Essential Amino Acid Composition Research Articles

Amino acid requirements of springbok ( Antidorcas marsupialis), blesbok ( Damaliscus dorcas phillipsi) and impala ( Aepyceros melampus) estimated by the whole empty body essential amino acid profile

The essential amino acid (EAA) profile of the duodenal digesta and whole empty body of springbok ( Antidorcas marsupialis), blesbok ( Damaliscus dorcas phillipsi) and impala ( Aepyceros melampus) were investigated. Significant differences were found between the whole empty body EAA composition of the three game species, whether protein quantity was taken into account (g AA/100 g crude protein (CP)) or not (expressed as % of lysine). The chemical scores indicated that the four most limiting amino acids (three for impala) in the duodenal digesta for whole empty body growth were: arginine, histidine, threonine, methionine for springbok; methionine, arginine, histidine, lysine for blesbok and methionine, histidine, arginine for impala. Excess levels of amino acids tends to be present in the duodenal digesta of blesbok (isoleucine) and impala (lysine, valine, leucine, threonine, isoleucine, phenylalanine). A similar trend was found in the EAA:Lysine ratios of the whole empty body for the three game species.

Whey Components: Millennia of Evolution Create Functionalities for Mammalian Nutrition: What We Know and What We May Be Overlooking

Referee: Dr. Phillip S. Tong, Associate Professor, Dairy Products Technology Center, California Polytechnic State University, San Luis Obispo, CA 93407Nutrition is undergoing a revolution owing to the recognition that some foods contain trophic, health-promoting factors distinct from essential nutrients. In this revolution, whey is increasingly being viewed as more than a source of proteins with a particularly nutritious composition of essential amino acids. Milk evolved under continuous Darwinian selection pressure to nourish mammalian neonates. Evolutionary pressure appears to have led to the elaboration of a complex food that contains proteins, peptides, complex lipids, and oligosaccharides that act as growth factors, toxin-binding factors, antimicrobial peptides, prebiotics, and immune regulatory factors within the mammalian intestine. Importantly, these trophic macromolecules are not essential, although the health benefits that their biological activities within the intestine provide likely contributed to neonatal survival. Human and bovine milks contain many homologous components, and bovine whey may prove to be a source for molecules capable of providing biological activities to humans when consumed as food ingredients. To approach this potential, food and nutrition research must move beyond the description of food ingredients as delivering only essential nutrients and develop a mechanistic understanding of the interactions between dietary components and the metabolic and physiological properties of the intestine.

The nutritional value of Lathyrus cicera and Lupinus angustifolius grain for sheep

