Chemical composition of alimentary canal contents of mullet (Teleostei: Mugilidae) caught in the Swartkops Estuary near Port Elizabeth,South Africa

Composition of alimentary canal contents (protein, ash, moisture and carbohydrate by difference) of four mullet species from the Swartkops Estuary, were determined monthly over a 13-month period. It was found that Liza tricuspidens consumed the most nutritious (highest protein and carbohydrate and lowest ash) material followed by Mugil cephalus, Liza richardsoni and lastly Liza dumerili, the most abundant mullet species in the estuary. It was also found that smaller specimens, irrespective of species, consumed the most nutritious food material. An attempt was made to relate chemical composition to the particular food and substrate preference of each species. Correlation coefficients between moisture and protein (positive), moisture and ash (negative) and ash and protein (negative) enabled the calculation of regression equations by which protein and ash can be determined from a relatively simple moisture determination.     

Susceptibility by amberjack (Seriola dumerili), yellowtail (S. quinqueradiata) and Japanese flounder (Paralichthys olivaceus) to Neobenedenia girellae (Monogenea) infection and their acquired protection

This study investigated: 1) susceptibility differences to infection by Neobenedenia girellae (Capsalidae) between amberjack Seriola dumerili (Carangidae), yellowtail S. quinqueradiata and Japanese flounder Paralichthys olivaceus (Paralichthyidae); 2) growth and egg production of N. girellae on each fish species; 3) acquired protection of each fish species against this parasite. The number of N. girellae on S. dumerili was significantly higher than on S. quinqueradiata and P. olivaceus when these fishes were exposed to oncomiracidia in the same aquarium. Neobenedenia girellae growth on S. dumerili was fastest and, thus the number of eggs laid by parasites on S. dumerili was greater than on the other two species. Seriola dumerili and P. olivaceus, which were previously infected with N. girellae and treated by freshwater bath, acquired partial protection against re-infection by N. girellae. The relative re-infection of three S. dumerili individuals out of eleven individuals was markedly low compared with the initial infection, and the relative initial infection and re-infection on two P. olivaceus out of eleven individuals was markedly low. The results of this study could be useful to control N. girellae infections when cultivating S. dumerili, S. quinqueradiata and P. olivaceus.     

Growth of the golden grey mullet (Liza aurata (Risso)) in saltwater ponds during 1974

The growth rates of Liza aurata in saltwater ponds were measured during 1972, 1973 and 1974. The growth rate of L. aurata young of the year was 0.6–0.95 g per fish per day and that of fish in their second year of life was 0.85–1.0 g per fish per day.Body composition analyses were conducted on L. aurata in both the first and second years of life.A significant difference in length and weight was found between males and females of L. aurata in their second year of life.The results show that L. aurata can be stocked in saltwater ponds but that they will not be the main crop of fish.     

Formulation of practical diets for rainbow trout based on desired performance and body composition

Rainbow trout (Salmo gairdneri) with an initial average weight of 1.8 g were fed eight experimental diets with 26 and 35% protein and varying amounts of lipid for 112 days. All experimental diets contained 10% fish meal (the only source of animal protein), as compared to a control diet with 35% fish meal. The energy content of the diet was the most important factor in determining growth rate. The percentage of dietary lipid was the dominant factor in determining the body composition of rainbow trout. Increased amounts of dietary lipid resulted in fish with increased amounts of whole-body fat and reduced amounts of whole-body protein and moisture. Body composition was more closely a function of nutritional history than of fish size. Protein retention and energy retention were negatively associated with the percentage of digestible protein in the diet. Mortality rates did not differ significantly among the groups tested; the general health of all fish examined was good.     

