Non-protein Diet Research Articles

Effects of Inclusion of N-Carbamylglutamate in the Non-Protein Diet on Growth and Slaughter Performance, Meat Quality, Nitrogen Metabolism and Antioxidant of Holstein Bulls.

Simple SummaryUsing dietary non-protein nitrogen is an effective way to decrease the dependence on protein resources in cattle production. N-carbamylglutamate (NCG) is a structural analogue of N-acetylglutamate (NAG), which is a precursor of endogenous Arg synthesis. NCG improves urea cycling and enhances the endogenous synthesis of Arg, nitric oxide synthase and NO. The present study showed that beef benefited from being fed NCG product in the urea diet by enhancing its growth and slaughter performance, meat quality, nitrogen metabolism and plasma amino acids.The objectives of this experiment were to investigate the effects of N-carbamylglutamate (NCG) on growth and slaughter performance, meat quality, nitrogen utilization, plasma antioxidant and amino acids of Holstein bulls. In this case, 24 Holstein bulls (490 ± 29.0 kg of body weights and 540 ± 6.1 d of age) were blocked by body weights and age and randomly assigned to 1 of 4 groups: (1) CON group: bulls were fed the control diet, (2) CON + NCG group: bulls were fed the control diet with 40 mg/kg BW NCG, (3) Urea group: bulls were fed the urea diet, and (4) Urea + NCG group: bulls were fed the urea diet with 40 mg/kg BW NCG. Feeding NCG significantly improved ADG, FCR, DM and CP digestibility, carcass weight, slaughter weight, DOP, eye muscle area, shear force (p = 0.001) and reduced L* of color, drip loss and cooking loss. Concurrently, feeding the urea diet induced a decreased ADG, carcass weight and slaughter weight, DOP, eye muscle area and shear force. NCG decreased contents of fecal N and urinary N, plasma urea in bulls and ammonia but increased N retention and utilization, plasma NO, plasma Arg, Leu, Ile and Tyr. On the other hand, feeding the urea diet increased urinary N, plasma urea and ammonia. Thus the study efficiently demonstrates that beef benefited from being fed a NCG product in the urea diet by enhancing its growth and slaughter performance, meat quality, nitrogen metabolism and plasma amino acids.

Dietary Protein Deficiency Affects Food Consumption and Torpor in the African Woodland Dormouse (Graphiurus murinus)

Many heterotherms employ torpor to conserve energy to cope with food shortage. Food shortage affects not only energy budgets but also other aspects of nutritional status. In addition to serving as an energy substrate, dietary proteins also provide vital nutrients including essential amino acids, some of which cannot be synthesized de novo. We evaluated the hypothesis that dietary protein deficiency induces torpor as a means of adjusting protein metabolism in the African woodland dormouse (Graphiurus murinus), a rodent with a protein-rich diet and lacking a cecum, which limits the potential for hindgut fermentation and coprophagy. Dormice were fed control and non-protein diets with equivalent energy content every two weeks under thermoneutral conditions. While the dormice did not express torpor under control conditions, some did under protein-deficient conditions. Among dormice expressing torpor, one maintained energy intake comparable to that during the control diet period, whereas the other reduced energy intake due to spontaneously reduced food consumption. These results suggest that torpor can be induced directly or indirectly by dietary protein deficiency even in the absence of energy constraints and thermal stress. In either case, torpor in response to deficiency in certain nutrients can reduce demands of the nutrient.

Influence of Non-protein Diets on Hepatic Metabolism and Endocrine in Barramundi (Lates calcarifer)

