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1.
The effects of partial replacement of fish meal (FM) with meal made from northern krill (Thysanoessa inermis), Antarctic krill (Euphausia superba) or Arctic amphipod (Themsto libellula) as protein source in the diets for Atlantic salmon (Salmo salar L.) and Atlantic halibut (Hippoglossus hippoglossus L.) on growth, feed conversion, macro‐nutrient utilization, muscle chemical composition and fish welfare were studied. Six experimental diets were prepared using a low‐temperature FM diet as control. The other diets included northern krill where 20, 40 or 60% of the dietary FM protein was replaced with protein from northern krill, and two diets where the FM protein was replaced with protein from Antarctic krill or Arctic amphipod at 40% protein replacement level. All diets were iso‐nitrogenous and iso‐caloric. Atlantic salmon grew from 410 g to approximately 1500 g during the 160 day experiment, and Atlantic halibut grew from 345 g to 500–600 g during the 150 day experiment. Inclusion of krill in the diets enhanced specific growth rate in salmon, especially during the first 100 days (P < 0.01), and in a dose–response manner in halibut for over the 150 day feeding period (P < 0.05). Feed conversion ratio did not differ between dietary treatments, and no difference was found in dry matter digestibility, protein digestibility and fish muscle composition. Good growth rates, blood parameters within normal ranges and low mortalities in all experimental treatments indicted that fish health was not affected either Atlantic salmon or Atlantic halibut fed the various zooplankton diets.  相似文献   

2.
In the present study the impact on autochthonous (adherent) bacteria in proximal intestine (PI) and distal intestine (DI) of Atlantic cod ( Gadus morhua L.) was evaluated following feeding of a control diet and a diet supplemented with 5% chitin. The autochthonous gut bacteria were investigated using denaturing gradient gel electrophoresis (DGGE). Analysis of the microbiota associated with PI and DI of Atlantic cod indicate that dietary chitin modulate the intestinal bacterial community. For example, band 25 ( Escherichia coli–like), band 14 ( Anaerorhabdus furcosa–like) and band 29 (uncultured bacterium–like) in PI were depressed by dietary chitin (P < 0.05). The number of bands (23.7 ± 5.4) in DI of fish fed chitin was marginally higher than the control fish (16.7 ± 2.1) (P = 0.065), and the relative abundances of band 6 (swine faecal bacterium–like) were marginally stimulated by dietary chitin (P = 0.095). Furthermore, the present study reports several novel sequences not previously reported in the gastrointestinal tract of Atlantic cod. Whether the dietary effect of chitin on gut bacterial community has any positive effect of fish health merits further investigations.  相似文献   

3.
A 10‐week study was conducted to investigate the effects of feeding rate and frequency on growth performance, digestion and nutrients balances of Atlantic salmon (Salmo salar) in replicated recirculating aquaculture systems (RAS). Replicated groups of juvenile salmon weighing 90 ± 2.5 g (mean ± SD) were fed a commercial feed (21.63 MJ kg?1 gross energy) to designed feeding rate (1.4%, 1.6% and 1.8% body weight day?1, BW day?1) and feeding frequency (2 and 4 meals day?1) combinations. Specific growth ratio varied between 1.15 ± 0.02 and 1.37 ± 0.16% day?1, and feed conversion ratio ranged from 0.96 ± 0.03 to 1.16 ± 0.02. The nitrogen and phosphorus retention rates were from 36.50 ± 1.94 to 47.08 ± 5.23% and from 20.42 ± 1.05 to 38.59 ± 2.80%. Apparent digestibility coefficients (ADC) in dry matter, protein, lipid and energy showed no significant differences for all groups. However, fish fed at 1.6% BW day?1 and 4 meal day?1 groups had relatively better growth and nutrient retention efficiency compared to other groups. In addition, concentrations of nitrogenous and phosphorous compounds were also detected in this study. These results suggested that salmon of 100–200 g in RAS could in practice be fed at 1.6% BW day?1 and 4 meals day?1, taking environmental impacts into account.  相似文献   