Certain Lathyrus species have recently been found suitable as multipurpose legume crops in the southern Australian dryland regions, with a potential growing area of 100,000–300,000 ha. However, their use is limited by the presence, mainly in seeds, of 3-(- N-oxalyl)- l-2,3-diamino propionic acid (ODAP), an agent which causes lathyrism. Researchers at the Centre for Legumes in Mediterranean Agriculture (CLIMA) have selected a high yielding variety of Lathyrus cicera (cv. Chalus) which contains consistently low levels of ODAP. The aim of the present study was to assess the nutritional value and animal health aspects of L. cicera cv. Chalus grain as a feed for sheep. Comparisons were made against lupin grain ( Lupinus angustifolius). Eighty individually penned Merino wethers (35±0.3 kg) were allocated to four treatment groups of 20 sheep. Following a 4-week adjustment period, sheep were fed ad libitum the following treatment diets for up to 13 weeks: 35% lathyrus, 35% lupin, 70% lathyrus and 70% lupin. The remainder of the diet was oaten hay and minerals. After 10 weeks on treatments, 14 sheep per group were killed for carcass assessment. The remaining six sheep were fed to maintenance ME requirements for 1 week followed by a 10-day faecal and urinary collection period. Analysis of the grains showed that lathyrus contained less protein (28% versus 36%), fat (0.7 versus 4.1%) and fibre (25% versus 36% NDF), but more starch (42% versus 1%) and anti-nutritional compounds (ODAP, tannins, trypsin inhibitor) than lupin. Essential amino acid composition was similar for the two grains, as were in sacco degradabilities of dry matter (DM) (84% versus 81%) and protein (92% versus 94%). The feeding experiment showed that lathyrus had a higher nutritional value than lupin in terms of voluntary feed intake, liveweight gain ( P<0.01), carcass weights ( P<0.05) and feed efficiency ( P=0.05). Wool growth reflected ME intake, and there was no independent effect of grain type ( P>0.05). Results from the balance study showed that ME concentration was the same for both grains (14 MJ/kg DM). Microbial crude protein (CP) synthesis, estimated from urinary purine derivatives, was significantly lower for lathyrus than lupin, and was lower at 70% grain inclusion than at 35% ( P<0.05). There were no visible or biochemical signs of ill health (in-appetence, lethargy, shaking or instability) in any sheep fed lathyrus. Several sheep fed the 70% lupin diet had mild diarrhoea, and two were eventually removed from the experiment due to anorexia. Meat from sheep fed lupin tended to be yellower than that from those fed lathyrus ( P=0.05). Apart from this, there were no differences in meat quality due to grain type (e.g. redness, pH, taste or tenderness). In conclusion, compared with lupin grain, low ODAP L. cicera grain appears to be of high nutritional value for sheep, with no evidence of adverse effects on sheep health.

Influence of feeding diets with and without fish meal by hand and by self-feeders on feed intake, growth and nutrient utilization of juvenile rainbow trout ( Oncorhynchus mykiss)

Feed intake, growth performance and nutrient utilization by juvenile rainbow trout fed diets with and without fish meal were compared between two feeding regimes: manual feeding and self-feeding. A fish meal-based diet and two non-fish meal diets, fortified with and without essential amino acids (EAA) to simulate the EAA composition of the fish meal diet, were prepared. The two non-fish meal diets were composed mainly of extruded defatted soybean meal (ExSBM), meat and bone meal (MBM) and corn gluten meal (CGM). Each diet was fed to four replicate groups (initial BW; 19.0±2.3 g, 700 g/60 l tank) either by hand to apparent satiation twice daily (0800 and 1730 h) or by self-feeders (feeds were dispensed by fish demands during the light phase) for 60 days at 17 °C under a 14 h light and 10 h dark cycle. Feeding regime did not significantly affect feed intake, weight gain, protein and energy retention, or whole body proximate composition ( P>0.05). Fish fed with the non-fish meal diet with EAA supplementation attained equivalent weight gain and retention of protein as the fish fed with the fish meal diet. However, these parameters for fish fed with the non-fish meal diet without EAA supplementation were significantly inferior ( P<0.05). The whole body fat content of fish fed with this diet was significantly higher than that of fish fed with the other diets. Free EAA levels in the plasma of fish fed with the EAA supplemented non-fish meal diet were similar to those fed with the fish meal diet except for threonine, which was lower in the EAA supplemented non-fish meal diet group. The branched-chain amino acid levels in the plasma of the two non-fish meal diet groups fed by hand increased more sharply and reached higher levels after feeding compared with fish fed with the same diets by self-feeders. The low levels of free threonine, methionine and lysine in the dorsal white muscle of fish fed with the EAA-unsupplemented non-fish meal diet increased in fish fed with the EAA supplemented non-fish meal diet, this increase was especially notable in the manually fed fish. Free non-essential amino acid levels in muscle of fish fed with the non-fish meal diet without EAA were generally the highest among the treatments. The feeding regime affected the levels of serine, glycine and hydroxyproline levels in the muscle (manual feeding<self-feeding). The results of this study indicate that a combination of ExSBM, MBM and CGM, when EAA are supplemented, has the potential to totally replace fish meal in juvenile rainbow trout diets. Feeding diets by self-feeders proved to attain growth and feed performance comparable to those fed by hand. Self-feeding non-fish meal diets affected certain amino acid levels in the plasma and muscle but the effects were not reflected in their growth and protein utilization in this 60-day feeding period.

