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1.
Four commercially available proteolytic enzymes active over a wide pH range were assessed as shrimp feed additives. Feeds were formulated to contain 1% of the test enzymes by weight. A feed of the same composition with no enzyme addition served as a control. In vitro feed protein digestibility of the feeds was determined using a modified pepsin digestibility method. In vitro protein digestibility results indicated that commercially available proteases added to a shrimp feed formulation and then hot pelleted/dried did retain enzyme activity. Feeds exhibited low weight losses through leaching (≤ 10.9%) and low or no losses of protein content (≤ 2.7%), indicating that the test feeds were available in their entirety to the shrimp. An 8-week feeding trial using the enzyme-supplemented feeds was conducted to evaluate shrimp growth. Mean shrimp survival was high for all treatments (> 90%). One-way analysis of variance did not detect significant differences (P > 0.05) among feeds in terms of survival, weight gain, specific growth rates and feed–weight gain ratios. Although in vitro digestibility indicated the presence of active enzymes in the feed, the feeding trial revealed that shrimp growth was not enhanced by the inclusion of proteases in these feeds. This study provides sufficient proof to emphasize the importance of in vivo investigations before enzyme-supplemented feeds are used with shrimp.  相似文献   

2.
This study was conducted to evaluate whether phospholipids have the potential to reduce the level of dietary fish oil inclusion in shrimp feeds in the presence and absence of phytoplankton. To do so, weight gain of juvenile Litopenaeus vannamei stocked at 80 shrimp m?2 fed different dietary levels of fish oil and soybean lecithin was determined. Six experimental 35% protein diets were formulated to contain 1%, 2% or 3% fish oil combined with either 1% or 4% soybean lecithin. Dietary effects were evaluated using a ‘clear‐water culture system’ without the presence of microalgae in 40‐L aquaria and a ‘green‐water culture system’ in 1.9‐MT tanks. After an 8‐week feeding period, shrimp cultured in both systems and fed diets containing 4% soybean lecithin had greater weight gain than those fed 1%. Thus, diets supplemented with phospholipids improved the efficiency of lipid utilization for growth: diets containing 1% fish oil in combination with 4% soybean lecithin can be used as a cost‐effective combination for commercial shrimp culture feeds. Weight gain in the green‐water system was 1.5–1.7 times greater than that for shrimp reared under clear‐water conditions, suggesting that phytoplankton contributes to shrimp growth through the continuous provision of nutrients.  相似文献   

3.
In adult sea urchins, formulated feeds can support both weight gain and gonad production; however, studies demonstrating the effects of formulated feeds on juvenile sea urchin growth are limited. In this study, juvenile sea urchins (test diameter: 3.20–7.33 mm, N = 12 per treatment) were reared individually in artificial seawater and fed with one of four experimental feeds: (1) mixed‐taxa algal biofilm (MTAB), (2) freeze‐dried MTAB, (3) a commercial, small‐mammal feed (Friskies® cat treats), or (4) a semipurified feed formulated for sea urchins. The MTAB and sea urchin feed supported weight gain and survival throughout the study; however, those individuals fed with the sea urchin feed exhibited a short lag period at the onset of feeding. This short lag period may be, in part, because of an initial lack of attraction of the urchins to the formulated feed. Furthermore, we hypothesize that gut physiology or gut flora must acclimatize to a new diet (all sea urchins were reared initially on the MTAB diet). The freeze‐dried MTAB and mammal feed did not support substantial weight gain. This study suggests that sea urchin juveniles as small as 3–4 mm can utilize formulated feeds for growth.  相似文献   

4.
Solvent-extracted cottonseed meal was used in shrimp Penaeus vannamei diets at levels of 0, 13.3, 26.5, 39.8, 53.0 and 66.3%, substituting on an equal nitrogen basis for 0, 20, 40, 60, 80 and 100% of animal protein mix (53% menhaden fish meal, 34% shrimp waste meal and 13% squid meal). The feeds were formulated to contain 32% crude protein and 3,100 kcal metabolizable energy/kg. Each diet was fed to juvenile shrimp to satiation four times daily for 8 wk. Shrimp fed the three lowest dietary levels of cottonseed meal (0, 13.3 and 26.5%) had similar weight gain, feed consumption and survival. The performance of shrimp was adversely affected when diets containing more than 26.5% cottonseed meal, or 1,100 ppm free gossypol, were fed. Shrimp fed the diet with 39.8% cottonseed meal or 1,600 ppm free gossypol had depressed weight gain, reduced feed intake and high mortality. The groups receiving the two highest dietary levels of cottonseed meal lost weight by the end of week 4 and all shrimp in these treatments died within 6 to 8 wk. These adverse effects were probably due to the toxicity of free gossypol. Shrimp appeared to accumulate gossypol in the body as evidenced by light yellow-green coloration in shrimp fed diets containing cottonseed meal.  相似文献   

