饲料添加剂在水产动物生长、营养及免疫中的应用进展

饲料添加剂是在基础饲料的生产加工或使用过程中添加微量物质,具有强化基础饲料营养价值,节省饲料成本,提高动物生产性能,改善肌肉品质等作用。目前国内外对饲料添加剂的研究众多,为突出饲料添加剂对水产动物在不同方面的影响,本文综述了饲料添加剂对水产动物生长性能、营养成分及免疫中的应用进展。     

玉米蛋白粉在水产饲料中应用的研究进展

介绍了玉米蛋白粉的营养价值,综述了在饲料中使用玉米蛋白粉对水产动物生长、原料表观消化率、饲料适口性、饲料氨基酸平衡、鱼体生化指标、肌肉成分以及养殖水环境的影响,初步探讨了改善水产动物对玉米蛋白粉利用率的途径,提出应加强不同水产动物就玉米蛋白粉在体内的代谢、对养殖水环境的影响、对机体抗病免疫力和肌肉风味的影响以及玉米蛋白粉对除鱼粉外的动物蛋白源的替代研究。     

寡糖在水产动物饲料上的应用

寡糖是一种绿色的水产动物饲料添加剂,能够促进水产动物肠道内有益菌增殖,抑制有害菌生长,维持正常的消化道环境,提高水产动物机体的免疫力、抗病力、饲料利用效率以及促进脂类的代谢等,本文就寡糖对水产动物的作用及其在水产动物饲料中的应用现状进行综述,并探讨应用中存在的问题,尝析寡糖在水产动物饲料中的应用前景。     

L-肉碱在水产养殖中的研究进展

综述了饲料中添加L-肉碱对不同水产动物摄食生长和营养代谢方面的影响。在饲料中添加适宜量的L-肉碱,可以提高鱼类、甲壳类、龟鳖类等水产动物的生长性能和饲料效率;可促进多数水产动物的脂肪酸氧化、蛋白质合成,降低机体脂肪含量。L-肉碱的作用因物种而异,在高脂饲料中作用更大,甲壳类饲料中的适宜添加量较其他水产动物更高,水产动物幼体的需求量比成体更高。     

甜菜碱在养殖业中的营养机理

甜菜碱作为饲料添加剂已经在养殖业上得到了广泛的应用,它具有调节动物脂肪代谢、改善家禽的生产能力、促进动物的生长和抗球虫病等疗效。本文对甜菜碱在脂肪代谢和甲基代谢中的机理进行了阐述,对甜菜碱与甲硫氨酸和胆碱在添加剂中的添加效果进行了比较,并就其对饲料中维生素的保护作用和在水产养殖中的营养机理进行了综述。甜菜碱作为安全高效的营养性饲料添加剂,具有广阔的应用前景。     

维生素C对水产动物促生长和免疫增强功能的研究进展

近十年来,有关维生素C的研究主要集中在水产动物对维生素C的需求量以及其对水产动物的生理影响的产生机理等方面。本文系统地综述了近些年来国际和国内关于维生素C在水产动物饲料中的主要应用衍生物的需求量以及其重要生理功能的研究成果。     

甜菜碱在养殖业中的营养机理

甜菜碱作为饲料添加剂已经在养殖业上得到了广泛的应用，它具有调节动物脂肪代谢、改善家禽的生产能力、促进动物的生长和抗球虫病等疗效。本文对甜菜碱在脂肪代谢和甲基代谢中的机理进行了阐述，对甜菜碱与甲硫氨酸和胆碱在添加荆中的添加效果进行了比较，并就其对饲料中维生素的保护作用和在水产养殖中的营养机理进行了综述。甜菜碱作为安全高效的营养性饲料添加剂，具有广阔的应用前景。     

水产养殖中螺旋藻的营养及其应用

螺旋藻是一种蛋白质营养突出且具有多种生物学活性的功能性藻类,作为饲料添加剂在水产养殖中可发挥促进水产动物生长、提高其抗病力等作用,本文就螺旋藻的生物学特性、营养特点和在水产养殖中的作用作一综述,为螺旋藻在水产养殖中的应用提供参考.     