Lupinus angustifolius protein isolates: chemical composition, functional properties and protein characterization

Abstract Two types of protein isolates were prepared from Lupinus angustifolius defatted flour by alkaline extraction, with (Isolate B) and without (Isolate A) sodium sulphite, and acid precipitation of proteins at the isoelectric point (IEP 4.3). Chemical composition, main functional properties and protein composition of L. angustifolius defatted flour and protein isolates were determined. Isolate A and B have 93.9 and 84.6% protein content, respectively, and had a balanced composition of essential amino acids, with respect to the FAO pattern except for lysine. The in vitro protein digestibility ranged between 86.3 and 93.9% for isolate A and B, respectively.

Expression of nutritionally well-balanced protein, AmA1, inSaccharomyces cerevisiae

Food yeast.Saccharomyces cerevisiae, is a safe organism with a long history of use for the production of biomass rich in high quality proteins and vitamins. AmA1, a seed storage albumin fromAmaranthus hypochondriacus, has a well-balanced amino acid composition and high levels of essential amino acids and offers the possibility of further improving food and animal feed additives. In order to find an effective means of expressingAmA1 in yeast, the gene was cloned into an episomal shuttle vector. Four different promoters were tested: the glyceraldehyde-3-phosphate dehydrogenase promoter, galactose dehydrogenase 10 promoter, alcohol dehydrogenase II promoter, and a hybrid ADH2-GPD promoter. The recombinantAmA1 genes were then introduced into the yeastSaccharomyces cerevisiae 2805. Northern and Western blot analyses of the yeast under appropriate conditions revealed thatAmA1 was expressed by all four promoters at varying levels. An enzyme-linked immunosorbent assay demonstrated that the amount of AmA1 protein in the recombinant yeast was 1.3–4.3% of the total soluble proteins. The highest expression level was obtained from the hybrid ADH2-GPD promoter.

Effect of temperature, pressure and alkaline treatments on meat meal quality

The recommendation of the 96/449/EC directive for processing mammalian animal waste does not ensure complete inactivation of transmissible spongiform encepalopathy (TSE) agents. The safety of the process might be ensured by adding alkaline treatments to the heating step. Evaluating the in vivo and in vitro nutritive value of meat meals produced according to 11 heat, time and pressure treatments, either with or without addition of alkali was completed. Meat meals were obtained from fresh soft bovine meat in a 20kg stirred displacement autoclave, resembling the standard equipment used in Italian rendering plants. Operating temperature and pressure were monitored continuously. Meat meals were analysed for crude protein and ash contents and pH was measured. The protein fraction was analysed for amino acids and lysinoalanine (LAL). Protein quality was evaluated in vivo with the rat-based protein efficiency ratio (PER) bioassay and in vitro by pepsin digestibility, the essential amino acids composition (DC-PER) and from both essential amino acid composition and enzyme digestibility (C-PER) of the protein. Compared to the standard procedure in use before 96/449/EC directive (MM8), implementing of the EC treatment did not reduce the nutritive value of the meat meal (MM), whereas negative effects were observed when the length of treatment was increased to 180min or when adding an alkaline step to the MM preparation. In particular, addition of alkali reduced the nutritive value of the MM as suggested by the PER bioassay, and increased the (LAL) content of the protein fraction. Data suggests that LAL content of the protein fraction could be used as an indicator of protein quality of meat meals. In vitro and in vivo results demonstrate the inadequacy of the in vitro technique (pepsin digestibility, C-PER and DC-PER) for evaluating the nutritive value of meat meals.