This study evaluated the effects of different dietary non-protein energy sources on hepatic metabolism and endocrine of barramundi. Fish were fed iso-energy diets (18 MJ kg–1) with two types of non-protein energy source in the experimental group and a regular diet was used as the control. The feeding trial lasted 56 days. In the present study, CPT1 and SCD expression in fish fed high lipid diet were upregulated and liver lipid metabolism was more active than the control group. Serum biochemical parameters including serum glucose, serum triacylglycerol and serum cholesterol were significantly increased. The IGF-I and IGF-II expressions were significantly upregulated, and growth performances were improved in fish fed the high lipid diet. When barramundi were fed with the high carbohydrate diet, GK expression was downregulated and cPEPCK expression was upregulated, indicating that glycogen might accumulate in liver. The fluctuation of serum biochemical parameters and the growth performance were not significantly different compared to the control group. In conclusion, high lipid diet can shorten the raising period, but it causes the change of metabolic level and the increase of useless adipose tissue; The high carbohydrate diet did not significantly improve the growth performance, and no significant metabolic abnormalities were observed, indicating that carbohydrate has the potential to be the feed energy supply source for juvenile barramundi. The results provide insights for further understanding the availability of non-protein energy sources in the diet of juvenile barramundi.

Effect of partial replacement of fat in sausage diet with different flours at 5%, 10% and 15% level of inclusion on performance, hematological and serum biochemistry of wistar albino rat

The demand for functional meats with reduced Animal Fat (AF) has increased globally. Chronic health disorders are often associated with high levels of dietary AF in meat products such as beef sausage (BS). Functional beef sausage (FBS) could be produced with alternative flours as replacer for AF. Effect of partial replacement of fat in sausage diet with different flours at 5%, 10% and 15% level of inclusion on performance, hematological and serum biochemistry of Wister albino rat was evaluated. The BS (g/100g: beef 65.0, lard 20.0, sodium chloride (SC) 2.0, others 13.0) was used. The FBS were developed using Wheat flour (WF), Irish potato flour (IPF) or corn flour (CF) at 5%, 10% and 15% to replace fat (lard) in beef sausage recipe. Functional properties of the flour were carried out using standard procedure. 60 weaned male albino rats (Wister strain) weighing between 60 - 62g were purchased. The rats were allotted to 12 dietary treatments with 6 rats per treatment in a completely randomised design. The study lasted 21 days and changes in their body weight were recorded. Feed Intake (FI), Feed Conversion Ratio (FCR), Protein Intake (PI) and Protein Efficiency Ratio (PER) were calculated. At the end of the feeding period, the animals were fasted of feed for 12 hours before blood samples were collected for hematological and serum biochemical analysis. Data were analysed using descriptive statistics and ANOVA at α0.05.Irish potato flour was significantly higher in bulk density, oil retention, foaming capacity, oil absorption capacity and emulsion activities compared to other flours. Corn flour was statistically higher (P<0.05) in water retention, foam stability and water absorption capacity. Significant differences (P<0.05) were observed in all the hematological indices except for red blood cell which had similar values (P>0.05). However, there were no consistent trend observed in white blood cell count and its differential counts, which were rather fluctuating. Rats fed Irish potato based sausage had the highest Alanine Amino transferase (ALT) value while rats fed wheat based sausage diet had the lowest ALT of 11.87i.u/L. The Aspartate Aminotransferase (AST) assay of rats reveals that rats fed casein-based diet and lard-based sausage had the highest AST values of 7.30i.u/L each with least AST in rats fed protein deficient diet. The urea value for rats on the casein-based diet was the highest (45.29 mg/dL) with least value in rats fed corn-based sausage diet. Rats fed wheat-based sausage had the highest cholesterol (107.97mg/dL), while corn-based sausage had the lowest cholesterol value of 56.16 mg/dL. Corn based breakfast sausage diet was higher (P<0.05) in protein efficiency ratio with least score in protein deficient diet. Corn-based sausage had the highest biological value (95.68) with protein deficient diet having the least value (15.49).It was observed that rats fed corn-based breakfast sausage had the highest gained weight of 27g, while rats fed non-protein diet had the lowest weight change of -11g. Replacement of animal fat with corn flour at 10% enhanced better growth performance, hematological and serum biochemistry.

Effect of leucine uptake on hepatic and skeletal muscle gene expression in rats: a microarray analysis.

