家蝇抗菌肽对凡纳滨对虾生长性能及免疫相关指标的影响

通过8周的生长实验研究了饲料中添加家蝇幼虫抗菌肽提取物对初始体质量为(0.86±0.01)g的凡纳滨对虾(Litopenaeus vannamei)的生长性能、体成分及免疫相关指标的影响。家蝇抗菌肽提取物添加量分别为0、1000mg/kg、2000mg/kg、3000mg/kg、4000mg/kg、5000mg/kg,每组饲料设4个重复,每个重复饲养40尾虾。结果显示,在一定添加水平范围内,家蝇抗菌肽能显著提高凡纳滨对虾成活率、增重率、特定生长率、饲料效率(P0.05),当抗菌肽提取物添加量为2000～3000mg/kg时,以上4个指标均达最高,且显著高于对照组(P0.05)。以增重率为评价指标,凡纳滨对虾饲料中家蝇抗菌肽提取物的最适添加量为2900mg/kg。当抗菌肽提取物添加量为2000～3000mg/kg时能显著提高虾体的粗蛋白和灰分含量,虾体粗脂肪不受添加抗菌肽水平的显著影响。添加2000～5000mg/kg抗菌肽提取物组与对照组相比能显著提高对虾血细胞数量;添加3000mg/kg抗菌肽提取物时对虾血细胞吞噬率最高。当抗菌肽提取物添加量为2000～3000mg/kg时,对虾血清中酚氧化酶PO、过氧化物酶POD、碱性磷酸酶AKP、溶菌酶LZM的活性和总抗氧化能力T-AOC均维持在一个较高的水平,且显著高于对照组;超氧化物歧化酶SOD的活性在各组组间差异不显著(P0.05)。肝胰腺中AKP、SOD、T-AOC活性各组间差异均不显著(P0.05);LZM活性以3000mg/kg组最高,显著高于其他组。结果表明,饲料中添加适量的家蝇抗菌肽对凡纳滨对虾有一定的促生长作用,并能提高对虾的免疫相关指标。     

Effects of Dietary Short-chain Fructooligosaccharides on Intestinal Microflora, Survival, and Growth Performance of Juvenile White Shrimp, Litopenaeus vannamei

Abstract.— Five groups of juvenile white shrimp, Litopenaeus vannamei , in triplicate were separately fed a compound diet with additional short-chain fructooligosaccharides (ScFOS, Profeed^® 95%) 0, 0.4, 0.8, 1.2, or 1.6 g/kg dried diet for 8 wk to investigate the effects of ScFOS on the intestinal microflora, survival, and growth performance of the shrimp. The juvenile shrimp with around 0.17 g of initial body weight were divided into 30 per tank and reared in a standard water recirculation system at 28 C. The shrimp were fed five times a day. At the end of experiment, the shrimp were weighed and their intestinal samples were analyzed for the amounts of Vibrio parahaemolyticus, Aeromonas hydrophila, Lactobacillus sp. , and Streptococcus faecalis using selective agar. The results showed that the shrimps' weight gain and specific growth rate increased with the increment of dietary ScFOS, while their feed conversion ratio decreased. The result was the best when an additional ScFOS 0.4 g/kg dried diet was used.     

The improvement of growth,digestive enzyme activity and disease resistance of white shrimp by the dietary citric acid

A 45-day feeding trial was conducted to evaluate the effects of dietary citric acid on growth, digestive enzyme and disease resistance of white shrimp, Litopenaeus vannamei. Shrimp with initial body weight of 5.57 ± 0.21 g were fed with basal diet supplemented with 0.0 g kg^?1 (control), 1.0, 2.0, 3.0, 4.0 and 5.0 g kg^?1 citric acid. Results showed that weight gain was increased by 15.9 % and feed conversion ratio was decreased by 0.17 by 2.0 g kg^?1 dietary citric acid compared with control group (P < 0.05). Intestinal protease activity of shrimp fed 2.0 g kg^?1 citric acid was significantly higher (P < 0.05) than that of control group. No significant difference was found in intestinal amylase activity among treatments (P > 0.05). The activities of serum phenoloxidase, superoxide dismutase and lysozyme in 2.0 and 3.0 g kg^?1 citric acid group were significantly higher, and accumulative mortalities of the two groups on the fourth day after injection of Vibrio alginolyticus were significantly lower than those of control group (P < 0.05). Results above demonstrated that dietary citric acid could improve growth performance, immunity and resistance against V. alginolyticus. The supplementation level of citric acid in diet was suggested to be 2.0–3.0 g kg^?1 for white shrimp.     

