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1.
Abstract.– Juvenile channel catfish Ictalurus punctatus (initial weight: 6.8 g/fish) were fed four practical diets containing 0, 250, 500, and 750 units of microbial phytase/kg and a diet containing 1% feed grade dicalcium phosphate (but no microbial phytase) under laboratory conditions for 12 wk. Fish fed the diets containing 250 units of microbial phytase/kg and above consumed more feed, gained more weight, and had a lower feed conversion ratio (FCR) in comparison to fish fed the basal diet containing no microbial phytase. Fish fed the diet containing dicalcium phosphate had intermediate weight gain and feed conversion ratio as compared to fish fed the basal diet and diets containing microbial phytase. Bone ash and phosphorus concentrations were lower for fish fed the basal diet than for fish fed other diets. No differences in weight gain, feed consumption, FCR, bone ash and bone phosphorus were observed among fish fed the diets containing various levels of microbial phytase. Fish fed the diet containing dicalcium phosphate had a lower bone phosphorus concentration than fish fed diets containing microbial phytase. Fecal phosphorus concentrations were lower for fish fed the diets containing microbial phytase than for fish fed the basal diet and the diet containing dicalcium phosphate. Results from the present study indicated that addition of 250 units of microbial phytase/kg to practical diets can effectively improve bioavailability of phytate phosphorus to channel catfish and may possibly eliminate the use of an inorganic phosphorus supplement in channel catfish diets. However, these data must be verified in trials conducted in ponds, prior to recommending removal of supplemental phosphorus from channel catfish diets.  相似文献   

2.
Year-2 channel catfish (average weight 765 g) were fed a commercial-type, all-plant diet containing supplemental phosphorus (0.40%) from one of various sources, or fungal phytase (1,000 and 3,000 units), in 1-m3 circular raceways for 21 d at a temperature of 28–30 C. Subsequently, net absorption of phosphorus from the diets was determined by the chromic oxide indicator method in which feces were collected from the rectum. Net absorption of the supplemental phosphorus was corrected for the absorbed residual phosphorus in the basal diet. Net absorption coefficients for monosodium phosphate, monoammonium phosphate, finely ground defluorinated rock phosphate and monocalcium phosphate were 88.6, 85.4, 81.7, and 81.2%, respectively, and were not significantly different. Net absorption coefficient for dicalcium phosphate was significantly lower, 74.8%, but was significantly higher than those for coarsely ground defluorinated rock phosphate and tricalcium phosphate, which were 55.1 and 54.8%, respectively. These data are in general agreement with relative bioavailability values based on growth response for channel catfish determined in other research, and should be appropriate for determining available phosphorus allowances in commercial feeds and establishing phosphorus budgets in aquaculture feeding operations. The net absorption of phosphorus from the all-plant basal diet was 31.2% and increased significantly to 55.1 and 62.5% with the addition of 1,000 and 3,000 units of fungal phytase, respectively.  相似文献   

3.
The efficacy of using weight gain and bone mineralization to estimate phosphorus availability from feed ingredients for channel catfish was investigated at the conclusion of a 12-wk feeding trial. Juvenile channel catfish (initial weight = 7.8 g/fish) were fed one of seven test diets each containing phosphorus from a single source. All diets were isocaloric, isonitrogenous, and met all nutrient requirements of channel catfish except for phosphorus, which was assumed to be the factor limiting growth. Phosphorus was considered to be 90% available to fish fed the diet containing monosodium phosphate, but a relative value of 100 was assigned to this treatment for purposes of comparison. All other availability values were calculated relative to this value. Phosphorus availabilities (based on weight gain) for wheat middlings, cottonseed meal, and soybean meal were 38%, 43%, and 49%, respectively, which are in the range previously reported for channel catfish. Phosphorus availability values (based on weight gain) for dicalcium phosphate, menhaden fish meal, and meat and bone/blood meal were 82%, 75%, and 84%, respectively. These values were considerably higher (93–96%) than previously reported for catfish when based on bone ash or bone phosphorus. However, availability data based on weight gain for feedstuffs of animal origin generally agreed with phosphorus availability data reported for rainbow trout. Based on our data, mineral utilization by animals in general, and on known physiology of channel catfish, we suggest that weight gain may be a reliable indicator of phosphorus availability and that phosphorus availability values may be overestimated when base on bone mineralization.  相似文献   