诱食剂在水产饲料中的应用

在水产饲料中添加适量的诱食剂可改善饲料的适口性，增进水产动物的食欲，提高饲料的消化吸收率，降低饲料系数，促进水产动物生长，并减轻水质的污染。本文论述了水产动物诱食剂的作用、种类及其在水产饲料中的应用效果。     

肠膜蛋白营养价值及其在水产动物饲料中的应用

简述了肠膜蛋白的营养价值,分析了肠膜蛋白对水产动物消化酶活性、营养物质消化率、免疫功能、肠道健康、蛋白质利用和生长性能以及饲料诱食性的影响。指出小肽类产品在水产动物饲料中的推广仍然处于发展阶段,提出从基础上加强小肽营养的理论研究,进一步研究小肽在不同种类水产动物中的吸收、代谢及其作用形式很有必要。     

Evaluation of dietary creatine and guanidinoacetic acid supplementation in juvenile red drum Sciaenops ocellatus

Two separate comparative feeding trials were conducted to evaluate if supplemental dietary guanidinoacetic acid (GDA), either singly or in combination with creatine, could enhance growth performance of red drum. The basal diet for both trials was formulated with practical ingredients but was not supplemented with creatine or GDA. For the experimental diets, creatine (0 or 20 g/kg) and GDA (0, 5 or 10 g/kg) were added to the basal diet in a 2 × 3 factorial arrangement for trial 1. Another 2 × 3 experimental design was adopted in trial 2 to further evaluate creatine (0 or 20 g/kg) and GDA (0, 10 or 20 g/kg) supplementation. Each diet was fed to juvenile red drum in either quadruplicate (trial 1) or triplicate (trial 2) aquaria twice daily for a total of 8 weeks. After each feeding trial, fish were sampled for body condition indices and whole‐body composition analysis, as well as determination of plasma, liver and muscle creatine concentrations. In trial 1, dietary creatine supplementation alone significantly (p < .05) improved weight gain and feed efficiency of red drum. An interaction between creatine and GDA was seen in whole‐body protein and lipid in the two trials. In trial 1, the highest levels of whole‐body protein and lipid were observed in fish fed 10 g GDA/kg, and in trial 2, supplementation of the diet with 10 g GDA/kg increased muscle protein and muscle lipid although there was a trending decline in fish fed the 20 g/kg GDA‐supplemented diet. In both trials of the present study, dietary GDA significantly (p < .05) enhanced liver creatine content. Dietary creatine also significantly (p < .05) enhanced plasma and muscle creatine content of red drum. Based on the results of this study, creatine was effective in enhancing weight gain and feed efficiency of red drum as seen in previous studies; however, GDA was not effective in influencing growth performance but limited synthesis of creatine from dietary GDA was apparent.     

Citrus x aurantium essential oil as feed additive improved growth performance,survival, metabolic,and oxidative parameters of silver catfish (Rhamdia quelen)

The effects of dietary supplementation of graded level (0, 0.25, 0.5, 1.0, and 2.0 ml/kg diet) of Citrus aurantium essential oil (EOCA) on the growth, metabolic, and oxidative parameters of silver catfish (Rhamdia quelen) were investigated in a 60‐day growth trial. Fish fed with 2.0 ml EOCA per kg exhibited significantly better growth performance than those fed the control diet. Glucose, lactate, and protein levels in liver and muscle were altered significantly by dietary addition of EOCA. Hepatic lipid peroxidation levels, measured using thiobarbituric acid reactive substance and lipid hydroperoxides assays, were reduced in animals receiving the diet containing EOCA. Superoxide dismutase activity was higher, while glutathione S‐transferase activity was lower in the liver of fish receiving 0.5, 1.0, and 2.0 ml EOCA per kg of diet than in control. The nonprotein thiols content was higher in fish receiving the EOCA‐containing diet. Thus, dietary addition of EOCA improved growth, biochemical, and antioxidant parameters in silver catfish and could be useful as dietary supplement.     