梭鱼肌肉营养成分与品质的评价

利用常规营养测试方法对6尾梭鱼(雌雄各半)的营养成分进行了测定,并做了较为全面的分析和比较。结果表明,其肌肉鲜样中水分含量为80.90%,粗蛋白含量为17.25%,粗脂肪含量为0.76%,灰分含量为0.83%,碳水化合物为0.26%。肌肉中17种氨基酸的总量为干重的82.51%。其中,7种必需氨基酸的总量占干重的33.14%,占氨基酸总量的40.18%,必需氨基酸与非必需氨基酸的比例为78.40%,符合FAO/WHO的标准。梭鱼的第一、二限制性氨基酸分别为蛋氨酸+胱氨酸和缬氨酸,必需氨基酸指数(EAAI)为59.63。梭鱼肌肉中含有24种脂肪酸,不饱和脂肪酸含量丰富,与饱和脂肪酸的比例约为3:1;必需脂肪酸ω-6和ω-3家族的比例(6.11:1)合理;EPA+DHA的含量占干重的4.32%,高于其他一些经济鱼类。梭鱼微量元素的比例合理。     

鲻梭鱼营养与环境因子方面的研究现状及展望

介绍了国内外有关鲻梭鱼营养(包括蛋白质、脂类、碳水化合物、矿物质与维生素、摄食水平与投喂频率)与环境(包括温度、盐度、光照及环境污染物)因子方面的研究现状,并对未来鲻梭鱼就营养与环境因子方面的研究工作进行了展望。     

Evaluation of three seaweeds Gracilaria bursa-pastoris, Ulva rigida and Gracilaria cornea as dietary ingredients in European sea bass (Dicentrarchus labrax) juveniles

The aim of this study was to evaluate the inclusion of three seaweeds Gracilaria bursa-pastoris (GP), Ulva rigida (UR) and Gracilaria cornea (GC) as dietary ingredients on the performance, nutrient utilisation and body composition of European sea bass juveniles. Six experimental diets were formulated to replace 5% (GP-5, UR-5, and GC-5 Diets) and 10% (GP-10, UR-10 and GC-10 Diets) fish protein hydrolysate (CPSP) by each of the three seaweeds. A control diet was used, without inclusion of any seaweed. Diets were fed to duplicate groups of 25 European sea bass (Dicentrarchus labrax) juveniles (IBW = 4.7 g) for 10 weeks. Growth performance was only significantly reduced (P < 0.05) in fish fed the GC-10 diet, whereas the feed conversion ratio increased significantly in those fish. The apparent digestibility coefficients of dry matter and lipid were significantly lower in fish fed diet GC-10 relative to those fed the control diet. Carcass composition was similar among treatments, although fish fed GC-10 exhibited significantly higher ash content.The results obtained in this study suggest that the inclusion of G. bursa-pastoris (GP) and U. rigida (UR), up to 10%, can be considered as very interesting ingredients in diets for sea bass juveniles, as no negative consequences on growth performance, nutrient utilization or body composition were observed. On the other hand, the inclusion of G. cornea (GC) should be limited to 5% of the diet.     

Seasonal variations in energy and biochemical components of an edible gastropod, Turbo sarmaticus (Turbinidae)

Protein, lipid, ash, moisture and energy contents were determined for four size classes of Turbo sarmaticus every second month for a year. Protein was the major component and was negatively correlated with carbohydrate and lipid and positively correlated with energy and gonadosomatic index values. Lipid values were positively correlated with temperature. Seasonal changes in energy and biochemical components of faeces were also monitored and faecal lipid and ash values were positively correlated with temperature.     

Nutritional study of jelawat, Leptobarbus hoevenii (Bleeker), fed on pelleted feed

The digestion coefficients of the nutrients in the ingredients used in formulating the diet (MARDI-37%) for the culturing of jelawat were evaluated. Cr₂O₃ was used as an internal marker for the evaluation of digestibility. The results indicate that jelawat can digest 100% of the protein, fat, carbohydrate and gross energy in fish meal, but only 69.50% protein, 60.70% fat, 73.82% carbohydrate and 59.30% gross energy in soyabean meal. Surprisingly, this fish can digest copra cake meal, an agricultural by-product in Malaysia, better than soyabean meal; the values were 75.36% protein, 98.36% fat, 50.03% carbohydrate, and 73.21% gross energy. Digestibility of maize, rice bran and tapioca was poor in this fish.There were no significant differences in the digestibility of dry matter, protein, fat, carbohydrate, ash and gross energy of the reference diet in jelawat specimens whose total length was greater than 12 cm, whereas in fish smaller than 12 cm digestibility was significantly lower.     

