Effects of dietary carbohydrates and temperatures on slow growing juvenile eels Anguilla anguilla

Synopsis The influence of the level of carbohydrate in a purified diet on the growth of slow-growing Anguilla anguilla maintained at different temperatures was examined. The average weight increase of eels maintained at temperatures of 25° or 27° C and fed a diet containing 20% or 30% glucose, was significantly higher than the mean weight increase of eels maintained at the same temperature but fed a diet containing soluble corn starch, at the same percentages. There was no significant difference in the mean weight of slow growing eels fed 10%, 20% and 30% soluble corn starch or 10% glucose. There was no significant difference in protein content (wet weight) among the experimental groups. However, elvers that were fed a high percentage of carbohydrates (glucose or starch) and maintained at 27° C had a higher percentage of lipids in body weight compared with the other experimental groups.     

芙蓉鲤鲫幼鱼饲料适宜淀粉含量

实验以鱼粉和酪蛋白为主要蛋白源、以鱼油和豆油为主要脂肪源(鱼油/豆油, 1/1), 设计了7组不同玉米淀粉水平(6%、12%、18%、24%、30%、36%和42%)的等氮(35%)等脂(8%)饲料来饲喂芙蓉鲤鲫(Carassiusauratus var Furong carp ♀Cyprinus carpio red crucian carp ♂)幼鱼(8.940.59) g以确定其最适饲料淀粉水平。实验周期为61d。结果表明, 随饲料玉米淀粉水平的增加实验鱼增重率、特定生长率和饲料效率先上升(P0.05)而后趋于稳定, 18%42%饲料玉米淀粉组之间差异不显著(P0.05)。鱼体蛋白沉积率随饲料玉米淀粉水平的增加而增加, 30%和42%处理组显著高于6%和12%处理组(P0.05)。血浆葡萄糖没有受饲料玉米淀粉水平的影响(P0.05), 血浆总胆固醇含量在30%处理组最高(P0.05), 血浆甘油三酯随饲料玉米淀粉水平的增加而上升(P0.05)。肝糖原随饲料玉米淀粉水平的增加而上升, 36%处理组显著高于6%和12%处理组(P0.05)。肌糖原和肠道淀粉酶活性随饲料玉米淀粉水平增加而显著上升(P0.05)。通过特定生长率和饲料淀粉水平的折线法分析表明, 芙蓉鲤鲫幼鱼达到最大生长时饲料淀粉水平为27.47%。     

The relationship of eel Anguilla anguilla (L.) body size, lipid, protein, glucose, ash, moisture composition and enzyme activity (aldolase)

Body composition: protein, lipid, ash, moisture; and enzyme activity (aldolase) were studied in European eels (Anguilla anguilla) of various sizes. The fish were brought to the laboratory as glass eels (0.35 g) and maintained under controlled conditions (23 degrees C) for one year. After one year of growth, various sizes (between 9 and 420 g) were found. Significant correlation coefficients of the equation W = a ln C + b (where W = body weight, in g; C = composition, % or activity, u; and a,b are constants) were found among the composition parameters: protein, lipid, glucose and aldolase. Relative amounts of protein, glucose, moisture, ash and aldolase activity were found to decrease with an increase in the weight of eels, but the percentage of fat was higher in large eels than in small ones.     

