Genetic parameters for spawning and growth traits in the Pacific white shrimp (Penaeus (Litopenaeus) vannamei)

The aim of this study was to estimate genetic parameters for spawning traits and growth traits in a breeding line of Pacific white shrimp, Penaeus (Litopenaeus) vannamei, selected for growth and survival. Traits studied were number of eggs (NE) and number of nauplii (NN) and female body weight at insemination (FWI) and body weight at 130 days of age (BW130). Genetic parameters were estimated using a multivariate animal model. Heritability for NE and NN were estimated as 0.13 ± 0.04 and 0.03 ± 0.04 respectively. The contribution to NN total variation due to ‘factors associated with male’ effect was estimated as 0.47 ± 0.07. In the cases of FWI and BW130, heritability was estimated as 0.44 ± 0.08 and 0.19 ± 0.03 respectively. Genetic correlation between FWI and NE was estimated as 0.49 ± 0.15, between FWI and NN as 0.54 ± 0.39 and between NE and NN as 0.27 ± 0.41, whereas the genetic correlations of FWI, NE and NN with BW130 were 0.30 ± 0.13, ?0.21 ± 0.19 and ?0.25 ± 0.38 respectively. Although it is important to perform more studies on this issue, our results found no evidence of a genetic antagonistic effect between female reproductive traits and body weight at harvesting (130 days of age) in P. vannamei.     

Yellow- and brown-seeded canola (Brassica napus), camelina (Camelina sativa) and Ethiopian mustard (Brassica carinata) in practical diets for rainbow trout fingerlings

Rainbow trout (initial body weight 2.5 ± 0.3 g; 30 fish/tank; 4 tanks/treatment) were offered either the control diet or one of four test diets. The test diets contained brown seed coat canola (BSC; Brassica napus), yellow seed coat canola (YSC; Brassica rapa), Brassica carinata (Ethiopian mustard; EM), or Camelina sativa (CAM), which were added to their respective diets at a 15% dietary inclusion level. Final weight of fish fed the control (101.0 g) was higher than that of fish fed BSC (80.7 g) and CAM (85.3 g) (P < 0.05). Fish fed the control also gained more weight (98.4g) than fish fed BSC (78.2 g) and CAM (83.0 g) (P < 0.05). Fish fed YSC and EM at a 15% dietary inclusion level had a final body weight and gain that was more similar to the control than fish fed BSC and CAM. Considering the fact that there was no significant difference among treatments for SGR and FCR for the entirety of the trial, all four oilseeds have potential for use in rainbow trout feeds.     

Phosphorus utilization in juvenile Clarias gariepinus fed phytase-supplemented diets based on soya bean (oil-extracted) and full-fat (roasted): A comparison

The effect of microbial phytase on phosphorus utilization in juvenile Clarias gariepinus (initial fish body weight 11.55 ± 0.2 g) was tested on two different diets based on oil-extracted soya bean (Experiment 1) and roasted soya bean meal (Experiment 2) using a 5 × 5 experimental design for 84 days. The basal isonitrogenous and isocaloric diets for oil-extracted and roasted soya bean were formulated to replace fish meal at 25% (S1E), 50% (S2E), 75% (S3E), 100% (S4E); and 25% (S1), 50% (S2), 75% (S3), 100% (S4), respectively. Each treatment was replicated four times. Microbial phytase was supplemented in each replicate at 250 FTU/g (P1), 500 FTU/g (P2), 750 FTU/g (P3), and 1,000 FTU/g (P4). Basal controls, which included a fish meal-based diet (S0), were not supplemented with phytase (P0). The result in Experiment 1 showed that there was a significant increase in whole-body protein and reduction in fat with phytase compared to a diet without phytase (P < 0.05). Serum total protein declined significantly with phytase supplementation (P < 0.05). Serum phosphorus and glucose were higher with phytase supplementation compared to control (P < 0.05). Bone minerals declined significantly with increasing level of soya bean compared to fish meal diet (P < 0.05). In Experiment 2, serum phosphorus was improved with phytase compared to control with no phytase (P > 0.05). A significant reduction in whole-body protein and increase in fat was observed for fish fed phytase diets compared to diets with no phytase, regardless of soya bean level (P < 0.05); however, ash content was improved with phytase (250 FTU/g) compared to control (P < 0.05). Phytase supplementation improved bone phosphorus (250 FTU/g), calcium (250 FTU/g), magnesium (250–500 FTU/g), and zinc (250–1,000 FTU/g) compared to control (P < 0.05). In conclusion, the research has demonstrated that improved bone phosphorus (P) and growth could be achieved with the supplementation of dietary phytase.     