Effect of ration size on growth, conversion efficiency and body composition of fingerling mrigal, Cirrhinus mrigala (Hamilton)

Optimum ration size of Indian major carp, Cirrhinus mrigala fingerlings was determined by feeding purified diet (40% crude protein (CP); 3.61 kcal g^?1) at five ration sizes (2%, 4%, 6%, 8% and 10% of body weight per day) for 6 weeks. Feeding trial was conducted in triplicate. Fishes were randomly stocked at the rate of 20 fish per trough fitted with water flow‐through system. The best feed conversion ratio (FCR), specific growth rate (%) and protein efficiency ratio (PER) were evident at the ration size of 4–6% body weight. Second‐degree polynomial regression analysis of the FCR, PER, and protein and energy retention data indicated the breakpoints at ration size of 5.16%, 5.24%, 5.52% and 5.42% body weight per day. Carcass composition of fish fed different ration sizes varied significantly. Maximum carcass protein and minimum moisture content were noticed at 4% and 6% ration levels. A linear increase in fat content was evident with increasing ration levels up to 6% body weight. Ash content remained insignificantly different among various ration levels except at 2%, showing the significantly highest value. Water temperature, dissolved oxygen, free carbon dioxide, pH and total alkalinity were recorded regularly during the length of the experiment. No mortality was observed during the feeding trial. Based on the above results, it is recommended that feeding in the range of 5–5.5% body weight per day corresponding to 20 g protein and 181 kcal energy to 22 g protein and 199 kcal energy per kg of the diet per day is optimum for the growth and efficient feed utilization of C. mrigala.     

Laboratory studies on food intake,growth and conversion efficiency of Palaemon lamarrei in relation to body size

The effects of body size on the food intake, growth and conversion efficiency of the freshwater prawn Palaemon lamarrei have been studied. In captivity, fed on a restricted diet of the muscles of the fish Gambusia affinis, moulting in these prawns occurred once in 18 ± 5 days at a temperature of 26 ± 1°C. The importance of these cast moults, contributing a sizable amount of organic matter to the detritus deposit of freshwater habitats has been indicated. In a log-log system, both food intake and growth per day, represented as a percentage of body weight, showed an inverse relationship to the body size. Animals in the size range of 600–800 mg exhibited the highest conversion efficiency. The present study indicates that these prawns can be successfully reared and grown under laboratory conditions.     

Effect of varying dietary energy level on feed intake, feed conversion, whole-body composition and growth of Malawian tilapia, Oreochromis shiranus– Boulenger

Four isonitrogenous [30% crude protein (CP)] diets containing different gross energy levels (13.39, 16.74, 20.50 and 23.85 kJ g⁻¹) were evaluated to determine the optimum energy for the Malawian tilapia Oreochromis shiranus. Each tank (120 L) was stocked with 18 juvenile tilapia (average weight 7.32±0.25 g) and they were fed the experimental diets for 10 weeks. The final average weight of the fish was approximately twofold higher (range: 12.64–16.77 g) than the initial weight. The dietary energy significantly (P<0.05) influenced growth. The average weight of fish fed dietary energy level 20.50 kJ g⁻¹ was significantly higher (P<0.05) than the weight of the fish fed any of the other experimental diets. There was no significant difference in growth of fish fed 13.39 and 16.74 kJ g⁻¹ energy levels, but 23.85 kJ g⁻¹ produced the lowest growth rates. There were no significant differences (P>0.05) between feed intake across the treatments. Feed conversion ratio (range: 2.2–3.0) and protein efficiency ratio (range: 1.10–1.50) among the dietary treatment groups were in agreement with trends for weight gain. Dietary energy level significantly (P<0.05) influenced the body composition of O. shiranus. Whole‐body moisture (range: 64.27–67.15%) and ash (range: 13.21–14.73%) decreased in all treatments. Whole‐body protein (range: 63.57–66.16%) increased only in groups fed on the diet containing 20.50 kJ g⁻¹. Whole‐body fat (range: 13.58–17.27%) and gross energy (range: 28.411–33.210 kJ g⁻¹) increased significantly (P<0.05). Fish survival was 100% in all treatments. The results demonstrated that to maximize growth at a temperature of 23°C, O. shiranus should be fed diets containing 20.50 kJ g⁻¹ gross energy.     

