Evaluation of commercial catfish, tilapia and salmonid diets for growth promotion of white suckers

In an attempt to identify appropriate diets for use in intensive baitfish culture, the efficacy of three commercial diet formulations, a high-protein, high-lipid, low-carbohydrate diet [a semi-moist salmonid diet (SD)] and two low-protein, low-lipid, high-carbohydrate diets [a catfish diet (CD) and a tilapia diet (TD)] on growth performance of juvenile white suckers, Catostomus commersoni, was examined. All three diets permitted growth during the 16 week trial. The SD promoted highest growth and somatic protein and lipid deposition, whereas the CD and TD formulations promoted markedly higher accumulations of glycogen in the carcass and liver. The high hepatic glycogen content was associated with an elevated hepatosomatic index in the CD- and TD-fed groups. Plasma T3 levels were lower in the CD- and TD-fed groups, possibly a response to the low dietary protein or indicative of dietary insufficiency in these fish. Of the three diets evaluated, the SD was considered to be the best in terms of the growth performance parameters measured, and offers an economical and appropriate diet for intensive culture of juvenile white suckers.     

In vitro protein digestion, and growth of Atlantic salmon with different trypsin isozymes

Growth and in vitro digestion was examined in three iso-trypsin phenotypes (patterns 1, 2 and 2) of Atlantic salmon, Salmo salar. Fish grew equally well during the 128 day experiment irrespective of phenotype. At day 64 and 91, weight-specific growth rate of 2 phenotype animals were significantly lower (p < 0.05). At the end of the experiment, significant differences (p < 0.05) were noted between groups with respect to size. An in vitro method was used to examine protein digestion by the different trypsin phenotypes. Three fish meals (FM I > FM II > FM III) of high, medium and low quality, as defined by chemical analyses, were used. Phenotype 1 was able to differentiate between three fish meals ranking FM I > FM II > FM III. In contrast, phenotypes 2 and 2 were not able to separate between meals. In vitro digestion efficiency was dependent upon the three salmon types, ranking phenotype 2 > 1 = 2.     

鱼粉质量对中国对虾、真鲷、饲料转化率和蛋白质消化率的影响

IntroductionInherent to the practice of intensive aquaculture is the generation of wastes having immediate and verybroad effects on the aquatic environment.There is a growing consensus about the need to reduce waste pro-duction in aquaculture to minimize the negative impacts on the environment.Nitrogen(N) and phosphorus(P) wastes are major concerns for many aquaculture operations.In the past,formulation of diets in intensive aquaculture was often aimed at meeting requirements formaximum growt…     

Evaluation of different protein sources in fingerling grey mullet <Emphasis Type="Italic">Mugil cephalus</Emphasis> practical diets

An eight-week experiment was carried out to evaluate the effects of different protein sources (fish and haemoglobin meal, soybean meal and torula yeast), in practical diets, on growth, body composition and gut morphology of fingerling grey mullet (Mugil cephalus). Weight gain (%), SGR, FCR, N retention, PER, PGR, FDR and carcass composition of fish were not significantly affected by the dietary protein source. Fish fed the torula yeast based diet showed reduction in growth performance. Histological examinations performed on the alimentary tract of the fish showed a normal structural pattern in the experimental groups, as fundamental histological and histochemical aspects were similar if compared to the control group. The lower growth performance observed in fish fed a torula yeast based diet may be tentatively correlated with the presence of some detrimental morpho-functional aspects in the gut of these fish if compared to fish fed the other diets. Further studies are necessary to confirm this hypothesis.     