5.
Two feeding trials were conducted to determine the optimal dietary carbohydrate to lipid (CHO:L) ratio for juvenile and grower rockfish. Triplicate groups of juvenile (initial mean weight 3.6 g) and duplicate groups of grower (initial mean weight 166 g) were fed the five isonitrogenous (51% CP) and isoenergetic (4.0 kcal g?1) diets with the different CHO:L ratios (0.4–5.6 g:g) for 8 weeks respectively. The survival of juvenile and grower was above 93% and was not affected by the dietary CHO:L ratios. Weight gain of juvenile fed the diets with CHO:L ratios of 0.8 and 1.6 was significantly higher than that of the fish fed diets with CHO:L ratios of 2.8 and 5.6 (P<0.05). The feed efficiency and protein efficiency ratio of juvenile fed the diet with CHO:L ratio of 5.6 were the lowest among all groups (P<0.05). The daily feed intake of juvenile fed the diet with a CHO:L ratio of 5.6 was significantly higher than that of the other groups (P<0.05). The condition factors of juvenile fed the diets with CHO:L ratios of 0.8 and 1.6 were significantly higher than that of 5.6 (P<0.05). The crude lipid content of whole body, liver and viscera of juvenile decreased as the dietary CHO:L ratio increased, and the opposite was found for the moisture content. Weight gain, feed efficiency, daily feed intake, protein efficiency ratio and condition factor of grower were not affected by the dietary CHO:L ratio. Hepatosomatic and viscerasomatic indexes of grower were significantly influenced by dietary CHO:L ratio (P<0.05). Significant differences were observed in the lipid content of whole body and viscera of grower. Dietary CHO:L ratios significantly affected the major fatty acid composition of whole body in both juvenile and grower. The contents of 18:2n‐6 and 18:3n‐3 linearly decreased as the dietary CHO:L ratio increased, whereas the 20:4n‐6, 20:5n‐3 and 22:6n‐3 contents increased. Based on growth, feed efficiency and body composition, the optimal dietary CHO:L ratio was 1.6 for juvenile rockfish fed isonitrogenous (51% CP) and isoenergetic (4.0 kcal g?1) diets, and starch could partially replace lipids in the diets with CHO:L ratios ranging from 0.4 to 5.6 for grower.  相似文献   

6.
Three feeding studies were conducted to evaluate the effects of total replacement of fish meal (FM) with a combination of soybean meal (SBM) and brewer's grains with yeast (BGY) in diets for two separate strains of juvenile Australian red claw crayfish. In Experiment 1, three practical diets were formulated to be isonitrogenous (40% protein) and isocaloric (4.0 kcal available energy/g diet) and contained either 25%, 10%, or 0% fish meal. Variable percentages of SBM (35%, 46.8%, and 79.8%, respectively) and BGY-35 (0%, 30%, and 5%, respectively) replaced the fish meal. In Experiments 2 and 3, four practical diets were formulated to be isonitrogenous (40% protein) and isocaloric (4 kcal available energy/g diet) containing 24% or 0% fish meal. Diet 1 contained 24% fish meal, 23% SBM, and 0% BGY-35. A variable percentage of SBM (56.75%, 47.75%, and 40.75%, respectively) and BGY-35 (10%, 20%, and 30%, respectively) replaced the fish meal in the remaining three diets.

In Experiment 1, after 8 weeks, juvenile red claw fed all three diets had no significant difference (P>0.05) in final weight, percentage weight gain, or survival, which averaged 7.90 g, 3848%, and 83%, respectively. In Experiment 2, after 8 weeks, juveniles fed all four diets had no significant difference in final weight, percentage weight gain, or specific growth rate which averaged 11.46 g, 977%, and 3.08%/day, respectively. Percentage survival was not significantly different among treatments and averaged 79%. In Experiment 3, after 8 weeks, juvenile red claw fed all four diets had no significant difference in final weight, percentage weight gain, or specific growth rate which averaged 16.22 g, 457%, and 2.34%/day, respectively. Percentage survival was not significantly different among treatments and averaged 98%.