4.
The growth and feed utilization of Atlantic cod (Gadus morhua) (437 g), Atlantic salmon (Salmo salar) (485 g) and rainbow trout (Oncorhynchus mykiss) (413 g) fed a diet (170 g kg−1 fat, 600 g kg−1 crude protein; LE) similar to that used in commercial cod production or one that was top dressed with additional fat (280 g kg−1 fat, 530 g kg−1 crude protein; HE), were compared in an 11‐week trial. In the cod, relative feed intake was 41–58% and thermal growth coefficient 63% of that in the salmonids, but the feed efficiency ratio (FER) was 38% better (P ≤ 0.05). In contrast to the cod where there was no effect of diet on feed intake, growth or FER, both the salmon and trout fed the HE diet had greater feed intake than those fed the LE diet, but the effect of this was only positive for growth in the salmon. The cod retained more of the digested nitrogen (44.9 ± 2.7%) than the salmon (39.4 ± 0.8%), and both of these species retained more than the trout (33.6 ± 1.1%) (P ≤ 0.05). The retention of digested energy was significantly higher in the salmon (52.2 ± 0.9%) than in the trout (44.8 ± 1.1%), with the cod (44.9 ± 4.9%) not different from either of the other species. There were no differences between the species in the retention of absorbed phosphorus (65.9 ± 3.6%). There were very few dietary effects on nutrient utilization in this trial and, for the cod, this indicates that higher energy diets may be feasible for use in production.  相似文献   

5.
The aim of the present work was to obtain the lipid utilization of Octopus vulgaris supplying formulated semi‐moist diets with different contents in cod oil (reduced from water content): 0 g kg?1 (A0, 138 g kg?1 lipids DW; N = 4), 100 g kg?1 (A100, 286 g kg?1 lipids DW; N = 6) and 200 g kg?1 (A200, 388 g kg?1 lipids DW; N = 6). The rest of the ingredients were constant in the three diets: 200 g kg?1 gelatin, 100 g kg?1 egg yolk powder, 150 g kg?1 freeze‐dried Todarodes sagittatus and 50 g kg?1 freeze‐dried Sardinella aurita). Survival was 100% with the three diets. The highest absolute feeding (15.8 ± 1.2 g day?1), growth (9.6 ± 1.4 g day?1; 0.91% BW day?1) and feed efficiency rates (60.3%) were obtained with diet A0. This diet also showed greater retention of lipid and protein than A100 and A200. Protein digestibility was above 95% in all of the diets. Only diet A0 led to a high lipid digestibility coefficient (81.25%), which fell drastically to 12.3% in A200. It was notable the high polar lipid digestibility rates (83–89%) respect to neutral lipids (2–87%) in all diets. The best results were obtained with lipid feeding rates of around 1 g day?1 and a suitable lipid content on 130–140 g kg?1 DW in formulated diets for O. vulgaris.  相似文献   

6.
The study aims to test whether predigested dietary protein enhances the utilization of formulated diets at weaning, and also whether it stimulates intestinal maturation. In this study, Atlantic cod [ Gadus morhua L.; 41 days posthatch (dph)] and Atlantic halibut [ Hippoglossus hippoglossus L.; 63 days postfirst feeding (dpff)] were weaned onto diets with graded levels of protein hydrolysate. By increasing the inclusion of dietary protein as hydrolysate from 0 to 400 g kg−1, cod increased the rate of survival from 7 ± 1% to 18 ± 2% (82 dph; regression, P =  4*10−7). In halibut, the survival rate decreased from 57 ± 9% to 22 ± 7% as the inclusion of protein in the form of hydrolysate increased from 0 to 450 g kg−1 (119 dpff; regression, P =  8*10−5). Growth was not affected in any of the species. Results in specific activities of the intestinal enzymes leucine aminopeptidase (LAP) and alkaline phospatase (AP) supported the results in survival in halibut and partly also in cod, by showing increased activities in groups with increased survival ( anova , P <  0.05). The lower optimal level of hydrolysed protein in halibut than in cod is suggested mainly because of a slower feeding practice in halibut, which allows more extensive nutrient leaching before ingestion.  相似文献   