Effect of Dietary Astaxanthin on Growth,Survival, and Stress Tolerance of Postlarval Shrimp,Litopenaeus vannamei

The effect of dietary astaxanthin on growth, survival, and stress tolerance was determined in postlarval Litopenaeus vannamei. An experiment was performed with postlarval shrimp (mean initial wet weight 1.2 mg) fed four isoenergic and isonitrogenous diets containing four supplemented levels of astaxanthin (0, 100, 200, and 400 mg/kg diet, respectively). Shrimp fed diets containing 100, 200, and 400 mg astaxanthin/kg diet for 30 d showed higher weight gain (WG, %) and survival compared to the control (without supplementation of astaxanthin). Specific growth rate (SGR, %/day) and final body wet weight (FBW, mg) showed the same pattern as WG. There were no significant differences in growth performance (FBW, WG, and SGR) among the groups fed the diets with astaxanthin supplementation at the termination of feeding trial. Survival of shrimp in the control and 100 mg/kg diet treatments was significantly lower than that of shrimp in the treatments with 200 and 400 mg/kg diet. After 9 d of a stress tolerance test, survival of shrimp in the 200 and 400 mg astaxanthin/kg treatments was significantly higher than that of shrimp in the 0 and 100 mg astaxanthin/kg treatments (P < 0.05). We concluded from this experiment that astaxanthin was a necessary ingredient for the development of larval L. vannamei. Considering the effect of astaxanthin on both, growth performance and survival of postlarval L. vannamei, the level of astaxanthin supplemented in the diet should be between 100 mg and 200 mg/kg of diet.     

饲料中黄曲霉毒素B1对凡纳滨对虾生长、肝胰腺和血淋巴生化指标及肝胰腺显微结构的影响

实验设置黄曲霉毒素B1(AFB1)为0、400、800、1200,1600、2000μg/kg6组饲料,饲养初始体质量为(0.3±0.02)g的凡纳滨对虾,经过8周的生长实验观察饲料中AFB1对凡纳滨对虾生长、体营养成分组成、肝胰腺显微结构以及血淋巴和肝胰腺生化指标的影响。实验结果表明:随着饲料中AFB1的增加,各组全虾粗蛋白量无显著性差异,1600μg/kg组和2000μg/kg组的全虾粗脂肪量高于其他组。AFB1为1200μg/kg时对虾增重率最低(304.67%),2000μg/kg时增重率显著高于其他组,但成活率最低(58.33%)。随着饲料中AFB1的升高酶活性普遍呈下降趋势。2000μg/kg组肝胰腺中总抗氧化能力(T-AOC)显著下降(P<0.05),1600μg/kg组肝胰腺中谷胱甘肽S转移酶(GST)、超微量ATP酶和超氧化物歧化酶(SOD)酶活力最低,但血淋巴中GST显著高于其他各组(P<0.05)。从凡纳滨对虾肝胰腺的组织切片可观察到,饲料中含有的AFB1越高,肝胰腺被破坏程度越高。随着饲料中AFB1含量增加,对虾肝胰腺中AFB1残留量逐渐增加,2000μg/kg组对虾肝胰腺中AFB1含量最高(95.49μg/kg),各实验组肌肉中无AFB1残留。     

Dietary administration of soybean isoflavones enhances the immunity of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

The growth response, total hemocyte count (THC), respiratory burst (release of superoxide anion), phenoloxidase (PO) activity, superoxide dismutase (SOD) activity, nitric oxide synthase (NOS) activity and resistance to the pathogen Vibrio alginolyticus were measured in white shrimp (Litopenaeus vannamei) which had been fed diets supplemented with soybean isoflavones (SI) at 0, 5, 10, 20, 40 mg kg^?1 feed for 8 weeks. Dietary SI had no significant influence on survival rate of the shrimp. Significantly greater SGR was observed in treatments with 10, 20 and 40 mg kg^?1 SI supplement than that in control (P < 0.05). Shrimp fed a diet with 20 mg kg^?1 SI showed significant increase in THC, PO activity, respiratory burst activity, SOD activity as well as NOS activity (P < 0.05). Increased THC, respiratory burst activity, SOD activity and NOS activity were also noticed in shrimp fed SI at 10 or 40 mg kg^?1 (P < 0.05). Significant lower cumulative mortality after challenge was observed in shrimp fed diets with SI supplement (10.0–13.3%) than that in control group (36.7%) (P < 0.05). It is therefore concluded that oral administration of SI at 20 mg kg^?1 for 8 weeks could enhance the immune ability of shrimp and improve production in shrimp farming.     

