Water, electrolyte and nitrogen balances of fat sand rats (Psammomys obesus) when consuming the saltbush Atriplex halimus

The fat sand rat (Psammomys obesus), a diurnal gerbillid rodent, is able to thrive while consuming only the saltbush Atriplex halimus. This plant has a high ash, nitrogen and water content but low energy yield. We measured the electrolyte, nitrogen (N) and water balances of fat sand rats in captivity when they were offered only A. halimus.
The fat sand rats scraped the outer layers of A. halimus leaves before consuming them. This removed 14.3% to 19.6% of the ash content of the leaves, and thus substantially reduced the electrolyte intake of the fat sand rats. Total urine osmolality ranged between 2739 and 3098 mOsm/kg, with Na+, K+ and CI - comprising 74.3% to 82.5% of the total osmolytes, percentages much higher than those usually found in desert rodents. Water intake was relatively high compared to other rodents because of the high water content of A. halimus. Evaporative water loss averaged approximately 50% of the total water output. Nitrogen requirements were easily fulfilled, even when the fat sand rats did not meet their energy requirements because of the high N content of the plant. Metabolic faecal nitrogen was 70.5 mg-kg-' 75.d-', endogenous urinary nitrogen was 171.9 mg. kg-0'75 d-' and minimal N requirements were 242.3 mg.k g-75d -1 . Minimal N requirements for the fat sand rats were approximately 98% of that expected for a eutherian mammal of its body mass.
It was concluded that fat sand rats can maintain water, electrolyte and nitrogen balances when consuming only A. halimus without producing highly concentrated urine. This is due, in part, to their ability to remove much of the electrolytes before consuming the plant and by producing urine of which Na+, K+ and C1- comprise a large percentage of the total osmolytes.     

Fiber digestion and energy utilization of fat sand rats (Psammomys obesus) consuming the chenopod Anabasis articulata

Most herbivorous rodents consume a variety of plants and, when available, select ones low in fiber content. In contrast, the fat sand rat (Psammomys obesus), a diurnal gerbillid rodent that is wholly herbivorous, is able to survive while consuming only the halophytic chenopod Anabasis articulata. We hypothesized that these gerbils are able to digest chenopods efficiently and that fiber digestion contributes substantially to their energy budget. Digestibility of total fibers (NDF), hemicellulose, and cellulose was 51.6%, 66.4%, and 44.0%, respectively. Energy derived from fiber digestion was 211.7 kJ kg(-0.75) d(-1) and resulted mostly from hemicellulose digestion. Average daily metabolic rate was 658.4 kJ kg(-0.75) d(-1), and basal metabolic rate (BMR) was determined to be close to 192.6 kJ kg(-0.75) d(-1). Therefore, fiber digestion provided 32% of maintenance requirements and 110% of BMR requirements, one of the highest values reported thus far for placental mammals. The efficiency of utilization of the chenopod was 0.29, a low value compared to other dietary items. We concluded that A. articulata fulfills all the energy and nutrient requirements of fat sand rats, even though energy yields and efficiency of utilization of its energy is low.     

Oxalate, calcium and ash intake and excretion balances in fat sand rats (Psammomys obesus) feeding on two different diets

Fat sand rats Psammomys obesus feed exclusively on plants of the family Chenopodiaceae, which contain high concentrations of chloride salts (NaCl, KCl) and oxalate salts. Ingestion of large quantities of oxalate is challenging for mammals because oxalate chelates Ca(2+) cations, reducing Ca(2+) availability. Oxalate is a metabolic end-point in mammalian metabolism, however it can be broken-down by intestinal bacteria. We predicted that in fat sand rats microbial breakdown of oxalate will be substantial due to the high dietary load. In addition, since a high concentration of soluble chloride salts increases the solubility of calcium oxalate in solution, we examined whether a change in the intake of chloride salts affects microbial oxalate breakdown and calcium excretion in fat sand rats. We measured oxalate, calcium and other inorganic matter (ash) intake and excretion in fat sand rats feeding on two different diets: saltbush (Atriplex halimus), their natural diet, and goose-foot (Chenopodium album), a non-native chenopod on which fat sand rats will readily feed and that has a similar oxalate content to saltbush but only 2/3 of the ash content. In animals feeding on both diets, 65-80% of the oxalate ingested did not appear in urine or faeces. In animals consuming the more saline saltbush, significantly more oxalate was apparently degraded (p<0.001), while significantly less oxalate was excreted in urine (p<0.01) and in faeces (p<0.05). We propose, therefore, that fat sand rats rely on symbiotic bacteria to remove a large portion of the oxalates ingested with their diet, and that the high dietary salt intake may play a beneficial role in their oxalate and calcium metabolism.     