7.
Dietary supplementation (0, 10, 20, 40, 60, 80 g kg?1) of a nucleotide source (NuPro®) was evaluated on growth, nutrient utilization, haemato‐immunological responses and resistance to experimental infection of Nile tilapia. Fish (2.63 ± 0.63 g) were fed experimental diets to satiation three times a day for 75 days. Feed intake increased linearly with increasing levels of NuPro® promoting higher weight gain (P < 0.05). Survival, feed conversion and protein retention were not affected. Following the growth trial, fish were challenged with Aeromonas hydrophila by intraperitoneal injection. Survival and innate immune responses (phagocytosis and lysozyme activity) were not significantly affected. However, among the haematological variables, thrombocyte, leucocyte and monocyte counts increased linearly (P < 0.05). The indirect measurement of digestibility in juvenile Nile tilapia (122.32 ± 11 g) indicated a linear decrease in protein (1.41%), dry matter (5.72%) and energy (4.10%) digestibility coefficients as dietary supplementation increased (P < 0.05). NuPro® showed to be a beneficial additive to be supplemented in diets for juvenile Nile tilapia, providing 32.8% increase in feed intake and 28.8% in weight gain, as well as in thrombocyte, leucocyte and monocyte counts in blood, possibly indicating a more efficient defence response in the highest dietary supplementation levels tested.  相似文献   

8.
Calanoid copepods are a rich source of marine lipid for potential use in aquafeeds. Copepod oil is primarily composed of wax esters (WE) and there are concerns over the efficiency of wax ester, versus triacylglycerol (TAG), digestion and utilization in fish. As smoltification represents a period of major physiological adaptation, the present study examined the digestibility of a high WE diet ( Calanus oil; 48% WE, 26% TAG), compared with a TAG diet (fish oil; 58% TAG), in Atlantic salmon freshwater presmolts and seawater postsmolts, of similar age (9 months) and weight (112 g and 141 g initial, respectively), over a 98-day period at constant temperature. Fish grew significantly better, and possessed lower feed conversion ratios (FCR), in seawater than freshwater. However, total lipid apparent digestibility coefficient (ADC) values were significantly lower in seawater fish, as were total fasted bile volumes. Dietary Calanus oil also had a significant effect, reducing growth and lipid ADC values in both freshwater and seawater groups. Postsmolts fed dietary Calanus oil had the poorest lipid ADC values and analysis of faecal lipid class composition revealed that 33% of the remaining lipid was WE and 32% fatty alcohols. Dietary prevalent 22:1n-11 and 20:1n-9 fatty alcohols were particularly poorly utilized. A decrease in primary bile acid, taurocholate, concentration was observed in the bile of dietary Calanus oil groups which could be related to the lower cholesterol content of the diet. The dietary WE : TAG ratio is discussed in relation to life stage and biliary intestinal adaptation to the seawater environment postsmoltification.  相似文献   