The value of sea urchin,Lytechinus variegatus,egesta consumed by shrimp,Litopenaeus vannamei

Sea urchins produce high‐energy, membrane‐bound fecal pellets that contain residual nutrients and large quantities of microbiota. These egesta are readily consumed by the shrimp, Litopenaeus vannamei. Egesta of the sea urchin, Lytechinus variegatus, were evaluated as a feed supplement or total replacement for a commercial shrimp diet. Shrimp were stocked at 0.49 g ± 0.06 g initial body weight and housed individually in 2.8‐L tanks in a commercial recirculating zebrafish system. Shrimp were assigned to one of six diets: commercial shrimp feed, reference sea urchin feed, collected dried sea urchin egesta, collected wet sea urchin egesta, half ration of shrimp feed and half collected wet sea urchin egesta, and egesta naturally produced by two sea urchins in polyculture. Equivalent dry matter amounts of each diet were proffered to shrimp in each treatment twice daily, except for those that had complete access to natural egesta excreted by sea urchins in polyculture. Sea urchins were proffered a reference sea urchin feed at 2% body weight daily. After 27 days, shrimp proffered collected dried or wet egesta did not differ significantly in percent weight gain and showed the lowest weight gain. The percent weight gain of shrimp fed the commercial shrimp diet did not differ significantly from that of the shrimp fed half commercial shrimp diet and half egesta. The highest weight gain was recorded for those shrimp that consumed the untouched egesta produced by sea urchins in polyculture. These data suggest that consumed egesta have noteworthy nutritional value and therefore would be beneficial to the culture of extractive species in an integrated multitrophic aquaculture system.     

Evaluation of Various Concentrations of Dietary Protein and Animal Protein for Pond-Raised Channel Catfish Ictalurus punctatus Fed to Satiation or at a Restricted Rate

A factorial experiment was conducted to evaluate effect of dietary protein (28% or 32%), animal protein (0, 3, or 6%), and feeding rate (satiation or >90 kg/ha per d) on production characteristics, processing yield, and body composition of pond-raised channel catfish Ictalurus punctatus . Fingerling channel catfish (average weight: 55 g/fish) were stocked into 60, 0.04-ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed once daily to satiation or no more than 90 kg/ha per d for 147 d. Fish fed at a rate of >90 kg/ha per d consumed about 85% of the amount of feed consumed by fish fed to satiation. Dietary protein did not affect the total amount of feed fed, amount of feed consumed per fish, weight gain, feed conversion efficiency, or fillet protein. Animal protein had no effect on the total amount of feed fed, amount of feed consumed per fish, weight gain, or fillet protein and ash. Fish fed a diet containing 6% animal protein converted feed more efficiently than fish fed diets containing 0% and 3% animal protein. Fish fed to satiation daily consumed more feed, gained more weight, converted the feed less efficiently, and had a higher carcass yield, a higher level of visceral fat as compared to fish fed at a rate of >90 kg/ha per d. Feeding rate had no effect on fillet protein. Results from this study indicated that both a 28% and a 32% protein diet with or without animal protein provided the same growth rate of channel catfish raised in ponds from fingerlings to marketable size if feed is not restricted below a maximum rate of 90 kg/ha per d. Even though there were some interactions among the three factors evaluated, dietary protein levels of 28% to 32% and animal protein levels of 0% to 6% do not appear to markedly affect carcass yield and fillet proximate composition of pond-raised channel catfish.     

