Effect of high levels of dietary vitamin C on the blood responses of matrinxã (Brycon amazonicus)

Juvenile matrinx? (Brycon amazonicus) were fed with different dietary vitamin C (ascorbic acid or AA) concentrations for 2 months in order to evaluate its effect on the physiological condition of this species. Five treatments were tested: Reference diet-RD (350 mg AA kg(-1) and 45% crude protein commercial feed); C400, C500, C600 and C800 with supplementation of 400, 500, 600 and 800 mg AA kg(-1). Fish fed 800 mg AA kg(-1) supplemented diets presented greater weight gain and survival. Hematocrit, hemoglobin concentrations and erythrocytes showed significant increase (p<0.05) in C600 and C800 relatively to the others. Total leukocyte values were significantly higher in fish fed vitamin C supplemented diets relatively to those fed RD and leukocytes count of C600 and C800 were the highest among the treatments. Monocytes were the only cells of fish defense mechanism that presented variation, and C600 and C800 presented the lowest values (P<0.05). Glucose level was significantly different relatively to RD only in C400 and the plasmatic total protein values for fish fed vitamin C supplemented diets were higher than for fish fed the RD. Fish plasmatic ions (Na(+) and Cl(-)) were significantly lower for C500, C600 and C800 relatively to C400 and RD. The physiological profile and the growth performance of matrinx? suggest that diet supplemented with 800 mg AA kg(-1) can improve its performance and increase the survival rate.     

Dietary nucleotides influence immune responses and intestinal morphology of red drum Sciaenops ocellatus

Dietary nucleotides have been shown to benefit many physiological and nutritional functions in higher vertebrates and fish. Therefore, a 6-week feeding trial was conducted to evaluate the effects of graded levels of a commercial nucleotide product on growth performance, immune responses and intestinal morphology of juvenile red drum (initial average weight of 7.1 g). The basal diet was formulated to contain 40% protein, 10% lipid and a digestible energy level of 3.5 kcal g^?1. Two levels of nucleotide (Ascogen P^®, 0.5% and 1% of diet) were added to the basal diet with menhaden fishmeal and menhaden oil adjusted to provide isonitrogenous and isolipidic diets. Nucleotide supplementation tended to improve weight gain and survival of red drum, but not at a significant level. Neutrophil oxidative radical anion production and serum lysozyme activity tended to be higher for fish fed diets supplemented with nucleotide, while extracellular superoxide anion production of head kidney macrophages from fish fed diets with 1% nucleotide was significantly (P < 0.05) increased, although no significant differences were observed between fish fed 0.5% nucleotide diet and the basal diet.Nucleotide supplementation significantly (P < 0.05) increased fold height in the proximal intestine, and enterocyte height in the pyloric caeca, proximal and distal enteric sections. A significantly (P < 0.05) higher microvilli height was observed in all evaluated enteric sections of fish fed with diets supplemented with nucleotides. It is therefore possible to use dietary nucleotides supplementation to significantly enhance the intestinal structure of red drum. Likewise, nucleotides in the diet may improve some components of the non-specific immune response of this sciaenid fish.     

Dietary vitamin C and its derivatives affect immune responses in grass shrimp, Penaeus monodon

Effects of L-ascorbic acid (AA) and its four derivatives, namely L-ascorbyl-2-sulfate (C2S), L-ascorbyl-2-polyphosphate (C2PP), L-ascorbyl-2-monophosphate-Na (C2MP-Na) and L-ascorbyl-2-monophosphate-Mg (C2MP-Mg) on the immune responses of juvenile grass shrimp, Penaeus monodon, were studied. The vitamin C deprived diet together with diets supplemented with either adequate or high (five times adequate) levels of AA, C2S, C2PP, C2MP-Na and C2MP-Mg were each fed to triplicate groups of shrimp (mean initial weight: 0.37 +/- 0.01 g) for 8 weeks. Significantly (P<0.01) higher weight gain (WG), feed efficiency (FE), survival, total haemocyte count (THC), superoxide anion (O2) production ratio and phenoloxidase (PO) activity were observed in shrimp fed diets supplemented with adequate and high levels of ascorbate than shrimp fed the vitamin C deprived diet, regardless of the ascorbate source. Among the ascorbate sources, shrimp fed C2MP-Mg and C2PP containing diets had higher THC than shrimp fed AA, C2S and C2MP-Na containing diets, regardless of the supplementation level. Shrimp fed adequate levels of C2MP-Mg and C2PP and high levels of C2MP-Mg containing diets had higher O2 production ratios than shrimp fed AA and C2S containing diets. Shrimp fed adequate levels of C2MP-Mg and C2PP and high levels of C2PP containing diets had higher PO activity than shrimp fed AA, C2S and C2MP-Na containing diets. These data suggest that dietary ascorbate enhances immune responses in P. monodon and different ascorbate sources may affect the immune responses differently.     