9.
Abstract The Australian native freshwater fish Murray cod, Maccullochella peelii pellii (Mitchell), currently supports a fledgling inland aquaculture industry, which is thought to have considerable growth potential. The aim of this study was to evaluate the suitability of two alternate protein sources [blood meal (BM) and defatted soybean meal (SBM)] as substitutes for fish meal at various levels of inclusion in diets for juvenile Murray cod. The growth performance of juvenile Murray cod in response to nine isonitrogenous and isocalorific diets (50% protein, 14% lipid, 20.2 kJ g?1) consisting of a control diet in which protein was supplied from fish meal, and test diets in which the fish meal protein was substituted at levels of 8%, 16%, 24%, and 32% with BM or SBM was evaluated from a 70‐day growth experiment. The per cent apparent dry matter (% ADCdm) and percentage protein digestibility (% ADCp) of the test diets were also determined using Cr2O3 as a marker. Survival in all the SBM dietary treatments was high but that of fish on the BM dietary treatments was significantly (P < 0.05) lower than in all the other dietary treatments. Specific growth rate (% day?1) of Murray cod fed SBM incorporated diets ranged from 1.63 ±  0.06 to 1.78 ±  0.10 and even at the highest level tested (32% of the dietary protein from SBM) was not significantly different (P > 0.05) from the fish fed the control diet (1.65 ±  0.09). Feed conversion ratios of the SBM dietary treatments ranged from 1.36 ±  0.08 to 1.45 ±  0.07. The protein efficiency ratios and protein conversion efficiencies of Murray cod in the soybean meal treatments were also good and for a majority of the SBM diets were better than those for the control diet. Per cent ADCdm and ADCp of the SBM diets tested ranged from 70.6 ±  1.46 to 72.3 ±  1.81% and 88.6 ±  0.57 to 90.3 ±  0.17%, respectively, and was not significantly different (P > 0.05) from the control diet (% ADCdm 74.3 ±  1.63; % ADCp 91.3 ±  0.55). The reasons for significantly poor survival and growth of Murray cod reared on BM incorporated diets, and relatively poor digestibility of these diets are discussed. The study shows that for Murray cod diets in which fish meal protein is substituted up to 32% performance or carcass composition is not compromised.  相似文献   

10.
The copepod, Calanus finmarchicus, has potential as a new ingredient in practical feeds for marine fish. Two experiments were conducted to evaluate the nutritional value of C. finmarchicus meals when fed to juvenile Atlantic halibut. The first study determined protein, lipid and energy digestibility coefficients of four C. finmarchicus meals prepared under different processing conditions. The second study evaluated growth and nutrient utilization efficiency of juveniles fed diets containing varying proportions of fish meal, plant meals and C. finmarchicus meal. Moisture, ash, protein, lipid and gross energy contents of the C. finmarchicus meals were 28–93, 74–138, 505–648, 123–269 g kg−1, and 21–26 MJ kg−1, respectively. Protein, lipid and energy digestibilities of C. finmarchicus meals were 91–99%, 90–95% and 90–99%. The digestibilities significantly decreased for the Calanus meals processed at higher temperatures. During the growth study, halibut fed a diet containing 240 g kg−1 C. finmarchicus meal had significantly higher weight gain and growth rate than all other groups. Nitrogen and energy retention efficiencies ranged between 35–45% and 33–43%, and were significantly higher for fish fed 160–240 g kg−1 C. finmarchicus meal than for fish fed plant protein and control diets. The results indicate that growth and nutrient utilization efficiency are improved in Atlantic halibut fed diets supplemented with C. finmarchicus meal.  相似文献   

11.
Feeds in modern aquaculture must be of high physical quality to withstand mechanical impacts. However, physical quality of feed has been shown to affect nutritional responses. In this study, different physical feed qualities were created using different drying time. Effects on physical feed quality, feed intake, nutrient digestibility and growth in Atlantic salmon were investigated. Different drying times of four commercial‐like diets resulted in dry matter contents of 95.9%, 94.1%, 92.3% and 90.8%. A fifth diet containing 70% dry matter was made by soaking pellets. Triplicate groups of Atlantic salmon (961 ± 12.1 g ind?1, mean ± SEM) were first fed ad libitum and thereafter a restricted ration. The diets differed significantly in bulk density, DORIS durability, hardness, water stability after 60 and 120 min, but not in water stability after 240 min. Feed intake and growth were not affected by physical quality of the dry diets, whereas soaking had a positive effect on feed intake. Restricted compared with ad libitum feeding increased nutrient digestibility, but digestibility was not affected by varying drying time among diets. However, soaking resulted in slightly reduced digestibility of starch. Most methods used to analyse physical quality did not correlate with feed intake and growth; only long‐term water stability affected feed intake.  相似文献   