[Purpose]This study was performed to explore the physiological functions of leucine by exploring genes with leucine-dependent variability using DNA microarray. [Methods]Sprague-Dawley rats (n = 20) were separated into a HPD (30% High Protein Diet, n = 10) group and a NPD (0% Non Protein Diet, n = 10) group and fed a protein diet for 2 weeks. At the end of the 2-week period, the rats were fasted for 12-16 hours, further separated into subgroups within the HPD (Saline, n = 5, Leucine, n = 5) and NPD (Saline, n = 5, Leucine, n = 5) groups and administered with a leucine solution. The liver and muscles were harvested after 2 hours for RNA extraction. RNA purification from the isolated muscles and target gene identification using DNA chip were performed. The target gene was determined based on the results of the DNA chip experiment, and mRNA expression of the target gene was analyzed using Real-Time PCR.[Results]In the skeletal muscle, 27 genes were upregulated while 52 genes were down regulated after leucine administration in the NPD group. In the liver, 160 genes were up-regulated while 126 were down-regulated. The per2 gene was one of the genes with leucine-dependent induction in muscles and liver.[Conclusion]This study was performed to explore the physiological functions of leucine, however, a large number of genes showed variability. Therefore, it was difficult to definitively identify the genes linked with a particular physiological function. Various nutritional effects of leucine were observed. High variability in cytokines, receptors, and various membrane proteins were observed, which suggests that leucine functions as more than a nutrient. The interpretation may depend on investigators’ perspectives, therefore, discussion with relevant experts and the BCAA (Branched-Chain Amino Acids) society may be needed for effective utilization of this data.

Formulation of Complementary Foods Developed from Plants Polypeptide (Parkia Biglobosa), Soy Bean and Maize

Researchers have shown that Locust bean (parkia biglobosa) is of Health Benefits and inevitable family needs. Locust bean is good for eyesight while the older ones need it for curing hypertension and its other related conditions like stroke and diabetes. Medically, it is employed in wound healing and serves as one of the ingredients that are used for treatment of leprosy. The purpose of this paper is to determine the nutritional efficacy of maize soybean, locust bean blends incorporating into com- plementary food. Maize, locust bean and soy bean were the sole energy and plants polypeptide sources, respectively. Diet 1 (Basal) diet 2(Control) diet 3(Locust bean: soy bean: Maize 10 10:80); diet 4 (locust bean: soy bean: Maize 10:5:85); diet 5 (locust bean: soy bean: Maize: 5: 10: 85) diet 6 (locust bean: Maize: 15: 100) diet 7 (locust bean: Maize: 20: 100). The formulated complementary diets were fed to 70 albino rats. A commercial product (Cerelac) manufactured by nestle plc was obtained at a local supermarket, Ile-Ife, Nigeria and was used as standard diet Results -- The results showed the growth rate for non-protein diet decreased from 45.57-43.43(1), protein diets increased from 45.57-97.77(2), 45.17-48.26(3), decreased from 45.60-38.90 (4), increased from 45.30- 67.23(5), decreased from 45.52- 40(6), 45.54-36.10 (7). The average nitrogen retained in various organs of experimental animals, such as liver, kidney and muscle was found higher in diets 5. The formulation was comparable to control, was found similar in terms of growth rate, PER, NPR and ensure optimum nitrogen content in the liver, kidney and tissues in diet 5. Conclusions -- The results showed that the complementary food formulation showed more efficacy in diet 5, which are not expensive, locally available, affordable, could be blended from locust bean, soy bean and maize, hence may be suitable to improve childhood nutrition, mental performance and eradicate protein energy malnutrition (PEM).

Dietas com nitrogênio não-proteico para fêmeas bovinas superovuladas sem prévia adaptação durante curto tempo e em diferentes fases do ciclo estral

