两种水温条件下团头鲂对7种蛋白源饲料表观消化率的比较

采用由30%待测蛋白源饲料原料和70%基础饲料组成的试验饲料,以三氧化二钇(Y_2O_3)作外源指示剂,添加量为0.05%,以平均体重(34.38±1.06)g的团头鲂(Megalobrama amblycephala)幼鱼作研究对象,在30℃和25℃两种水温条件下比较研究其对鱼粉(FM)、豆粕(SBM)、菜粕(RSM)、棉粕(CSM)、酵母浸粉(YEF)、肉骨粉(MBM)和花生粕(PNM)7种蛋白源饲料原料的干物质(DM)、粗蛋白(CP)、总能(GE)、总氨基酸(TAA)及必需氨基酸(EAA)的表观消化率。结果显示:水温30℃时,酵母浸粉的干物质、总能、粗蛋白和必需氨基酸的表观消化率最高;水温25℃时,原料干物质和总能的表观消化率最高的为鱼粉,粗蛋白、必需氨基酸和总氨基酸的表观消化率最高的为豆粕。在两个水温下,原料干物质、粗蛋白、总氨基酸和必需氨基酸的表观消化率最低的均是肉骨粉,总能的表观消化率最低的是棉粕。在30℃时团头鲂对蛋白源饲料原料各营养成分的表观消化率高于25℃时,且酵母浸粉在两个水温下各营养成分的消化率差异显著(P0.05)。在30℃时,酵母浸粉的各养分表观消化率较高,但其氨基酸平衡性较差,需适量添加蛋氨酸,满足团头鲂对氨基酸的需求;在25℃时,豆粕和鱼粉各养分表观消化率较高,可作为团头鲂饲料的优质蛋白源饲料原料。肉骨粉在两个水温下均表现出最低表观消化率,需搭配其他饲料适量使用。     

凝结芽孢杆菌对奥尼罗非鱼消化酶活性、消化率及生长性能的影响

在基础饲料中分别添加不同剂量的凝结芽孢杆菌(Ⅰ:1.0×1011cfu/kg饲料,Ⅱ:3.0×1011cfu/kg饲料,Ⅲ:6.0×1011cfu/kg),室外水族箱中饲养奥尼罗非鱼(Oreochromis niloticus×O.aureus)(34.50±0.25 g),用基础饲料投喂作为对照,每饲料组设三个重复,每水族箱随机放养16尾鱼,投喂率为3%。采用静水饲养以避免各箱之间水的交换。56 d后测定鱼体的生长和消化酶活性。结果显示:不同添加量的凝结芽孢杆菌均能显著提高奥尼罗非鱼胃、肝胰脏和肠道蛋白酶活性(P<0.05),但酶的活性随添加量的提高呈下降趋势。凝结芽孢杆菌的添加对胃、肝胰脏和肠道淀粉酶及脂肪酶活性没有显著影响(P>0.05)。Ⅰ组和Ⅱ组的干物质表观消化率、蛋白质消化率、相对增重率、饵料系数和蛋白质效率均显著高于对照组(P<0.05),而Ⅲ组和对照组之间差异不显著(P>0.05)。结果提示,饲料中添加1.0×1011cfu/kg饲料的凝结芽孢杆菌就能显著促进奥尼罗非鱼的生长和饲料营养物质的利用,满足最佳生长。     

团头鲂对7种饲料的蛋白质、氨基酸及磷的表观消化率

本实验以0.5%的三氧化二铬(Cr2O3)为指示剂,研究分别以鱼粉、肉骨粉、豆粕、花生粕、棉粕、酒精糟及其残液干燥物(DDGS)和菜粕作为蛋白饲料,将这7种饲料原料与基础日粮按照3:7的比例组成实验日粮,观测团头鲂(Megalalobrama amblycephala Yih)对这7种饲料的干物质、粗蛋白、氨基酸及总磷的表观消化率.实验鱼初始体质量为(296.54±1.71)g,分别投喂相应的实验饲料5周后采用自排法收集粪便.结果表明,7种饲料原料的干物质、蛋白质、总氨基酸以及总磷的表观消化率的范围分别为53.65%～77.48%、78.66%～93.63%、80.12%～94.83%、3.21%～48.02%.其中粗蛋白及总氨基酸的表观消化率均以菜粕最高;花生粕、豆粕与鱼粉相接近;肉骨粉最低.磷的表观消化率以DDGS最高,菜粕和肉骨粉最低,其他4种原料的磷的表观消化率范围为11.81%～29.10%.由此可见,菜粕、豆粕、花生粕可作为团头鲂优质的植物蛋白源,在实际生产配方中可部分替代鱼粉.DDGS蛋白消化率高于肉骨粉,且磷的表观消化率较高,也可作为一种优质的鱼用饲料原料.     