虹鳟幼鱼对不同淀粉的利用

试验旨在考察不同淀粉种类对虹鳟(Oncorhynchus mykiss)幼鱼生长性能、血清生化指标、肝脏糖代谢酶、肝脏组织学和摄食后血糖含量的影响。选用木薯淀粉、小麦淀粉、豌豆淀粉和玉米淀粉为淀粉源,设置相同的淀粉水平(15%),配制4组等氮等脂饲料,饲喂初始体重(7.7±0.1) g的虹鳟56d。结果表明,木薯淀粉组增重率最高(1049.3%),饲料系数最低(0.83)。各组脏体比、肝体比、全鱼和肝脏常规组成无显著差异(P>0.05);豌豆淀粉组肝糖原含量显著低于其他组(P<0.05)。各组血清甘油三酯、总胆固醇、谷草转氨酶和谷丙转氨酶无显著差异(P>0.05)。木薯淀粉组和小麦淀粉组肝脏己糖激酶活性显著高于豌豆淀粉组和玉米淀粉组(P<0.05),玉米淀粉组肝脏磷酸果糖激酶活性显著低于木薯淀粉组和小麦淀粉组(P<0.05)。摄食后,各组的血糖含量均在7h达到最高,木薯淀粉组在摄食后1—7h内的血糖含量显著高于其余3组(P<0.05)。各组的肝脏组织形态无显著差异。综上,木薯淀粉较其他3种淀粉更适宜作为虹鳟饲料的淀粉源。     

Response of hexokinase enzymes and the insulin system to dietary carbohydrates in the common carp, Cyprinus carpio

The response of the common carp to diets with varying amounts of digestible starch, provided either as pea meal (LP, HP, 30 and 46% peas, respectively) or as cereal (LW, HW, 30 and 46% wheat, respectively), was studied and compared with the response to a carbohydrate-free protein-rich diet (CF). Here we focused on the utilisation of dietary carbohydrates by examining the relationship between dietary starch intake, hepatic hexokinase activities, circulating insulin and muscle insulin receptor system. Plasma glucose concentration and hepatic high Km hexokinase (glucokinase, GK) activity were not affected by the content of digestible starch, but 6 h after feeding enzyme activity was higher in the fish fed carbohydrate diets. Similarly, low Km hexokinase (HK) activity was also higher in the fish 24 h after feeding. Fat gain and protein retention were significantly improved by increased digestible starch intake, especially in the HP group, which in turn, presented the highest plasma insulin levels. Glycogen stores were moderately increased by the ingestion of digestible starch. The number of insulin receptors was greater in the CF group than in fish on carbohydrates, except the HP group. Our results confirmed that the common carp uses dietary carbohydrates efficiently, especially when there are provided by peas. This efficiency might be related to the enhanced response of postprandial insulin observed in the HP group.     

The effect of dietary fat on the activity,content, rates of synthesis,and degradation and translation of messenger RNA coding for malic enzyme in mouse liver

The specific activity (units activity/mg cytosolic protein) of malic enzyme was found to be three-fold higher in the livers of mice fed a semipurified diet containing 50% ($\text{w}\text{w}$) glucose and 15% ($\text{w}\text{w}$) saturated and monounsaturated but no polyunsaturated fat (hydrogenated cottonseed oil) over an 11-day period than in the livers of mice fed a standard laboratory mouse chow (Purina) diet. In contrast, when other lab chow-fed mice were fed an isocaloric diet containing 15% ($\text{w}\text{w}$) polyunsaturated fat (corn oil), no change in the specific activity of malic enzyme occurred over a similar period of time. Rocket immunoelectrophoresis performed on cytosols from both dietary groups demonstrated that the livers of mice consuming the hydrogenated cottonseed oil diet contained approximately three times more malic enzyme protein than did the livers from the corn oil-fed animals. In mice pulse-labeled with l-[4,5-³H]leucine, the rate of hepatic malic enzyme synthesis (relative to that for total protein) was approximately twofold greater in the hydrogenated cottonseed oil-fed mice than in their corn oil-fed counterparts whereas the rate of hepatic malic enzyme degradation was similar for both groups. Immunotitration of liver malic enzyme from hydrogenated cottonseed oil-fed and corn oil-fed mice revealed identical equivalence points, demonstrating that the catalytic efficiency of mouse liver malic enzyme had not been affected by the type of dietary fat administered. When total liver RNA, isolated from the hydrogenated cottonseed oil- and the corn oil-fed animals, was translated in cell-free translation systems (wheat germ extract and reticulocyte lysate) we found that both dietary treatments had resulted in an increase in the activity of malic enzyme messenger RNA. Furthermore, there were no significant differences between the two dietary groups in this regard. These results suggest that hepatic malic enzyme specific activity in high-carbohydrate polyunsaturated fat-fed mice is regulated principally by dietary-induced changes in the rate of enzyme synthesis and not by the activity of messenger RNA coding for the enzyme.     