12.
Stress in response to anesthesia with benzocaine, MS-222, metomidate and isoeugenol was studied in Atlantic salmon (Salmo salar), Atlantic halibut (Hippoglossus hippoglossus), and Atlantic cod (Gadus morhua) with no concomitant stress from handling or confinement in association with anesthesia or sampling. All of the anesthetics tested induced a stress response in all species, displayed by a release of cortisol to the water. MS-222 anesthesia elicited the highest cortisol release rates, reaching maximum levels 0.5 h post-exposure and returning to basal levels after 3–4 h. Benzocaine anesthesia caused a bimodal response where the initial peak in cortisol release rate was followed by a second increase lasting towards the end of the trial (6 h). This bimodality was more profound in Atlantic salmon than in Atlantic halibut and Atlantic cod. Metomidate anesthesia induced the lowest release of cortisol of the agents tested in both Atlantic halibut and Atlantic cod, but resulted in a bimodal response in Atlantic salmon where the initial increase in cortisol release was followed by a larger increase peaking at 2–2.5 h post exposure before returning to basal levels after 5 h. The stress induced in Atlantic salmon by isoeugenol anesthesia resembled that of MS-222, but did not reach the same elevated level. Overall, the cortisol release was most profound in Atlantic salmon followed by Atlantic halibut and Atlantic cod.  相似文献   

13.
Two trials with Atlantic salmon (Salmo salar) were conducted to evaluate the potential of krill meal to improve feed intake. In the first experiment, after transfer to sea water, salmon smolts were fed diets added 75 or 150 g kg?1 Antarctic krill meal in substitution for fish meal for 13 weeks. The apparent digestibility coefficient for crude protein and the majority of the amino acids was significantly lower in the feeds added krill meal (around 83.5%) than in the control diet (84.9%), whereas the digestibility of crude lipids, dry matter and energy was not significantly different among the three diets. Krill meal addition resulted in higher feed intake, which led to higher growth rates and final body weights. In the second experiment, large salmon were fed a diet containing 100 g kg?1 krill meal for 6 weeks before slaughter. Their feed intake and growth performance were assessed, and fillet and visceral fat contents were measured. Salmon fed the 100 g kg?1 krill meal diet tended to eat more, resulting in significantly increased growth rates, when compared to control fish. Fish fed krill meal also had a significantly lower condition factor.  相似文献   

14.
A 126‐day experiment was carried out under controlled conditions to compare the effects of five levels (0.5, 1.0, 1.5, 2.0 and 2.5 g kg?1) of dietary nucleotide (Vannagen®) on the growth performance and biological indices of juvenile crayfish (8.25 ± 0.39 g). The protein efficiency ratio (PER, 1.69–2.17), lipid efficiency ratio (LER, 2.29–3.00), energy efficiency ratio (EER, 2.68–3.65), protein productive value (PPV, 57.01–68.95%), lipid productive value (LPV, 63.02–75.15%) and energy productive value (EPV, 68.20–88.15%) increased significantly (P < 0.05) as linear response to increased dietary nucleotide from 0.5 to 2.5 g kg?1 in the feed. With an increase in the dietary nucleotide, the uricase activity (654.29–827.63 U g?1) and lactobacillus count to total count ratio (1.21–2.17) of crayfish fed the experimental diets increased significantly (P < 0.05). Crayfish fed the diets containing different levels of nucleotide (from 0.5 to 2.5 g kg?1) had higher phenoloxidase activity (1.57–2.11 U min?1) than that of control after air exposure challenge. At the levels tested, 2 g kg?1 nucleotide in the diet was considered optimum for growth performance, digestibility and immune responses. It can be concluded that dietary nucleotide exerted positive effects on growth performance, feed utilization and accelerate crayfish immune response against air exposure challenge.  相似文献   