Growth and fry production of Nile tilapia, Oreochromis niloticus (L.), on different feeding schedules

The effect of scheduled use of high‐protein and low‐protein diets on body weight and fry production of Nile tilapia, Oreochromis niloticus (L.), was determined. A preliminary feeding trial was first conducted on fingerlings. These were fed a high‐protein diet (H, 25% protein) or a low‐protein diet (L, 18% protein) daily, or diet H for 1–3 days followed by diet L for 1–4 days. Final body weight was significantly higher (P < 0.05) in fish fed diet H daily and in fish fed diet H for 2–3 days followed by diet L for 1 day (2H?1L and 3H?1L). Fingerlings on 1H?1L and 3H?2L had slightly lower growth. Based on the response of the fingerlings, five feeding schedules were tested with the broodstock. A high‐protein diet (HP, 40%) and a low‐protein diet (LP, 25%; same as H for fingerlings) were used. Feeding schedules significantly influenced body weight of female but not the male fish. Fry production was not significantly affected by the feeding schedule for broodstock. When growth, fry production and saving in feed cost were all considered, the broodstock on 1HP?1LP and 3HP?2LP feeding schedules both gave the highest overall performance. These findings give fish farmers an option in the management of feeding of tilapia broodstock.     

Effect of salinity on occurrence of notochord deformities in Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis> larvae

One of the difficulties to rear Anguilla japonica larvae is the frequent occurrence of notochord deformities. We tested the effect of salinity on the occurrence of the deformities, because we have been using 50 % diluted seawater (50 % SW) for glass eel production, on the basis of the fact that intermediate salinity saves energy due to lower cost for osmoregulation and contributes higher survival and growth rates. We reared 6-day-old larvae in 50 and 100 % SW for 85 days and observed their morphology. The occurrence rate of deformed larvae, including kyphosis and scoliosis, was significantly higher in 50 % SW (35.8 %) than in 100 % SW (25.4 %), while survival rate was significantly higher in 50 % SW (69.8 %) than in 100 % SW (32.3 %) and growth in 50 % SW (mean body depth: 7.9 ± 5.3 mm) was better than in 100 % SW (6.8 ± 4.6 mm). We speculate that the most of severely deformed larvae could not survive in the tougher condition of 100 % SW, showing the lower occurrence of deformed larvae. Eventually, the yield of normal larvae after 85 days rearing was 1.9-fold higher in 50 % SW than in 100 % SW, implying that the advantage of 50 % SW for rearing eel larvae outweighs the risk of deformities.     

The effect of cyclooxygenase (COX) inhibitors on Japanese medaka (Oryzias latipes) reproduction parameters fed with high level of arachidonic acid (20:4 n-6)

Broodstock of mature Japanese medaka (Oryzias latipes Temminck and Schlegel, 1846) (mean weight 0.45 ± 0.03 g; age 6 months) were maintained in glass aquaria (8 males and 8 females in each aquarium). The fish were fed commercial feed (group C) or this feed was supplemented with arachidonic acid ARA (2 % of total fatty acids in feed; group A) and one of the COX inhibitors: resveratrol (group AR) or NS-398 (group ANS) with amount 20 mg kg^?1 BW day^?1 of one of the COX inhibitors. The effect of 2 weeks of feeding experimental diets on reproductive parameters (fecundity, embryo and larval survival, hatching rate, and larvae body weight) was analyzed. Larvae (obtained from experimental dietary treatments) were reared for 2 weeks. The percent of spawning female and fecundity was similar in dietary treatments. COX inhibitors in broodstock diet caused a decrease in embryo survival rate. Eggs of medaka from group ANS and AR revealed the lowest hatchability rate. In contrast, group A revealed a higher hatchability rate at the same time. Larval body weight after hatching was significantly the highest in this group. At the end of the experiment, larvae body weight ranged from 1.62 ± 0.43 mg in group AN to 2.89 ± 0.74 mg in group A. These results show that the COX inhibitors decreased gamete and larval quality regardless of high levels of ARA in broodstock diet.     