Effect of dietary ascorbic acid on growth and non-specific immune responses of tiger puffer, Takifugu rubripes

We report nutritional physiology and non-specific immune responses of ascorbic acid (AA) in puffer fish for the first time. This study aimed to examine the essentiality and requirements of AA in diets for the tiger puffer, Takifugu rubripes based on growth performance, liver AA and bone collagen concentration, and non-specific immune responses. Five casein-gelatin based semi-purified diets were formulated to contain five graded levels of l-ascorbyl-2-monophosphate at 0, 40, 80, 160 and 700mg/kg (designated as AMP0, AMP40, AMP80, AMP160 and AMP700, respectively) and fed to triplicate groups of fish. After 10weeks of feeding trial, growth performances of fish (initial body weight, 35g) fed the AMP0 were significantly lower compared to that of fish fed diets supplemented with AMP. The fish fed the AMP0 diet also exhibited significantly lower hematocrit, condition factor and hepatosomatic index compared to the fish fed diets supplemented with AMP. Phagocytic activity (NBT assay) was significantly lower in fish fed the AMP0 diet than in fish fed the AMP containing diets. Plasma lysozyme activity of fish fed the AMP80 and AMP160 was significantly higher than that of fish fed the AMP0. Dietary supplementation of AMP significantly increased the liver superoxide dismutase in the fish. Myeloperoxidase activity of fish fed the AMP0 was significantly lower compared to that of fish fed the AMP containing diets. Bone collagen level tended to increase numerically and total AA concentration in liver of fish was significantly increased in a dose dependent manner by the supplementation of AMP. Therefore, tiger puffer requires exogenous ascorbic acid and the optimum dietary level could be 29mg AA/kg diet for normal growth and physiology. Dietary AA concentration over 82mg/kg could be required to enhance non-specific immune responses of the fish. However, it does not seem that the fish needs an overdose of dietary AA (>160mg/kg) for better non-specific immune responses.     

Effect of dietary vitamin C on the growth performance and innate immunity of juvenile cobia (Rachycentron canadum)

This study was conducted to evaluate the effects of dietary vitamin C on growth performance, hematologic parameters and innate immune responses in juvenile cobia, Rachycentron canadum. Seven practical diets were formulated to contain 0.0 (as the basal diet), 13.6, 27.2, 54.4, 96.6, 193.4 and 386.5 mg ascorbic acid equivalent kg(-1) diet. Each diet was fed to triplicate groups of juvenile cobia with initial body weight of 5.5 g in 500-L cylindrical fiberglass tank. The results of 8 weeks feeding trial showed that typical vitamin C-deficient signs such as spinal deformation and body nigrescence were observed in the fish fed the basal diet. Fish fed the basal diet had significantly lower weight gain, specific growth rate (SGR), protein efficiency ratio (PER) and feed efficiency (FE) than those fed the diets supplemented with vitamin C, but no significant differences were observed among diets supplemented with vitamin C. However, survival rate was significantly affected by the dietary vitamin C levels, fish fed the basal diet had lower survival rate than those fed the diets supplemented with vitamin C. The ascorbic acid concentration in liver was correlated positively with the dietary vitamin C levels, however, the thiobarbituric acid reactive substances (TBARS) concentrations in liver was not significantly affected by the dietary vitamin C levels, although, fish fed the basal diet had the highest TBARS values among all treatments. The activities of serum lysozyme, superoxide dismutase (SOD), alkaline phophatase (AKP) and total immunoglobulin (Ig) were significantly influenced by the dietary vitamin C levels, fish fed the basal diet had lower lysozyme, SOD, AKP and total Ig than those fed diets supplemented with vitamin C. The serum glucose and triglyceride concentrations were significantly affected by the dietary vitamin C levels. Fish fed the basal diet had lower red blood cell and hemoglobin values than those fed the vitamin C supplemented diets. The challenge experiment with Vibrio harveyi showed that lower cumulative survival was in fish fed the unsupplemented diet, the cumulative survival were significantly increased with increase of the dietary ascorbic acid levels from 13.6 to 96.6 mg kg(-1), while the cumulative survival reached plateau when dietary ascorbic acid levels increased from 96.6 to 386.5 mg kg(-1). These results indicated that dietary vitamin C did significantly influence on growth performance and immune response of juvenile cobia.     