4.
Plant protein sources were evaluated in 32% protein grow-out feeds for channel catfish (initial weight: 180 g/fish) stocked at high densities (24,700 fish/ha) in 0.04 ha earthen ponds. Each of the eight practical-type feeds was assigned for five replicate ponds. The fish were fed to satiation once daily for 170 d. Specifically, cottonseed meal and cottonseed meal plus supplemental lysine were evaluated as replacements for soybean meal. Soybean meal, a combination of soybean meal and cottonseed meal, or a combination of soybean meal and cottonseed meal plus supplemental lysine were evaluated as a substitute for animal protein sources. Based on weight pin, feed conversion ratio, body composition, percentage visceral fat, and dressed yield, the data indicated that cottonseed meal plus lysine can be used as a total substitute for soybean meal in catfish feeds. However, it is not recommended that more than 30% cottonseed meal be used in catfish feeds until additional data are available on the effects of gossypol on reproduction in catfish. Also, data indicated that plant proteins can be used as a total replacement for animal protein without detrimental effects. Reduced weight gain was observed in fish fed a feed that contained 68% of the established available lysine requirement. However, fish fed feeds estimated to contain only 76 or 82% of the available lysine requirement did not show reduced weight gain. This suggests that lysine may be more highly available from cottonseed meal than previously estimated, or that natural food organisms in the pond contributed nutrients including lysine, or that fish were able to consume enough of the marginally deficient feeds to meet their requirement for lysine. This study was conducted with large catfish fed a 32% protein feed to satiation once daily. If smaller fish, a lower protein fed, or a restricted feeding regimen had been used, the results may have been different.  相似文献   

5.
Two experiments were conducted in consecutive years to evaluate the responses of hybrid catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus, to “superdosing” of 6‐phytase added to existing commercial catfish feeds. In each experiment, two diets with or without a phytase superdose (2500 and 5000 phytase units/kg, respectively) were compared. In Experiment 1, fingerlings (mean weight: 59 g/fish) were stocked in 17 0.4‐ha earthen ponds at 17,290 fish/ha and were fed once daily to apparent satiation for 198 d. In Experiment 2, fingerlings (mean weight: 47 g/fish) were stocked in 10 0.4‐ha ponds at 24,710 fish/ha and were fed for 128 d. In both experiments, there were no significant differences in total feed fed, gross yield, final fish weight, survival, or Blood packed cell volume between fish fed diets with or without phytase. The diets also had no significant effects on pond water column total phosphorus or chlorophyll a concentrations, but soluble reactive phosphorus concentrations were significantly higher in ponds receiving the phytase diet in Experiment 2. Phytase superdosing of nutritionally complete feeds does not appear to have additional benefits beyond the standard phytase dose on production characteristics or packed cell volume of pond‐raised hybrid catfish and had no beneficial effects on water quality.  相似文献   