Dietary supplementation of L-tryptophan: Effect on growth and survival of Pabda,Ompok bimaculatus (Bloch) fry

ABSTRACT

A 30-day experiment was conducted to assess the effect of tryptophan-supplemented diets on growth and survival of Pabda, Ompok bimaculatus fry. Fifty pabda fry (0.114 ± 0.02 g; 2.45 ± 0.13 cm) were stocked into each aerated aquarium following a completely randomized design consisting of four treatments with triplicate each. Four iso-proteinious purified diets were prepared with different levels of tryptophan—0%, 1%, 2%, and 3%—of the dry diet and were designated as Control, TRP1, TRP2, and TRP3 respectively. Fishes were fed with the experimental diet ad libitum four times a day. The results showed that fish fed with tryptophan-supplemented diets exhibited significantly (P < 0.05) lower cannibalism and higher survival than the control diet. Further, the tryptophan-supplemented groups showed a significantly lower coefficient of variation (%) and size heterogeneity (P < 0.05). However, the growth as measured by body weight gain, length increment, and specific growth rate of fry in tryptophan-supplemented groups was significantly lower than the control group (P < 0.05). Moreover, maximum survival (52.67 ± 1.76%) and minimum cannibalism (21.33 ± 5.70%) coupled with higher growth and performance index (0.38 ± 0.01) were recorded in the 2% tryptophan-supplemented group compared to other tryptophan-fed groups. Overall interpretation from the present study concludes that the dietary supplementation of 2% tryptophan is recommended for better survival of pabda fish, although growth was compromised.     

Effect of exposure to low salinity water on plasma ion regulation and survival rates in artificially wounded devil stinger <Emphasis Type="Italic">Inimicus japonicus</Emphasis>

We investigated the effect of exposure to low salinity water on plasma ion regulation and survival rates in artificially wounded devil stinger Inimicus japonicus. All fishes survived in 33% seawater (SW), while survival rate in 100% SW was 5.1% at 24 h. In 100% SW, plasma Na⁺, K⁺, Mg²⁺, and Ca²⁺ concentrations significantly increased to 238?±?49.9, 9.6?±?2.4, 15.1?±?3.5 and 5.0?±?0.7 mmol/l at 6 h, respectively; the gill Na⁺/K⁺–ATPase (NKA) activity was almost stable, although only one fish survived to 24 h. In 33% SW, plasma Na⁺ and K⁺ concentrations remained at the same level, and plasma Mg²⁺ and Ca²⁺ concentrations gradually increased to 16.2?±?0.7 and 4.5?±?0.2 mmol/l until 24 h, respectively. The NKA activity significantly increased to 5.1?±?1.1 µmol ADP/mg protein per h at 6 h. A positive correlation was observed between the wound surface area against body weight and the plasma ion concentrations, although no difference was observed in the restoration rate of the wounded area between 100 and 33% SW. These results indicate that exposure of wounded fish to low salinity water improves survivability by favoring plasma ion regulation without influencing the restoration rate.     