Pigmentation of Pacific White Shrimp,Litopenaeus vannamei,by Dietary Astaxanthin Extracted from Haematococcus pluvialis

This study investigated the effectiveness of dietary supplementation of astaxanthin (Ax) from the Haematococcus pluvialis on growth, survival, and pigmentation in Pacific white shrimp. Ten test diets were processed to contain five levels of Ax (25, 50, 75, 100, and 150 mg/kg as fed basis) by adding the natural or synthetic Ax to a basal diet containing no Ax. Each diet and a commercial shrimp feed were fed to four replicate tanks of shrimp (12 shrimp/tank) for 8 wk. Neither the natural nor synthetic Ax affected shrimp growth or survival. After cooking, shrimp fed the diets containing the natural Ax exhibited a strong red color, compared to the light pink color of shrimp fed the remaining diets. Colorimetric readings and Ax content in cooked shrimp demonstrated that the natural esterified Ax had greater pigmentation efficiency than synthetic free Ax (P < 0.05). The Ax contents in shrimp tail muscle demonstrated significant correlation with the levels of dietary Ax. The supplementation level of the natural Ax for optimum pigmentation efficiency is in a range of 75–100 mg/kg diet. The Ax product used in this study contained only a small amount (ca. 5.0%) of other carotenoids, indicating that the high pigmentation efficiency was mainly due to algal esterified Ax.     

Palatability of Sarafloxacin HCl-Medicated Feed to Channel Catfish

Two experiments were conducted to evaluate the palatability of sarafloxacin HCl to channel catfish, Ictalurus punctatus. Fingerling channel catfish were raised in 110-1 glass aquaria supplied with flowing well water at a rate of 1 l/min. Fish were fed to satiation once daily either a purified or a practical diet formulated to contain 0, 500, 1,000, 2,000, or 4,000 mg active sarafloxin HCl/kg of diet. Feed consumption was quantified daily for 5 days. All fish were weighed at the beginning and at the end of each experiment. There was a significant decrease in feed consumption of fish fed purified diets with increasing levels of sarafloxacin HCl. However, feed consumption was adequate to provide the proposed dosage regardless of drug concentration. Fingerling channel catfish readily consumed practical diets containing sarafloxacin HCl; feed consumption and weight gain of fish fed medicated and non-medicated practical diets did not differ. There were no apparent palatability problems that would negate use of sarafloxacin HCl in commercial channel catfish feeds.     

Using a fermented mixture of soybean meal and earthworm meal to replace fish meal in the diet of white shrimp,Penaeus vannamei (Boone)

An experiment was conducted to evaluate the potential of a Bacillus subtilis E20‐fermented mixture (FSFEM) containing soybean meal (SBM) and Eisenia fetida earthworm meal (EM) at a ratio of 4:1 to increase the methionine level in order to satisfy the methionine requirement of white shrimp, Penaeus vannamei in a diet with fish meal (FM) completely replaced by mixtures. B. subtilis E20 fermentation improved the mixture's palatability and utilization based on better growth performance in comparison to shrimp fed FSEM (contains fermented SBM and EM at a ratio of 4:1) diets. FSFEM is a good substitute for FM. Maximal replacement levels of FM with FSFEM were 80% in a shrimp diet with 37% of crude protein and 7% of crude lipid based on weight gain and 100% based on feeding efficiency. In addition, shrimp fed experimental diets had no significant differences in survival after being challenged by Vibrio alginolyticus. It is suggested that B. subtilis E20‐FSFEM has the potential to replace FM in cultured shrimp diets.     

Effects of dietary β‐glucan and glycyrrhizin on non‐specific immunity and disease resistance of white shrimp,Litopenaeus vannamei (Boone) challenged with Vibrio alginolyticus

The white shrimp Litopenaeus vannamei, fed immunostimulant‐free, 0.2%β‐glucan and 0.06% glycyrrhizin diets for 18 days, respectively, were challenged with Vibrio alginolyticus at 6.4 × 10⁴ CFU shrimp^?1. The total haemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB) and superoxide dismutase (SOD) activity changes for a 120‐h period were investigated, and shrimp mortality was also recorded. The results showed that PO activity, RB and SOD activity were significantly higher in shrimp fed the two immunostimulant diets after 18 days than those in shrimp fed immunostimulant‐free diets. The THC and SOD activity decreased significantly from 0 to 24 h post challenge, and then reverted to normal levels at 96 and 72 h respectively. The values for PO activity and RB increased from 0 to 48 h post challenge. Compared with those fed the control diets, shrimp fed immunostimulants had significantly higher PO activity and RB values at 120 h post challenge. Mortalities after challenge with V. alginolyticus were significantly lower in shrimp fed with β‐glucan or glycyrrhizin than in those fed with a diet without immunostimulants. It was concluded that dietary β‐glucan and glycyrrhizin increased the shrimp immunity. Furthermore, β‐glucan caused an increase in some immune parameters 12 h earlier than glycyrrhizin after V. alginolyticus challenge.     