6.
Abstract

A feeding trial was conducted to evaluate low-quality diets for growout of pond-raised channel catfish. Five practical diets containing various levels of protein (10-28%) of varying quality (with or without animal protein and/or soybean meal), and with or without certain nutrient supplements (vitamin, minerals, lysine, or fat) were fed to channel catfish, Ictalurus punctatusstocked in 0.04-ha earthen ponds at a rate of 17,290 fish/ha. The diets were as follows: (1) 28% protein, nutritionally complete control; (2) 28% protein without supplemental vitamins, minerals, or fat; (3) 18% protein + supplemental lysine, vitamins, and minerals, but without animal protein; (4) 10% protein without animal protein, soybean meal, or supplemental vitamins and minerals; and (5) 10% protein + supplemental lysine, vitamins, and minerals, but without animal protein or soybean meal. Each diet was fed once daily to apparent satiation to fish in five replicate ponds for a single growing season. Fish fed diets containing 18% or 28% protein without supplements had similar diet consumption rates and weight gain as those fed the 28% control diet, but the fish fed the control diet converted diet more efficiently. Fish fed the 10% protein diet without supplements consumed less diet, converted diet less efficiently, and gained less weight than fish fed diets containing higher levels of protein. The addition of supplements to the 10% protein diet increased weight gain and processing yield as compared to fish fed the 10% protein diet without supplements. Body fattiness increased, fillet protein decreased, and carcass, fillet and nugget yields decreased as dietary protein decreased. The data show that pond-raised channel catfish can be grown effectively on a diet containing 18% protein that is of relatively low quality, but fattiness is increased and processing yield is decreased. However, because of the negative aspects of this diet, we would not recommend it for general use in commercial catfish culture. It could be used where fattiness and processing yield are not of consequence, such as recreational ponds. For that matter, the 10% diet without supplements could be used as well in these situations if maximum growth is not desired.  相似文献   

7.
A 10-wk feeding trial was conducted in the laboratory during which channel catfish Ictalurus punctatus (average initial weight: 6.5 g/fish) were fed five practical diets containing either 0, 500, 1,000, 2,000, or 4,000 units of microbial phytase/kg diet. Fish fed diets containing 500 or more units of microbial phytase/kg consumed more feed and gained more weight than fish fed the basal diet without supplemental phytase. Feed conversion ratios (FCR) did not differ among treatments except the FCR for fish fed 1,000 units of microbial phytase/kg diet was lower than that of fish fed no supplemental phytase. Fish survival was not different among treatments. Contrast analysis showed that weight gain, feed consumption, bone ash, and bone phosphorus were higher and feed conversion ratio was lower for fish fed diets supplemented with phytase as compared to fish fed no supplemental phytase. The concentration of fecal phosphorus decreased linearly as phytase supplementation increased. Results from this study demonstrate that microbial phytase is effective in improving bioavailability of phytate phosphorus to channel catfish, which may eventually lead to a reduction in the amount of supplemental phosphorus added to commercial channel catfish feeds.  相似文献   

8.
Effects of feeding 17-α-methyltestosterone (MT) to channel catfish ( Icralurus punctatus ) grown to harvestable size in earthen ponds were examined. Channel catfish fingerlings (mean weight, 14.4 g), stocked in 0.04 ha ponds (7,410 fish/ha) were fed diets containing MT at concentrations of 0, 2.5, and 10 mg/kg for 123 days. Weight gain by fish fed the control diet (0 MT) was higher ( P < 0.05) than that of fish fed the treated diets. Increasing the dietary concentration of MT reduced weight gain further ( P < 0.05). Both male and female fish fed MT had enlarged and thickened heads, and their skins were dark. Their dorsal and pectoral spines were short and the tips, which are normally very sharp, were soft and blunt. Weight of the rib bones per unit of length decreased ( P < 0.05) as MT was added to the diet. Breaking strength of the ribs (force required to break the bone at its midpoint) measured by an Instron shear press, was less ( P < 0.05) for fish fed MT than for control fish. The ratio of calcium to phosphorus in bones was lower ( P < 0.05) in fish fed MT. These results indicate that feeding MT at these doses (2.5 mg/kg or above) to channel catfish suppresses growth rate and reduces size and strength of bones.  相似文献   

9.
The present study was based on a 2 × 4 factorial design with two levels of dietary protein (33% or 37% CP) and four phytase levels (0.0, 750, 1,000, and 1,250 FTU/kg diet). African catfish, Clarias gariepinus (B.) (10.7 ± 0.4 g), were distributed into earthen ponds (100 m2 surface area per each) at a density of 4.5 fish per m2. Fish were fed on the experimental diets up to satiation twice a day for 3 months. Another experiment with the same treatments was conducted in 45-L tanks for 2 months to evaluate nutrient retention and digestibility. The growth and production of African catfish fed phytase-enriched diets were higher than those fed the control diet. The highest fish performance and production was observed with fish fed 37% CP enriched with a 1,200 FTU/kg diet of phytase. Feed intake was significantly affected by supplemental phytase alone, where it increased significantly as dietary phytase increased at both protein levels, resulting in similar FCR values (1.31–1.46). Additionally, the maximum values of protein efficiency ratio, protein retention, and phosphorus retention were obtained at 33% CP with phytase levels of 750–1,000 FTU/kg diet. It is also noticed that organic matter, protein, and phosphorus were more digestible in fish fed a 37% CP diet with high phytase levels. These results suggest that the optimum performance and production of African catfish were observed at a 37.0% CP diet enriched with a phytase level of 1,200 FTU/kg diet.  相似文献   