Dietary Effects on Sperm Quality of Litopenaeus vannamei Broodstock

A 56‐d feeding trial was conducted to investigate the effect of diet on sperm quality of Pacific white shrimp Litopenaeus vannamei broodstock. Dietary treatments consisted of a combination of 75% dry maturation diet and 25% fresh‐frozen squid (dry‐weight basis). Supplemental nutrients of the maturation diet were selectively deleted and replaced with wheat starch to produce the following treatments: 1) 75% basal maturation diet plus 25% squid (control); 2) 75% maturation diet without supplemental vitamins plus 25% squid; 3) 75% maturation diet without supplemental cholesterol and phospholipids plus 25% squid; 4) 75% maturation diet without supplemental astaxanthin plus 25% squid; and 5) a fresh diet composed of 60% squid and 40% Maine bloodworms. Shrimp fed the control diet and the diet without supplemental astaxanthin had significantly higher mean (± SEM) change in sperm count (4.6 ± 3.2 million sperm cells and 2.9 ± 2.5 million sperm cells, respectively), with respect to baseline (8.7 ± 1.0, 6.4 ± 1.0, 9.0 ± 1.3, 6.6 ± 0.7, and 6.0 ± 0.8 million sperm cells for treatments 1, 2, 3, 4, and 5, respectively), than shrimp fed the diet without supplemental vitamins (‐1.7 ± 2.6 million sperm cells), but not significantly higher than those of shrimp receiving the diets without supplemental cholesterol‐phospholipids (1.2 ± 2.5 million sperm cells) and the fresh diet (1.3 ± 1.6 million sperm cells). Dietary deficiencies also were reflected in weight gain of shrimp fed the diet without supplemental vitamins (‐2.0 g) and the fresh diet (‐0.8 g). which were significantly lower than weight gain of shrimp fed the control diet (1.1 g) and the diet without supplemental cholesterol‐phospholipids (0.8 g). No significant differences were detected among treatments for percentage of abnormal sperm and survival data. Results demonstrated a significant effect of diet on reproductive quality of male L. vannamei and indicated that the typical combination of fresh‐food organisms used is not nutritionally optimal for male broodstock.     

Spermatophore cryopreservation and artificial insemination of black tiger shrimp, Penaeus monodon (Fabricius)

To develop an appropriate cryopreservation protocol for spermatophores of black tiger shrimp, Penaeus monodon, three cryoprotectants (dimethyl sulphoxide (DMSO), methanol (MeOH) and ethylene glycol (EG)) at two concentrations (5% and 10%) were examined. Artificial implantation of spermatophores was also carried out to assess the fertilizing ability of fresh and post‐thaw spermatophores. Spermatophores were collected during consecutive regenerations (15‐day intervals) and assessed for qualitative and quantitative changes and also for fertilizing ability by implantation. The mean fertilization rate for artificial insemination using post‐thaw spermatophore was 79.9±3.7%, lower than the fertilization rates observed for artificial implantation using fresh spermatophore and natural mating. Mean hatch rates for fresh spermatophore, frozen‐thawed spermatophore and natural mating were 88.8±0.6%, 87.8±0.4% and 88.3±0.5%, respectively; and there was no difference among the three groups. The mean fertilization rate of spermatophores collected during the first stripping was higher (90.6±0.6) than during the second stripping (85.7±2.6), but the mean hatch rate was not different between the two strippings. The highest mean sperm viability (79.7±0.4%) was obtained from DMSO (5%), with no survival observed in the 10% MeOH treatment. Spermatophore weight, total sperm count and percentage of abnormal sperm were not different between spermatophores collected at the first and second stripping. This is the first study to report high fertilization and hatch rates from cryopreserved spermatophore using artificial implantation of spermatophore before spawning.     

不同规格中华绒螯蟹亲本子一代在扣蟹阶段养殖性能的比较研究

为探究中华绒螯蟹(Eriocheir sinensis)亲本规格对其子代在扣蟹阶段养殖性能的影响,本试验在相同的养殖环境下将4种规格河蟹亲本(规格I:雌90~110 g、雄140~160 g;规格Ⅱ:雌115~135 g、雄160~180 g;规格Ⅲ:雌140~160 g、雄220~240 g;规格Ⅳ:雌190~210 g、雄290~310 g)所产的大眼幼体养殖至扣蟹,并比较各组扣蟹的体质量、增重率、特定生长率、成活率及最终产量差异。试验结果显示:(1)不同规格的河蟹亲本,其子一代在大眼幼体至豆蟹阶段的平均体质量、成活率以及增重倍数均无明显差异(P>0.05);(2)在豆蟹至扣蟹养殖阶段,各组幼蟹的生长速度差异大体上与其亲本规格的差异相一致,其中Ⅰ组幼蟹在8—10月期间的平均体质量均显著低于Ⅳ组(P<0.05);(3)养殖效果方面,各组扣蟹平均规格和最终产量均随着亲本规格的提高而提高,其中Ⅳ组扣蟹的最终平均体质量显著高于Ⅰ组扣蟹(P<0.05);(4)就规格分布而言,Ⅳ组扣蟹2.00~3.99 g规格的比例显著低于另外3组,而≥6.00 g规格的比例显著高于另外3组(P<0.05)。结果表明,中华绒螯蟹亲本规格对其后代的养殖性能存在影响,大规格河蟹亲本子一代在扣蟹生产阶段生长速度快、养殖效果好,因此建议在生产上选择大规格亲本的后代用于扣蟹养殖。     