These results indicate that fish meal and shrimp meal can be totally replaced with soybean meal and BGY in diets for juvenile red claw crayfish. This may allow for less expensive diets by red claw producers, which may increase profitability.  相似文献   


7.
This study was conducted in 36 indoor 40‐L fibreglass aquaria to determine the weight gain and survival of Litopenaeus vannamei fed different dietary levels of fish (FM) and squid meal (SM) and to evaluate the potential of phytoplankton to reduce FM and SM levels in shrimp feeds. Six experimental isonitrogenous (35% protein) and isocaloric (17.5 kJ g?1) diets were formulated to contain either 5%, 10% or 20% SM combined with either 6.5% or 12% FM. Dietary effects on growth and survival were compared in two systems: a ‘CLEAR water system’ (CWS) without the presence of microalgae and a ‘GREEN water system’ (GWS) with microalgae in the culture water. Shrimp cultured in the GWS had 28–57% greater weight gain than those cultured in the CWS, regardless of dietary treatment. However, survival was not different. Shrimp cultured in the CWS or the GWS, and fed diets containing combinations of FM and SM did not show differences in weight gain and feed conversion ratio. These results suggest that under the conditions existing during this research, 6.5% FM and 5% SM can be used as a cost‐effective combination in commercial feeds for shrimp production and that growth can be enhanced in the presence of primary productivity.  相似文献   

8.
The Australian red claw crayfish, Cherax quadricarinatus, has recently attracted attention as a potential candidate for aquaculture in the United States. This paper reports the first experimental yield trials of the red claw crayfish in the central United States. Two earthen ponds (0.30 and 0.31 ha) were stocked with juvenile red claw crayfish at either 3.5 or 7.0 crayfish/m2. Crayfish were fed a diet of pelletized shrimp ration supplemented with corn silage. When stocked at 3.5/m2, red claw crayfish grew from an average weight of 3.0 g to 27.0 g in 97 days; average survival was 79.6%; net yield was 653 kg/ha; and feed conversion was 1.4. When stocked at 7.0/m2 red claw crayfish grew from an average weight of 4.1 g to 19.7 g in 99 days; average survival was 70.0%; net yield was 678.9 kg/ha; and feed conversion was 1.8. During the yield trial, temperatures were optimal for growth (25 to 33°C) 60% of the time. These findings are sufficiently encouraging to warrant further trials in locations with a longer growing season, in order to evaluate more fully the potential of the red claw crayfish as a candidate for aquaculture in the United States.  相似文献   

9.
Culture of hybrid striped bass has been expanding in the United States and further growth has been predicted, however, several problem areas exist, including a lack of nutritional information. This series of studies offered reciprocal cross juvenile hybrids several of the commercially available feeds and several different types of purified experimental diets. Weight gain and feed efficiency of fish fed the commercially available feeds formulated to meet the general requirements of salmonids were better than fish fed feeds formulated to meet the nutritional requirements of catfish. Experimental diets containing casein as the primary protein source were unpalatable regardless of the level of fish oil added (6 or 12%) but were accepted if 10% menhaden fish meal was added. Addition of lower levels of fish meal resulted in decreasing degrees of acceptance. Thus, the minimum level of fish meal that elicited a feeding response appeared to be between 510% of the dry diet. A crystalline amino acid test diet was palatable, and weight gain of fish fed that diet was 65–91% of the weight gain recorded for fish fed the positive control diets. Addition of L-arginine, L-methionine or L-cystine to a purified diet containing casein did not result in dietary acceptance. Whole-body proximate composition offish revealed a general trend toward increased lipid levels with increasing levels of dietary lipid. All fish exhibited microvessicular hepatopathy, regardless of diet fed. Hepatocytes contained both glycogen and lipid in the cytoplasm.  相似文献   