饲料脂肪水平和投喂频率对大黄鱼生长、体组成及脂肪沉积的影响

本实验以我国重要的海水养殖鱼类大黄鱼[初始体质量(13.57±0.33)g]为研究对象,在浮式网箱中进行为期8周的摄食生长实验,探讨饲料脂肪水平和投喂频率对大黄鱼生长、体组成及脂肪沉积的影响。采用3×2双因子实验设计,其中饲料脂肪水平分别为9%、12%和15%,投喂频率分别为2次/天和1次/天。结果表明:投喂频率对大黄鱼特定生长率(SGR)和饲料效率(FER)均有显著影响(P<0.05),而饲料脂肪水平仅对FER有显著影响(P<0.05)。2次/天投喂组的大黄鱼末体质量和SGR均显著高于1次/天投喂组,而饲料效率显著低(P<0.05)。在2次/天投喂时,各个饲料脂肪水平对SGR和FER没有显著影响(P>0.05)。而在1次/天投喂时,随着饲料脂肪水平的提高,SGR和FER均显著提高(P<0.05)。2次/天投喂组的大黄鱼全鱼水分含量显著低于1次/天投喂组,而粗脂肪含量显著高(P<0.05)。大黄鱼全鱼粗脂肪含量随着饲料脂肪水平的增加而显著升高(P<0.05)。然而在1次/天投喂时,饲料脂肪水平未对全鱼体粗脂肪含量产生显著影响(P>0.05)。大黄鱼的肝脏和肌肉脂肪含量、肝体比(HSI)以及脏体比(VSI)受到了饲料脂肪水平的显著影响(P<0.05)。在2次/天投喂时,肝脏和肌肉脂肪含量、HSI以及VSI随饲料脂肪水平的升高而显著增加(P<0.05);而在1次/天投喂时,各个饲料脂肪组大黄鱼肝脏和肌肉脂肪含量、HSI以及VSI均无显著差异(P>0.05)。饲料脂肪水平和投喂频率仅对大黄鱼的生长、饲料效率的影响存在显著的交互作用(P<0.05),而对大黄鱼体组成、形态学指标以及肝脏和肌肉脂肪含量无显著的交互作用(P>0.05)。     

Partial and total replacement of fishmeal with poultry by-product meal in diets for gibel carp, Carassius auratus gibelio Bloch

Triplicate groups of gibel carp Carassius auratus gibelio Bloch (initial body weight: 4.89 g) were fed for 8 weeks at 24.8–30.8°C with nine isonitrogenous and isoenergetic diets. The control diet (F1) used white fishmeal (FM) as the sole protein source. In the other eight diets (F2–F9), 40.5–100% of FM protein was substituted by poultry by‐product meal (PBM) at 8.5% increments. The specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio, protein retention efficiency and energy retention rate for fish fed PBM diets (F2–F9) were all higher, but not always significantly, than those for fish fed F1. All apparent digestibility coefficients for fish fed PBM diets were lower than those for fish fed F1. Fish fed F1 had a significantly higher hepatosomatic index value than fish fed PBM diets (P<0.05). No significant (P>0.05) effect of diet was found in whole‐body moisture and fat content. Whole‐body protein and energy content for fish fed PBM diets were slightly higher than that for fish fed F1. The optimal replacement level of FM by PBM was estimated by second‐order polynomial regression to be 66.5% in protein.     

Effect of Dietary Protein Concentration on Growth and Processing Yield of Channel Catfish,Ictalurus punctatus Raised from Advanced Fingerlings to Large Marketable Size

Abstract

This study evaluated the effects of dietary protein concentration (26, 28, and 32%) and an all-plant protein diet (28% protein) on growth, feed efficiency, processing yield, and body composition of channel catfish, Ictalurus punctatus raised from advanced fingerlings to large marketable size (about 800 to 900 g/fish) for two growing seasons. Fingerling channel catfish (average weight = 56 g/fish) were stocked into twenty 0.04-ha ponds at a density of 18,525 fish/ha. Fish were fed once daily to satiation during the two growing seasons and fed according to recommended winter feeding schedules during the winter. There were no differences in diet consumption, weight gain, feed conversion ratio, survival, processing yields (carcass, shank fillet, and nugget), or fillet composition (moisture, protein, fat, and ash) among fish fed the various diets. These results indicate that a 26% protein diet containing plant and animal proteins or a 28% all-plant protein diet is adequate for channel catfish raised in ponds from advanced fingerlings to large marketable size without adversely affecting weight gain, feed efficiency, processing yield, or body composition. Large marketable-size channel catfish appear to use diets less efficiently but give higher processing yields compared to small marketable-size fish.     