Underutilised legumes: potential sources for low-cost protein

Seeds of 104 leguminous species belonging to 17 genera were analysed for their protein contents. The promising ones were investigated for fibre, carbohydrate, ash, oil, fatty acids, amino acid profile and trypsin inhibitor activity (TIA). The variation of fibre contents was 4.1-8.9%, carbohydrate 18.4-49.2%, ash 1.8-7.2%, TIA 48.7-87.5 mg/g, oil 1.3-19.8% and protein 11.0-51.6%. The protein content (41-45%) in Acacia mellifera (41.6%), Albizzia lebbek (43.6%), Bauhinia triandra (42.7%), Lathyrus odoratus (42.8%), Parkinsonia aculeata (41.6%), Psophocarpus tetragonolobus (41.9%), Sesbania paludosa (41.2%) and S. sesban (43.8%) was in close proximity to soybean (42.8%), whereas Bauhinia retusa (51.6%), B. variegata (46.5%), Delonix elata (48.7%) and Gliricidia maculata (46.3%) showed higher percentages of protein than soybean. The essential amino acid composition of some of the seed proteins was reasonably well balanced (lysine up to 7.6%). The seeds of Bauhinia retusa (18.6%), B. triandra (16.5%), B. variegata (17.3%), Gliricidia maculata (16.2%), Parkia biglandulosa (18.9%) and Psophocarpus tetragonolobus (19.8%) had a good amount of oil, comparable to soybean (18-22%). The fatty acid composition of some genera/species was quite promising with high amount of unsaturated fatty acids.

Características químicas dos mingaus desidratados de arroz e soja

O presente trabalho teve por objetivo caracterizar quimicamente os mingaus desidratados de arroz e soja nas respectivas proporcoes 100:0, 90:10, 80:20, 70:30, 60:40 e 50:50% e verificar a possibilidade do uso de alguns destes mingaus como ingredientes na formulacao de alimentos infantis com base nos resultados discutidos. O processo utilizado para sua obtencao foi decorticagem dos graos de soja, branqueamento, desintegracao e homogeneizacao do arroz e soja, assim como secagem por atomizacao. A caracterizacao quimica foi realizada atraves das seguintes determinacoes: composicao centesimal, composicao de minerais e de aminoacidos, e atividade do inibidor de tripsina. Com o aumento das proporcoes de soja (de 0 a 50%), os mingaus desidratados tiveram aumento nos teores de proteina, extrato etereo, cinzas, fibra bruta, fosforo, calcio, potassio, magnesio, ferro, cobre, zinco, selenio, manganes e molibdenio, porem diminuicao nos teores de carboidrato, sodio e cromo. Contudo, os valores de cobalto nao foram alterados. Os teores de potassio, magnesio, ferro e cobre foram altos e os teores de cromo, selenio, manganes e molibdenio foram suficientes em 100g de mingaus desidratados de arroz e soja com 40 e 50% de soja, atendendo 100% das recomendacoes da RDA para lactentes, podendo estes formulados para alimentos infantis. Houve uma melhoria nos escores de aminoacidos essenciais com as crescentes proporcoes de soja, exceto para os aminoacidos sulfurados. A composicao em aminoacidos foi adequada e comparavel ao padrao da FAO/WHO para lactentes, exceto para lisina e metionina. Em relacao a lisina, os mingaus desidratados com 30, 40 e 50% de soja mostraram os maiores escores para pre-escolares, nao havendo deficiencia para escolares. Por outro lado, a metionina nao foi deficiente para pre-escolares e escolares. A atividade residual do inibidor de tripsina nao foi observada nos mingaus desidratados estudados.