10.
This study was conducted to evaluate the use of low protein diets for channel catfish Ictalurus punctatus raised in earthen ponds at high density. Fingerling channel catfish were stocked into 0.04-ha earthen ponds at a rate 24,700 fish/ha and fed experimental diets daily to satiation from April to October 1995. The five diets contained either 32, 28, 24, 20, or 16% crude protein with digestible energy to protein (DE:P) ratios ranging from 8.9 to 16.2 kcal/ g protein. Weight gain was not different among channel catfish fed diets containing 32, 28, or 24% crude protein. Fish fed diets containing 20% or 16% crude protein gained less weight than fish fed the diets containing 28% or 24% crude protein, but not statistically less than the fish fed the 32% crude protein diet. Feed consumption data followed similar trends as weight gain data. Feed conversion ratio increased linearly as dietary protein decreased, but was not significantly different (multiple range test) for fish fed diets containing either 32% or 28% crude protein. There were no differences in survival and hematocrit of fish fed the different diets. No differences (multiple range test) were observed in dressout percentages for fish fed the various diets, but dressout percentage tended to decrease linearly as dietary protein decreased. Visceral fat and fillet fat increased and fillet protein and moisture decreased linearly as dietary protein decreased. Results from this study indicated that dietary protein concentrations as low as 24% are adequate for maximum weight gain of pond-raised channel catfish fed daily to satiation. Fish fed dietary protein levels below 24% grew relatively well, particularly considering that dietary protein was reduced 40–50% below that typically used in commercial channel catfish feeds. However, dietary protein levels below 24% may increase fattiness to an unacceptable level presumably because of the high digestible energy to protein ratio.  相似文献   

11.
ABSTRACT

Animal protein, generally fish meal, has traditionally been used in the diet of channel catfish. However, our previous research indicates that animal protein is not needed for growing stocker-size catfish to food fish when the fish are stocked at densities typical of those used in commercial catfish culture. Whether this holds when fish are stocked at high densities is not known; thus, we conducted an experiment to evaluate the effect of feeding diets with and without fish meal to channel catfish stocked in earthen ponds at different densities. Two 32% protein-practical diets containing 0% or 6% menhaden fish meal were compared for pond-raised channel catfish, Ictalurus punctatus, stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48 g/fish were stocked into 30 0.04-ha ponds. Five ponds were randomly allotted for each fish meal level?×?stocking density combination. Fish were fed once daily to satiation for two growing seasons. There was a significant interaction between stocking density and fish meal for net production; net production increased in fish fed a diet containing fish meal compared with those fed an all-plant diet at the highest stocking density, but not at the two lower stocking densities. Net production of fish fed diets with and without fish meal increased as stocking density increased. Viewing the main effect means, weight gain decreased and feed conversion ratio increased for fish stocked at the two highest densities, and survival was significantly lower at the highest stocking density. Visceral fat decreased in fish at the two highest stocking densities. Body composition data were largely unaffected by experimental treatment except for a reduction in percentage filet fat in fish at the highest stocking density, and fish that were fed diets containing fish meal had a lower percentage fillet protein and a higher percentage fillet fat. It appears that at stocking densities two to three times higher than generally used, animal protein (fish meal) may be beneficial in the diet of channel catfish. In regard to stocking densities, high stocking results in higher overall production, but the average fish size decreased as stocking density increased.  相似文献   