Objetivou-se neste estudo avaliar o efeito do fornecimento, sem prévia adaptação, durante curto tempo e em diferentes fases do ciclo estral, de dietas contendo nitrogênio não-proteico (NNP) na produção, na qualidade e no grau de desenvolvimento de embriões recuperados em fêmeas bovinas superovuladas. Sessenta e oito vacas Nelore foram distribuídas em três grupos: um controle e dois com fornecimento de ureia antes (UA = do dia -5 ao dia 0) e após (UD = dia 0 ao dia 5) a inseminação artificial. As vacas foram mantidas em pastagem e receberam concentrado (3,0 kg/animal/dia) durante 16 dias. Foram formulados dois concentrados, e as dietas totais (concentrado e consumo estimado de pastagem) apresentaram 12,0% (dieta controle) e 14,6% (dieta NNP) de proteína bruta (PB). As vacas foram sincronizadas, superovuladas e inseminadas. Sete dias (dia 7) após a inseminação (dia 0), realizou-se a colheita e análise dos embriões. Amostras de sangue foram coletadas nos dias -5, 0 e 5 para determinação da concentração de nitrogênio ureico plasmático (NUP), glicose, insulina e progesterona. A época de fornecimento de ureia influenciou as concentrações médias de NUP nos dias -5, 0 e 5, mas não tiveram efeito nas concentrações de glicose, insulina e progesterona. O período de fornecimento da ureia teve efeito na porcentagem de mórulas compactas em relação ao total de estruturas (UA = 51,4 vs. UD = 15,3%), em relação ao total de oócitos fecundados (UA = 62,5 vs. UD = 30,6%) e em relação ao total de embriões viáveis (UA = 68,8 vs. UD = 38,6%). No grupo que recebeu ureia depois da inseminação artificial, houve redução de 70,2% da proporção de mórulas compactas por total de estruturas em relação ao grupo que recebeu ureia antes da inseminação. Dietas com nitrogênio não-proteico fornecidas imediatamente após a inseminação promovem aceleração do desenvolvimento embrionário inicial.

Composição química e valor protéico do resíduo de soja em relação ao grão de soja

Este trabalho teve por objetivo avaliar a composição química e o valor protéico do resíduo de soja, subproduto do processo de extração do óleo de soja. Determinou-se a composição centesimal, o valor energético e o perfil de aminoácidos do resíduo e do grão de soja. O valor protéico foi avaliado mediante índices biológicos. Ratos Wistar machos, recém-desmamados (n = 24), distribuídos em quatro grupos, foram alimentados por dez dias com rações contendo 10% de proteína (resíduo de soja, soja integral, caseína - controle) ou com ração aprotéica. O resíduo apresentou maior conteúdo protéico (47%) e menor teor energético (334 kcal/100 g) em relação ao grão de soja (40% e 452 kcal/100 g, respectivamente), além de perfil de aminoácidos essenciais com escore de 101% em relação ao padrão de referência e digestibilidade protéica de 88%. Segundo os índices RNPR (Relative Net Protein Ratio) e PDCAAS (escore de aminoácidos corrigido pela digestibilidade), a qualidade da proteína do resíduo de soja é similar à do grão integral (valores protéicos de 87% e 85%, respectivamente). O resíduo de soja é fonte de carboidratos, minerais, fibras e proteína de qualidade nutricional adequada, apresentando vantagens em relação à soja integral tais como menor teor energético e maior concentração protéica.

Innovations in the treatment of psoriasis

In 1925, William Goeckerman presented a patient who had failed treatment of severe psoriasis with emetin, arsphenamin, intramuscular injection of mercury, staphylococcal vaccine, 25 injections of a streptococcal vaccine, Fowler's solution, autoserum injections, a 7 month nonprotein diet, x-ray therapy, tonsillectomy, and the extraction of seven teeth.1 In that paper, he described a successful regimen using tar and ultraviolet light to clear the patient. That regimen, known as the Goeckerman regimen, still remains a useful treatment of psoriasis; but over the decades since its publication there have been many improvements in the regimen, and phototherapy with ultraviolet B (UVB) remains a valuable part of psoriasis therapy. Fortunately, psoriasis, more than any other disease in dermatology, has paved the way for new treatments that have been introduced over the past 25 years, in large part through publication in the Journal of the American Academy of Dermatology.

Biological evaluation of tomato waste seed meals and protein concentrate

Whole meal, deoiled meal and protein concentrate (PC) of tomato seeds were fed to male albino rats to study weight gain, along with standard and non-protein diets. Corrected protein efficiency ratio was 1.82 for whole meal, 1.93 for deoiled meal and 1.99 for PC as compared to 2.5 for casein. The net protein retention (NPR) was highest for casein (2.91), followed by whole meal (2.65) and deoiled meal (2.52) and least for PC (2.51). Tomato seeds contained high quality plant proteins that could be supplemented into various food products.