Effects of Different Dietary Lipid Sources on Growth Performance,Fatty Acid Composition,and Antioxidant Enzyme Activity of Juvenile Rockfish,Sebastes schlegeli

This study was carried out to investigate and compare the effects of various dietary lipid sources on growth performance, body composition, fatty acid profiles, and hepatic and plasma antioxidant enzyme activities of juvenile rockfish, Sebastes schlegeli. Three replicate groups of fish (initial mean weight, 1.7 ± 0.04 g) were fed four isonitrogenous and isolipidic diets containing either fish oil (FO), soybean oil (SO), linseed oil (LO), or a mixture of SO and LO (SO + LO) for 8 wk. There were no significant differences in survival, weight gain, feed efficiency, and protein efficiency ratios of fish fed the diets containing different lipid sources (P > 0.05). The fatty acids compositions of the liver and muscle tissues reflected the dietary fatty acid compositions. Liver and muscle of fish fed the SO diet had high concentration of linoleic acid, whereas those of fish fed the LO diet were rich in linolenic acid. Liver and muscle of fish fed the FO diet had significantly (P < 0.05) higher levels of eicosapentaenoic acid and docosahexaenoic acid than those of fish fed the SO and LO diets. Dietary lipid source had no significant effect on the hepatic and plasma enzyme activities of superoxide dismutase and glutathione peroxidase. The results of this study suggest that SO and LO can be used as a replacement for FO in the diets of juvenile rockfish without incurring any negative effects on growth, feed utilization, and antioxidant enzyme activity, when the dietary essential fatty acid requirements are satisfied for rockfish.     

Effect of dietary fish oil replacement by rapeseed oil on the growth,fatty acid composition and serum non‐specific immunity response of fingerling black carp,Mylopharyngodon piceus

An 8‐week experiment on fingerling black carp Mylopharyngodon piceus was conducted to evaluate the effects of dietary fish oil (FO) supplement on growth, fatty acid composition and non‐specific immunity responses. Five triplicate fingerling groups (initial weight = 2.72 ± 0.35 g) were fed isoenergetic and isonitrogenous diets in which the dietary FO was replaced with rapeseed oil (RO) in graded increments of 25% (0–100%). No significant effects were observed on specific growth rates, survival rates and feed conversion ratios, but there were significant differences in whole body moisture and liver lipid contents (P < 0.05), and the 100% RO replacement diet significantly enhanced hepatosomatic indexes compared to control group (P < 0.05). Other approximate whole body constituents, viscerasomatic ratios and condition factors were not influenced by dietary oil treatments. Fatty acid composition of muscle and liver was influenced by dietary fatty acid input, α‐linoleic acid and γ‐linolenic acid were significantly increased with increasing RO, but eicosapentaenoic acid, docosahexaenoic acid and the n‐3/n‐6 ratio were significantly reduced (P < 0.05). Alternative complement pathway, lysozyme and superoxide dismutase activities were not significantly influenced. These results indicate that black carp fed diets with FO supplement had similar growth and non‐specific immunity to the fish fed diet with RO.     

Growth,body composition,intestinal enzyme activities and microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of dietary valine

This study investigated the effects of valine on growth, intestinal enzyme activities and microflora in juvenile Jian carp (Cyprinus carpio var. Jian). A total of 1200 fish with an average initial weight of 9.67 ± 0.03 g were fed diets containing 5.3 (unsupplemented control), 8.7, 11.8, 14.9, 18.7 and 20.1 g valine kg^?1 diet for 60 days. Results indicated that the specific growth rate, feed efficiency, body protein and lipid content of fish were significantly improved by the dietary valine (P < 0.05). The hepatopancreas weight and activities of trypsin, amylase, lipase, chymotrypsin, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) took the similar trends. Similarly, the optimum levels of dietary valine induced increases in the intestinal length, weight, folds height and activities of alkaline phosphatase, gamma‐glutamyl transpeptidase and creatine kinase. In contrast, the trends of muscle GOT activity and plasma ammonia content were opposite. Intestinal Aeromonas, Escherichia coli, Lactobacillus and Bacillus were changed by dietary valine supplementations. The dietary valine requirement for Jian carp (9.67–76.4 g) based on SGR was 13.7 g valine kg^?1 diet (4.0 g valine 100 g^?1 CP). Together, these results indicated that valine improved fish growth, digestive and absorptive ability.     