Dietary folic acid requirement determined for grass shrimp, Penaeus monodon

A feeding trial was conducted to determine the dietary folic acid requirement of juvenile grass shrimp, Penaeus monodon. Purified basal diets were formulated using vitamin-free casein as the protein source. Graded levels (0, 1, 2, 5, 10, 15, 30, and 60 mg folic acid/kg diet) of folic acid were added to the basal diet, resulting in eight dietary treatments in the experiment. Each diet was fed to three replicate groups of shrimp initially averaging 0.79±0.01 g for 8 weeks. Shrimp fed diets supplemented with 2 mg folic acid/kg diet had greater (P<0.05) weight gain and hepatopancreatic folic acid concentrations than shrimp fed the unsupplemented control diet. Feed efficiency (FE) was highest in shrimp fed the diets supplemented with 2 mg folic acid/kg diet, followed by the groups fed 1 mg/kg, then the control group. Hepatosomatic index (HSI) was highest in shrimp fed the control diet, followed by 1 mg folic acid/kg and lowest in shrimp fed diets supplemented with 2 mg folic acid/kg. Weight gain percentage, hepatopancreatic folic acid concentration and hepatosomatic index of the shrimp analyzed by broken-line regression indicated that the adequate dietary folic acid concentration in growing P. monodon is 1.9–2.1 mg/kg diet.     

饲料中不同泛酸水平对凡纳滨对虾生长性能、饲料利用及血清指标的影响

为研究饲料中不同泛酸水平对凡纳滨对虾生长性能、饲料利用及血清指标的影响,实验配制6种等氮等脂(41%粗蛋白质和8%粗脂肪)的实验饲料,泛酸添加水平分别为0(对照组)、50、100、150、300和600 mg/kg,饲料中实测泛酸水平分别为20.9、69.3、99.0、150.2、304.4和513.6 mg/kg。选用初始体质量为(0.73±0.12)g的凡纳滨对虾720尾,随机分为6组(每组3个重复,每个重复40尾),进行为期8周的养殖实验。结果显示,饲料中不同泛酸水平对凡纳滨对虾增重率和特定生长率的影响不显著;对照组凡纳滨对虾成活率显著低于泛酸添加组,然而各泛酸添加组的成活率组间差异不显著。随着泛酸水平从20.9 m.g/kg增加到99.0 mg/kg时,饲料效率和蛋白质效率显著提高,而随着泛酸水平的进一步增加,饲料效率和蛋白质效率显著降低。饲料中泛酸水平对凡纳滨对虾全虾和肌肉主要成分无显著性影响。对照组对虾血清葡萄糖含量显著低于泛酸各添加组,然而泛酸各添加组之间无显著差异;投喂150.2 mg/kg泛酸组血清甘油三酯含量显著低于对照组和513.6 mg/kg;而血清总蛋白和胆固醇含量不受饲料中泛酸水平的影响。随着饲料中泛酸水平由20.9 mg/kg增至150.2 mg/kg,血清超氧化物歧化酶活力显著提高,而随着饲料中泛酸水平的进一步增加,血清超氧化物歧化酶活力显著降低;饲料中泛酸水平为99.0mg/kg组凡纳滨对虾血清总氧化能力显著高于其他各组;投喂对照组和泛酸水平为69.3mg/kg组的凡纳滨对虾血清丙二醛含量最高,投喂泛酸水平为150.2 mg/kg组血清的丙二醛含量显著低于其他各组。以凡纳滨对虾的饲料效率和蛋白质沉积率为评价指标,通过折线模型分析得到凡纳滨对虾泛酸最适需要量分别为113.40和119.87mg/kg。     

An acoustic based approach to evaluate the effect of different diet lengths on feeding behavior of Litopenaeus vannamei