12.
Two experiments were conducted in earthen ponds to evaluate the effect of dietary protein concentration and feeding rate on weight gain, feed efficiency, and body composition of channel catfish. In Experiment 1, two dietary protein concentrations (28% or 32%) and four feeding rates (≤ 90. ≤ 112, ≤ 135 kg/ha per d, or satiation) were used in a factorial arrangement. Channel catfish Ictalurus punctatus fingerlings (average size: 27 g/fish) were stocked into 0.04-ha ponds at a rate of 24,700 fish/ha. Fish were fed once daily at the predetermined maximum feeding rates for 282 d (two growing seasons). In Experiment 2, three dietary protein concentrations (24, 28, or 32%) and two feeding rates (≤ 135 kg/ha per d or satiation) were used. Channel catfish (average size: 373 g/fish) were stocked into 0.04-ha ponds at a rate of 17,300 fish/ha. Fish were fed once daily for 155 d. In both experiments, five ponds were used for each dietary treatment. Results from Experiment 1 showed no differences in total feed fed, feed consumption per fish, weight gain, feed conversion ratio (FCR), or survival between fish fed diets containing 28% and 32% protein diets. As maximum feeding rate increased, total feed fed, feed consumption per fish, and weight gain increased. There were no differences in total feed fed, feed consumption per fish, or weight gain between fish fed at ≤ 135 kg/ha per d and those fed to satiation. Fish fed the 28% protein diet had a lower percentage carcass dressout and higher percentage visceral fat than fish fed the 32% protein diet. Dietary protein concentrations of 28% or 32% had no effect on fillet protein, fat, moisture, and ash. Feeding rate did not affect FCR, survival, percentage carcass dressout, or fillet composition, except fillet fat. As feeding rate increased, percentage visceral fat increased. Fish fed at ≤ 90 kg/ha per d had a lower percentage fillet fat than fish fed at higher feeding rates. In Experiment 2, dietary protein concentration or maximum feeding rate did not affect total feed fed, feed consumption per fish, weight gain, FCR, or survival of channel catfish. Feeding rate had no effect on percentage carcass dressout and visceral fat, or fillet composition. This was due to the similar feed consumption by the fish fed at the two feeding rates. Fish fed the 24% protein diet had lower carcass dressout, higher visceral fat and fillet fat than those fed the 28% or 32% protein diet. Results from the present study indicate that both 28% and 32% protein diets provide satisfactory fish production, dressed yield, and body composition characteristics for pond-raised channel catfish fed a maximum rate of 90 kg/ha per d or ahove.  相似文献   

13.
A factorial experiment was conducted to examine effects of dietary protein concentration (24, 28, 32, or 36%) and feeding regimen (feeding once daily or every other day [EOD]) on channel catfish, Ictalurus punctatus, production in earthen ponds. Compared with fish fed daily, fish fed EOD had lower feed consumption, weight gain, net production, and percentage of market‐size fish but had high feed efficiency and required fewer hours of aeration. Fish fed EOD also had lower carcass yield, fillet yield, and visceral and fillet fat. There was a significant interaction between dietary protein and feeding regimen for weight gain. No significant differences were observed in weight gain of fish fed daily with diets containing various levels of protein, whereas weight gain of fish fed EOD with a 24% protein diet was lower than those fed EOD with higher protein diets. Results suggest that response of channel catfish to dietary protein levels depends on whether the fish were fed daily or EOD. Feeding EOD to satiation improved feed efficiency and required less aeration compared with fish fed daily but also reduced net production and processing yield; therefore, EOD feeding should be examined closely before implementation.  相似文献   