Feeding high inclusion of whole grain white lupin (Lupinus albus) to rainbow trout (Oncorhynchus mykiss): effects on growth,nutrient digestibility,liver and intestine histology and muscle fatty acid composition

The effect of dietary inclusion of whole grain white lupin (Lupinus albus) on growth performance, histology, muscle fatty acid composition and nutrient digestibility was investigated in an 11‐week growth and a 4‐week digestibility trial with rainbow trout (initial body weight of 54.0 ± 6.2 and 181.9 ± 3.4 g respectively). Four experimental extruded diets were formulated to contain 0%, 30%, 40% and 50% of whole grain lupin and fed to triplicate groups of fish twice a day until apparent satiation. Faeces were collected daily from each digestibility tank by decantation. No significant trends were observed with respect to growth, feed utilization, apparent digestibility coefficients or whole‐body composition (P>0.05). Conversely, increasing levels of dietary lupin led to significant decreases in the Hepatosomatic index (R²=0.75, P<0.05) and slight lipid infiltration into hepatocytes and enterocytes. Muscle fatty acid compositions were slightly affected by the dietary treatment. Polynomial regression of dietary inclusion of lupin and muscle fatty acid concentrations showed an increase in C18:1n‐9, C18:2n‐6 and C18:3n‐3 and a decrease in C20:5n‐3 with increasing dietary lupin level. These results demonstrated that whole grain lupin can be included up to 50% in commercial rainbow trout diets without negative effects.     

Effect of dietary n‐3 HUFA on growth performance and tissue fatty acid composition of gibel carp Carassius auratus gibelio

A 12‐week growth trial was conducted with gibel carp Carassius auratus gibelio (initial weight: 2.69 g) to evaluate the effects of dietary n‐3 highly unsaturated fatty acids (n‐3 HUFA) on growth performance and tissue fatty acid composition. Five diets of different n‐3 HUFA levels from 0 to 17 g kg^?1 diet were supplemented at 80 g kg^?1 dietary lipid by including fish oil (FO) at 0, 25, 50, 75 and 100% of supplemental lipid. The remainder was coconut oil. The results showed that fish fed FO₂₅ and FO₅₀ obtained highest specific growth rate and lowest with FO₀. Feed efficiency was highest at FO₁₀₀ and lowest at FO₀. Apparent digestibility coefficient of lipid increased with increasing dietary n‐3 HUFA. The fish fed FO₀ diet had the lowest thiobarbituric acid reactive substance in serum and muscle and highest moisture and lowest lipid content in viscera. Fatty acid compositions of muscle and liver were correlated with dietary fatty acids. Fish muscle concentration of 20:5n‐3 increased with increasing dietary n‐3 HUFA while the concentration of 22:6n‐3 was distinctly reduced in FO₀ group. It suggested that 4 g kg^?1 n‐3 HUFA in diet could permit gibel carp normal growth performance and provide considerable n‐3 HUFA in fish muscle. Excessive n‐3 HUFA showed impact on growth performance of gibel carp.     

Effects of dietary oxidized oil and vitamin E on the growth,blood parameters and body composition of juvenile Atlantic cod Gadus morhua (Linnaeus 1758)

The effects of oxidized dietary lipid and the role of vitamin E on the growth performance, blood parameters and body composition of juvenile Atlantic cod (Gadus morhua) were evaluated over a 9‐week feeding period. Four isonitrogenous experimental diets containing fresh or oxidized fish oil with or without added vitamin E (α‐tocopherol or mixed tocopherols) were fed to juvenile cod. The oxidized lipid used had a peroxide value of 94 mEq kg^?1 oil. No significant (P>0.05) differences in growth performance (weight gain and specific growth rate) or feed utilization (feed consumption and feed efficiency ratio) were observed when oxidized dietary lipid was used. The hepatosomatic index (HSI), viscerosomatic index (VSI) and haematocrit did not show any significant (P>0.05) differences among the treatments. However, erythrocyte osmotic fragility (EOF), referred to as susceptibility to haemolysis, of fish fed oxidized oil without added vitamin E was high in comparison with those fed unoxidized oil. Supplementation with α‐tocopherol appeared to decrease haemolysis, but mixed tocopherols had no significant (P>0.05) effect on EOF. The proximate composition of fish whole body was also affected by diet treatment. Fatty acid composition of liver total lipid reflected that of dietary lipid. Variations in tissue (liver and muscle) fatty acid composition among the treatments followed the same trend as those of the dietary fatty acids. Fish fed fresh oil had a higher proportion of polyunsaturated fatty acids (PUFA) in muscle and liver lipid than those fed oxidized oil. The results suggest that oxidized dietary oil affected juvenile Atlantic cod in certain tissues and that these effects could be alleviated by supplementation of sufficient amounts of vitamin E in the diet.     