Fat distribution in Atlantic salmon Salmo salar L. in relation to body size and feeding regime

Tissue (fillet, viscera and carcass) distributions of fat were examined in Atlantic salmon, Salmo salar L. (≈740→≈1400→≈2000 g) to test the hypothesis that the fillet becomes increasingly important as a fat depot when fish increase in size. The salmon were fed for 11 weeks on either a high‐fat feed (H: ≈39% fat) or a low‐fat feed (L: ≈28% fat), and half of the fish were then subjected to a dietary switch to create four feed treatments (HH, HL, LL and LH). Fillet fat concentration increased with the passage of time, and the fillet also represented an increasing percentage of the body mass (≈48.5→≈55→≈58.5%) as the fish increased in size. As a consequence, the fillet became increasingly important as a fat depot, containing ≈30% of the body fat in the small fish at the start of the experiment, and ≈50% in the fish sampled at the end of the trial. The proportion of fat localised in the viscera was little influenced by either fish size or feeding treatment, and was within the range of 19–25%, whereas the carcass held a decreasing percentage of the body fat stores as fish size increased. There was a highly significant negative correlation between the percentages of body fat found within the carcass (C) and fillet (F): F = 73.589–0.9285C (R² = 0.973; n = 13). Although the fillet became more important as a fat depot as fish increased in size, the percentage of the body fat reserves found within this tissue appeared to plateau at 50–55%.     

Rearing of African catfish (Clarias gariepinus) and vundu catfish (Heterobranchus longifilis) in traditional fish ponds (whedos): Effect of stocking density on growth, production and body composition

African catfish (Clarias gariepinus) (initial body weight: 34.8 ± 4.8 g) and vundu catfish (Heterobranchus longifilis) (initial body weight: 39.1 ± 8.2 g) fingerlings were stocked at densities of 4, 6 or 8 fish m^− 3 in traditional fish ponds (whedos) constructed in the floodplain of the Oueme River (South Benin, West Africa), for 70 days from March to June 2005. Fish were fed twice a day with 34% crude protein feed formulated with locally available ingredients. The effects of stocking density were evaluated in growth responses, gross production and body composition. Water quality variables were similar (p > 0.05) in all compartments. Temperature and pH were at the optimum level for fish. Dissolved oxygen ranged from 0.9 to 1.2 mg l^− 1 during the experiment and secchi disc transparency was low (< 14 cm). In both species, growth responses increased with the increasing density, significantly in African catfish stocked at density of 8 fish m^− 3 compared to the other densities (4 and 6 fish m^− 3) but not significantly in vundu catfish. Production data ranged from 3.1 ± 0.5 to 22.8 ± 4.5 t ha^− 1 year^− 1 in African catfish and from 6.1 ± 1.2 to 15.1 ± 3.1 t ha^− 1 year^− 1 in vundu catfish. Production increased with increasing stocking densities but only significantly (p < 0.05) between the density of 8 fish m^− 3 and the other densities. In both species, carcass fat increased with increasing density (p < 0.05) while carcass protein and moisture decreased (p > 0.05). These results are important because they indicate that, as far as growth rate and production are concerned, African catfish is more profitable than vundu catfish for culture at high density in whedo.     

Osmoregulation and differential penetration of two grey mullets, Chelon labrosus (Risso) and Liza ramada (Risso) in estuarine fish ponds