两种水温条件下吉富罗非鱼对两种工艺饲料的表观消化率的比较

本试验采用相同的基础饲料配方,制成膨化浮性饲料(D_1)和沉性颗粒饲料(D_2),以0.1%的TiO_2为外源指示剂,以平均初始体重为(54.21±0.47)g的吉富罗非鱼(Oreochromis niloticus)为研究对象,在22℃和28℃两种温度条件下比较研究其对这两种工艺饲料中常规营养成分和氨基酸的表观消化率。结果显示:在22℃条件下,D_1组和D_2组的增重率、特定生长率及对饲料中粗蛋白和氨基酸(除苯丙氨酸)的表观消化率无显著性差异;而D_1组的摄食率、饲料系数显著低于D_2组;D_1组粗脂肪的表观消化率显著高于D_2组。在28℃条件下,D_1组粗脂肪和粗蛋白的表观消化率显著高于D_2组。与28℃组相比,22℃组的增重率、特定生长率、摄食率以及对饲料中干物质、粗蛋白的表观消化率显著降低,饲料系数显著增大,而必需氨基酸和总氨基酸的表观消化率无显著性差异。结果表明:膨化浮性饲料显著提高了两种温度下吉富罗非鱼粗脂肪的表观消化率。而22℃的温度条件下,降低了吉富罗非鱼对两种饲料中的干物质、粗蛋白的表观消化率。     

红鳍东方鲀对8种饲料原料的表观消化率

本研究旨在探讨红鳍东方鲀(Takifugu rubripes)幼鱼对红鱼粉、白鱼粉、豆粕、菜粕、花生粕、棉粕、玉米酒糟蛋白(DDGS)和肉骨粉中干物质、粗蛋白、粗脂肪、氨基酸、总能和总磷的表观消化率。实验饲料由70%的基础饲料和30%的待测饲料原料组成，并添加0.1%的三氧化二钇(Y2O3)作为外源添加剂，选取平均体重为37.90 g的红鳍东方鲀幼鱼，随机分成8组，每组3个重复，每个重复30尾鱼，按照不同处理分别投喂相应饲料，采用虹吸法收集粪便。结果显示，白鱼粉、红鱼粉和豆粕的干物质表观消化率分别为70.54%、69.02%和60.37%，显著高于菜粕、棉粕及DDGS(P<0.05)；粗蛋白的表观消化率为50.91%~92.78%，肉骨粉粗蛋白表观消化率最低(50.91%)，显著低于白鱼粉、红鱼粉、豆粕、菜粕、花生粕和DDGS(P<0.05)，各待测饲料原料中总氨基酸表观消化率的变化趋势与粗蛋白的表观消化率基本一致；粗脂肪的表观消化率为70.6%~94.19%，白鱼粉粗脂肪表观消化率最高(94.19%)，显著高于棉粕和肉骨粉(P<0.05)；能量的表观消化率为30.58%~90.01%，白鱼粉、红鱼粉、豆粕和花生粕总能的表观消化率最高(76.26%~90.01%)(P<0.05)；磷的表观消化率为9.13%~68.14%，白鱼粉和红鱼粉的总磷表观消化率最高(分别为66.98%和68.14%)(P<0.05)。白鱼粉、红鱼粉的各种营养成分的表观消化率均较佳，肉骨粉及棉粕各种营养成分的表观消化率相对较差；豆粕及花生粕的粗蛋白消化率及必需氨基酸的消化率优于其他植物蛋白，菜粕次之。     