Preliminary evaluation of purified lignin and hemicellulose as prebiotics candidates for Atlantic Salmon,Salmo salar L.

A study was conducted to investigate the potential of purified lignin and hemicellulose as prebiotics in diets for Atlantic salmon, Salmo salar L., postsmolt in seawater (30 ppt) at 14.9 ± 1.2°C. Triplicate groups of fish (initial individual body mass of 101.6 ± 1.2 g) were fed either the fishmeal-dense (32% of fishmeal) control diet (A) or one of the nine diets (15% fishmeal) supplemented with lignin:hemicellulose ratios (% diet:% diet) of 0.05:0 (B), 0.25:0 (C), 0.50:0 (D), 1.00:0 (E), 0:0.05 (F), 0:0.25 (G), 0:0.50 (H), 0.05:0.25 (I), and 0.25:0.50 (J) for 12 weeks in a complete randomized experimental design. At the end of the experiment, the thermal-unit growth coefficient (TGC) was significantly lower in salmon fed diets with 0.50% and 1.00% purified lignin than those fed the control diet, while there was no significant difference between the other treatments and the control diet (P < 0.05). The feed efficiency (FE) was significantly lower in salmon fed diets with 0.50% and 1.00% purified lignin and 0.05% hemicellulose than those fed the control diet, while there was no significant difference between the other treatments and the control diet (P < 0.05). The hepatosomatic index (HSI), intestinal villus length, and apparent digestibility coefficient (ADC) of nutrients in diets were similar (P > 0.05) among all the diets. This study demonstrated that inclusions of up to 0.25% of dietary purified lignin alone, and 0.25%–0.50% of dietary hemicellulose alone or in combination with dietary lignin can be considered as candidate prebiotics in Atlantic salmon nutrition.     

凡纳滨对虾(Litopenaeus vannamei)选育群体与杂交群体遗传多样性差异及其在低温条件下生长性能的比较

选取连续3年选育的凡纳滨对虾(Litopenaeus vannamei)群体作为选育群体(SP),选育群体与引进的凡纳滨对虾群体的杂交F1代群体(HP),探究了这2个群体在低温条件下的生长性能及遗传多样性的差异.结果显示,在生长性能方面,HP群体与SP群体的平均体重分别为(13.18±3.65)g和(12.20±3.14)g,变异系数(CV)分别为27.69％和25.74％.HP群体的体重和其他可测量性状的平均值均大于SP群体.单因素方差分析(One-way ANOVA)表明,2个群体体重(BW)和第3腹节宽(TASW)存在极显著差异(P＜0.01).HP群体的特定增长率(SGR)和绝对增重率(AGR)分别为(5.09±0.61) ％/d和(0.26±0.60) g/d,SP群体的SGR和AGR分别为(4.94±0.57) ％/d和(0.24±0.63) g/d,HP群体的SGR和AGR均极显著高于SP群体(P＜0.01),表明HP群体相对于SP群体有着明显的生长优势.在遗传多样性方面,HP群体的平均等位基因数(Na=7.9)略高于SP群体(Na=7.6).HP群体和SP群体的平均多态信息含量(PIC)分别为0.63和0.62,均为高度多态.2个群体的平均观测杂合度(Ho)分别为0.492(HP群体)和0.483(SP群体),平均期望杂合度(He)分别为0.675(HP群体)和0.663(SP群体),HP群体的He和Ho均略高于SP群体,表明HP群体相比SP群体有着更加丰富的遗传多样性.遗传分化分析表明,2个群体间遗传分化指数(Fst)为0.1556,表明群体间遗传分化水平显著.     