15.
New cultured ornamental fish namely Lake Kurumoi rainbowfish Melanotaenia parva (Allen) run into reduced of colour performances when reared in the aquaria, consequently, fish feed must be added with carotenoids as a pigment source. The aim of this study was to evaluate the digestibility, growth and pigmentation of astaxanthin, canthaxanthin and lutein in diet. Apparent digestibility coefficients (ADC) of dry matter, lipid, protein, carotenoids, growth and pigmentation were studied in twenty fish after 14 and 56 days of observation. The single‐dose supplementation of 100 mg/kg of astaxanthin, canthaxanthin, or lutein diets on fish was fed by apparent satiation. The basal diet without carotenoids was used as control. The result showed that the ADC of carotenoids of test diets was higher compared to control. Fish fed astaxanthin diet had higher survival rate (96.67 ± 2.89%), colour measurements of lightness (57.60 ± 7.46%), a*‐values (4.66 ± 1.20), total carotenoids content in skin (33.75 ± 5.02 mg/kg) and muscle (2.16 ± 0.74 mg/kg). Astaxanthin also increased the growth after 14 days (2.00% ± 0.19%/days) but there was no significantly different at the end of experiment. The yellowish‐orange colour performance was more rapidly achieved by fish fed astaxanthin diet after 28 days experimentation. These values suggested that dietary carotenoids were required and astaxanthin diet was superior to other diets for skin pigmentation of Lake Kurumoi rainbowfish.  相似文献   

16.
Abstract Release strategies of hatchery‐reared Atlantic salmon, Salmo salar L., smolts were compared by studying survival and migration of smolts (n = 99) and their predators (Atlantic cod, Gadus morhua L., n = 8; and saithe, Pollachius virens (L.), n = 2) during the first 37 km of the marine migration using acoustic telemetry. Survivorship was higher in smolts released at the river mouth (30%) compared with smolts released in the river (12%). This was likely due to mortality or reduced migratory behaviour in fresh water. The marine mortality was 37% during the first 2 km after leaving the river (at least 25% mortality because of predation from marine fishes), and total marine mortality over 37 km was 68%. Detection‐depth data were useful for evaluating whether the tagged smolts were alive or predated; mortality during the first 2 km of outward migration would have been underestimated at 26% instead of 37% without the analysis of depth detection. Transmitters from consumed post‐smolts remained in predators for up to 47 days (average 29 days).  相似文献   

17.
Juvenile Atlantic cod (Gadus morhua) were fed extruded feeds formulated to contain 360–660 g kg?1 protein, 80–280 g kg?1 lipid and 80–180 g kg?1 starch at feeding frequencies of either once per day or every second day to satiation. The trial was conducted at 8 °C and lasted for 28 weeks during which fish were weighed five times at regular intervals. Sampling for proximate analysis was performed at the start, after 12 weeks and at the end of the trial. Fish grew from an average weight of 192 g to between 750 and 866 g, with growth being negatively affected by low dietary protein concentration. High dietary starch concentrations had some negative effects on growth, whereas changes in dietary fat concentration had no significant effect on growth. Liver indices (at the end of the experiment) varied between 80 and 170 g kg?1, and there was a negative correlation between the ratio of protein to fat and liver index. Feed conversion ratio (FCR) ranged between 0.74 and 0.88, and feed utilization improved with increasing concentrations of dietary protein and fat. Increasing dietary starch concentrations resulted in poorer feed utilization. To achieve good growth and protein retention, and avoid excessive liver size in juvenile cod, feeds should contain 500–600 g kg?1 crude protein, 130–200 g kg?1 lipid and <150 g kg?1 starch.  相似文献   