团头鲂对8种非常规饲料原料中营养物质的表观消化率

以0.5%的三氧化二铬(Cr2O3)为指示剂,由70%基础日粮和30%试验原料组成试验日粮研究了团头鲂对膨化羽毛粉、酶解羽毛粉、血粉、蚕蛹粉、玉米蛋白粉、玉米、碎米和大麦8种饲料原料的干物质、粗蛋白、粗脂肪、氨基酸、总磷及总能的表观消化率。试验鱼［平均体质量(250.83±2.12) g ］养殖于室内水族箱中(3.0 m×0.8 m×0.8 m),分别投喂相应的试验饲料1周后采用自排法收粪。结果表明:8种饲料原料的干物质、粗蛋白、粗脂肪、总氨基酸、总磷及总能的表观消化率的范围分别是68.07%～92.69%、81.54%～92.75%、84.82%～103.44%、63.07%～95.56%、41.48%～97.55%、68.91%～97.81%。其中各项营养物质的表观消化率均以玉米蛋白粉最高;4种动物蛋白原料中以蚕蛹粉中营养物质表观消化率最高,血粉次之;除粗脂肪外,酶解羽毛粉的消化率均高于膨化羽毛粉;3种能量饲料中,以大麦的蛋白及氨基酸表观消化率最高,但干物质、粗脂肪及能量的表观消化率均显著低于玉米和碎米。由此可见,玉米蛋白粉和蚕蛹粉分别可作为团头鲂优质的植物蛋白源和动物蛋白源,血粉、羽毛粉可搭配其他饲料少量使用。玉米和碎米能值较高,可作为团头鲂的主要能量饲料,大麦由于氨基酸组成较好,也可适量使用。     

花生粕替代鱼粉对黄颡鱼生长及饲料表观消化率的影响

试验旨在探讨花生粕替代鱼粉对全雄黄颡鱼生长及饲料表观消化率的影响。选择初始体质量为(9.12±0.05)g全雄黄颡鱼240尾,随机分成2组,每组4个重复,每个重复30尾鱼,分别投喂基础饲料(对照组)和16.98%花生粕替代11.5%鱼粉的等氮等脂饲料(替代组),进行55 d生长及消化试验。结果表明:(1)替代组体增重、增重率、特定生长率、蛋白质效率及饲料系数与对照组差异不具有统计学意义(P0.05);(2)饲料干物质、粗蛋白、粗脂肪、粗灰分、能量、总氨基酸、必需氨基酸和非必需氨基酸表观消化率两组间无统计学意义差异(P0.05);替代组饲料苏氨酸和缬氨酸表观消化率显著低于对照组(P0.05),精氨酸表观消化率显著高于对照组(P0.05)。结论:用花生粕部分替代鱼粉应用于全雄黄颡鱼饲料是可行的。     

鲤对添加硅肥饲料中干物质、蛋白质及脂肪表观消化率的研究

采用Cr2O3为外源指示剂,测定了鲤对添加不同剂量硅肥的饲料中干物质、粗蛋白和粗脂肪的表观消化率。试验结果表明:鲤对添加硅肥质量分数1%试验饲料干物质和粗蛋白质表观消化率最高,分别为59.70%和85.49%;对添加硅肥质量分数2%的试验饲料粗脂肪表观消化率最高,为66.93%。     

富硒饲料对仿刺参成参的饲喂效果研究

选用养殖规格仿刺参Apostichopus japonicus成参72头(40.31±1.27g),分别按蛋氨酸硒添加量0、0.2、0.4、0.6、0.8、1.0 mg/kg进行分组强化饲喂。试验进行28天,平均水温13℃,盐度27‰,p H 8.1,试验结束时分别测定各组成参的特定生长率(SGR)、摄食率(IR)、排粪率(FPR)、饲料转化率(FCR)和表观消化率(AD)。结果表明:特定生长率、摄食率和排粪率在硒添加量为0.6 mg/kg时分别达到最大值0.22%/d、0.0121 g/g·d、0.006 4 g/g·d,与对照组差异显著(P0.05);饲料转化率在硒添加量为0.4 mg/kg时达到最大值为18.37%,与对照组差异不显著(P0.05);成参对饲料中干物质、粗蛋白的表观消化率在硒添加量为0.6 mg/kg时达到最大值42.25%,79.61%,与对照组差异显著(P0.05),饲料粗脂肪的表观消化率在硒添加量为0.8 mg/kg时达到最大值95.52%,与对照组差异显著(P0.05)。综合生长性能和饲料利用情况,饲料中添加0.6~0.8 mg/kg的硒较为适宜。     