Effect of leucine-rich dietary protein on in vitro protein synthesis in porcine muscle

Experiments were conducted to determine the effect of feeding diets containing leucine-rich proteins on in vitro protein synthesis in porcine muscle. Swine (10 kg initial weight) were fed for 4 weeks diets composed mainly of corn gluten meal, corn and soybean meal, and containing a total of 2.00, 2.33, 2.92, 3.12, 3.53, and 4.01% leucine. At the end of the growing period, six swine fed each diet were killed and samples of biceps femoris, longissimus dorsi, and triceps brachii were excised. Incorporation of [14C]phenylalanine into newly synthesized protein was measured using a cell-free in vitro system following recombination of purified soluble protein and ribosomal fractions. The feeding of diets containing increasing amounts of leucine-rich protein increased the free leucine concentration in plasma and skeletal muscle. There was no significant effect of diet on incorporation of [14C]phenylalanine into muscle protein following simple recombination of soluble protein and ribosomal fractions from the same tissues. Combination of muscle soluble protein from animals fed 2.00% leucine with ribosomal fractions of animals fed increasing quantities of leucine-rich protein, however, indicated increased protein synthetic activity of the ribosomal fraction in all muscles tested. Protein synthetic activity of the soluble protein fraction was not affected by diet. It was concluded that the feeding of leucine-rich dietary proteins beyond requirements for maximal rate of growth can increase the protein synthetic potential of porcine muscle cells although whole body growth is depressed.     

Effect of water temperature and dietary starch on growth and metabolic utilization of diets in gilthead sea bream (Sparus aurata) juveniles

We evaluated the effect of dietary starch level on growth performance, feed utilization, whole-body composition and activity of selected key enzymes of intermediary metabolism in gilthead sea bream juveniles reared at 18 and 25 degrees C. A diet was formulated to contain 48% crude protein, 12% lipids and 30% gelatinized maize starch (diet 30GS). Two other diets were formulated to include the same level of ingredients as diet 30GS except for the gelatinized starch, which was included at 20% (diet 20GS) or 10% (diet 10GS). No adjustment to diet composition was otherwise made. Each diet was fed to triplicate groups of gilthead sea bream (30 g initial mass) for 8 weeks, on a pair-feeding scheme. The higher temperature improved growth performance but the opposite was true for feed efficiency and protein efficiency ratio. Independently of temperature, growth performance, feed efficiency and protein efficiency ratio were lower in fish fed diet 30GS. No effect of temperature or dietary starch level on whole-body composition was noticed. Hepatosomatic index and liver glycogen were higher at 18 degrees C and, within each temperature, in fish fed diet 30GS. Glycemia was not affected by temperature, but was lower in fish fed diet 10GS. Data on enzyme activities showed that increasing water temperature enhances liver glucokinase (GK) and pyruvate kinase (PK) activities, suggesting that gilthead sea bream is more apt to use dietary starch at higher temperatures. No effect of temperature was noticed on hexokinase (HK), fructose-1,6-bisphosphatase (FBPase), glucose-6-phosphate dehydrogenase (G6PD) and glutamate dehydrogenase (GDH) activities. Dietary starch enhanced PK and FBPase activities while depressed GDH activity, suggesting a lack of significant regulation of hepatic glucose utilization and production in this species. HK, GK and G6PD activities were unaffected by dietary composition. Irrespectively of water temperature, gelatinized starch may be included up to 20% in diets for gilthead sea bream juveniles; at higher dietary levels, growth and efficiency of feed utilization are depressed.     