Lysine and arginine requirements of juvenile Asian sea bass (Lates calcarifer)

Two separate experiments were conducted to determine the dietary requirements of juvenile Asian sea bass Lates calcarifer Bloch for lysine and arginine. Fish (average initial weight: lysine experiment, 13.12 ± 0.12 g; arginine experiment, 2.56 ± 0.13 g) were given amino acid test diets for 12 weeks containing fish meal, zein, squid meal, and crystalline amino acids. Each set of isonitrogenous and isocaloric test diets contained graded levels of L ‐lysine or L ‐arginine. The feeding rate in the lysine experiment was at 4–2.5% of the body weight day^?1, while in the arginine experiment it was at 10–4% of the body weight day^?1. The fish (20 per tank, lysine experiment; 15 per tank, arginine experiment) were reared in 500‐L fibreglass tanks with continuous flowthrough sea water at 27 °C and salinity of 31 ppt in the lysine experiment and at 29 °C and salinity of 29 ppt in the arginine experiment. The experiments were in a completely randomized design with two replicates per treatment. Survival was high in fish given adequate lysine or arginine. Mean percentage weight gains were significantly different in fish fed varying levels of lysine or arginine. Fish fed high levels of L ‐arginine suffered high mortalities. No significant differences were obtained in the feed efficiency ratios (FER, g gain g^?1 feed) of fish fed graded lysine, although the values tended to increase as the dietary lysine level was increased up to the requirement level. In contrast, in the arginine experiment, significant differences in FER of fish among treatments were obtained; the highest FER was observed in fish fed the diet containing an optimum arginine level. On the basis of the growth response, survival, and FER, the lysine and arginine requirements of juvenile Asian sea bass were estimated to be 20.6 g kg^?1 dry diet (4.5% protein) and 18.2 g kg^?1 dry diet (3.8% protein), respectively. These data will be useful in the further refinement of practical diet formulations for the Asian sea bass.     

Effects of amino acid supplementation on the nutritive quality of fermented linseed meal protein in the diets for rohu, Labeo rohita, fingerlings

A feeding trial was conducted for 8 weeks to examine the effects of partial substitution of fish meal (FM) protein (crude protein content: 58.5%) with linseed meal protein with and without supplemental amino acids in diets for rohu Labeo rohita (Hamilton), fingerlings (mean weight: 1.50 ± 0.3 g). Prior to incorporation into the diets, linseed meal was fermented with lactic acid bacteria ( Lactobacillus acidophilus ) to reduce/eliminate the antinutritional tannin and phytic acid factors. Twelve experimental diets (diets D1–D12) were formulated to replace the FM protein from a reference diet (RD) with linseed meal protein at different levels (four sets of diets, of which each set of three diets contained 25%, 50% and 75% replacement of FM protein by linseed meal protein, respectively). Diets D1–D3 were not supplemented with any amino acid. Lysine was supplemented in diets D4–D6. Diets D7–D9 were supplemented with methionine + cystine (together), and diets D10–D12 contained lysine and methionine + cystine (together). Lysine and methionine + cystine (together) were added to the diets at 5.7% and 3.1% of dietary protein, respectively. The groups of fish fed diets without amino acid supplementation had significantly lower percentages of weight gain, specific growth rate and high feed : gain ratio than the fish groups fed other experimental diets. The addition of lysine and methionine + cystine to the diet in which 50% of the FM protein was replaced by linseed meal protein (diet D11) significantly improved fish performance. The results of the present study suggest that rohu fingerlings can effectively utilize the supplemented amino acids and that linseed meal protein can replace up to 50% of the FM protein in rohu diets if the linseed meal is properly processed (fermented) and supplemented with the lacking amino acids.     