Amino acid composition of whole body tissue of Atlantic halibut ( Hippoglossus hippoglossus), yellowtail flounder ( Pleuronectes ferruginea) and Japanese flounder ( Paralichthys olivaceus)

Amino acid and proximate composition of the whole body tissue of juvenile Atlantic halibut, yellowtail flounder and Japanese flounder were determined. Higher protein and lower lipid levels were found in whole body of Japanese flounder than the other two species. The amino acid composition was, however, not significantly different among species when expressed as g/100 g amino acids. The values were also found to be very similar to those of rainbow trout and Atlantic salmon. The A/ E ratios [(each essential amino acid content/total essential amino acid content including cystine and tyrosine)×1000] based on the essential amino acid composition of whole body tissue, suggest that the amino acid requirements of flatfish may not be greatly different among species.

The effect of protein inclusion level in diets formulated to contain an ideal amino acid composition for growing pigs

The aim of the study was to determine the optimum protein inclusion level in diets containing an ideal amino acid balance for growing pigs. The performance of commercial crossbred grower-pigs was studied in two trials in which the experimental animals were housed either in commercial-type group housing (experiment1) or in individual pens (experiment 2). Treatments consisted of diets containing 14%, 16%, 18% or 20% crude protein. Lysine, tryptophan, threonine and total sulphur-containing amino acids were included in all diets at levels equivalent to that supplied by the 18% crude protein diet. In experiment one, 144 pigs (72 boars and 72 gilts) of initial mass 30 kg were fed until slaughter at 70 kg. In experiment two, 80 pigs (40 boars and 40 gilts) of live masses ranging from 17.5 to 31.1 kg were fed until slaughter at masses between 64 and 105.5 kg. There were no differences between treatments (p > 0,05) for daily gain, feed conversion ratio, daily intake or carcass classification, but feed conversion ratio differed between sexes in experiment two (p < 0.05). It was concluded that protein inclusion levels in pig growth diets could be decreased from 18% to 14% without any detrimental effect on performance, provided that the digestible essential amino acid composition is adjusted to meet requirements. This practice is however not economically viable for South African pig producers at the prevailing price of synthetic amino acids. (South African Journal of Animal Science: 2000, 30(1): 57-61)

Homeostasis in the essential amino acid composition of the marine copepod Euterpina acutifrons

The essential amino acid composition (EAA) of females and eggs of Euterpina acutifrons and their food was analyzed on copepods fed with different microalgae and collected from the field. There were not significant differences in the EAA of females, but the EAA of eggs varied according to food source. As predicted by homeostasis theory, a higher reproductive success was observed as the EAA of females and food became more similar. This chemical homeostasis explains the selective retention of amino acids observed in copepods, tells why conversion efficiencies of ingested nitrogen may vary according to the food source, and shows the importance of food quality on reproductive success in copepods.

Examination of the nitrogen limitation hypothesis in non‐cyclic populations of cotton rats (Sigmodon hispidus)

1. Nitrogen‐containing nutrients have long been considered a frequently limiting resource to the growth of herbivore populations (nitrogen limitation hypothesis). To explore this hypothesis, we examined the relationships between availability of essential amino acids and concentrations of phenolics in the diets of hispid cotton rats (Sigmodon hispidus) in central Oklahoma and the intrinsic characteristics of their non‐cyclic populations. We posited that lower quality proteins (i.e. essential amino acid composition) and elevated phenolic levels (protein digestion inhibitors) in diets of cotton rats from low‐ compared to high‐density populations, especially during the breeding season, would be supportive of the nitrogen limitation hypothesis. Replicated low‐ and high‐density populations were censused by live‐trapping at 3‐month intervals. Samples of stomach digesta were collected from cotton rats in similar habitats adjacent to trapping grids to determine the botanical and nutrient composition of their diets. 2. During the breeding season, concentrations of essential amino acids were as much as 43% greater in diets of cotton rats from high‐density populations. Dicots, typically higher in protein than monocots, were an important component of diets and were preferred forage in all seasonal collections. Seeds and arthropods were frequently utilized by cotton rats as additional high‐quality sources of essential amino acids. Concentrations of total phenolics in the diet (greater in diets from low‐density populations) were consistent with the nitrogen limitation hypothesis. 3. Density was consistently higher in the high‐density populations throughout the study. Other demographic and body condition parameters were similar between low‐ and high‐density populations in the non‐breeding season, but reproductive activity was greater in high‐density populations during the breeding season. Total number of juveniles recruited into the trappable population over the entire study was about five times greater in high‐ compared to low‐density populations. 4. Our data did not refute the nitrogen limitation hypothesis where levels of essential amino acids and phenolic compounds in the diet during the breeding season may determine annual peak densities of cotton rats that can be supported in their habitat. However, we could not rule out the involvement of other environmental variables such as overhead cover (as well as other unmeasured variables) as contributing factors to determining annual peak densities.