Effects of ammonia on growth and molting of Litopenaeus vannamei postlarvae reared under two salinity levels

ABSTRACT

Litopenaeus vannamei postlarvae were exposed to 0, 6, 13, and 19 mg/L total ammonia nitrogen (TAN) treatments. After 45 days, shrimp weight and length were lowest under TAN concentrations of 13 and 19 mg/L (P ≤ 0.05). Maximum weight gain was observed in control and 6 mg/L treatments. Mortality was highest (80.55 ± 4.80%) under 19 mg/L reared in 35 ppt salinity. Average intermolt periods of PLs exposed to 0, 6, 13, and 19 mg/L TAN were 11.5 ± 0.7, 10.8 ± 1.3, 9.4 ± 1.0, and 8.7 ± 0.6 days under 35 ppt and 11.1 ± 0.5, 10.7 ± 0.6, 10.1 ± 0.5, and 9.5 ± 0.2 days under 45 ppt salinity. Although TAN increased postlarvae molting frequency, its negative effects on the shrimp growth and survival of PLs was directly linked to its concentration and exposure duration. Higher salinity reduces the effects of ammonia and increases the survival.     

Dietary biotin requirement of fingerling Channa punctatus (Bloch)

ABSTRACT

Dietary biotin requirement of fingerling Channa punctatus (4.52 ± 0.46 g) was estimated by conducting a 16-week growth trial. Fish were fed casein gelatin-based purified diets (450 g/kg crude protein, 18.39 kJ/g gross energy) with seven levels of dietary biotin (0, 0.04, 0.09, 0.47, 1.02, 1.43, and 1.96 mg/kg diet) to triplicate groups near to satiation. Significantly higher absolute weight gain (P = 0.0018), specific growth rate (P = 0.0027), protein gain (P = 0.0016), protein deposition (P = 0.0038), and lower feed conversion ratio (P = 0.0003) were shown in fish fed diet containing 0.47 mg/kg biotin, whereas liver biotin concentration showed a significant improvement (P = 0.0021) with increasing levels of dietary biotin up to 1.02 mg/kg. Broken-line analysis of absolute weight gain, protein gain, and liver biotin concentrations indicated that fingerling C. punctatus require biotin at 0.46, 0.44, and 0.97 mg/kg diet. Based on protein gain, optimum pyridoxine requirement for fingerling C. punctatus is recommended at 0.44 mg/kg diet.     

不同地理群体菲律宾蛤仔表型性状的相关性与通径分析

随机选取繁殖时期的南方群体北方养殖菲律宾蛤仔(SN)、北方土著品种(NN)和南方群体南方养殖蛤仔(SS),测量其壳长(SL)、壳高(SH)、壳宽(SW)、活体质量(mL)、软体质量(mM)和烘干后软体部干质量(mF),采用相关与通径分析方法分析不同地理群体的菲律宾蛤仔表型性状对软体质量的作用效果,为菲律宾蛤仔的选择育种提供理论依据和测度指标。试验结果表明,不同地理群体菲律宾蛤仔的形态学指标无显著差异(P>0.05);不同地理群体各数量性状之间的相关关系均达到极显著水平(P<0.01);决定系数分析表明,不同地理群体菲律宾蛤仔影响软体质量的主要表型性状并不相同,南方群体北方养殖蛤仔群体的壳宽直接作用最大,壳宽通过壳高的间接作用是次要因素;北方土著品种群体壳长是主要因素,壳长通过壳高的间接作用是次要因素;南方群体南方养殖蛤仔群体壳高的直接作用是主要因素,壳长通过壳高的间接作用是次要因素。对通径系数检验不显著的自变量进行删除,利用逐步回归的方法,建立不同地理群体菲律宾蛤仔软体质量的最优回归方程:SN群体,mM1=-4.276+0.211SH+0.116SW;NN群体,mM2=-2.806+0.088SL+0.087SH;SS群体,mM3=-3.101+0.290SH。回归方程分析表明回归关系均达到极显著水平(P<0.01)。     

Nutritive value of copra cake meal fermented with Rhizopus spp. and its use as a protein source in practical diets for rabbitfish (Siganus javus)