Copper transporter 1, metallothionein and glutathione reductase genes are differentially expressed in tissues of sea bream (Sparus aurata) after exposure to dietary or waterborne copper

The high affinity copper transporter 1 (Ctr1), metallothionein (MT) and glutathione reductase (GR) are essential for copper uptake, sequestration and defense respectively. Following rearing on a normal commercial diet (12.6+/-0.2 mg kg(-1) Cu), sea bream were fed an experimental control diet lacking mineral mix (7.7+/-0.3 mg kg(-1) Cu), an experimental diet enhanced with Cu (135+/-4 mg kg(-1) Cu) or an experimental diet (7.7+/-0.3 mg kg(-1) Cu) whilst exposed to Cu in water (0.294+/-0.013 mg L(-1)). Fish were sampled at 0, 15 and 30 days after exposures. Fish fed the Cu-enhanced experimental diet showed lower levels of expression of Ctr1 in the intestine and liver compared to fish fed control experimental diets, whilst Ctr1 expression in the gill and kidney was unaffected by excess dietary Cu exposure. Waterborne-Cu exposure increased Ctr1 mRNA levels in the intestine and the kidney compared to experimental controls. Excess dietary Cu exposure had no effect on levels of metallothionein (MT) mRNA, and the only effect of dietary excess Cu on glutathione reductase (GR) mRNA was a decrease in the intestine. Both MT mRNA and GR were increased in the liver and gill after waterborne-Cu exposure, compared to levels in fish fed experimental control low Cu diets. Thus, Ctr1, MT and GR mRNA expression in response to excess Cu is dependent on the route of exposure. Furthermore, the tissue expression profile of sea bream Ctr1 is consistent with the known physiology of copper exposure in fish and indicates a role both in essential copper uptake and in avoidance of excess dietary and waterborne copper influx.     

Effect of low-protein amino acid-supplemented diets on the growth performance, gut morphology, organ weights and digesta characteristics of weaned pigs

A 21-day study was conducted to determine whether isoleucine might limit the performance of piglets fed low-crude protein (CP), amino acid (AA)-supplemented diets and to investigate the potential benefits of low-CP diets on gastrointestinal health in weaned pigs. Ninety-six piglets (initial BW = 6.44 ± 0.14 kg), housed four per pen, were randomly assigned to one of four diets, resulting in six replicate pens per diet. Dietary treatments were as follows: (1) 210 g/kg CP diet, (2) 190 g/kg CP diet deficient in isoleucine, (3) 190 g/kg CP diet supplemented with crystalline isoleucine up to the level in the 210 g/kg CP diet and (4) 170 g/kg CP diet supplemented with isoleucine and valine on the ideal protein ratio basis (60% and 70% relative to lysine, respectively). Pigs were allowed to adapt to the new environment for 4 days before the experiment commenced. Overall, pigs fed the 210 g/kg CP diet had higher (P < 0.05) average daily gain and lower (P < 0.05) feed : gain ratio compared with those fed the other diets. The faecal consistency score of pigs fed the 210 g/kg CP diet was higher (P < 0.05) than those fed the other diets. Pigs fed the 170 g/kg diet had lower (P=0.02) small intestine weight than those fed the 210 g/kg CP diet. Pigs fed the 210 g/kg CP diet had deeper (P < 0.05) crypt in the duodenum and ileum and higher (P < 0.05) ammonia N concentration in caecal digesta than those fed the other diets. There were no effects of diet on microbial population and volatile fatty acid concentration in the caecal digesta except for propionic acid whose concentration was higher (P < 0.05) for pigs fed the 170 g/kg diet than those fed the 190+isoleucine and the 210 g/kg CP diets. The results indicate that the low-CP, AA-supplemented diet reduced crypt hypertrophy, ammonia N concentration in the caecal digesta, small intestine weight and the performance of piglets. Also, the results of the current study were inconclusive with respect to whether isoleucine may limit the performance of pigs fed a low-CP, AA-supplemented diet.     