10.
Two experiments were done to evaluate the effects of poultry meal (PM), meat meal (MM) or solvent-extracted soybean meal (SBM) inclusion on the performance of Australian snapper Pagrus auratus. In each experiment, test feeds were formulated with similar contents of digestible protein (DP) and digestible energy (DE) using previously determined digestibility coefficients for this species. In experiment 1, groups of snapper (initial weight 14 g) were fed 4 feeds containing 360, 480, 610 or 730 g kg−1 PM; 3 feeds containing 345, 320 or 500 g kg−1 MM; 3 feeds containing 420, 600 or 780 g kg−1 SBM. In experiment 2, groups of snapper (initial weight 87 g) were fed 3 extruded test feeds that contained combinations of PM, MM, SBM or blood meal (BM) which replaced all but 600, 250 or 160 g kg−1 of fishmeal in respective diet formulations. Both experiments included a proprietary extruded aquafeed (COM) to benchmark fish performance. In experiment 1, weight gain was highest in snapper fed feeds containing 360, 345 or 420 g kg−1 of PM, MM or SBM, respectively, and was similar (P > 0.05) to snapper fed the COM feed. Nonetheless, weight gain and protein retention efficiency tended to decrease as the amount of each test ingredient was increased. Relative feed intake was not affected by the inclusion level of PM, MM or BM, but declined significantly in snapper fed diets containing 600 or 780 g kg−1 SBM. Feeding behaviour indicated fish found these feeds unpalatable. In experiment 2, the harvest weight of snapper fed the 3 extruded test feeds was similar (P > 0.05), but lower than snapper fed the COM feed (i.e. 234 vs. 256 g). Feed conversion ratio (FCR) was best in snapper fed the COM feed (FCR = 1.53); however, the FCR of snapper fed feeds containing 160 (FCR = 1.66), 250 (FCR = 1.70) or 600 g kg−1 fishmeal (FCR = 1.60) was not different (P > 0.05). Australian snapper will readily accept feeds containing high levels of PM, MM or SBM and feeds containing these ingredients will support rapid weight and protein gain with little affect on whole body composition. In combination, these feed ingredients were able to replace all but 160 g kg−1 of fishmeal in an extruded test feed. As such, they serve as valuable alternatives to fishmeal and extend the manufacturing options available to aquafeed producers.  相似文献   

11.
Three independent studies were conducted in which supplemental food was provided to juvenile Orconectes virilis reared at varying densities. One study was conducted in fiberglass tanks (densities of either 13, 27 or 54 individuals/m2) and two were conducted in outdoor pools (densities of either 2.5, 5, 10, 20 or 30 individuals/m2). Crayfish were offered a variety of foods ranging from a formulated diet to agricultural forages. Weight gain of crayfish fed a formulated diet and reared at varying densities was similar in the study conducted in tanks, but survival was significantly lower at the two highest densities (27 and 54/m2). Weight gain, survival and yield decreased as density increased in the studies conducted in outdoor pools. The highest weight gain and survival were at a density of 2.5/m2. Wheat straw was used as the source of nutrients. Use of formulated diets did not result in rapid weight gain when crayfish were reared at higher densities.  相似文献   

12.
The effect of adding carotenoids from various sources to feed of juvenile freshwater crayfish Cherax quadricarinatus on pigmentation, growth and survival was examined under laboratory conditions. Juvenile crayfish were fed diets fortified with carotenoids at a level of 100 μg g−1 for a period of either 49 or 55 days. Carotenoid sources were: dried algal cells prepared from Dunaliella salina in which the main carotenoid is β-carotene; a synthetic carotenoid, astaxanthin (Carophyll Pink 8%, manufactured by Hoffman–La Roche) and alfalfa meal. Crayfish receiving feeds fortified with carotenoids exhibited better body colouration than those in the control group, which were fed a diet to which no carotenoids were added. Growth and survival of the crayfish were not affected by the addition of carotenoids to their diet.  相似文献   

13.
Culture of walleye Sfizostedion vitreum is one of the largest components of public sector aquaculture in the eastern U.S. and there is increasing interest in private sector culture. However, the nutritional requirements of walleye are unknown and experimental diets for use in quantifying nutritional requirements have not been identified. We formulated four experimental and four practical diets and fed those to triplicate groups of walleye with an initial weight of 13 g per fish. The experimental diets contained either casein (CAS), casein + gelatin (CG), casein + arginine (CA), or casein + gelatin + crystalline amino acids (CGAA) as sources of amino acids. The practical diets were formulated to mimic salmon grower (SG) and trout grower (TG) diets, a fish meal‐free diet for trout (TFMF), and a walleye grower (WG) diet. Fish were fed twice daily to satiation for 9 wk. Feed consumption, percent weight gain, specific growth rates, feed efficiency, protein efficiency ratio, and protein retention efficiency were not significantly different among fish fed CGAA, SG, and TG, but those values were significantly higher than in fish fed other diets. Weight gain of fish fed CGAA was approximately 80% of that in fish fed SG and 91% of that in fish fed TG. Protein retention efficiency of fish fed CGAA was approximately 69% and 81% of that observed for fish fed SG, and TG, respectively. In general, the carcasses of fish fed diets CGAA, SG and TG had significantly lower moisture and ash concentrations, and higher lipid levels than fish fed other diets. There were no significant differences in carcass protein concentration, muscle proximate composition, or liver lipid concentration among treatments. Livers from fish fed all diets were characterized by microvesicular degeneration and glycogen accumulation in hepatocytes. Results from the study indicate that CGAA can be used as a basal experimental diet in future nutritional research with juvenile walleye and confirms the benefits of trout and salmon grower diets. Fish meal‐free diets formulated around the requirements for rainbow trout were consumed at approximately 80% of the values in fish fed TG and SG, but weight gain was approximately 20% of that in fish fed TG and SG. It appears the nutritional requirements for walleye are different than those of rainbow trout.  相似文献   