18.
A feeding trial was conducted for 8 weeks to evaluate the effects of supplemental phytic acid (PA) on the apparent digestibility and utilization of dietary amino acids (AAs) and minerals in juvenile grass carp. Five experimental diets consisted of graded levels of PA (0.2, 4.7, 9.5, 19.1 and 38.3 g kg?1, named as P0, P5, P10, P20 and P40). Triplicate groups of fish (initial weight, 22.37 ± 0.16 g) were fed twice daily (08:00 and 16:00 h). The crude protein content in whole body significantly (p < .05) decreased in fish fed with 19.1 and 38.3 g PA kg?1 diet. Supplemental PA (>4.7 g kg?1) significantly reduced the apparent digestibility coefficient (ADC) of AAs (Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ile, Leu, Phe, Lys, Pro, His and Arg) and the ADC of minerals (P, Ca, Mg, Zn, Cu, Fe and Mn) in grass carp. The contents of minerals (P, Ca, Mg and Zn) in whole body and bone were also found to be significantly reduced in dietary PA > 4.7 g kg?1, while the bone ash, serum Alkp and Zn contents were found to be significantly decreased when the PA supplementation level was above 9.5 g kg?1, and the contents of serum Ca and Mg were found to be markedly altered in higher PA‐supplemented groups. The results indicated that supplemental PA decreased the apparent digestibility and utilization of AAs and minerals, and thus reduced the feed utilization of grass carp, suggesting that the level of total PA should be below 4.7 g kg?1 in grass carp diet.  相似文献   

19.
A feeding trial of 84 days was carried out to evaluate the effects of olive cake (OC) on growth, feed utilization, digestibility of nutrient, haematological values and some blood chemistry parameters of juvenile hybrid tilapia (Oreochromis niloticus × Oreochromis aereus). Four diets were prepared including OC at levels of 0, 120, 240 and 360 g kg?1. Twenty fish per tank (initial weight 8.58 ± 0.09 g) were randomly distributed into 200‐L fibreglass tanks. Final body weight and specific growth rate of fish fed with diets OC12 were not significantly different compared to fish fed with the control diet. The best feed conversion rate and protein efficiency rate were obtained from the fish fed with the control and OC12 diets. Growth performance, feed conversion rate and protein efficiency rate of fish fed diets with OC incorporation levels of more than 12 per cent tended to decrease significantly (P < 0.05) compared to the control and OC12 diet groups. The apparent digestibility coefficients (ADC) of dry matter significantly decreased (P < 0.05) with the increase of dietary OC levels, whereas the ADC of protein was not affected by dietary treatment. The ADC of lipid of fish fed with control and OC12 diets were significantly (P < 0.05) higher than those of fish fed with OC24 and OC36 diets. Mean corpuscular haemoglobin, cholesterol and triglycerides were affected by dietary OC level. The findings of this study show that OC can be incorporated to diets of juvenile hybrid tilapia up to 120 g kg?1 without any adverse effect on fish growth and feed utilization.  相似文献   

20.
Three‐year classes of Atlantic cod Gadus morhua were studied throughout their rearing in the eastern coast of Iceland from 2004 to 2011. The growth and status of maturity were recorded during the rearing. For one of the year classes, genetic parameters for body weight and maturity status were estimated from 757 individuals, which were the offspring of 40 dams and 20 sires. The estimate for heritability of body weight was h2 = 0.34 at the average weight of 630 g, and heritability for proportion of maturity was h2 = 0.17 given the same weight. The relationship between body weight and the proportion of mature individuals at first winter revealed a strong genetic correlation of rG = 0.90. The phenotypic relationship between body weight and proportion of maturity was estimated with a Bayesian logistic regression as P(yi = 1(mature)) = Φ(β0 + β1weight + β2sex). The best fit yielded β0 = ?2.9320 with a 95% interval between ?3.2807 and ?2.5394, β1weight = 0.0041 with a 95% interval ranging from 0.0035 to 0.0046 and β1sex = ?0.0201 with a 95% interval from ?0.2003 to 0.1445. The gender had no notable effect. This strong phenotypic and genetic correlation in body weight and maturation suggests that an increased growth rate will consequently lead to a higher proportion of mature individuals in the population. As a consequence, genetic manipulations to simultaneously increase growth and delay maturation may present a challenge.  相似文献   

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