中华鳖日本品系对6种饲料蛋白原料表观消化率的研究

研究了中华鳖日本品系(Pelodiscus sinensis,Japanese strain)幼鳖对蝇蛆蛋白粉、虾壳粉、发酵豆粕、豌豆浓缩蛋白、大豆浓缩蛋白以及玉米蛋白粉的干物质、粗蛋白质、氨基酸、粗脂肪和总能的表观消化率。试验饲料由70%基础饲料和30%待测饲料原料组成,并以0.5%的三氧化二铬(Cr2O3)为外源指示剂。选取平均体重为(14.69±0.55)g的中华鳖日本品系幼鳖180只,随机分成6组,每组3个重复,每个重复10只,投喂试验饲料养殖4周,采用虹吸法收集粪便进行表观消化率测定。结果表明,6组饲料的干物质、粗蛋白质、粗脂肪以及总能表观消化率范围为77.8%~85.6%、73.2%~83.7%、81.2%~91.1%和78.8%~85.6%,其中蝇蛆蛋白粉和发酵豆粕的干物质表观消化率较高,大豆浓缩蛋白的粗蛋白、粗脂肪及总能表观消化率较高;各原料总氨基酸表观消化率在75.8%~86.1%,最高值和最低值分别出现在大豆浓缩蛋白和虾壳粉。     

Effect of dietary probiotics on apparent digestibility coefficients of nutrients of white shrimp Litopenaeus vannamei Boone

Apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, phosphorus (P), essential amino acids (EAA), non‐essential amino acids (NEAA) and fatty acids were determined for white shrimp (Litopenaeus vannamei). A probiotic (Bacillus sp.) was used at 0% (diet 1), 0.5% (diet 2), 1.0% (diet 3), 3.0% (diet 4) and 5.0% (diet 5) inclusion rates in experiment diets. Apparent digestibility coefficients was determined using 0.01% Y₂O₃ as an indicator. A total of 300 shrimp (initial mean body weight 11.5±0.6 g) were randomly stocked into fifteen 500‐L outdoor concrete tanks. Faeces were collected from three replicate groups of shrimp three times a day. The ADCs of five diets were: DM, 66.1–69.6%; CP, 80.4–84.7%; lipid, 82.2–84.9%; P, 25.4–28.5%; EAA, 82.0–85.4%; NEAA, 81.5–85.1%; saturated fatty acids (SFA), 79.6–82.4%; monounsaturates (MUFA), 81.6–84.2% and polyunsaturates (PUFA)+highly unsaturates (HUFA), 83.4–86.6%. Apparent digestibility coefficients of DM, CP, lipid, P, amino acids and fatty acids in diet 1 were significantly lower than in other diets (P<0.05). Apparent digestibility coefficient of P in diets increased as probiotic increased. Apparent digestibility coefficient of lipid in diet 3 was the highest, but the difference was not significant among diets. In general, ADCs of most amino acids and fatty acids were over 80% in all diets, and PUFA+HUFA>MUFA>SFA. The results showed that ADCs of diets supplemented with 10, 30 and 50 g probiotic kg^?1 basal diet were higher than in other diets except lipid, and the difference was significant.     

Effects of dietary essential amino acid deficiencies on the growth performance and humoral immune response in silvery‐black porgy (Sparidentex hasta) juveniles

A 6‐week feeding trial was conducted for determining the effects of dietary essential amino acids (EAA) deficiencies on growth performance and non‐specific immune responses in silvery‐black porgy juveniles (4.7 ± 0.1 g initial weight). Eleven isoproteic (ca. 47%) diets were formulated including a control diet containing the optimum quantity of EAA, and ten EAA‐deficient diets. All diets contained 36% fish meal and 18.5% crystalline EAA and non‐essential amino acids (NEAA) as the main source of dietary proteins. All the EAA and NEAA incorporated in the crystalline amino acids mixture of the control diet simulated the amino acids profile of the fish meal. The other 10 EAA‐deficient diets were formulated by the deletion of each of the 10 EAA (crystalline form) from the control diet and replaced by a mixture of NEAA for the adjustment of dietary nitrogen contents. At the end of the experiment, fish fed with threonine‐deficient diet showed the lowest survival rate (p < .05), whereas growth performance decreased in fish fed all EAA‐deficient diets, although the reduction in body growth varied depending on the EAA considered. Plasma total protein decreased in all experimental groups except for fish fed the phenylalanine‐deficient diet. Fish fed with arginine‐ and lysine‐deficient diets had the lowest plasma C3, C4, lysozyme, total immunoglobulin and total superoxide dismutase activity (p < .05). Present results indicated that lysine, methionine and threonine were the most limiting EAA in terms of growth performance; however, arginine, threonine and lysine were the most limiting EAA for innate immunity responses in silvery‐black porgy juveniles.     