Effects of dietary lipid source on reproductive performance and tissue lipid levels of Nile tilapia Oreochromis niloticus (Linnaeus) broodstock

Nile tilapia were fed diets supplemented with one of the following lipid sources at 5% level: cod liver oil, corn oil, soybean oil, a coconut oil-based cooking oil or a combination of cod liver oil and corn oil (1 : 1). The control diet had no lipid supplement and tad fish meal as a sole protein source. A diet with soybean meal as a protein source was also tested. The number of females that spawned, spawning frequency, number of fry per spawning, and total fry production were increased at varying degrees by the supplemental lipid sources except for the cod liver oil. Fish fed the soybean oil diet tad the best overall reproductive performance over a 24-week period. Fish fed the cod liver oil diet had the highest weight gain but the poorest reproductive performance. The suplemental lipids significantly increased crude fat levels in the liver and ovaries. Both males and females Ld the cod liver oil diet had the highest levels of fat in the liver and muscle. The ratio of total n-6/n-3 fatty acid in the liver, ovaries and testes was influenced by the supplemental lipid sources. It was highest in fish fed either the soybean oil diet, the corn oil diet, or the soybean meal diet and lowest in fish fed the control diet or the cod liver oil diet.     

碳源和氮源对黑盖木层孔菌菌丝生长的影响

研究了四种碳源(蔗糖、乳糖、葡萄糖、可溶性淀粉)和九种氮源(玉米面、麸皮、马铃薯、大豆粉、酵母粉、蛋白胨、硝酸钾、硝酸铵、尿素)对黑盖木层孔菌菌丝生长的影响。从不同代数的菌丝体中提取多糖,并测定多糖含量、分子量分布范围及单糖组成。结果表明:黑盖木层孔菌菌丝生长的最佳碳源为可溶性淀粉,最佳氮源为玉米面,最优碳氮组合为蔗糖和玉米面的组合。不同代数的菌丝体多糖性状基本稳定。     

Glycemic index of a meal fed before exercise alters substrate use and glucose flux in exercising horses.

In a randomized, balanced, crossover study each of six fit, adult horses ran on a treadmill at 50% of maximal rate of oxygen consumption for 60 min after being denied access to food for 18 h and then 1) fed corn (51.4 kJ/kg digestible energy), or 2) fed an isocaloric amount of alfalfa 2-3 h before exercise, or 3) not fed before exercise. Feeding corn, compared with fasting, resulted in higher plasma glucose and serum insulin and lower serum nonesterified fatty acid concentrations before exercise (P < 0.05) and in lower plasma glucose, serum glycerol, and serum nonesterified fatty acid concentrations and higher skeletal muscle utilization of blood-borne glucose during exercise (P < 0.05). Feeding corn, compared with feeding alfalfa, resulted in higher carbohydrate oxidation and lower lipid oxidation during exercise (P < 0.05). Feeding a soluble carbohydrate-rich meal (corn) to horses before exercise results in increased muscle utilization of blood-borne glucose and carbohydrate oxidation and in decreased lipid oxidation compared with a meal of insoluble carbohydrate (alfalfa) or not feeding. Carbohydrate feedings did not produce a sparing of muscle glycogen compared with fasting.     

Dietary protein source affects lipid metabolism in the European seabass (Dicentrarchus labrax)

The study was undertaken to evaluate the effects of dietary protein sources on lipogenesis and fat deposition in a marine teleost, the European seabass (Dicentrarchus labrax). Four isonitrogenous (crude protein (CP, Nx6.25), 44% DM) and isoenergetic (22-23 kJ/g DM) diets were formulated to contain one of the following as the major protein source: fish meal (FM), one of two soy protein concentrates (SPC) and corn gluten meal (CGM). Apparent digestibility coefficients of the diets and raw ingredients, as well as soluble nitrogen (ammonia and urea) and phosphorus excretion were measured. Growth rates of seabass fed plant protein-based diets were significantly lower than those fed fish meal based diet. The protein utilisation was strongly correlated to the dietary essential amino acids index. Measurements of N excretion (ammonia and urea nitrogen) confirmed these data. Daily fat gain at the whole body level ranged between 1.1 to 1.7 g/kg BW, with the highest values being recorded in fish fed the fish meal based diet. Levels of plasma triglycerides and cholesterol were lower in fish fed soy protein diets than in those fed the diet solely based on fish meal. Soy protein rich diets decreased the activities of selected hepatic lipogenic enzymes (glucose 6-phosphate dehydrogenase, malic enzyme, ATP-citrate lysase, acetylcoenzyme A carboxylase and fatty acid synthetase). Highest lipogenic enzyme activities where found in fish fed the fish meal diet, except for fatty acid synthetase which was increased in seabass fed the corn-gluten meal based diets. Overall data suggest that dietary protein sources affects fat deposition and the lipogenic potential in European seabass.     