Partial replacement of monocalcium phosphate with neutral phytase in diets for grass carp,Ctenopharyngodon idellus

A 9‐week experiment was designed to study the effects of partial replacement of monocalcium phosphate (MCP) with neutral phytase on growth, body compositions, serum biochemical statuses and intestinal digestive enzyme activities of grass carp, Ctenopharyngodon idellus. The control diet (designated as P2.0) was prepared with 2.0% MCP but without phytase. The three other diets (designated as PP1.5, PP1.0 and PP0.5, respectively) were supplemented with 1.5, 1.0 and 0.5% MCP, respectively, along with 500 FTU of neutral phytase kg^?1 diet in each. After a 9‐week feeding trial, fish (initial body weight: 43.44 ± 2.37 g) fed with PP1.5 and PP1.0 had no significant change in weight gain (WG), specific growth rate (SGR), protein efficiency rate (PER) or feed conversion ratio (FCR) compared with the control (P > 0.05) whereas fish fed with PP0.5 showed significantly lower growth performance in the above parameters. The crude lipid content in whole body or muscle of the fish fed with PP1.5 was significantly lower than the control while significantly higher in fish fed with PP0.5 (P < 0.05), whereas no obvious change was observed in the fish fed with PP1.0. For serum indices, higher serum alkaline phosphatase (Alkp), phosphorus (P) and calcium (Ca) contents were observed in fish fed with phytase‐supplemented diets in comparison with the control. In addition, dietary phytase supplementation increased amylase activity and decreased lipase activity in both foregut and hindgut. The present study suggests that dietary MCP can be reduced when neutral phytase is added to the grass carp diet, and that the maximum MCP reduction level can be up to 1% when neutral phytase is supplemented at 500 FTU kg^?1 diet.     

In vivo fractional P(i) absorption and NaPi-II mRNA expression in rainbow trout are upregulated by dietary P restriction

Mammalian type II sodium-phosphate cotransporter (NaPi-II) and inorganic phosphate uptake stimulator (PiUS) genes are upregulated by dietary phosphorus (P) restriction to increase intestinal and renal P transport, but little is known about NaPi-II and PiUS regulation in other vertebrates. We studied the 1). the tissue distribution and dietary regulation of NaPi-II, PiUS, and sodium-glucose cotransporter (SGLT1) mRNA and NaPi-II protein in juvenile rainbow trout (Oncorhynchus mykiss) and 2). effects of dietary P on intestinal Pi absorption in vivo. NaPi-II, PiUS, and SGLT1 mRNA were found in the proximal and distal intestine, pyloric ceca, and kidney. PiUS mRNA was also found in the heart, gill, blood, stomach, liver, skin, and muscle. Tissue distribution of NaPi-II protein correlated with that of NaPi-II mRNA except in gill ionocytes where NaPi-II antibodies recognized related epitopes. Chronic consumption of a low-P diet increased NaPi-II and PiUS but not SGLT1 mRNA abundance in the intestine and kidney. Unlike mammals, there was no detectable shift in tissue or cellular localization of NaPi-II protein in response to dietary P restriction. Regulation of NaPi and PiUS mRNA expression was observed only in fish grown under optimal aqueous oxygen concentrations. In vivo fractional absorption of Pi by the intestine decreased in fish fed high-P diets. Decreases in absorption were less pronounced in fish previously fed low-P diets, suggesting that diet history modulates acute regulation of P absorption. Regulation of dietary Pi absorption in vivo may involve a specific change in intestinal NaPi-II and PiUS gene expression.     