Essential amino acid composition of fleshy fruits versus maintenance requirements of passerine birds

Nutritional analyses were performed on 27 fruit species that are eaten by frugivorous birds in east Mediterranean habitats in Israel. The essential amino acid (EAA) profile [compared by principal component analysis (PCA)] of these fruits indicated two distinct groups of fruits. The main group consisted of 23 species that were similar in their relatively low total EAA quantities and unbalanced EAA profiles. On average, the EAAs phenylalanine and tyrosine were most concentrated and histidine least (tryptophan was not measured). Comparing the relative amounts of EAAs in fruits with required amounts for maintenance of granivorous passerine birds revealed that these fruits are deficient in all or most EAAs. The sulfur-containing amino acids (methionine and cystine) were most limiting relative to the required amount (41–61% below requirement), while four others (arginine, lysine, isoleucine, and leucine) were severely deficient (30–37% below requirement). These results complement reports suggesting that frugivorous birds have lower total protein demands than granivores. The second group of four fruit species had relatively high total EAA contents. Each of these fruits appeared to contain especially large quantities of some EAAs, but it was uncertain whether some high concentrations could have resulted from interactions in the pulp during preparation and chemical analysis.

Free lysine ( l-lysine · HCl) is utilized for growth less efficiently than protein-bound lysine (soybean meal) in practical diets by young channel catfish ( Ictalurus punctatus)

Two 10-week feeding experiments were conducted with channel catfish fingerlings in aquaria to compare the efficiency of utilization for growth of free versus protein bound lysine in practical diets. In experiment 1, a basal, 26% protein diet, deficient only in lysine, was formulated with a combination of peanut meal and corn gluten meal as the primary protein source. The diet was then supplemented with graded levels of lysine by either adding l—lysine · HCl or substituting soybean meal for the peanut meal—corn gluten meal combination to produce two series of diets with increasing concentrations of either free lysine or protein-bound lysine. In experiment 2, the basal diet contained sesame meal as the primary protein source and was supplemented with free or protein-bound lysine as in experiment 1. Slope ratio analysis of response data showed that the efficiency of utilization of protein-bound lysine in soybean meal relative to free lysine from lysine-HCl was 196 and 163% for experiments 1 and 2, respectively, based on weight gain. A subsequent feeding experiment was conducted in which the peanut meal-corn gluten meal basal diet was supplemented with lysine alone or with lysine plus histidine, isoleucine, threonine, and tryptophan to match the essential amino acid composition of the diet in which soybean meal provided the protein. Supplementation of the basal diet with the additional amino acids did not improve fish weight gain relative to that from supplementation with lysine alone. Overfortification of the basal diet with free lysine improved weight gain of fish to equal that obtained with the diet containing soybean meal. Loss of lysine due to leaching of diets in water was 12.7 and 2.0% of the original lysine concentration for free lysine and protein-bound lysine, respectively. When leaching losses are subtracted from the lysine concentrations in the test diets, the efficiency of utilization of protein-bound lysine is still higher than that of free lysine, 175 and 146%, based on weight gain, for experiments 1 and 2, respectively. These results indicate that protein-bound lysine is more efficiently utilized than free lysine in practical type diets for young channel catfish.