Apparent digestibility coefficients of European grain legumes in rainbow trout (Oncorhynchus mykiss) and Nile tilapia (Oreochromis niloticus)

Two trials were carried out to evaluate the apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipids, starch and gross energy (GE) of six European varieties of grain legumes, namely chickpea‐type Kabuli (CHK), chickpea‐type Desi (CHD), field pea (FP), faba bean (FB), white lupin (WL) and chickling vetch (CV), in rainbow trout and Nile tilapia juveniles. The ADCs were measured using a reference diet and six experimental diets (700 g/kg of the reference diet and 300 g/kg of each raw grain legume) containing 10 g/kg chromic oxide as inert marker. Additionally, grain legumes were analysed for the organic acids profile. In rainbow trout, FP presented the highest ADCs of DM, CP and GE, whereas chickpeas and FB had the lowest DM, GE and starch ADC values. In Nile tilapia, the lowest values of nutrients (except starch) and energy ADCs were found for FP and CV. Nutrients and energy of chickpeas, WL and FB were better digested by tilapia, whereas FP was better digested by trout. Overall results reveal raw grain legumes as promising feed sources for both fish species.     

察尔森水库细鳞斜颌鲴营养成分分析及评价

本试验对察尔森水库细鳞斜颌鲴(Plagiognathops microlepis)肌肉营养成分进行了分析及评价。试验采用常规营养成分分析法对细鳞斜颌鲴肌肉一般营养成分、氨基酸组成、脂肪酸组成进行了测定。结果表明:细鳞斜颌鲴肌肉中水分含量为79.31%、粗蛋白含量为16.56%、粗脂肪含量为0.94%、灰分含量为1.13%、总糖含量为0.38%。细鳞斜颌鲴肌肉共检出18种氨基酸,其中必需氨基酸(EAA)8种,非必需氨基酸(NEAA)10种,总氨基酸(TAA)含量为16.28%,EAA含量为6.72%,NEAA含量为9.56%;EAA/TAA(41.29%)及EAA/NEAA(70.32%)均在FAO/WHO推荐值以上。氨基酸评分(AAS)和化学评分(CS)结果是第一限制性氨基酸均为色氨酸(Trp),而第二限制性氨基酸,AAS是苏氨酸(Thr),CS是苯丙氨酸+酪氨酸(Phe+Tyr)。细鳞斜颌鲴肌肉共检出21种脂肪酸,其中7种饱和脂肪酸(SFA)、3种单不饱和脂肪酸(MUFA)、11种多不饱和脂肪酸(PUFA),分别占脂肪酸总量的25.22%、22.02%、37.76%;C20∶5n3(EPA)含量为11.87%,C22∶6n3(DHA)含量为11.55%。从营养分析结果来看,细鳞斜颌鲴是一种营养价值极高的食用鱼类。     

Apparent digestibility coefficients of animal and plant feed ingredients for juvenile Pseudobagrus ussuriensis