Heat production and substrate oxidation in rats fed at maintenance level and during fasting

A total of 36 Wistar rats were fed a commercial diet to a stipulated live weight of 75 g (Group A), 100 g (Group B) and 225 g (Group C). All rats were measured in energy balance experiments, in which the animals were fed near maintenance level, followed by a period of fasting with measurements of the gas exchange. The rats in Group A, B and C were fasted for 2, 3 and 4 days, respectively. The minimum heat production on the last day of fasting for all groups was proportional to metabolic body weight (kg0.75) with a regression: heat production, kJ day-1 = 321 x kg0.75 (R2 = 0.994). In rats fed near maintenance level, heat production was provided by oxidation of carbohydrates in 80-85%, oxidation of protein was 10-15%, while oxidation of fat contributed less than 10%. It is suggested that in the fasting period, the contribution to the total heat production from oxidized carbohydrate and fat depended on the size of the fat depots, a large fat depot giving rise to fat oxidation. On the last day of fasting, 24, 51 and 90% of the total heat originated from fat oxidation in Group A, B and C, respectively.     

Oxalate balance in fat sand rats feeding on high and low calcium diets

Oxalate reduces calcium availability of food because it chelates calcium, forming the sparingly soluble salt calcium-oxalate. Nevertheless, fat sand rats (Psammomys obesus; Gerbillinae) feed exclusively on plants containing much oxalate. We measured the effects of calcium intake on oxalate balance by comparing oxalate intake and excretion in wild fat sand rats feeding on their natural, oxalate-rich, calcium-poor diet with commercially-bred fat sand rats feeding on an artificial, calcium-rich, oxalate-poor diet of rodent pellets. We also tested for the presence of the oxalate degrading bacterium Oxalobacter sp. in the faeces of both groups. Fat sand rats feeding on saltbush ingested significantly more oxalate than fat sand rats feeding on pellets (P < 0.001) and excreted significantly more oxalate in urine and faeces (P < 0.01 for both). However the fraction of oxalate recovered in excreta [(oxalate excreted in urine + oxalate excreted in faeces)/oxalate ingested] was significantly higher in pellet-fed fat sand rats (61%) than saltbush-fed fat sand rats (27%). We found O. sp. in the faeces of both groups indicating that fat sand rats harbor oxalate degrading bacteria, and these are able, to some extent, to degrade oxalate in its insoluble form.     

Dietary protein content alters energy expenditure and composition of the mass gain in grizzly bears (Ursus arctos horribilis)

Many fruits contain high levels of available energy but very low levels of protein and other nutrients. The discrepancy between available energy and protein creates a physiological paradox for many animals consuming high-fruit diets, as they will be protein deficient if they eat to meet their minimum energy requirement. We fed young grizzly bears both high-energy pelleted and fruit diets containing from 1.6% to 15.4% protein to examine the role of diet-induced thermogenesis and fat synthesis in dealing with high-energy-low-protein diets. Digestible energy intake at mass maintenance increased 2.1 times, and composition of the gain changed from primarily lean mass to entirely fat when the protein content of the diet decreased from 15.4% to 1.6%. Daily fat gain was up to three times higher in bears fed low-protein diets ad lib., compared with bears consuming the higher-protein diet and gaining mass at the same rate. Thus, bears eating fruit can either consume other foods to increase dietary protein content and reduce energy expenditure, intake, and potentially foraging time or overeat high-fruit diets and use diet-induced thermogenesis and fat synthesis to deal with their skewed energy-to-protein ratio. These are not discrete options but a continuum that creates numerous solutions for balancing energy expenditure, intake, foraging time, fat accumulation, and ultimately fitness, depending on food availability, foraging efficiency, bear size, and body condition.     