Effect of Feeding Maize/Legume Mixtures on Biochemical Indices in Rats

Protein-energy malnutrition is one of the major public health problems in developing countries of the world due to prevailing socio-economic problems. This study aimed to observe the effect of formulated complementary blends on biochemical parameters of rats. Extruded complementary blends from maize fortified with cowpea or soybean at a level of 35% and 25% respectively were fed to 4 groups of rats for 28 days. Similarly, 3 other groups of rats were placed on casein, non-protein or rat pellet diet. Biochemical analysis was done on blood samples of the rats. Results from previous studies show the protein content of the formulated diets to range from 15.75% in UMC to 17.24% in MMS. Significantly (p < 0.05) lower WBC, Hb, MCHC, total protein, albumin and globulin values were recorded for the rats fed a non-protein diet (NP). The serum AST level was 75.5, 71.2, 63.2, 51.0, 60.5 and 55.7, respectively, for rats on casein, rat pellet, MMS, UMS, MMC and UMC (list of abbreviations is shown in the appendix) diets. Alkaline phosphatase was significantly (p < 0.05) higher in soybean-based diets while cholesterol was lowest in rats fed the non-protein diet (NP). The value obtained for serum electrolyte concentration in the rats fed NP compared well with rats on other diets but, however, had a significantly (p < 0.05) higher serum sodium value. These results confirm that the experimental diets supported growth, as shown in a previous study, and had no harmful consequence.

Effect of soaking prior to cooking on the levels of phytate and tannin of the common bean (Phaseolus vulgaris, L.) and the protein value.

The effect of soaking in domestic processing, on the nutritive value of the common bean (Phaseolus vulgaris, L.) cv IAC-Carioca, was studied. Five treatments were carried out with experimental diets, and offered to male, recently weaned Wistar rats. The protein sources were, respectively, control diet (casein) (CC), casein plus the soluble solids found in the soaking water (CSS), freeze dried bean cooked without soaking (BNS), freeze dried bean cooked with the non-absorbed soaking water (BSW), freeze dried bean cooked without the non-absorbed soaking water (BSNW). and an aproteic diet (AP) for corrective purposes. The anti-nutritional factors (phytates and tannins), were determined in the differently processed beans and in the soaking water. The following values for the reduction of phytates were obtained: BNS (20.9%), BSNW (60.8%) and BSW (53.0%), and the tannins were reduced by: BNS (86.6%), BSNW (88.7%) and BSW (89.0%). No significant differences were observed between the various treatments using the common bean as protein source, with respect to the net protein ratio (NPR). With respect to the digestibility corrected by non-protein diet, values varying between 94.1% and 94.6% for casein, and between 57.5% and 61.4% for the common bean, were observed, the treatment BNS being more digestible. It was concluded that soaking did not interfere with the NPR of the experimental diets containing the common bean as protein source, nor did it reduce the tannin content. However soaking was capable of reducing the phytate levels in the common bean. On the other hand, soaking was unable to increase the protein digestibility of the common bean, since the treatment BNS showed the highest value for digestibility.

Release of hypothalamic norepinephrine during MSG intake in rats fed normal and nonprotein diet

Effects of monosodium l-glutamate (MSG) solution (0.06 M) on interstitial levels of norepinephrine (NE) were measured in the lateral hypothalamus (LH). Wistar male rats, housed in standard operant boxes, were fed either normal or nonprotein diet for 3 days. Beside a daily bar-mediated drinking session (75 min), animals were without access to fluids. Microdialysates, collected from the LH during the 75 min of drinking, were analyzed using high-pressure liquid chromatography. No significant responses of the LH NE to the drinking of distilled water, MSG, NaCl (0.06 M), and glucose solution (0.6 M) were found in normally fed rats. However, a specific decline in LH NE release was detected during MSG solution-drinking in rats fed nonprotein diet. As MSG preference indicates protein intake, it is possible that LH NE is, at least partially, one of the brain signals that relate MSG preference to dietary protein intake.