The aims of this study were to evaluate fermentation of copra cake meal with Rhizopus spp. to enhance its nutritive value and to determine the optimum supplementation levels of the fermented meal on the growth performance and feed utilization of the rabbitfish, Siganus javus. Copra cake meal was fermented with Rhizopus spp. and included in four iso-nitrogenous diets at 0, 150, 300, and 450 g/kg. Rabbitfish (88.3 ± 1.7 g initial body mass) were fed with the test diets at 2.5%–3.0% of biomass/d for 12 weeks. After fermentation, the crude protein content of copra cake increased significantly (P < 0.05) from 218 ± 16 g/kg (mean ± SD) to 293 ± 4 g/kg, while lipid decreased from around 127 ± 4 g/kg to 60 ± 11 g/kg. Total amino acid content of copra cake meal increased after fermentation from 176 ± 12 g/kg to 207 ± 18 g/kg. Based on the third-order (cubic) polynomial regression, inclusion of fermented copra cake meal (FCCM) in test diets had significant (P < 0.05) effects on all parameters observed except for feed intake and survival rate. Fish fed the FCCM0 and FCCM150 diets had a similar protein retention (PR) but significantly differed (P < 0.05) from the diets containing higher FCCM inclusion rates. The breakpoint of two regressions fitted to specific growth rate (SGR) determined that the optimum inclusion rate is 137 g FCCM /kg diet, and at this level, protein from soybean meal can be included at approximately 315 g/kg diet for grow-out of rabbitfish, S. javus, in floating net cages.     

Effects of total replacement of dietary fish oil on growth performance and fatty acid compositions of hybrid tilapia (Oreochromis niloticus × O. aureus)

The aim of this study is to evaluate the effects of total replacement of fish oil (FO) with pork lard (PL), soybean oil (SO), or tea seed oil (TO) on growth and fatty acid compositions of hybrid tilapia (Oreochromis niloticus × O. aureus). Four diets were formulated to contain 4.5 % of each of the different lipid sources. Each diet was assigned to triplicate groups of 15 hybrid tilapia with the same initial body weight (4.6 ± 0.5 g). After a 10-week feeding, the FO, SO, and TO groups had similar final body weight. The mean hepatosomatic index in the FO group was significantly lower than the other groups (2.5 vs 2.9–3.0; P < 0.05). Whole-body lipid levels were highest in the TO group (5.2 ± 0.4 %) and lowest in the FO group (4.3 ± 0.5 %). Total n-3 polyunsaturated fatty acids (PUFA) concentrations were greater in the SO and FO groups (5.5 ± 0.1 and 7.1 ± 0.2, respectively) than in the PL and TO groups (1.7 ± 0.1 and 1.4 ± 0.1, respectively). The FO group had a 2- to 4-fold reduction in the n-6/n-3 PUFA ratio relative to the other groups. The concentrations of both docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were significantly (P < 0.05) higher in the FO group than in the other groups. Our data demonstrate that total replacement of dietary FO with SO or TO has little effects on growth of hybrid tilapia but reduces the contents of health-benefiting DHA and EPA in fish body.     

Dietary pyridoxine requirement of fingerling Channa punctatus (Bloch) based on growth performance,liver pyridoxine concentration,and carcass composition

Seven casein gelatin-based diets containing 450 g/kg CP and 18.39 kJ/g GE with different levels of pyridoxine (0, 2, 4, 6, 8, 10, and 12 mg/kg diet) were fed to fingerling Channa punctatus (4.66 ± 0.46 g) for 12 weeks to determine pyridoxine requirement. Highest absolute weight gain (AWG; 25.81 g/fish, P < 0.05), protein retention (PRE; 23.69%, P < 0.05), energy retention efficiencies (ERE; 69.63%, P < 0.05), and minimum feed conversion ratio (FCR; 1.48) were noted at 8 mg pyridoxine/kg diet. However, liver pyridoxine content achieved the positive correlation as the dietary pyridoxine increased up to 10mg/kg. On the basis of broken-line analysis of AWG, PRE, FCR, and liver pyridoxine data, pyridoxine requirement is recommended between 7.6 and 10.4 mg/kg of dry diet.