Effect of dietary protein:energy ratio on intake, growth and metabolism of juvenile green abalone Haliotis fulgens

Juvenile green abalone Haliotis rufescens were grown under laboratory conditions at 21±1 °C and fed formulated diets consisting of different protein:energy ratios (mg protein/kcal), 62, 74, 85, 100, 108, for 60 days. The level of crude protein ranged from approximately 26% to 44% while the energy content remained constant at about 4.1 kcal g⁻¹. Growth ranged from 3.63 to 12.33 mg day⁻¹. The growth of abalone fed the 100 and 108 diets was significantly greater than that of each of the other diets. Protein efficiency ratio increased as the dietary protein content increased except for the T108 diet (44% crude protein). Abalone apparently consume food to satisfy an energy requirement. Caloric expenditure due to metabolism was estimated for abalone fed diets with protein ratios of 62, 85, 100. Energy loss due to respiration did not vary appreciably among abalone fed the different diets. The proportional distribution of dietary energy into fecal, digestible, growth, and metabolic energy was estimated for abalone fed these diets. Apparent dry matter digestibility was among the lowest for abalone fed the 100 P:E diet, but growth of abalone fed this diet was significantly higher than that of each of the other treatments except the 108 diet. Unexplained energy loss to achieve balance ranged from 7% to 28.5%, some of which is probably due to differential mucus and ammonia production. Results suggest a potential for the reduction of both dietary protein and lipid without causing any adverse effects on the growth response.     

Advanced oxidation protein products are generated by bovine neutrophils and inhibit free radical production in vitro

Despite the recognised importance of oxidative stress in the health and immune function of dairy cows, protein oxidation markers have been poorly studied in this species. The current study aimed to characterise markers of protein oxidation generated by activated bovine neutrophils and investigate the biological effects of advanced oxidation protein products (AOPP) on bovine neutrophils. Markers of protein oxidation (AOPP, dityrosines and carbonyls) were measured in culture medium containing bovine serum albumin (BSA) exposed to neutrophils. The effect of AOPP-BSA on generation of reactive oxygen species (ROS) was assessed by chemiluminescence. Activation of caspases-3, -8 and -9 and the presence of DNA laddering were used as apoptosis markers.Greater amounts of AOPP were generated by phorbol myristate acetate (PMA)-activated than non-activated neutrophils (1.46 ± 0.13 vs. 0.75 ± 0.13 nmol/mg protein, respectively; P < 0.05). Activated neutrophils and hypochlorous acid generated slightly different patterns of oxidized protein markers. Exposure to AOPP-BSA did not stimulate ROS production. Activated neutrophils generated a lesser amount of ROS when incubated with AOPP-BSA (P < 0.001). Activation with PMA induced a loss of viable neutrophils after 3 h, which was greater with AOPP-BSA incubation (P < 0.05). Detectable amounts of active caspases-3, -8 and -9 were found in nearly all samples but differences in caspase activation or DNA laddering were not observed comparing treatment groups. Apoptosis was unlikely to be responsible for the greater loss of PMA-activated neutrophils cultured in AOPP-BSA and it is possible that primary necrosis occurred. The results suggest that accumulation of oxidized proteins at an inflammatory site might result in a progressive reduction of neutrophil viability.     

Effects of different dietary energy and protein levels and sex on growth performance,carcass characteristics and meat quality of F1 Angus x Chinese Xiangxi yellow cattle

Background：The experiment evaluated the effect of nutrition levels and sex on the growth performance,carcass characteristics and meat quality of F1 Angus × Chinese Xiangxi yellow cattle.Methods：During the background period of 184 d,23 steers and 24 heifers were fed the same ration,then put into a2×2×2 factorial arrangement under two levels of- dietary energy（TON：70/80%DM）,protein（CP：11.9/14.3%DM）and sex（S：male/female） during the finishing phase of 146 d.The treatments were-（1） high energy/low protein（HELP）,（2） high energy/high protein（HEHP）,（3） low energy/low protein（LELP） and（4） low energy/high protein（LEHP）.Each treatment used 6 steers and 6 heifers,except for HELP- 5 steers and 6 heifers.Results：Growth rate and final carcass weight were unaffected by dietary energy and protein levels or by sex.Compared with the LE diet group,the HE group had significantly lower dry matter intake（DMI,6.76 vs.7.48 kg DM/d）,greater chest girth increments（46.1 vs.36.8 cm）,higher carcass fat（19.9 vs.16.3%） and intramuscular fat content（29.9 vs.22.8%DM）.The HE group also had improved yields of top and medium top grade commercial meat cuts（39.9 vs.36.5%）.The dressing percentage was higher for the HP group than the LP group（53.4 vs.54.9%）.Steers had a greater length increment（9.0 vs.8.3 cm）,but lower carcass fat content（16.8 vs.19.4%） than heifers.The meat quality traits（shear force value,drip loss,cooking loss and water holding capacity） were not affected by treatments or sex,averaging 3.14 kg,2.5,31.5 and 52.9%,respectively.The nutritive profiles（both fatty and amino acid composition） were not influenced by the energy or protein levels or by sex.Conclusions：The dietary energy and protein levels and sex significantly influenced the carcass characteristics and chemical composition of meat but not thegrowth performance,meat quality traits and nutritive profiles.     