A study was conducted to determine apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), lipid, gross energy, phosphorus and amino acids (AAs) from Peruvian fish meal (PFM), native fish meal (NFM), meat bone meal (MBM), dried daphnia meal (DDM), soybean meal (SBM), full‐fat soybean (FSBM), cottonseed meals (CSM), rapeseed meal (RSM) and corn gluten meal (CGM) for Pseudobagrus ussuriensis (7.8 ± 0.06 g). Test diets were formulated to contain a 70:30 mixture of reference diet to test ingredient with chromic oxide (5 g kg^–1) serving as the inert marker. ADCs of DM ranged from 49.94% (CGM) to 87.11% (PFM), the highest ADCs of DM were observed in PFM and the lowest was found in CGM. ADCs of CP in the test ingredients ranged from 74.92% (CGM) to 93.41% (SBM). ADCs of crude lipid ranged from 51.80% (CGM) to 94.07% (PFM) for fish. ADCs of energy ranged from 56.42% (CGM) to 90.09% (PFM). ADCs of phosphorus ranged from 21.81% (CSM) to 65.70% (PFM). AA availability for the test ingredients followed a similar pattern to ADCs of CP, in which values for PFM, NFM and MBM were generally higher (p < .05) than those of other protein ingredients. Among all plant meals, the AA availability values in SBM were higher (p < .05) than those in CGM, CSM and RSM. The availability of most AAs in CGM was the lowest (p < .05) among all tested ingredients. In conclusion, PFM and NFM are good sources of available protein and AAs. When fishmeal supply is limited, MBM and DDM are substitutes for fishmeal reduction in P. ussuriensis diets; at the same time, SBM and FSBM are also very acceptable protein feedstuffs. However, CSM, RSM and CGM could not be used at high levels in P. ussuriensis diets because of their inferior digestibilities.     

The optimum dietary essential: nonessential amino acid ratio for rainbow trout (Oncorhynchus mykiss), which maximizes nitrogen retention and minimizes nitrogen excretion

Although the ratio of essential to nonessential amino acids (EAA:NEAA ratio) in dietary protein has important effects on protein utilization by fish, there has thus far been little research aimed at quantifying these effects. In this study, we investigated the effect of dietary EAA:NEAA ratio on nitrogen (N) utilization and excretion of rainbow trout (Oncorhynchus mykiss). A 6-week dose-response experiment was conducted, with 6 levels of dietary EAA:NEAA ratio, ranging from 23:77 to 66:34. Protein content of all diets was 350 g kg^?1. Each experimental diet was fed to four replicate tanks of fish (35 fish per tank). Fish were fed a limited ration on the first two feedings of each day, and were fed to apparent satiation on the third feeding of each day. Response variables included feed intake, weight gain, lipid deposition, thermal-unit growth coefficient (TGC), feed efficiency ratio (FER), N retention, and N excretion (g kg^?1 gain). Mean feed intake, weight gain, TGC, FER and N retention all increased as EAA:NEAA ratio increased up to 57:43, and then decreased slightly as EAA:NEAA ratio increased further to 66:34. Maximum mean N retention of 46% and minimum mean N excretion of 29 g N kg^?1 gain was achieved by fish fed the diet containing an EAA:NEAA ratio of 57:43. Non-linear regression using a 2^nd order polynomial equation showed that 95% of the maximum N retention could be achieved with an EAA:NEAA ratio of 46:54, and 98% with an EAA:NEAA ratio ranging from 49:51 to 62:38.     

Dietary l‐methionine requirement of juvenile black sea bream (Sparus macrocephalus) at a constant dietary cystine level

An 8‐week feeding trial was conducted to determine the effects of dietary methionine level on juvenile black sea bream Sparus macrocephalus. Fish (initial body weight: 14.21 ± 0.24 g) were reared in eighteen 350‐L indoors flow‐through circular fibreglass tanks (20 fish per tank). Isoenergetic and isonitrogenous diets contained six levels of L‐methionine ranging from 7.5 to 23.5 g kg⁻¹ of dry diet in 3.0 g kg⁻¹ increments at a constant dietary cystine level of 3.1 g kg⁻¹. Growth performance and feed utilization were significantly influenced by dietary methionine levels (P < 0.05). Maximum weight gain (WG), specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio and protein productive value (PPV) occurred at 17.2 g methionine kg⁻¹ diet, beyond which they showed declining tendency. Protein contents in whole fish body and dorsal muscle were positively correlated with dietary methionine level, while muscle lipid content was negatively correlated with it. Apparent digestibility coefficients (ADCs) of dietary nutrients were significantly affected by dietary treatments except for ADCs of crude lipid. Fish fed the grade level of methionine demonstrated a significant improvement in whole‐body methionine content, total essential amino acids (∑EAA), total non‐essential amino acids (∑NEAAs) and ∑EAA/∑NEAA ratio (P < 0.05). Regarding serum characteristics, significant differences were observed in total cholesterol, glucose and free methionine concentration (P > 0.05), while total protein level and triacylglycerol concentration kept relatively constant among treatments (P < 0.05). Analysis of dose response with second‐order polynomial regression on the basis of either SGR or PPV, the optimum dietary methionine requirements of juvenile black sea bream were estimated to be 17.1 g kg⁻¹ of diet (45.0 g kg⁻¹ methionine of protein) and 17.2 g kg⁻¹ of diet (45.3 g kg⁻¹ methionine of protein) in the presence of 3.1 g kg⁻¹ cystine, respectively.     