Grey mullet ponds situated in Arcachon Bay on the western Atlantic coast of France, display contrasting mixohaline habitats.The pattern of osmoregulation of Chelon labrosus and Liza ramada exhibiting differential penetration of fish ponds has been investigated. Key variables of salinity and temperature have been considered. The tolerances to low salinities and to fresh water have been determined. The dynamics of variation in plasma osmotic pressure and major plasma electrolytes (Na⁺, Cl^?, K⁺) were studied in terms of: (1) gradual adaptation to a decreasing salinity gradient; (2) effects of a long-term adaptation in fresh water; (3) effects of low temperatures on sea water adapted fish.Both species can adapt to a wide range of salinities; however, while L. ramada show a good hypoosmotic regulation, with no alteration in plasma concentration over a wide range of salinity and after a long stay (5 months) in fresh water, C. labrosus cannot live for long periods of time in a wholly fresh water habitat. Both field samples obtained from thick-lipped grey mullets forced to stay in a freshwater pond and experimentally adapted fish showed, after 3 months, an unequivoqual decrease in plasma sodium and chloride, and plasma osmolality decreased to the same extent; this pattern of no compensation is bound, sooner or later, to end in death. The inability of C. labrosus to develop a long-term hypoosmoregulation in fresh water is referred to salinity preferences which probably limit the upstream penetration of this species.Plasma osmolality and major electrolytes (sodium and chloride) increased in cold (4 °C) sea water. This response might be due to a reduced ability of grey mullets to osmoregulate in cold waters. In the poly-mesohaline ponds, Winter drop in temperature (4–6 °C) causes grey mullets to migrate to the meso-oligohaline ponds where the mean temperature is more elevated (8 °C) and temperature changes less rapid (6–9 °C).     

Colonisation tactics of three temperate catadromous species,eel Anguilla anguilla,mullet Liza ramada and flounder Plathychtys flesus,revealed by Bayesian multielemental otolith microchemistry approach

Daverat F, Martin J, Fablet R, Pécheyran C. Colonisation tactics of three temperate catadromous species, eel Anguilla anguilla, mullet Liza ramada and flounder Plathychtys flesus, revealed by Bayesian multielemental otolith microchemistry approach.
Ecology of Freshwater Fish 2011: 20: 42–51. © 2010 John Wiley & Sons A/S Abstract – The colonisation of Gironde (SW France) river catchment by juvenile, eel, Anguilla anguilla, flounder Platychtys flesus and thinlipp mullet Liza ramada was investigated comparatively using Sr:Ca and Ba:Ca composition of otolith. The relation between Sr, Ba and habitat was investigated based on Sr and Ba water composition sampled each month along the estuary‐river gradient. A total of 50 mullets, 30 eels and 47 flounders were collected in the Gironde river catchment. Analysis was performed with a Femtosecond LA‐ICPMS along a trajectory from the core to the edge. Sr and Ba water concentrations discriminated three habitats within the Gironde system, the lower estuary, the upper estuary and the freshwater sites. A signal processing method based on Gaussian hidden Markov models was applied to the multielemental life‐history data. The linear model used to allocate a Gironde habitat to coupled Sr, Ca values was parameterised with seasonal patterns and magnitude of Sr and Ba water values in the different habitats. The results showed that the three species used three different habitats and they had a large diversity of habitat use patterns with resident and nomadic tactics. Resident tactics were less frequent than nomadic tactics that suggested individual fish used two or more habitats. Mullet used a wider range of habitats in the lower part of the estuary than eel and flounder and switched habitats more frequently. Flounders tended to colonise initially freshwater, and then estuarine habitats later in life while mullets used the entire range of available catchment habitats throughout their life.     

中国近海棱梭拉丁名的更正

为解决我国棱梭(原定名为Liza carinata)命名的问题,本研究采集了中国近海7个地理群体的棱梭样品,并进行形态特征分析和DNA条形码研究。形态学研究结果显示,中国近海棱梭样品的胸鳍长度/体长、头长/体长的比值分别为15.0%~18.3%、22.5%~25.1%,与前人记录的Liza affinis的胸鳍长度/体长(14.5%~18.4%)、头长/体长比值(22.1%~26.9%)相吻合,而与Liza carinata胸鳍长度/体长(19.8%~23.9%)、头长/体长比值(27.0%~31.3%)范围不相符。DNA条形码分析结果表明,Gen Bank中Liza carinata和Liza affinis的COI基因同源序列遗传距离为13.11%,而本研究所采集样品种内差异为0.08%。NJ邻接关系树显示,本研究所使用样品与Liza affinis聚为一支,遗传距离为0.08%,而与Liza carinata的遗传距离为13.06%,已达到种以上水平。综上,本研究认为中国近海棱梭的拉丁名应为Liza affinis,我国近海是否存在真正的Liza carinata尚需进一步研究。