High-level medium-chain triglyceride feeding and energy expenditure in normal-weight women

The objective of this study was to assess how short-term feeding of high levels of dietary medium-chain triglyceride (MCT) affect energy expenditure and postprandial substrate oxidation rates in normal-weight, premenopausal women. Eight healthy women were fed both a MCT-rich and an isocaloric long-chain triglyceride (LCT)-rich diet for two 1-week periods separated by a minimum of 21 days. The energy intake in each diet was 45% carbohydrates, 40% fat, and 15% protein. The 2 diets had either 60.81% or 1.11% of total fat energy from MCT with the remaining fat energy intake from LCT. On days 1 and 7 of each diet, resting metabolic rate and postprandial energy expenditure (EE) were measured by indirect calorimetry with a ventilated hood. Results indicated on days 1 and 7, there were no significant differences between diets for resting metabolic rate or mean postprandial EE. On both days 1 and 7, fat oxidation for the MCT-rich diet was significantly greater (0.0001 相似文献   

光周期和高脂食物对雌性高山姬鼠能量代谢和产热的影响

为了研究光周期和高脂食物对小型哺乳动物能量代谢和产热的影响,将成年雌性高山姬鼠分别驯化于长光照低脂、高脂食物和短光照低脂、高脂食物条件下,7周后测定动物的体重、能量摄入、产热、身体组成、血清瘦素浓度以及体脂含量等参数。结果发现:1)短光照抑制体重增长,降低血清瘦素浓度,增加非颤抖性产热;2)高脂食物使摄入能减少,消化率和体脂含量提高,但未显著影响体重、基础代谢率、非颤抖性产热和血清瘦素浓度;3)血清瘦素浓度与摄入能不相关,但与体脂重量正相关。结果暗示:短光照下瘦素作用敏感性增加和产热能力增强,可能介导了抵抗高脂食物诱导的肥胖。在野外条件下,高山姬鼠能通过能量代谢和产热的适应性调节避免体重的过度增长,有利于降低捕食风险,增强生存能力。     

Adult Female Rats Defend “Appropriate” Energy Intake after Adaptation to Dietary Energy

Objective: To determine if adult female rats adapt to lower and higher dietary energy density. Research Methods and Procedures: Study 1 compared high‐fat (56%), high‐energy density (HD) (21.6 kJ/g) and high‐fat (56%), low‐energy density (LD) (16.0 kJ/g) diets before surgery (two groups, 2 weeks, n = 16) and after surgery [ovariectomy (O) Sham (S); 2 × 2 factorial, n = 8; 6 weeks]. The second study (no surgery) compared high‐fat (60.0%), high‐energy (22.0 kJ/g) and low‐fat (10.0%), low‐energy (15.1 kJ/g) diets (n = 8). Results: In study 1, food intake was similar for the first 2 weeks, but rats on the LD diet consumed less energy, gained less weight, and had lower nonfasted serum leptin (all p < 0.0001) than rats on the HD diet. After surgery, rats on the LD and HD diets had similar weight gain, but rats on the LD diet consumed more food (p < 0.0001) and less energy (p < 0.009). O rats consumed more food and gained more weight (p < 0.0001) than S rats. Results from study 2 were similar to those from study 1. Discussion: The results demonstrated that O and S surgery rats and rats with no surgery adjust their food intake to defend a level of energy intake. This defense only occurred after a 2‐week adaptation period. The major differences in final body weights and abdominal fat resulted from the initial 2 weeks before adaptation to energy density. Rats fed higher‐energy diets seemed to “settle” at a higher level of adiposity, and rats fed lower‐energy diets consumed more food to increase energy consumption.     

Energy balance and brown adipose tissue thermogenesis during chronic endotoxemia in rats

The effects of continuously administered endotoxin on 7-day energy balance were investigated in male rats. Three groups of rats were implanted with osmotic pumps; two groups received saline-filled pumps, whereas the third received endotoxin. One of the saline groups was pair fed to match the food intake of the endotoxemic rats. After 7 days, body energy and protein and fat contents of rats were determined together with the energy content of food and feces. Endotoxin infusion not only induced fever, but it also suppressed appetite and significantly decreased body weight gain. Metabolizable energy intake was reduced by approximately 20% in infected rats. Although protein and fat gains were lowest in the endotoxin group, there appeared to be a selective loss of protein when considered as percent of body weight. Percent body fat was unaltered between the groups. Energy expenditure considered in absolute (kJ) or body weight-independent (kJ/kg0.67) terms yielded similar patterns of results; expenditure (kJ) was 10 and 20% (P less than 0.05, P less than 0.01) lower in the endotoxemic and pair-fed rats, respectively, compared with controls. Hence, compared with pair-fed rats, endotoxin-infused animals had a 10% rise in their expenditure. Brown adipose tissue thermogenesis was assessed by mitochondrial binding of guanosine 5'-diphosphate, and results showed that binding was greatest in endotoxemic rats and lowest in the pair-fed animals. The present results suggest that in this endotoxemic model appetite suppression exacerbates changes in energy balance. However, the reduction in body weight gain is also dependent on a decrease in metabolic efficiency and an increase in total energy expenditure.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of fibre in the diet on growth rates and the digestibility of nutrients in the greater cane rat (Thryonomys swinderianus).