Indispensable amino acid concentrations decrease in tissues of stomachless fish,common carp in response to free amino acid- or peptide-based diets

Summary. The premise that free amino acid or dipeptide based diets will resolve the nutritional inadequacy of formulated feeds for larval and juvenile fish and improve utilization of nitrogen in comparison to protein-based diets was tested in stomachless fish, common carp (Cyprinus carpio L.) larvae. We examined the postprandial whole body free amino acid (FAA) pool in fish that were offered a FAA mixture based diet for the duration of 2 or 4 weeks. We found that the total amount and all indispensable amino acids concentrations in the whole body decreased after a meal. We then fed juvenile carp with dietary amino acids provided in the FAA, dipeptide (PP), or protein (live feed organisms; brine shrimp Artemia salina nauplii, AS) forms. Histidine concentrations in the whole fish body increased in all dietary groups after feeding whereas all other indispensable amino acids decreased in FAA and PP groups in comparison to the AS group. Taurine appears to be the major osmotic pressure balancing free amino acid in larval freshwater fish which may indicate a conditional requirement. We present the first evidence in larval fish that in response to synthetic FAA and PP diets, the whole body indispensable free AA concentrations decreased after feeding. This study shows that amino acids given entirely as FAA or PP cannot sustain stomachless larval fish growth, and may result in depletion of body indispensable AA and most of dispensable AA. The understanding of these responses will determine necessary changes in diet formulations that prevent accelerated excretion of amino acids without protein synthesis.     

Effects of feeding low protein diets to piglets on plasma urea nitrogen, faecal ammonia nitrogen, the incidence of diarrhoea and performance after weaning

This study evaluated the effects of feeding pigs low protein (LP) diets for different lengths of time after weaning on indices of protein fermentation, the incidence of postweaning diarrhoea (PWD), growth performance, and total-tract apparent digestibility. Sixty weaner pigs weighing 6.1 +/- 0.13 kg (mean +/- SEM) were used in a completely randomised design having five treatments: (i) a high protein diet (HP, 243 g/kg CP) fed for 14 d after weaning (HP14); (ii) a low protein diet (LP, 173 g CP/kg) fed for 5 d after weaning (LP5); (iii) LP diet fed for 7 d after weaning (LP7); (iv) LP diet fed for 10 d after weaning (LP10), and (v) LP diet fed for 14 d after weaning (LP14). All diets were supplemented with lysine, methionine, tryptophan and threonine, with all LP diets additionally fortified with crystalline isoleucine and valine to conform to a proposed ideal amino acid (AA) pattern. A second-stage diet (215 g CP/kg) was fed to pigs at the conclusion of each treatment. None of the diets contained antimicrobial compounds. Feeding a LP diet, regardless of duration of feeding, decreased plasma urea nitrogen (p < 0.001) and faecal ammonia-nitrogen (p < 0.001) contents. Feeding a LP diet, irrespective of feeding duration, decreased the incidence of PWD at day 8 after weaning (p = 0.044), and pigs fed diets LP7, LP010 and LP14 had firmer faeces (p = 0.030, p = 0.047 and p = 0.007, respectively) between days 10 and 12 after weaning. Treatments LP5, LP7, LP10 and LP14 did not reduce (p > 0.05) growth performance up to 106 days after weaning compared to pigs fed the HP diet. Total-tract apparent digestibility of dry matter, energy and crude protein were similar (p > 0.05) between treatments. Our data suggest that feeding a LP diet, supplemented with AA to conform to an ideal AA pattern, for 7-10 days after weaning can reduce PWD in pigs fed antibiotic-free diets without compromising production.     

Estimation of protein digestibility—IV. Digestive proteinases from the pyloric caeca of coho salmon (Oncorhynchus kisutch) fed diets containing soybean meal

