum TO HIGH TEMPERATURE

There were large losses of exotic species Elodea nuttallii during summer in eutrophic lakes of the middle and lower reaches of the Yanatze River, China. To investigate the main causes, the heat tolerance of E. nuttallii was studied and compared with that of native species Ceratopkyllum demersum by using an aquaria system in the laboratory. Under 4500 lx light intensity and 12-h L/12-h D cycle, E. nuttallii cultured in 1/5 Hoaglands solution at 39 degrees C showed a positive growth rate during the first 15 days, and the growth rate was higher than that at 35 degrees C. But after 15 days, the growth rates became negative for those cultured both at 39 and 35 degrees C. However, the growth rate was positive for more than 20 days for those cultured at 25 degrees C. Under the same conditions, the growth rate, productivity and chlorophyll content of E. nuttallii were significantly higher than that of C. demersum. Heat tolerance of E. nuttallii was also stronger than that of C. demersum. The optimal temperature for the growth of the two plants depended on the experimental period: both plants grew at an optimal rate at higher temperature if the experimental period was short; nevertheless the plants achieved optimal growth at a lower temperature if the experiment was conducted for a longer period. At the same light intensity, the heat tolerance of C. demersum in tap water with sediment was markedly stronger than that of E. nuttallii at 39 degrees C. Average growth rate of C. demersum was 4.5 times higher than that of E. nuttallii within 25 days. The positive growth period lasted for less than 25 days for E. nuttallii and for more than 25 days for C. demersum. When they were cultured in 1/5 Hoaglands solution and in tap water with sediment, the growth rate of C. demersum increased from 0.4 to 79.4 mg/d.g fresh weight (FW) within 20 days. E. nuttallii increased from 8.3 to 24.4 mg/d-g FW within 20 days. Both grew better in tap water with sediment than in 1/5 Hoaglands solution. The results demonstrated that the nutritional status of the water other than the high temperature affected the heat tolerance of E. nuttallii during summer. E. nuttallii has great ecological safe risk in China.

The effect of different dietary iron levels on growth and hepatic iron concentration in juvenile gibel carp (Carassius auratus gibelio)

P>An 83-day growth trial was conducted using a flow-through system to examine the effects of different dietary iron levels on growth and hepatic iron concentration in juvenile gibel carp (Carassius auratus gibelio). Six purified diets supplemented with different levels of iron (0, 10, 30, 60, 100 and 200 mg kg(-1)) (as ferrous sulfate) were fed to triplicate groups of fish (initial weight 2.12 +/- 0.00 g per fish). The results showed that the addition of iron to the basal diet did not significantly affect the specific growth rate (SGR), feed efficiency (FE), survival, red blood cell amount (RBC), hemoglobin content (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) or mean corpuscular hemoglobin concentration (MCHC). Hepatic iron concentration and hematocrit (Hct) were significantly influenced by dietary iron level (P < 0.05). On the basis of the iron concentration for the maintenance of optimum hepatic iron concentration and Hct, it was concluded that the dietary iron concentration of juvenile gibel carp should be not less than 202 mg Fe kg(-1) diet.

Dietary phosphorus requirement of juvenile black seabream, Sparus macrocephalus

A growth trial was conducted to estimate the optimum requirement of dietary available phosphorus (P) for black seabream (Sparus macrocephalus) in indoor net cages (1.5x1.0x1.0 m). Triplicate groups of black seabream (11.45 +/- 0.02 g) were fed diets containing graded levels (0.18, 0.36, 0.54, 0.72, 0.89 and 1.07%) of available P to satiation for 8 weeks. The basal diet (diet 1), containing 0.18% available P, was supplemented with graded levels of monosodium phosphate (NaH2PO4 2H(2)O) to formulate five experimental diets. The fish were fed twice daily (08:00 h and 16:00 h) and reared in seawater (salinity, 26-29 g l(-1)) at a temperature of 28 +/- 1 degrees C. Dissolved oxygen during the experiment was above 5 mg l(-1). The specific growth rate (SGR), weight gain (WG), feed efficiency (FE) and protein efficiency ratio (PER) were all significantly improved by dietary phosphorus up to 0.54% (P<0.05) and then leveled off beyond this level. Hepatosomatic index (HSI) was inversely correlated with dietary phosphorus levels (P< 0.05). Efficiency of P utilization stabled in fish fed diets containing 0.18%-0.54% available P and then decreased dramatically with further supplementation of dietary phosphorus. Body composition analysis showed that the whole-body lipid, ash, calcium and phosphorus contents were all significantly affected by dietary available P concentration (P<0.05), however, no significance were found in whole-body calcium/phosphorus (Ca/P) ratios among all the treatments (P>0.05). Dietary phosphorus levels also affected the mineralization of vertebrae, skin and scale (P<0.05). Ca/P ratios in vertebrae and scale were not influenced by dietary P supplementation, while skin Ca/P ratio increased statistically with dietary available P levels (quadratic effect, P<0.001). The blood chemistry analysis showed that dietary available P had distinct effects on enzyme activities of alkaline phosphatase (ALP) and plasma lysozyme (LSZ), as well as contents of triacyglycerol (TG) and total cholesterol (T-CHO) (P<0.05). Broken-line analysis showed maximum weight gain (WG) was obtained at dietary available P concentrations of 0.55%. Quadratic analysis based on P contents in whole fish, vertebrae or scale indicated that the requirements were 0.81, 0.87 and 0.88%, respectively. Signs of phosphorus deficiency were characterized by poor growth, slightly reduced mineralization and an increase in body lipid content. (C) 2008 Published by Elsevier B.V.