The greater cane rat Thryonomys swinderianus is a coprophagous rodent in which fermentation occurs in the large caecum. The extent to which a 45% increase in the fibre component of the diet influenced growth rates of cane rats and the digestibility of nutrients and energy was investigated in two feeding trials. Higher fibre levels in the diet reduced the digestibility of dry matter, protein and fat, while animals digested fibre components (neutral-detergent fibre, acid detergent fibre, hemicellulose and cellulose) with a comparable efficiency to those maintained on a low fibre diet. In one of the trials animals fed the high fibre diet exhibited significantly lower growth rates than animals fed the low fibre diet. Digestibility coefficients of the cane rats for neutral-detergent fibre and protein seem to be intermediate to high when compared to reported values for the porcupine, guinea-pig, degu and rabbit. It is suggested that the ability of cane rats to utilise large quantities of fibre enable them to survive periods when only dry grass is available.     

Effects of phenotype, sex, and diet on plasma lipids in LA/N-cp rats

The LA/N-corpulent (cp) rat is a recently developed congenic strain which exhibits obesity. The effects of phenotype and sex on serum and lipoprotein lipid content were examined in LA/N-cp rats fed either a control or an atherogenic diet high in saturated fat and protein. Obese rats were pair-fed to equivalent lean animals. Results from this study indicate that sex, phenotype, and diet exert significant effects on plasma and lipoprotein cholesterol content. Plasma cholesterol levels were higher in obese compared with lean rats, females than in males, and rats consuming the atherogenic diet compared with the control diet. Plasma and lipoprotein triglyceride levels were significantly increased only in obese compared with lean animals. The increased plasma cholesterol and triglyceride was observed primarily in the chylomicron and very low density lipoprotein fractions. Increased levels of plasma cholesterol were not a result of increased dietary cholesterol absorption or increased liver cholesterol biosynthesis. These data suggest that LA/N-cp rats can serve as a unique rodent model for the study of the interrelationships between hyperlipidemia, obesity, and coronary heart disease.     

Influence of oat bran on sucrose-induced blood pressure elevations in SHR

To determine whether oat fiber influences BP, we gave spontaneously hypertensive rats (SHR) a diet high in sucrose and low in protein (calories: sucrose 52%, protein 15%, fat 33%) or a diet low in sucrose and high in protein (calories: sucrose 13%, protein 52%, fat 35%). The amount of fat in these particular diets has not been shown to influence BP, so we modified the 2 diets by replacing fat with oat bran (10% w/w). Accordingly, we examined 4 groups of 5 rats consuming different diets: high sucrose, high sucrose + oat bran, low sucrose, and low sucrose + oat bran. Not unexpectedly, SHR consuming the diet high in sucrose had a significantly higher BP after 2 weeks than those consuming the diet low in sucrose. The significant difference in BP continued over the next 3 weeks. At the end of 6 week duration of study, we found the following BP: SHR ingesting the high sucrose diet, 217 mm Hg +/- 5 (SEM) vs SHR consuming the low sucrose diet, 187 mm Hg +/- 4 (SEM) p less than .0001]. SHR eating the low sucrose diet and consuming supplemental bran showed no significant change in BP after 6 weeks compared to SHR eating the basic diet alone, 188 mm Hg +/- 6 (SEM); however, 5 SHR consuming the high sucrose diet with added oat bran showed a significantly lower BP 200 mm Hg +/- 2 (SEM) than SHR ingesting the basic high sucrose diet devoid of oat bran [p less than .01]. We conclude that addition of oat bran to the diet can ameliorate sucrose-induced BP elevations in SHR.     

Underyearling pink and chum salmon in the western Bering Sea during the fall season (September and October 2013): Distribution,feeding habits,and growth patterns

The ontogeny of a year class of pink and chum salmon is described for the period after the redistribution of underyearling individuals from coastal waters to deep-sea areas of the western Bering Sea in September and October, 2013. The intensity of their feeding was high; their diet included hyperiids, pteropods, and juvenile euphausiids. The metabolic costs of growth reached only 20% of the consumed food, which indicates significant energy costs for locomotion; moreover, as the body size increases, the level of metabolic functions rises at a decreasing rate, which causes the body growth to slow down and food consumption to decrease. The main items in the diet of underyearling salmon are characterized by a low content of dry matter, low lipid content, and, consequently, a low calorie content, i.e., underyearlings mainly consume protein-rich food with a low fat content. The chemical composition of the tissues almost did not differ between underyearling pink and chum salmon. Both species typically had a low fat content in their muscles. Thus, fat is not accumulated at this stage of ontogeny; all energy that is obtained with food, after being used for locomotion and metabolism, is spent for linear growth.     