The nutritional toxicity of sweet lupin (Lupinus angustifolius) seed proteins

The effects of raw sweet lupin (Lupinus angustifolius) meal on the growth and N utilisation of rats were determined in two ad libitum and two restricted-feeding net protein utilisation (NPU) and five N balance experiments. Sweet lupin seed grown in Western Australia, obtained as meal, either unsupplemented (LMU) or fully supplemented with required amino acids (360 g kg−1) (LMFS), was tested. Rats fed lactalbumin (130 g kg−1) (LACT) were used as positive controls, while rats fed a non-protein diet (NPC) were used as negative controls. In addition, seed protein, extracted at pH 7.0 with water and insoluble after dialysis at pH 7.0 (LPADI; 124 g kg−1), was also used. The diets contained the same amounts of energy and protein and were supplemented with essential amino acids, vitamins and minerals to target requirements for rats. Inclusion of LPADI in the diet of growing rats caused urinary losses of N, almost all as urea, hypoproteinaemia and increase in body water that resulted in the lowest NPU values, N balance and growth rate as compared with other diets used. These rats developed atrophy of the spleen (low dry weight) and had a comparatively smaller thymus gland than those given raw meals. Furthermore, the LPADI fraction was shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to contain three polypeptides with molecular weights between 30 and 36 kDa which are similar to lectins obtained from Phaseolus vulgaris, Abrus precatorius and Ricinus communis. It is possible that the toxic protein component in the sweet lupin, which has negligible in vitro haemagglutination properties and is extremely toxic in vivo, exerts toxicity by interfering with protein synthesis in the liver, while the immune responses are secondary to azotaemia (high level of urea in the blood) or cytotoxicity action on lymphocytes. The unusual depletion of fat from the body, however, was due to the failure of absorbed amino acids to assimilate as proteins, creating dietary protein restriction and leading to lipolysis. It is therefore tentatively suggested that sweet lupin seed contains a lectin-like protein that is concentrated in this fraction. Further purification and biological evaluation to establish the exact nature of this protein may be important. © 2000 Society of Chemical Industry

The nutritional toxicity of sweet lupin (Lupinus angustifolius) seed proteins

The effects of raw sweet lupin (Lupinus angustifolius) meal on the growth and N utilisation of rats were determined in two ad libitum and two restricted-feeding net protein utilisation (NPU) and five N balance experiments. Sweet lupin seed grown in Western Australia, obtained as meal, either unsupplemented (LMU) or fully supplemented with required amino acids (360 g kg−1) (LMFS), was tested. Rats fed lactalbumin (130 g kg−1) (LACT) were used as positive controls, while rats fed a non-protein diet (NPC) were used as negative controls. In addition, seed protein, extracted at pH 7.0 with water and insoluble after dialysis at pH 7.0 (LPADI; 124 g kg−1), was also used. The diets contained the same amounts of energy and protein and were supplemented with essential amino acids, vitamins and minerals to target requirements for rats. Inclusion of LPADI in the diet of growing rats caused urinary losses of N, almost all as urea, hypoproteinaemia and increase in body water that resulted in the lowest NPU values, N balance and growth rate as compared with other diets used. These rats developed atrophy of the spleen (low dry weight) and had a comparatively smaller thymus gland than those given raw meals. Furthermore, the LPADI fraction was shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to contain three polypeptides with molecular weights between 30 and 36 kDa which are similar to lectins obtained from Phaseolus vulgaris, Abrus precatorius and Ricinus communis. It is possible that the toxic protein component in the sweet lupin, which has negligible in vitro haemagglutination properties and is extremely toxic in vivo, exerts toxicity by interfering with protein synthesis in the liver, while the immune responses are secondary to azotaemia (high level of urea in the blood) or cytotoxicity action on lymphocytes. The unusual depletion of fat from the body, however, was due to the failure of absorbed amino acids to assimilate as proteins, creating dietary protein restriction and leading to lipolysis. It is therefore tentatively suggested that sweet lupin seed contains a lectin-like protein that is concentrated in this fraction. Further purification and biological evaluation to establish the exact nature of this protein may be important. © 2000 Society of Chemical Industry

A combination of dietary protein depletion and PHA-induced gut growth reduce the mass of a murine non-Hodgkin lymphoma