Effects of the protein/carbohydrate ratio of extruded diets on protein synthesis, protein growth and body composition in juvenile brown trout (Salmo trutta)

High levels of protein in fish feeds result in higher costs and nitrogen waste. Therefore, studies focused on protein substitution by alternative energy sources are necessary. Here we examine whether the protein:carbohydrate ratio in extruded diets affects protein-turnover parameters and the main tissue components in brown trout. Juvenile fish were adapted to two extruded diets: one higher in protein and lower in carbohydrate, C: 45/28 and the other higher in carbohydrate and lower in protein, HC: 37/40. Gross energy was 19 MJ kg⁻¹ DM in both diets. Protein and lipid digestibility were high and similar in both groups (≈90%), whereas total and carbohydrate digestibility and digestible energy were lower in the HC-fed group than in the C-fed group. Consequently, when fish were adapted to the diets, plasma levels of glucose and insulin differed between diets. HC-group presented higher plasma glucose levels and lower plasma insulin levels than C-group. Protein synthesis rates in white muscle, liver and whole body did not differ significantly between diets. In contrast, protein accretion rate of white muscle and whole body were significantly lower in the HC group, indicating an increase of protein degradation in these tissues and a decrease of synthesis retention efficiency. In spite of the daily protein intake of HC group was lower than C-group, the anabolic stimulation efficiency was increased by 34% in HC group. Protein and lipid contents in white muscle and liver were stable throughout the experiment. No hepatomegalia or increased fat deposition was observed in fish fed HC. Differences in specific growth rates (C: 0.88%; HC: 0.77%) were associated more with the lower protein consumption rate and the lower level of digestible energy in fish fed HC than with the higher dietary carbohydrate content of the diet.     

The effect of dietary protein source on growth and carcass composition in juvenile Australian freshwater crayfish

A feed trial was conducted for 12 weeks on juvenile Australian freshwater crayfish (Cherax destructor) (mean weight (SE) 0.82 (0.02)g) maintained on five isoenergetic diets with a protein content of 30%. Diets differed in the primary source of protein used, with meat, snail, soybean, yabby, and zooplankton meals comprising the major protein ingredient, varying from 56–60% of total protein. Mean percentage weight gain per day ranged from 7.57% (yabby meal diet), to 9.42% (snail meal diet). No significant difference occurred in mean weight, percentage weight gain, specific growth rate (%), or survival among diets. A maximum size of 16.44g was attained on the yabby meal diet. Largest mean weight was 8.27g on the snail-based diet. Food conversion ratios were all good, with a minimum value of 0.95 recorded for the snail-based diet. Initial food consumption per day was approximately 5% of mean animal weight, decreasing to around 2.4%, and is collectively described by a power curve. Protein retention ranged from 29.57% in the zooplankton meal diet to 41.15% in the snail-based diet. Carcass composition was influenced by feed type, with the most marked difference occurring in carapace colour. Animals fed the zooplankton-based pellets developed the strongest pigmentation. Recommendations are made for including certain protein-based ingredients in manufactured yabby diets.