Studying shrimp feeding behavior is challenging and, traditionally, studies have been using direct visual observation or video recordings with image analysis under laboratory conditions. Passive acoustics monitoring (PAM) is a non-invasive approach to study feeding behavior of penaeids, as their mandibles emit clicking sounds during feed ingestion. Considering the wide variation available in shrimp diet lengths, our knowledge is still limited about their effects on feeding behavior. The present study was designed to use acoustics to evaluate the feeding behavior of Litopenaeus vannamei fed different diet lengths. A commercial pelleted diet with similar diameter (2.4 mm) and three different lengths was used as treatments “small” (2.35 mm), “medium” (4.26 mm) and “large” (8.42 mm). Three separate trials were performed with fastened shrimp (20 g), using omnidirectional hydrophones and external audio recorders. Our approach started with the characterization of the click acoustic parameters produced by three shrimps when fed the different diet lengths in anechoic chambers (15 L). We then analyze the number of clicks produced per pellet and duration of the clicking activity when shrimp fed a single pellet in individual tanks (1 L). Finally, the acoustic energy of feeding activity and feed consumption, as well as theirs relationship to predict feed intake was evaluated in aquaria (70 L) with five shrimps. The acoustic parameters of isolated clicks were not affected by the different diet lengths, however, doubling the length of the pellet resulted in doubling the number of clicks emitted during feeding activity. The duration of clicking activity per pellet indicated that small pellets are consumed 2.9 and 4.7 times faster than medium and large pellets, respectively. Furthermore, feeding acoustic energy of small pellets decreased rapidly after feed offer, as their faster consumption probably contributed to shrimps achieved satiety earlier than larger diets. Feed consumption was similar among diets length, but significantly correlated with the feeding acoustic energy emitted by L. vannamei, which is a breakthrough in feeding behavioral research. The results highlight the potential and possibilities of an acoustic approach to estimate feed consumption, as well as an alternative to traditional methods in feeding behavioral studies to improve efficiency of feed management.     

团头鲂对饲料中Zn的需求量

为了研究团头鲂对饲料中Zn的需要量,以平均体质量50 g的团头鲂为实验对象,采用半纯化饲料,以ZnSO4·H2O为锌源,设置Zn添加量分别为0、68、137、206、275 mg/kg(饲料中Zn总量为22.85、98.07、164.00、235.43、307.96 mg/kg)共5个Zn含量梯度,每个实验组设4个平行,在池塘网箱中养殖43 d。经过回归拟合分析,饲料中Zn添加量、饲料中Zn总量与团头鲂特定生长率、饲料系数、蛋白质沉积率、脂肪沉积率的关系,得到团头鲂对饲料中无机Zn补充量为155.86~161.25 mg/kg,对饲料总Zn需要量为184.85~190.39 mg/kg;在日均摄食量为5.12 g/100 g体质量下,团头鲂对饲料Zn日需求量为0.798~0.825 mg/100 g体质量,对饲料总Zn日需要量为0.946~0.974 mg/100 g体质量。饲料中Zn含量对团头鲂的成活率、肥满度、内脏指数、鳞片重/体质量、体质量/体长、脊椎骨重/体质量无显著影响(P0.05)。饲料中Zn含量对团头鲂的脊椎骨长/体长有显著影响(P0.05);饲料中Zn的补充,有利于团头鲂脊椎骨的生长。     

Vc-2-多聚磷酸酯对中国对虾幼体生长和存活的影响

用添加了不同含量Vc-2-多聚磷酸酯(600 mg/kg,3000 mg/kg、6000 mg/kg,对照)的饲料分别投喂中国对虾幼体(Z1-P5),测定其对幼体生长、变态、非特异性免疫以及体内Vc积累量的影响。结果显示:6000 mg/kg处理组显著促进了幼体的生长和变态(P<0.05);超氧化物岐化酶和抗菌活力较对照组和600 mg/kg处理组均达到了显著水平(P<0.05)。第20 d用副溶血弧菌攻毒,3000、6000mg/kg处理组均显著提高了幼体存活率;高效液相色谱法检测幼体体内的Vc含量发现,其体内Vc含量随着饲料中Vc-2-多聚磷酸酯含量的增加而增加。以生长、变态、超氧化物岐化酶、抗菌活力为评价指标,建议中国对虾幼体饲料中Vc-2-多聚磷酸酯的添加量为6000 mg/kg。     