Responses to dietary starch or sucrose on protein and glucose kinetics in goats fed a high-concentrate diet

Responses of whole body protein synthesis (WBPS) and glucose irreversible loss rate (ILR) were compared between dietary starch and sucrose in four male goats. Diets were fed at 1.2 times maintenance requirements of ME and CP with 30% of the ME as starch, starch plus sucrose or sucrose, twice daily. The diets consisted of 33, 32, 11 and 24% of alfalfa hay, corn, soybean meal and the carbohydrates, respectively. The WBPS and glucose ILR during 5-7 h after feeding were determined by an isotope dilution method of [2H5]phenylalanine, [2H2]tyrosine, [2H4]tyrosine and [13C6]glucose. Sucrose elevated ammonia nitrogen and lowered acetate concentrations in the rumen, but did not differ from starch in nitrogen retention. Glucose ILR and WBPS were similar between the carbohydrates. It was concluded that dietary sucrose would have effects similar to starch on WBPS and glucose kinetics in the absorptive state in goats fed a high-concentrate diet.     

南极磷虾粉替代鱼粉对雌性黄鳝生长及生殖性能的影响

试验旨在研究南极磷虾粉替代鱼粉对雌性黄鳝(Monopterus albus)生长性能、体组成、抗氧化能力、非特异性免疫能力及生殖力的影响。选取二冬龄雌性黄鳝[初始体重(36.41±3.62) g]900尾,随机分为6组(每组3个重复,每个重复50尾),分别饲喂以南极磷虾粉替代饲料中0(对照)、20%、40%、60%、80%和100%的鱼粉制成的6种等氮等能配合饲料,试验周期12周。结果表明:20%磷虾粉替代鱼粉时,雌性黄鳝的增重率(WGR)、特定生长率(SGR)与对照组无显著性差异(P>0.05),但随着替代水平的进一步提高其生长性能显著下降(P<0.05)。20%替代组黄鳝肌肉的粗蛋白质含量显著高于其他组(P<0.05),而粗脂肪、粗灰分各组间无显著差异(P>0.05)。对黄鳝卵巢营养成分进行分析表明,当磷虾粉替代鱼粉比例超过60%时,其粗蛋白、粗脂肪含量均显著下降,水分含量逐渐升高(P<0.05)。进一步对黄鳝肝脏的抗氧化能力进行分析显示,当磷虾粉替代鱼粉比例大于40%时,其超氧化物歧化酶(SOD)活性逐渐下降,而丙二醛(MDA)含量逐渐升高; 100...     

Characterization of acid-stable glucose isomerase from Streptomyces sp., and development of single-step processes for high-fructose corn sweetener (HFCS) production

The glucose isomerase from Streptomyces olivaceoviridis E-86 was purified by chromatographic procedures, showing one single protein band in the SDS-PAGE. The enzyme had high acid stability, and there was no loss in enzyme activity at pH 5.0 after incubation at 60 degrees C for 30 hr. The enzyme had sufficients activity at 60 degrees C, pH 5.5, (which is the reaction condition for a single-step process with a glucoamylase from A. niger), and at 58 degrees C, pH 6.0, (condition with a glucoamylase from R. niveus). By using this acid-stable glucose isomerase, a single-step process to produce high-fructose corn sweetener (HFCS) from liquefied starch was formed without any reductant or other reagents for enzyme stabilization. The HFCS produced was about fifty percent fructose and less than 1.5% unknown oligosaccharides.     