14.
Provision of a suitable feed is paramount for the ongoing success of spiny lobster culture. This study compared and evaluated the performance of seven diets for first instar juvenile spiny lobster Panulirus argus [5–6 mm carapace length (CL)] based on growth rates, survival, and feed conversion ratio. Results demonstrated that a seafood-based juvenile formulation produced the fastest growth rate (3.49% weight gain day−1 and 0.90% CL increase day−1 over a 28-day period). These growth rates were also reflected by a low feed conversion rate (3.04) for this formulated feed. Similar results were also obtained for juveniles fed a frozen seafood diet, however, frozen brine shrimp, Artemia salina (both enriched and un-enriched), frozen enriched mysis shrimp, a dry pellet, and a meal-based juvenile formulation did not produce consistent growth rates. Survival rates ranged between 38% and 85% and demonstrate that juvenile lobsters have better likelihoods of survival in captive culture environments compared to the wild. Although further nutritional refinement is recommended, the results from this research have significant implication for the possible expansion of juvenile spiny lobster growout to a larger scale.  相似文献   

15.
The basal diet (C), with 0.20% medicinal herbs (M) and 0.30% Bacillus (BM1), with 0.10% medicinal herbs and 0.15% Bacillus (BM2), and with 0.30% Bacillus (B), was used to feed white shrimps (Litopenaeus vannamei) (1.91 ± 0.03 g) in order to assess survival, growth, body composition, and digestive enzyme activity. At the end of the feeding trial, survival ranged from 95.83 to 98.33% with no significant difference (P > 0.05) among all groups. Growth measured as weight gain was significantly (P < 0.05) higher in shrimp fed with BM2, BM1, and M compared to that of C. However, no significant differences were found among B, BM1, and M. In the case of specific growth rate, the shrimp fed with BM1 and BM2 exhibited significantly (P < 0.05) higher values than that of C. The contents of body moisture, crude protein, and ash seemed to be unaffected by the feed supplements, though lipid content was found to be significantly (P < 0.05) different among the treatments. The shrimp fed with BM1 and BM2 had the lowest and highest lipid contents, respectively. The digestive enzyme activity assessed using shrimp hepatopancreas revealed that the activities of amylase and protease in shrimp fed with BM2 were significantly (P < 0.05) higher than those of C at the end of the 2nd and 6th weeks. However, better performance of the specific amylase activity was shown by the shrimp fed with B at the end of the 8th week.  相似文献   

16.
Problems of limited number of dry feeds as supplement or replacement of live feeds have led to poor larval nutrition in many species of fish. Therefore, the suitability of co‐feeding 8‐day‐old African catfish (Clarias gariepinus) posthatch larvae using live feed (Artemia salina) and formulated dry diet containing freshwater atyid shrimp (Caridina nilotica) during weaning was investigated. The experiment ended after 21 days of culture and respective groups compared on the basis of growth performance, survival, feed utilization and nutrient utilization. Larvae co‐fed using 50%Artemia and 50% formulated dry diet resulted in significantly (P < 0.05) better growth performance, food gain ratio (FGR), protein efficiency ratio (PER) and productive protein values (PPV) than other treatments. The lowest growth performance occurred in larvae weaned using 100% formulated and commercial dry diets. Better survival of over 90% was obtained in larvae weaned using 50%Artemia and 50% dry diet, while abrupt weaning using 100% dry diets resulted in lower survival (<75%). These results support a recommendation of co‐feeding C. gariepinus larvae using a formulated dry diet containing C. nilotica and 50% live feed when weaning is performed after 8 days posthatching period.  相似文献   