14.
Three experiments were performed in single-pass, flow-through systems to determine the dietary phosphorus requirement of striped bass Morone saxatilis. In Experiment 1, three semi-purified diets were formulated to contain 0.20, 0.40, or 0.60% total phosphorus (entirely from animal protein) and were fed to striped bass having an average initial weight of 321 g. After 14 wk of feeding, significant differences in bone and scale mineralization were found among treatment groups. At a level of 0.40% dietary phosphorus there was a significant improvement of serum calcium (Ca) and tissue mineralization. In Experiment 2, five diets were formulated with graded levels of monopotassium phosphate to yield total phosphorus levels of 0.15 (no P supplementation), 0.35, 0.55, 0.75, and 0.95% and fed to juvenile striped bass initially weighing an average of 7.9 g. After 6 wk, significant improvement in scale and vertebral mineralization occurred when fish were fed diets containing at least 0.55% phosphorus. Improvements were observed in growth, serum phosphorus, incidence of scoliosis, survival, and feed efficiency when the diet contained at least 0.35% P. In Experiment 3, the dietary phosphorus levels fed were 0.30, 0.38, 0.46, 0.54, and 0.62% total phosphorus using graded levels of monopotassium phosphate. Diets were fed to striped bass fingerlings initially weighing an average of 48 g. After 10 wk, significant improvement in scale, vertebral, and dorsal fin mineralization was observed when dietary phosphorus was at least 0.46%. A summary of the broken-line regression analyses of the data from these experiments indicated that the average total dietary phosphorus level required for optimal growth and mineralization of striped bass was 0.58%.  相似文献   

15.
Growth and yield (kg ha?1) of the channel catfish (Ictalurus punctatus, Rafinesque, 1818) and the channel × blue hybrid catfish [I. punctatus female ×I. furcatus (Lesueur, 1840) male], which shared the Jubilee strain of channel catfish as the maternal parent, were compared in sixteen 0.1 ha earthen ponds (14 852 fish ha?1) during the April to November growing season. Each fish genetic group was fed a commercially formulated 32% protein feed daily to apparent satiation or at 80% of the mean daily satiation ration. Net yield and individual weight were higher for channel × blue hybrid catfish compared with channel catfish and for fish fed a full ration compared with a restricted ration. When fed a full ration, the channel × blue hybrid catfish grew faster from May to September than did the purebred channel catfish because the hybrid catfish consumed a greater percentage of its body weight at each feeding. Net yield within each fish genetic group was lower when feed ration was restricted. The per cent reduction in net yield in response to feed restriction was similar for each fish genetic group.  相似文献   

16.
The effects of long-term feeding of cottonseed meal on growth, testis development, and sperm motility of male channel catfish Ictulurus punctatus were studied. Brood-sized male channel catfish were stocked into 0.04-ha earthen ponds in April 1992 at the rate of 120 fish per pond. The fish were fed a diet (32% protein floating catfish feed) containing either 0, 25, 375, or 52% cottonseed meal to satiation daily, except for winter months when fish were fed on days when the water temperature was 15 C or above. Fish were harvested in July 1994. Feed consumption was similar for fish regardless of dietary treatment. Feed conversion was higher for fish fed the two highest levels of cottonseed meal and weight gain was depressed in these groups. Testis weight, gonosomatic index, and sperm motility were not negatively affected by high levels of dietary cottonseed meal indicating that reproductive capacity was not diminished. Thus it wonld appepr that up to 52% cottonseed meal could be used in the diets of brood-sized channel catfish unless maximum gain is important. In a practical situation, growth rates of brood-sized channel catfish are not as important as reproductive performance.  相似文献   

17.
Two studies were conducted to evaluate cottonseed meal (CSM) with and without supplemental lysine as a substitute for soybean meal (SBM) in catfish feeds. One study was conducted in aquaria under controlled environmental conditions with fingerling channel catfish, and the other was conducted with fish raised in 6-m3 net pens suspended in a 1.6-ha earthen pond. In each study, solvent extracted CSM was substituted for SBM on a nitrogen basis. Supplemental lysine was added to the feeds in which CSM replaced 50 and 100% of the SBM because they were estimated to be deficient in available lysine. In the aquarium study, 0, 25, 50, and 100% of the SBM was replaced with CSM. The same feeds used in the aquarium study were used in the net pen study, except that the 25% substitution was not used. Fish raised in aquaria were fed 4% body weight divided into two equal daily feedings, and those raised in net pens were fed to station once daily. Data presented herein demonstrate that channel catfish can effectively utilize supplemental amino acids (even if offered in a single daily feeding) and that CSM can be used to replace 100% of the SBM in catfish feeds if supplemental lysine is used. It appears that about one-half of the SBM can be replaced with CSM without the use of supplemental lysine.  相似文献   