Hepatic glucokinase and glucose-6-phosphatase responses to dietary glucose and starch in gilthead sea bream (Sparus aurata) juveniles reared at two temperatures

The effects of carbohydrate sources/complexity and rearing temperature on hepatic glucokinase (GK) and glucose-6-phosphatase (G6Pase) activities and gene expression were studied in gilthead sea bream juveniles. Two isonitrogenous (50% crude protein) and isolipidic (19% crude lipids) diets were formulated to contain 20% waxy maize starch or 20% glucose. Triplicate groups of fish (63.5 g initial body weight) were fed each diet to near satiation during four weeks at 18 degrees C or 25 degrees C. Growth, feed intake, feed efficiency and protein efficiency ratio, were higher at the higher water temperature. At each water temperatures fish growth and feed efficiency were higher with the glucose diet. Plasma glucose levels were not influenced by water temperature but were higher in fish fed the glucose diet. Hepatosomatic index and liver glycogen were higher at the lower water temperature and within each water temperature in fish fed the glucose diet. No effect of water temperature on enzymes activities was observed, except for hexokinase and GK which were higher at 25 degrees C. Hepatic hexokinase and pyruvate kinase activities were not influenced by diet composition, whereas glucose-6-phosphate dehydrogenase activity was higher in fish fed the glucose diet. Higher GK activity was observed in fish fed the glucose diet. GK gene expression was higher at 25 degrees C in fish fed the waxy maize starch diet while in fish fed the glucose diet, no temperature effect on GK gene expression was observed. Hepatic G6Pase activities and gene expression were neither influenced by dietary carbohydrates nor water temperature. Overall, our data suggest that in gilthead sea bream juveniles hepatocytes dietary carbohydrate source and temperature affect more intensively GK, the enzyme responsible for the first step of glucose uptake, than G6Pase the enzyme involved in the last step of glucose hepatic release.     

Hepatic glucokinase and glucose-6-phosphatase responses to dietary glucose and starch in gilthead sea bream (Sparus aurata) juveniles reared at two temperatures.

The effects of carbohydrate sources/complexity and rearing temperature on hepatic glucokinase (GK) and glucose-6-phosphatase (G6Pase) activities and gene expression were studied in gilthead sea bream juveniles. Two isonitrogenous (50% crude protein) and isolipidic (19% crude lipids) diets were formulated to contain 20% waxy maize starch or 20% glucose. Triplicate groups of fish (63.5 g initial body weight) were fed each diet to near satiation during four weeks at 18 degrees C or 25 degrees C. Growth, feed intake, feed efficiency and protein efficiency ratio, were higher at the higher water temperature. At each water temperatures fish growth and feed efficiency were higher with the glucose diet. Plasma glucose levels were not influenced by water temperature but were higher in fish fed the glucose diet. Hepatosomatic index and liver glycogen were higher at the lower water temperature and within each water temperature in fish fed the glucose diet. No effect of water temperature on enzymes activities was observed, except for hexokinase and GK which were higher at 25 degrees C. Hepatic hexokinase and pyruvate kinase activities were not influenced by diet composition, whereas glucose-6-phosphate dehydrogenase activity was higher in fish fed the glucose diet. Higher GK activity was observed in fish fed the glucose diet. GK gene expression was higher at 25 degrees C in fish fed the waxy maize starch diet while in fish fed the glucose diet, no temperature effect on GK gene expression was observed. Hepatic G6Pase activities and gene expression were neither influenced by dietary carbohydrates nor water temperature. Overall, our data suggest that in gilthead sea bream juveniles hepatocytes dietary carbohydrate source and temperature affect more intensively GK, the enzyme responsible for the first step of glucose uptake, than G6Pase the enzyme involved in the last step of glucose hepatic release.     