Elimination of oxalate by fat sand rats (Psammomys obesus): wild and laboratory-bred animals compared

Wild fat sand rats (Psammomys obesus) can feed exclusively on plants containing much oxalate, but little calcium; oxalate intake may exceed 300 mg/d, while calcium intake is approximately 30 mg/day. By contrast, for generations, laboratory bred P. obesus have been fed a low-oxalate (<100 mg/day), high-calcium (approximately 150 mg/day) rodent chow. We compared oxalate intake and excretion between wild and laboratory-bred animals, both fed the natural high-oxalate diet, to determine whether these different dietary histories are reflected in the animal's ability to eliminate dietary oxalate. Since both wild and laboratory-bred P. obesus harbor intestinal oxalate-degrading bacteria, we predicted that their oxalate intake and excretion would be similar. Indeed, we found no significant differences in oxalate intake or excretion between the groups fed either saltbush or alfalfa (p>0.05). However, due to the differences in dietary calcium intake between the two diets, in both groups only part (23-25%) of the ingested oxalate was excreted when the animals were fed the oxalate-rich saltbush, yet most (87-90%) was excreted when feeding on calcium-rich alfalfa. Thus, even after generations of feeding on a commercial low-oxalate diet, fat sand rats maintain intestinal oxalate-degrading bacteria that appear to increase in number and activity when presented with their natural diet.     

Role of Choline Deficiency in the Fatty Liver?Phenotype of Mice Fed a Low Protein,Very Low Carbohydrate Ketogenic Diet

Though widely employed for clinical intervention in obesity, metabolic syndrome, seizure disorders and other neurodegenerative diseases, the mechanisms through which low carbohydrate ketogenic diets exert their ameliorative effects still remain to be elucidated. Rodent models have been used to identify the metabolic and physiologic alterations provoked by ketogenic diets. A commonly used rodent ketogenic diet (Bio-Serv F3666) that is very high in fat (~94% kcal), very low in carbohydrate (~1% kcal), low in protein (~5% kcal), and choline restricted (~300 mg/kg) provokes robust ketosis and weight loss in mice, but through unknown mechanisms, also causes significant hepatic steatosis, inflammation, and cellular injury. To understand the independent and synergistic roles of protein restriction and choline deficiency on the pleiotropic effects of rodent ketogenic diets, we studied four custom diets that differ only in protein (5% kcal vs. 10% kcal) and choline contents (300 mg/kg vs. 5 g/kg). C57BL/6J mice maintained on the two 5% kcal protein diets induced the most significant ketoses, which was only partially diminished by choline replacement. Choline restriction in the setting of 10% kcal protein also caused moderate ketosis and hepatic fat accumulation, which were again attenuated when choline was replete. Key effects of the 5% kcal protein diet – weight loss, hepatic fat accumulation, and mitochondrial ultrastructural disarray and bioenergetic dysfunction – were mitigated by choline repletion. These studies indicate that synergistic effects of protein restriction and choline deficiency influence integrated metabolism and hepatic pathology in mice when nutritional fat content is very high, and support the consideration of dietary choline content in ketogenic diet studies in rodents to limit hepatic mitochondrial dysfunction and fat accumulation.     

Oleoyl-estrone induces the massive loss of body weight in Zucker fa/fa rats fed a high-energy hyperlipidic diet

To test whether oleoyl-estrone plus a hyperlipidic diet affects body weight in Zucker fa/fa rats, 13-week-old male Zucker obese (fa/fa) rats initially weighing 440-470 g were used. They were fed for 15 days with a powdered hyperlipidic diet (16.97 MJ/kg metabolizable energy) in which 46.6% was lipid-derived and 16.1% was protein-derived energy and containing 1.23 +/- 0.39 μmol/kg of fatty-acyl esters of estrone. This diet was supplemented with added oleoyl-estrone to produce a diet with 33.3 μmol/kg of fatty-acyl estrone. Oral administration of oleoyl-estrone in a hyperlipidic diet (at a mean dose of 0.5 μmol. kg(-1).d(-1)) resulted in significant losses of fat, energy and, ultimately, weight. Treatment induced the maintenance of energy expenditure combined with lower food intake, creating an energy gap that was filled with internal fat stores while preserving body protein, in contrast with the marked growth of controls fed the hyperlipidic diet. Treatment of genetically obese rats with a hyperlipidic diet containing additional oleoyl-estrone resulted in the loss of fat reserves with scant modification of other metabolic parameters, except for lower plasma glucose and insulin levels. The results agree with the postulated role of oleoyl-estrone as a ponderostat signal.     