The goal of this study was to better understand why dietary soybean products are poorly utilized by salmonids. The influence of dietary intake on coho salmon fingerling weight gain and specific properties of pyloric caeca enzymes was investigated. Fingerlings were fed diets containing heated or unheated soybean meal (SBM) or Promoveal™, as 15–25% herring meal replacer, for 8–12 weeks. Fish fed to apparent satiation with diets containing heated SBM replacer gained more weight than those fed unheated SBM at the same level. Fish increased in body weight at the same rate when fed restricted rations containing either 15% SBM replacer that was variously heated up to 20 min, 15% Promoveal™ replacer or the herring meal basal diet. After the experimental diets were fed, digestive proteinases were isolated from the pyloric caeca. Yield of pyloric caeca enzymes (PCE), recovery of trypsin in PCE, soybean trypsin inhibitor (SBTI) sensitivity of PCE trypsin, specific activity of PCE trypsin and in vitro casein digestibility by PCE were determined for each dietary group. Weight gain vs in vitro casein digestibility by PCE was linear for animals fed unheated SBM to apparent satiation (r² = 0.71, P < 0.1) but not for animals fed either heated SBM to apparent satiation or variously heated SBM as 15% replacer at restricted levels. Trypsin from fish fed diets with heated or unheated SBM, but not Promoveal™ replacer, was less sensitive to SBTI than fish fed no SBM. For fish fed diets with variously heated SBM as 15% replacer, the SBTI activity of the SBM and SBTI inhibition of PCE trypsin were inversely related (r² = 0.88, P < 0.05). The yield of PCE was higher for fish fed 25% of heated SBM replacer than it was for diet groups fed less SBM. The yield of PCE trypsin was higher from animals fed 25% heated SBM replacer than those fed diets with a lower percentage of heated SBM replacer. Feeding coho fingerlings rations with SBM replacer appears to promote physiological compensation of PCE. Heat stable and/or heat-activated factor(s) and SBTI appear to cause the compensation of salmon digestive proteinases from coho salmon fed diets with SBM.     

不同人工饲料对刀鲚幼鱼生长、血清生化指标及脂质代谢酶活性的影响

试验选择体长、体质量基本一致的6月龄刀鲚,分别投喂日粮1(人工配合软颗粒饲料)、日粮2(人工配合饲料与鱼油混合的软颗粒饲料)及日粮3(人工配合缓沉硬颗粒料)3种配合饲料60 d,探讨不同人工饲料对刀鲚幼鱼生长性能、血清生化指标及脂质代谢酶活性的影响.结果表明: 日粮2组和日粮3组的幼鱼体质量、体质量增长率、特定生长率和肥满度显著高于日粮1组;日粮3组的饵料系数显著低于日粮1组和日粮2组;各组间体长、体长/体高、体长/体厚、肝体比及脏体比等生长指标及总蛋白、白蛋白、血糖、胆固醇和甘油三酯等血清生化指标均无显著差异;日粮1组的肉碱软脂酰基转移酶-Ⅰ(CPT-Ⅰ)含量显著高于日粮2组和日粮3组;日粮2组的肉碱软脂酰基转移酶-Ⅱ(CPT-Ⅱ)含量显著低于日粮1组和日粮3组;各组间淀粉酶、胃蛋白酶、脂肪酶活性及脂蛋白脂酶(LPL)和乙酰辅酶A羧化酶(ACC)含量均值无显著差异.表明日粮中添加多不饱和脂肪酸有利于刀鲚幼鱼的生长,缓沉饲料的利用效率最高,适合于刀鲚幼鱼驯养阶段使用.     

Phytase can reduce theneedfor monocalcium phosphate supplementation in soybean and rapeseed meal‐based diets of black sea bream,Acanthopagrus schlegelii (Bleeker, 1854)