The results presented in this study show that a switch from a non-protein diet (NPD) to one of a normal protein content (LA) on the day of subcutaneous injection of non-Hodgkin lymphoma tumour cells greatly favoured the development and growth of the tumour. Interestingly, however, inclusion of the plant lectin phytohaemagglutinin (PHA) in the LA diet appeared to compete with the effect of switch to the protein-rich diet, resulting in decreased tumour size and an increased incidence of necrosis. PHA was shown to induce hyperplasia of the gut even in the presence of the growing tumour. This observation together with the fact that gut hyperplasia also occurred in animals which were fed NPD supplemented with PHA, indicated the strength of PHA as a growth signal. It would seem likely that this ‘normal’ growth is able to compete with the tumour for important growth factors and nutrients, including polyamines, effectively starving the tumour for these molecules and resulting in its decreased rate of proliferation.

The nutritional toxicity of sweet lupin (Lupinus angustifolius) seed proteins

The effects of raw sweet lupin (Lupinus angustifolius) meal on the growth and N utilisation of rats were determined in two ad libitum and two restricted-feeding net protein utilisation (NPU) and five N balance experiments. Sweet lupin seed grown in Western Australia, obtained as meal, either unsupplemented (LMU) or fully supplemented with required amino acids (360 g kg−1) (LMFS), was tested. Rats fed lactalbumin (130 g kg−1) (LACT) were used as positive controls, while rats fed a non-protein diet (NPC) were used as negative controls. In addition, seed protein, extracted at pH 7.0 with water and insoluble after dialysis at pH 7.0 (LPADI; 124 g kg−1), was also used. The diets contained the same amounts of energy and protein and were supplemented with essential amino acids, vitamins and minerals to target requirements for rats. Inclusion of LPADI in the diet of growing rats caused urinary losses of N, almost all as urea, hypoproteinaemia and increase in body water that resulted in the lowest NPU values, N balance and growth rate as compared with other diets used. These rats developed atrophy of the spleen (low dry weight) and had a comparatively smaller thymus gland than those given raw meals. Furthermore, the LPADI fraction was shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to contain three polypeptides with molecular weights between 30 and 36 kDa which are similar to lectins obtained from Phaseolus vulgaris, Abrus precatorius and Ricinus communis. It is possible that the toxic protein component in the sweet lupin, which has negligible in vitro haemagglutination properties and is extremely toxic in vivo, exerts toxicity by interfering with protein synthesis in the liver, while the immune responses are secondary to azotaemia (high level of urea in the blood) or cytotoxicity action on lymphocytes. The unusual depletion of fat from the body, however, was due to the failure of absorbed amino acids to assimilate as proteins, creating dietary protein restriction and leading to lipolysis. It is therefore tentatively suggested that sweet lupin seed contains a lectin-like protein that is concentrated in this fraction. Further purification and biological evaluation to establish the exact nature of this protein may be important. © 2000 Society of Chemical Industry

Quantification of Hemolymph Proteins as a Fast Method for Testing Protein Diets for Honey Bees (Hymenoptera: Apidae)

Hemolymph protein measurements in honey bees, Apis mellifera L., were used to determine the efficiency of protein diets as pollen substitutes. Groups of 120 newly emerged worker bees were kept in small cages in the laboratory and fed on bee bread or unprocessed pollen (natural protein diets), soybean/yeast or corn meal (alternative protein diets), or a sucrose solution (nonprotein diet), from adult emergence until 6 d later. The protein content in hemolymph was determined in these bees at 0, 2, 4, and 6 d of adult life. Additionally, vitellogenin (a major protein in young adult worker bees) titer was measured through rocket immunoelectrophoresis of the hemolymph of 6-d-old bees. A significant and progressive rise in protein titers was observed from o to the 6th d of adult life in the hemolymph of bees fed on bee bread, soybean/yeast, or pollen. However, a significant protein reduction was recorded in bees fed on corn meal or sucrose only. The protein titer of 6-d-old bees gave the best discrimination between diets. Protein titers were highly correlated with vitellogenin levels in 6-d-old bees, when the different diets were compared. The protein values reflected the quantity and usability of the protein in the diets and not the consumption, which was similar for all protein diets used. Both total protein measurement and vitellogenin level determination proved to be objective methods for comparing the effectiveness of protein diets; however, the former is faster and less expensive and could easily be used for routine analyses.