17.
Two growth trials were conducted to evaluate and confirm the efficacy of a porcine meal (PM) with high protein content (>90%) as an alternative feed ingredient in commercial‐type feed formulation for Pacific white shrimp, Litopenaeus vannamei. Six experimental diets were formulated for the two growth trials. The first five diets contained increasing levels (0, 1, 2, 4, and 6%) of PM as a replacement for soybean meal in a plant‐based diet with low inclusion level (6%) of fish meal (FM). The last experimental diet was produced utilizing 4.2% PM to completely replace FM. In Trial 1, shrimp (1.5 g initial mean weight, 20 shrimp/tank, n = 4) were offered test diets for 6 wk in a semirecirculation system. At the end of Trial 1, shrimp fed with the diet containing 6% PM exhibited significantly enhanced weight gain (WG), feed conversion ratio (FCR), and survival compared to those fed with the diet devoid of FM. As survival was poor across all treatments and different densities could mask growth results the trial was repeated. In Trial 2, shrimp (0.85 g, 15 shrimp/tank, n = 4) were offered diets for 6 wk. Dietary supplementation of PM at 6% significantly improved WG, FCR, and apparent net protein retention in contrast with the treatment devoid of FM, confirming the same trends in Trial 1. No significant difference was detected in protein, lipid, moisture, and mineral profiles of whole‐body shrimp as well as survival across all the treatments. Results of this study indicate that PM is a good high protein source in shrimp feeds, which can be included up to 6% in the low FM‐based diet without compromising the growth of shrimp.  相似文献   

18.
Abstract. Four experimental diets were formulated to resemble practical rainbow trout, Salmo gairdneri Richardson, grower feeds based on medium and moderate lipid inclusions of 10 and 14% (standard energy levels) to relatively 'high energy' diets containing 18 and 22% lipid respectively. Each of these diets was isonitrogenous with a defined protein content of 42%. During a 10-week growth trial period, juvenile rainbow trout of initial mean weight of 10g were fed each ration to satiation. At the end of the study, there was a significant gain (P> 0.05) in the mean live weights of fish receiving the higher energy diets associated with improved feed conversion ratio (FCR) and net protein utilization (NPU). Although there was a declining trend in voluntary food intake relative to body weight with increasing dietary lipid content, this was insufficient to prevent greater deposition of body fat.
The results are discussed in relation to practical trout feeds in order to achieve a desired growth performance and acceptable body composition with intensive feeding regimes.  相似文献   

19.
Quadruplicate groups of juvenile red drum (initial mean weight 2.7 g; 20 fish per replicate) were fed experimental diets containing 35% crude protein and graded levels of lysine for eight weeks. Lysine concentration in the basal diet was 1.2% and was supplied by a combination of peanut meal and shrimp-head meal. The basal diet was supplemented with lysine-HCI to provide 1.6, 2.0, and 2.4% lysine. Each of these diets contained an essential amino acid (EAA) premix. Two additional diets were formulated to contain 1.2 and 2.4% lysine without the EAA premix. Weight gain and feed efficiency (FE) data indicated between 1.2 and 1.6% dietary lysine was adequate. However, serum lysine concentrations indicated 1.6–2.0% lysine was required. Fish fed 1.2 or 2.4% lysine, without the EAA premix, exhibited reduced weight gain and feed efficiency. Results indicated that red drum were able to utilize crystalline amino acids when incorporated into diets containing intact protein and, when lysine was adequate, the proteins were deficient in at least one other essential amino acid. It is recommended that a dietary lysine level of 5.7% of the dietary protein be used in formulating red drum diets.  相似文献   

20.
Abstract Growth rates of juvenile yabbies Cherax destructor fed a variety of natural and an artificial diet were compared under controlled conditions. Newly independent (stage 3) juveniles were reared individually in 1-L pomades for 35 d. The best survival and growth were obtained on live zooplankton, frozen zooplankton, shrimp meal pellets and tubifex worms (survival, 100%; mean weights, 608, 444, 380 and 338 mg, respectively). Intermediate growth and survival was exhibited by crayfish fed chironomid larvae, snails and mussels (survival, 80–100%; mean weight, 138–169 mg). Juveniles fed trout muscle, beef heart and yabby tail gave very poor growth and survival (survival, 50–80%; mean weight, 50–55 mg). The use of shrimp meal pellets as a reference diet for juvenile yabbies is discussed.  相似文献   

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