18.
Cottonseed meals were evaluted as partial and complete replacements for soybean meal in pond feeds for channel catfish grown at densities of 5,300/ha. The following dietary treatments were used: 1) glanded cottonseed meal (GC) in which ½ of the soybean meal was replaced; 2) glandless cottonseed meal (GLC) in which all of the soybean was replaced, 3) a control feed (C) typical of commercial catfish feeds. The feeding trial was conducted in 0.04 ha earthen ponds for a period of 176 days. Natural prey species were present in all ponds. Final weights and condition factors of fish fed the GC feed were reduced compared to those fed the GLC or C feeds. This response did not appear to be related to dietary gossypol levels. Even though the GLC feed appeared to be deficient in available lysine, final weight and feed conversion of fish fed the GLC feed were equal to those fed the C feed. Possible nutrient contributions of natural food available in the ponds could not be determined. There were no significant differences in feed conversions or dressout percentages of fish regardless of dietary treatment. Fish fed the GLC feed exhibited a higher percentage of fat and lower percentages of moisture, protein and ash (dry weight basis) in edible tissue than fish fed the other feeds. Free gossypol levels in edible fish tissue were below 100 ppm.  相似文献   

19.
Two studies were conducted to evaluate the effects of (I) high-protein (38%) finisher feed fed to satiation for 30,45,60, or 90 days prior to harvest and (2) dietary protein (32 vs. 38%) and feeding regimen (satiation or restricted) on growth and fattiness of channel catfish. Each study was conducted for two years in earthen ponds stocked with channel catfish at a rate of 13,590 fish/ha (35 to 40 g initial weight) for year 1 and 6,800 fish/ha (0.45 to 0.6 kg initial weight) for year 2. Years refer to year of experiment and not fish age class. There were no significant differences in total yield, dressed yield, or muscle fat, regardless of diet or feeding regimen within year. Year-one fish (study 2) fed to satiation tended to gain more weight and appeared to convert feed better than fish fed at a restricted rate. In study 2 there were significant interactions between year and feed, and between year and feeding regimen. Percentage visceral fat was reduced by feeding a high-protein feed during year 1 (study 1). Females also generally had a higher percentage visceral fat than males, regardless of diet. Year-two-fish generally contained a higher percentage of visceral fat as compared to year-one fish. In study 2, there was a significant interaction effect between year, feed, feeding regimen, and sex on visceral fat. Increasing dietary protein or restricting feed appeared to have only marginal effects on fattiness in channel catfish. Fish size and/or age appeared to influence fattiness more than diet or feeding regimen.  相似文献   

20.
Three isonitrogenous and isocaloric rations containing various levels of commercially dehulled soybean meal as replacement for menhaden fish meal were fed to four replicate groups of channel catfish, Ictalurus punctatus (Rafinesque), fingerlings, mean initial live weight 13. 7 g, in 0.4-ha earthen ponds for 114 days. As fish meal was removed from the experimental diets, vegetable fat, soybean meal, and inorganic phosphorus were increased to maintain 35% crude protein, 11. 7 Mj of digestible energy (DE) per kg, and a minimum of 0.45% available phosphorus. The percentage of the whole body weight made up of dressed carcass, head, skin and viscera did not vary significantly among dietary treatments. Average values for dressed carcass, head, skin and viscera were 60.8%, 20.8%, 6.7% and 9.7%, respectively. The chemical composition of the various body parts was not significantly affected by diet. Average fat percentages for dressed carcass, head, skin, and viscera were 8.2%, 7.3%, 16.0% and 26.4%, respectively. Average protein percentage were 15.7%, 14.9%, 22.2% and 11.4%, respectively. These results indicate that varying the percentage of fat added to a practical catfish diet from 0% to 3.8%, but holding the DE constant, will not affect dressing percentage or body composition of the fed fish.  相似文献   

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