Ability of European seabass (Dicentrarchus labrax) to digest rendered animal fats from fish,poultry and mammals

This study evaluates the in vivo apparent digestibility coefficients (ADC) of rendered animal by‐product fats in European seabass (Dicentrarchus labrax) juveniles. Diets contained fish oil (FOd), poultry fat (PFd) or mammal fat (MFd), from rendering animal by‐products, at 140 g/kg. Macronutrient and fatty acids ADCs were evaluated in quadruplicate tanks with fifteen 100 g fish. While total lipids ADCs (88%–90%) were unaffected, individual fatty acids ADC varied significantly among diets. Monounsaturated fatty acids ADCs were similar (94%–95%), saturated fatty acids ADCs were lowest in MFd (85% vs. 91% in PFd and FOd), and polyunsaturated fatty acids (PUFA) ADCs were lowest in PFd (96 vs. 97%–98%). Total n‐3 PUFA were better digested in FOd than in the other diets (98 vs. 96%–97%), while MFd had the highest total n‐6 PUFA ADC. FOd showed significantly higher EPA (20:5n‐3) and DHA (22:6n‐3) ADCs compared to the other test diets. The obtained results suggest that rendered animal fats can be considered feasible alternatives to fish oil in seabass. Nevertheless, that lack of EPA and DHA in land animal fats, combined with the reduced digestibility of these fatty acids, may compromise its dietary inclusion at high levels.     

Apparent Digestibility Coefficients and Amino Acid Availability of Cricket Meal,Gryllus bimaculatus,and Fishmeal in African Catfish,Clarias gariepinus,Diet

A study was conducted on African catfish, Clarias gariepinus, to examine the apparent digestibility coefficient (ADC) of protein, dry matter, lipid, and energy, and the apparent availability coefficient (AAC) of essential amino acid (EAA) for a cricket meal (CM) diet, Gryllus bimaculatus, and fishmeal (FM). Both diets consisted of 30% isonitrogenous levels with a 70:30 ratio of basal diet to test ingredient. Chromic oxide (0.5%) was added to the diet as an inert marker. The ADCs of crude protein (CP) in CM (81.21%), lipid (89.82%), gross energy (64.42%), and dry matter (73.97%) was significantly higher (P < 0.05) than the value of CP (78.22%), lipid (82.03%), gross energy (56.52%), and dry matter (62.26%) in FM. All EAAs were present in both diets. The AACs for both diets ranged from 0.906 to 0.961 and 0.812 to 0.938 for the CM and FM diets, respectively. The growth performance of fish fed with CM exhibited significantly higher (P < 0.05) weight gain, feed conversion ratio, and protein efficiency ratio compared with FM. Overall, the results suggest that CM could be included in the African catfish diet without affecting their nutrient and amino acid digestibility as well as growth performance.     

The growth and apparent digestibility of white shrimp,Litopenaeus vannamei,are increased with the probiotic,Bacillus subtilis

The aims of this study were to evaluate the probiotic efficiency of Bacillus subtilis E20 (10⁹ colony‐forming units kg^?1) on the growth and apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), amino acids (AAs), and crude lipids (CLs) of the white shrimp, Litopenaeus vannamei. A control diet without probiotic supplementation was used. Shrimp exhibited significant increases in growth performance and feed utilization after being fed the test diet for 56 days. Shrimp were then used to evaluate the apparent nutrient digestibility using 0.1% Cr₂O₃ in the diet as an indicator. During the trial, faeces was collected from triplicate groups of shrimp twice daily. ADCs of CP and DM in the test diet significantly increased compared to those of the control diet. Although the ADCs of CLs did not significantly differ between the control and probiotic group, the ADC of CLs was higher in the probiotic group than in the control group. In addition, ADCs of most AAs in the test diet were significantly higher compared to those of the control diet. These results suggest that shrimp in the test group had significantly better growth performance, which was due to increases in nutrient digestibility and absorption.