Fatty acid oxidation and fatty acid synthesis in energy restricted rats

The importance of fat oxidation and fatty acid synthesis were examined in rats fed approximately one half their ad libitum food intake for a period of 13 days followed by 7 days of ad libitum feeding (refed rats). This study was undertaken because previous reports demonstrated that refed rats rapidly accumulated body fat. Our results confirmed this observation: refed rats accrued body fat and body weight at rates that were approximately 3 times higher than controls. Evidence for a period of increased metabolic efficiency was demonstrated by measuring the net energy requirement for maintenance over the refeeding period: refed rats had a reduced metabolic rate during the period of energy restriction (approximately 30% lower than control) and this persisted up to 2 days after the reintroduction of ad libitum feeding. The major factor responsible for the rapid fat gain was a depressed rate of fatty acid oxidation. Calculations of protein and carbohydrate intake over the refeeding period showed that the simplest explanation for the decrease in fatty acid oxidation is fat sparing. This is possible because of the large increase in dietary carbohydrate and protein intake during the refeeding period when metabolic rates are still depressed. The increased carbohydrate and protein may adequately compensate for the increasing energy requirements of the ER rats over the refeeding period affording rats the luxury of storing the excess dietary fat energy.     

Diet selection and energy and water budgets of the common spiny mouse Acomys cahivinus

The common spiny mouse, Acomys cahirinus (body mass=47 g), is widely distributed in Israeli deserts where it inhabits natural crevices on rocky slopes. This omnivorous rodent consumes a varied diet, and in particular snails. We determined diet selection and energy and water balances of spiny mice when they were offered snails and seeds. The spiny mice maintained steady state body mass. Dry matter consumption of snails was 0.014 g* g⁻¹.-d⁻¹ and of seeds was 0.049g*.g⁻¹d⁻¹ for a total of 0.063 g*g⁻¹*d⁻¹. Total water intake was 0.101ml-g⁻¹.d⁻¹ and metabolizable energy intakewas 0.990 kJ. gxs^-1.d⁻¹ for a ratio (ml: kJ) of 0.102. This ratio was similar to that reported in a previously published study on free-living spiny mice. We concluded that snails and seeds allowed spiny mice to fulfil their energy and water requirements with minimal dry matter and fresh matter intakes. Furthermore, spiny mice selected a diet that provided them with a water (ml) to energy (kJ) ratio of approximately 0.1, although it appeared that they are able to survive on a much drier diet.     

Nutritional value of the marine algae wakame (Undaria pinnatifida) and nori (Porphyra purpurea) as food supplements

The nutritional properties of seaweeds are incompletely known, and studies on nutrient bioavailability are scarce, although such information is required to evaluate seaweed as a foodstuff. In the present study, samples of wakame (Undaria pinnatifida) and nori (Porphyra purpurea) were analysed to determine their chemical composition. To evaluate the algae as dietary supplements, the effects on rats of the inclusion of these seaweeds in a standard rodent diet were investigated. The control rats were fed a diet containing 100 % standard rodent diet. The wakame diet was obtained by mixing 10 % dried wakame with 90 % standard rodent diet, and the nori diet was obtained by mixing 10 % dried nori with 80 % standard rodent diet and 10 % starch. Food intake and the body weight were measured. Nitrogen ingested and excreted were determined to calculate true digestibility, biological value, net protein utilization and nitrogen balance. Biochemical determinations were made on serum blood samples. The protein content was high (16.8 % for wakame and 33.2 % for nori), the fat content was low (1 % for wakame and 2.8 % for nori) and the carbohydrates comprised 37 % for both seaweeds. The fibre and ash contents in wakame were 16.9 and 28.3 %, respectively, and in nori, they were 7.5 and 21.3 %, respectively. Both seaweeds contain high concentrations of calcium, sodium, potassium, iron and magnesium, and the most abundant vitamin was vitamin A. Few changes were observed in the nutritional parameters, but LDL cholesterol levels were significantly lower in rats fed with seaweed-supplemented diets than in the control rats. Wakame and nori are excellent sources of nutrients and are well accepted by experimental animals.