The evaluation of practical diets on a basis of digestible crude protein,lysine and methionine for Litopenaeus vannamei

A feeding trial was conducted to evaluate the efficacy of replacing fish meal (FM) with blood meal (BM), poultry by‐product meal (PBM), meat and bone meal (MBM) and shrimp head meal (SHM), rapeseed meal (RM) and peanut meal (PM) on a digestible basis of crude protein and lysine and methionine in five practical diets for the Pacific white shrimp at the FM levels of 300, 250, 200, 150 and 100 g kg^?1 under laboratory conditions. Each of the five experimental diets was hand‐fed to four replicate tanks of shrimp with an average weight of 0.33 ± 0.03 g to satiation at each meal. The shrimp were fed three times a day over a six‐week period. The per cent weight gain of initial body weight (WG%) was significantly lower in shrimp fed 100 g kg^?1 FM diet, but the value for hepatosomatic index (HSI) and the level of blood urea nitrogen (BUN) tended to be higher in shrimp fed 100 g kg^?1 FM diet than those in shrimp fed other diets. The lowest value for feeding rate (FR) occurred for shrimp fed the basal diet and was significantly lower than that in shrimp fed the FM diets at 100–150 g kg^?1. Shrimp fed diets containing 200 g kg^?1 or lower FM had significantly lower feed utilization than those fed the 250 g kg^?1 FM diet and the basal diet. The protein efficiency ratio (PER) in the shrimp fed the basal diet was significantly higher than in the other FM diets. Decreasing the FM replacement level significantly reduced nutrient digestibility except in the cases of ash and gross energy, but it did not affect the survival, condition factor (CF), body composition, digestive enzyme activity or plasma transaminase activity. The results of the study indicate that feeding a diet formulated on a digestible basis and involving FM replacement with other protein sources at a greater replacement proportion will not produce a level of shrimp growth equal to that achieved by feeding the basal diet.     

Effects of various corn distillers by‐products on growth,feed efficiency,and body composition of channel catfish,Ictalurus punctatus

A study was conducted to examine the use of corn distillers’ by‐products in diets and the effects of additional dietary fat on channel catfish, Ictalurus punctatus, performance. Juvenile channel catfish (initial weight: 12.6 g per fish) were stocked in flow‐through aquaria and fed one of six practical diets for 9 weeks. Fish fed the control + fat diet consumed more diet and had higher feed efficiency ratio (FER) than fish fed the control diet, but weight gain was not significantly different between fish fed these two diets. Fish fed the diet containing 300 g kg^?1 distillers dried grains with solubles (DDGS) consumed more diet and gained more weight, but had similar FER compared with fish fed the control + fat diet. The diet containing 200 g kg^?1 high‐protein distillers grains (HPDDG) resulted in similar diet consumption, weight gain and FER as the control + fat diet. Fish fed the diet containing 100 g kg^?1 distillers solubles (DS) consumed more diet, but had similar weight gain and FER compared with fish fed the 300 g kg^?1 DDGS diet. The presence of distillers solubles in the diet (300 g kg^?1 DDGS, 100 g kg^?1 DS, 100 g kg^?1 EDS diets) appears to increase diet consumption, weight gain, and FER over the control diets with or without additional fat.     

中草药对斑节对虾生长、饲料利用和肌肉营养成分的影响

研究了中草药对斑节对虾Penaeusmonodon(初始体重0.30g.尾-1)生长性能、饲料利用以及肌肉营养成分和氨基酸的影响。6种实验饲料(按顺序分别为1,2,3,4,5和6)中中草药的添加量分别为0,0.5,1.0,2.0,4.0和8.0g·kg-1饲料。除了饲料2之外,斑节对虾的成活率、饲料系数和蛋白质效率都显著(P<0.05)优于对照组(饲料1)。投喂饲料3的斑节对虾增重率与对照组相比,虽然统计学上不存在显著差异,但有较大幅度的提高。投喂添加中草药的饲料对斑节对虾肌肉的水分和蛋白质含量无显著影响,但脂肪含量明显下降。结果表明,斑节对虾饲料中添加适量的中草药能够促进生长、显著提高成活率和降低饲料系数,并改变斑节对虾肌肉中脂肪含量和氨基酸组成。