A feeding trial was conducted to study the effect of partial replacement of dietary monocalcium phosphate (MCP) with phytase on growth performance, feed utilization and phosphorus discharge in black sea bream, Acanthopagrus schlegelii. In the feeding trial, the control diet (designated as P1.5) was prepared with 1.5% MCP but without phytase, and the three other diets (designated as PP1.0, PP0.5 and PP0, respectively) were supplemented with 1.0%, 0.5% and 0% MCP, respectively, along with 200 mg (400 U) phytase/kg diet in each. Each diet was tested in triplicate tanks and fish were fed twice daily to satiation. After an 8‐week feeding trial in indoor flow‐through cylindrical fibreglass tanks (25 fish per tank, initial body weight: 11.5 ± 0.12 g), fish fed with PP1.0 and PP0.5 had no significant change in weight gain (WG), specific growth rate (SGR), protein efficiency rate (PER) or feed conversion ratio (FCR) compared to the control (p > .05), whereas fish fed with PP0 showed a significantly lower growth performance in the above parameters (p < .05). The addition of phytase did not affect the body composition or muscle composition. The apparent digestibility coefficients (ADCs) of crude protein and phosphorus increased when fish were fed diets in which MCP was replaced by phytase. Phosphorus discharge was also significantly reduced in fish fed diets in which MCP was replaced by phytase (10.2 ± 0.50 to 8.01 ± 0.47 g/kg weight gain). The present study suggests that dietary MCP can be reduced when phytase is added to the black sea bream diet, with a maximum MCP reduction level of up to 1% when phytase is supplemented at 200 mg (400 U)/kg diet. Thus, phytase in the diet of black sea bream is economically and ecologically beneficial.     

Ileal and total tract digestibility and nitrogen utilisation in blue fox (Vulpes lagopus) fed low-protein diets supplemented with DL-methionine and L-histidine

ABSTRACT

To formulate low-protein diets for blue foxes with sufficient amounts of amino acids (AA), AA digestibility and AA requirements of the animals are crucial information. Therefore, a digestibility and nitrogen (N) balance trial was conducted with 20 blue foxes to determine the macronutrient and AA digestibility and N utilisation in low-protein diets supplemented with DL-methionine (Met) and L-histidine (His). In addition, plasma urea and plasma AA were measured. The diets were designated as P24 (control), P20, P20M, P16M and P16MH and contained energy from digestible crude protein (DCP) at 24%, 20% or 16% of total dietary metabolisable energy (ME). The 20% protein level was fed with or without Met and the 16% protein level was fed with Met and with or without His. The apparent total-tract digestibility (ATTD) of crude protein linearly decreased with decreasing dietary protein level. The ATTD of dry matter, organic matter and crude carbohydrates increased when wheat starch was added as a replacement for protein. The apparent ileal digestibility (AID) and ATTD methods were compared to determine the AA digestibility. The decreasing dietary protein supply decreased the ATTD of most of the AA: threonine, tryptophan (Trp), valine, alanine (Ala), aspartic acid (Asp), glutamic acid, glycine (Gly), proline (Pro), serine (Ser) and total AA. The AID of the AA was constant between diets. Diverging AA showed higher or lower digestibility when determined in the AID or ATTD methods. Isoleucine, lysine, Met, Ala and tyrosine showed higher levels of AID. Arginine, His, cysteine (Cys), Trp, Asp, Gly, Pro and Ser showed higher levels of ATTD, which may reflect the net loss of these AA in the large intestine. Met and His supplementation improved the ATTD and AID of the AA in question, respectively, but did not affect the other variables examined. N retention did not differ between diets and renal N excretion decreased with decreasing protein level; thus N utilisation improved. It was concluded that the protein supply and AA composition in low-protein diets with supplemented Met were adequate for adult blue foxes, since the lower protein supply improved N utilisation and did not affect N retention. However, His supplementation failed to reach the designed level and therefore showed no clear results.     

AMINO ACIDS AND CEREBRAL EXCITABILITY1

Abstract— —Seizure threshold, measured with hexafluorodiethyl ether, was shown to be reduced in immature albino rats fed a diet containing excess tryptophan. Similar diets containing excess glycine, serine, leucine, valine or lysine had no effect on seizure threshold. Previous studies had shown phenylalanine, tyrosine and methionine to enhance cerebral excitability with the same technique. The increased cerebral excitability was shown to occur within 24 hr following diet supplementation with phenylalanine. Brain concentration of hexafluorodiethyl ether was identical in control and experimental animals, although the experimental animals had lowered seizure thresholds; this established an alteration in cerebral excitability rather than variation in tissue penetration by the convulsant. Alterations were found in blood and brain ammonia in serine, lysine and methionine supplemented animals. Brain glutamate and glutamine were lowered in methionine-supplemented animals; however, it was concluded that this effect was not causally related to the increased cerebral excitability.