Canola oil,as a good alternative dietary lipid source in sturgeon: Effects on growth,physiology and fatty acid profile in Beluga sturgeon Huso huso L.

An 8‐week feeding trial was conducted on juvenile beluga sturgeon Huso huso to evaluate the effects of different dietary lipid levels and sources on growth performance, physiological indices, proximate composition and fatty acid (FA) profile. Four practical diets, which had either low level (120 g/kg) of canola oil (LCO) and fish oil (LFO) or high level (240 g/kg) of canola oil (HCO) and fish oil (HFO), were fed to triplicate groups of 25 beluga (mean initial body weight 207 ± 0.5 g). The growth performance of beluga was improved by replacing dietary fish oil with canola oil and increasing dietary lipid level. Except the number of red blood cells, lymphocytes, neutrophils and eosinophils, the rest of haematological factors including the values of haemoglobin, haematocrit, number of white blood cells, mean corpuscular haemoglobin concentration, cholesterol and triglyceride concentrations and the number of basophils and monocytes were not significantly affected by dietary lipid sources or levels. Results showed that both moisture and crude fat of the beluga muscle were affected by dietary lipid. The highest moisture and the lowest fat contents were found in the muscle of beluga fed fish oil (LFO). Moreover, the lowest moisture and the highest fat contents were observed in the muscle of beluga fed canola oil (HCO) (p < .05). The FA profile of the beluga muscle was significantly influenced by dietary treatments. The highest monounsaturated fatty acids, total n‐6 fatty acids containing linoleic acid and arachidonic acid, and total unsaturated fatty acids were found in fish fed canola oil (LCO and/or HCO) (p < .05). However, n‐3 fatty acids containing linolenic acid, eicosapentaenoic acid and docosahexaenoic acid were not affected by the diet (p > .05). FA profile of the beluga muscles reflected the proportions of CO and FO in the diet except that there was a decrease in oleic acid and linolenic acid, but an increase in arachidonic acid (C20:4n‐6), eicosapentaenoic acid and docosahexaenoic acid. The obtained data showed that canola oil is an excellent source of supplemental dietary lipid in a practical fish‐meal‐based diet of beluga sturgeon under the experimental conditions. Moreover, the data demonstrated that increasing dietary lipid up to 240 g/kg in beluga sturgeon resulted to improve growth performance and haematology.     

Relative contribution of alternative proteins to the growth of Juvenile Cobia,Rachycentron canadum (Linnaeus)

Five isonitrogenous and isocaloric diets were fed to juvenile cobia, to assess the relative contribution of different proteins (fish meal, soybean meal, corn gluten and beer yeast) to the growth of cobia. The dietary effects on nitrogen and carbon turnover and on the isotopic diet‐consumer discrimination factors (Δ¹⁵N and Δ¹³C) were also assessed. Growth results showed that the final body weight, growth rate, feed conversion ratio and protein efficiency ratio of cobia fed diets with alternative protein were significantly lower (P < 0.05) than cobia fed diet formulated with 100% fish meal. The estimated half‐lives of nitrogen and carbon ranged between 9–11 days and 6–8 days, respectively, with significant differences among treatments (P < 0.05). Δ¹⁵N ranged between 0.0–1.2‰ and ?0.1–1.6‰ in whole fish and muscle and Δ¹³C ranged between 3.8–5.1‰ and 4.0–5.1‰ in whole fish and muscle respectively. Diets were formulated with low levels of dietary nitrogen (10%) supplied by alternative protein sources substituting fish meal. The relative contributions of the dietary nitrogen supplied from these sources to the growth of whole fish and muscle tissue ranged between 4.9–5.2% and 5.9–7.7% respectively. Results indicated that growth accounted for the majority of observed isotopic change in animals under all treatments. In whole animals and muscle tissue, isotopic change due to metabolism occurred faster for carbon stable isotopes than for nitrogen stable isotopes. Cobia fed diets formulated with alternative proteins showed reduced nitrogen turnover rate and increased Δ¹⁵N.