Nutritional evaluation of sweet lupin (Lupinus angustifolius): net protein utilization (NPU), nitrogen balance and fractionation studies

The effects of raw sweet lupin (Lupinus angustifolius) meal and its fractions on the growth and N utilization of rats were determined in two NPU and five N balance experiments. Sweet lupinseed grown in Western Australia, obtained as meal, unsupplemented (LMU), or fully supplemented with required amino acids (360 g/kg diet) (LMFS) was tested. In addition, six fractions were tested: aqueous non-dialysed extract at pH 7·0 (LPAND), dialysed extracts soluble (LPAD) and insoluble at pH 7·0 (LPADI), buffer-soluble extract at pH 7·0 (BUSOL), buffer-insoluble extract after dialysis at pH 7·0 (BUDI) and the residue (LMR) containing most of the material from meal insoluble in water and phosphate-citrate buffer. All diets based on fractions contained the same amounts of energy and protein and were supplemented with amino acids, vitamins and minerals to target requirements. Body N and lipid contents of rats fed on LMU and LMFS were reduced significantly in comparison with rats fed on positive lactalbumin (LACT) and non-protein diets (NPC) as negative controls. This wasdue in part to the lower retention of the absorbed N. As a result, the NPU and the biological value (BV) of sweet lupinseed proteins were less than expected. Urea-N outputs of the LMU- and LMFS-fed rats were also elevated. In contrast, true N and DM digestibilities of rats fed on LMU and LMFS were not significantly affected by the difference in the energy content of the diet. The replacement of lactalbumin in thediet with LPAND (196 g/kg), LPAD (148 g/kg), LPADI (124 g/kg), BUSOL (136 g/kg) or BUDI (119 g/kg) reduced dry body weight, N and lipid contents, NPU and BV compared with those obtained from the LACT control, even though the N and DM digestibilitieswere not significantly different. Inclusion of the residue fraction (170 g LMR/kg) had no apparent effect on any of the variables studied. Since sweet lupinseed had asmall amount of non-reactive lectin and LMR had some undesirable side-effects in these rats, it appears that the low nutritional value of LMFS for rats (NPU 0·62) despite the very high level of digestibility of its N, results from disturbances in N metabolism, and particularly from the low retention value of the absorbed N

The ε-(γ-Glutamyl)lysine Moiety in Crosslinked Casein Is an Available Source of Lysine for Rats

To determine bioavailability, expressed as the protein efficiency ratio (PER) and biological value (BV) in rats, of the ε-(γ-glutamyl)lysine [ε-(γ-Glu)Lys] moiety in crosslinked proteins, we prepared heavily crosslinked [21.5 μmol ε-(γ-Glu)Lys/g casein] and intermediately crosslinked [13.6 μmol ε-(γ-Glu)Lys/g casein] casein, using microbial transglutaminase. In Experiment 1, rats were assigned to one of four diets (heavily or intermediately crosslinked caseins, intact casein or non-protein diet) for 4 wk to evaluate the bioavailability of the ε-(γ-Glu)Lys moiety in crosslinked casein as the sole source of dietary protein. Rats that were fed intact casein and the two crosslinked caseins had similar growth rates, PER, and BV, indicating that crosslinked caseins supported the growth of rats similarly to the intact casein. In Experiment 2, heavily crosslinked casein was added to wheat gluten-based diets in concentrations of 20 and 40 g/kg diet to evaluate the bioavailability of lysine in the ε-(γ-Glu)Lys moiety of the casein as a lysine supplement for lysine-poor gluten. One of six diets (heavily crosslinked or intact casein diets in the two concentrations, gluten diet, or non-protein diet) was fed to rats for 4 wk. No significant differences in food intake, body weight gain, PER or BV were observed among rats fed the intact or crosslinked casein diets at either 2 or 4 g/100 g casein. These results suggest that the ε-(γ-Glu)Lys moiety in crosslinked caseins are absorbed and therefore supplement the gluten. HPLC analysis of urine and feces of rats fed the crosslinked caseins actually confirmed that ε99% of the ε-(γ-Glu)Lys moiety was absorbed in the body.