Dietary fish oil normalize dyslipidemia and glucose intolerance with unchanged insulin levels in rats fed a high sucrose diet

The aim of this study was to investigate the relationship between the lipid-lowering effects of fish oils and concomitant consequences on glucose tolerance and insulin sensitivity in an experimental animal model of hypertriglyceridemia induced by high sucrose intake. To achieve this goal, male Wistar rats were fed a semi-synthetic sucrose rich diet (SRD) (w/w: 62.3% sucrose, 8% corn oil, 17% protein) for 90 days. At the time, a well established and permanent hypertriglyceridemia accompanied by glucose intolerance was present. After that, one half of the animals continued on the SRD up to 120 days. The other half received an SRD in which the source of fat was substituted by cod liver oil (w/w 7% CLO plus 1% corn oil) from day 90 to 120 (SRD + CLO). Control rats were fed a semi-synthetic diet (CD) (w/w: 62.5% corn starch, 8% corn oil, 17% protein) throughout the 120 days experimental period. Results obtained after the experimental period show that the hypertriglyceridemia and glucose intolerance ensuing long term feeding normal rats with a sucrose-rich diet could be completely reversed mediating no change in circulating insulin levels by shifting the source of fat in the diet from corn oil to cod liver oil. These findings suggest that manipulation of dietary fats may play a role in the management of the lipid disorders associated with glucose intolerance and insulin resistance.     

Apparent digestibility of crude protein and gross energy in some plant and animal-based feedstuffs by Clarias isheriensis (Siluriformes: Clariidae) (Sydenham 1980)

Apparent digestibility coefficient (ACD) of dry matter, crude protein and gross energy of white fish meal, blood meal, poultry by-product meal, hydrolysed feather meal, shrimp head meal, meat and bone meal, soybean meal, cottonseed meal, peanut meal, yellow maize, corn starch, cassava meal, sorghum, rice bran and cocoa pod meal were determined for Clarias isheriensis (47.5–51.2 g) fed to satiation with diets containing each test feedstuff in a 30:70 mixture with a reference diet, and chromium oxide as an indicator using the dissection technique. ADC_protein values ranged from 50 to 93 % while ADC_energy ranged from 42 to 98 %. Protein and energy content of animal or plant feed-stuffs were equally digestible to C. isheriensis.     

Effects of chronic modification of dietary fat and carbohydrate in rats.

1. Rats were fed on diets enriched with starch, sucrose, corn oil or beef tallow for 3 weeks and the activities of various enzymes in the liver were measured. 2. The mitochondrial glycerol phosphate acyltransferase activity was lower in rats fed on the starch diet than on the two high-fat diets. 3. The non-microsomal (presumably peroxisomal) dihydroxyacetone phosphate acyltransferase activity was higher in rats fed on the starch diet and corn-oil diets than in those fed on the sucrose and beef-tallow diets. Urate oxidase activity was higher in rats fed on the starch diet than in the three other groups. There were no significant differences in the activity of acyl-CoA oxidase among the groups. 4. The activity of soluble phosphatidate phosphohydrolase was not significantly different among the dietary groups. There were increases of 3.3--4.3-fold in this activity in the dietary groups 6h after injection of corticotropin. The equivalent increases for the mitochondrial glycerol phosphate acyltransferase were 1.4--1.6 fold. 5. The corticosterone responses to the corticotropin injection were not significantly different between dietary groups. However, the corticosterone response of the rats fed on the two high-fat diets was prolonged when the rats were given an acute load of fructose [Brindley, Cooling, Glenny, Burditt & McKechnie (1981) Biochem. J. 200. 275--283]. 6. Rats fed on the high-fat diets had higher concentrations of circulating cholesterol than those fed on the starch and sucrose diets. Serum triacylglycerol concentrations were lower in the rats fed on the starch diet than in the three other groups. 7. The results are discussed in terms of the relationship between diet, hormonal balance and hepatic glycerolipid metabolism.