Genetic and Environmental Variation for Seed Yield, Protein, Lipid and Amino Acid Composition in Cowpea (Vigna unguiculata (L) Walp)

The genetic and environmental variability for seed yield (kg ha-1), protein content (g kg-1 DM), lipid content (mg g-1 DM) and essential amino acid composition (g per 16 gN) of cowpea seeds using 15 cultivars grown in three locations (Kano (12°00′ N 8°31′ E), Mokwa (9°17′ N 5°04′ E) and Ago-Iwoye (6°58′ N 4°00′ E)) that differ markedly in climate was studied. The environmental effect accounted largely for the variability observed in yield (93%), protein (71%), lipid (100%), threonine (96%), cystine (80%) and arginine (81%) while the genotypic effect accounted largely for the variability observed in methionine (56%) and lysine (51%) contents. Correlation coefficients (pooled data) from the three locations indicated that yield was negatively correlated to protein content (r=-0·87, P<0·001) and positively correlated to lipid content (r=0·73, P<0·001). Protein content was negatively correlated to lipid content (r=-0·67, P<0·001) and positively correlated to threonine (r=0·66, P<0·01), cystine (r=0·69, P<0·001) and methionine (r=0·88, P<0·001) contents. Similarly, yield was positively correlated to threonine (r=0·22, 0·01<P<0·05), cystine (r=0·38, 0·001<P<0·01) and methionine (r=0·67, 0·001<P<0·01). Yield showed a strong negative correlation with protein content (r=-0·81) and a strong positive correlation with lipid content (r=0·97) at the environmental level. Cystine, methionine and to some extent, threonine were the limiting amino acids in the three environments. This research established the degree of variability for these characters in cowpea and indicated that concurrent selection for yield, lipid content, threonine and sulphur amino acids compositions is feasible. © 1997 SCI.

Chemical and essential amino acid composition of South African Mutton Merino lamb carcasses

Chemical and essential amino acid composition of South African Mutton Merino lamb carcasses

Dietary Influences on Endogenous Ileal Protein and Amino Acid Loss in the Pig—A Review

Abstract The basis for using determined values of endogenous ileal protein and amino acid losses in the protein evaluation of pig feeds is reviewed. The amounts of endogenous protein and amino acids in ileal digesta may be determined by numerous methods. These include N-free diets, regression analysis, enzyme hydrolysed casein (EHC) coupled with ultra-filtration, modifying lysine to homoarginine, isotope dilution techniques and calculations based on the difference between the in vitro and in vivo digestibility of protein and amino acids. Endogenous ileal protein loss seems to be influenced primarily by dietary dry matter intake and secondarily by the composition of the diet and can be divided into a basal and an extra loss. The basal loss after ingestion of experimental N-free diets is 10-15 kg−1 DM intake, but, under more physiologically normal conditions when protein-containing diets are ingested, the basal loss seems to be about 20 g kg−1 DM intake. When vegetable feedstuffs are ingested there is often an extra loss specifically induced by the presence of dietary fibre and/or antinutritional factors (ANFs), resulting in total losses that are typically in the range of 20 to 40 g kg−1 DM intake. The amino acid composition of endogenous protein is relatively constant for different diets and methods of determination and seems not to be influenced significantly by the amount of loss and liveweight of pig. For practical purposes, and lacking evidence to the contrary, the composition can be considered to be constant and the following general composition (g per 160 g N) of essential amino acids is pro posed: lysine 30, methionine 10, cystine 16, threonine 45, tryptophan 12, isoleucine 25, leucine 40, histidine 15, phenylalanine 30, tyrosine 20, valine 35. The composition is, compared with ideal protein and most feedstuffs, characterized by a relatively low contribution of all essential amino acids, except threonine, cystine and tryptophan.

Biological and chemical evaluation of chick pea seed proteins as affected by germination, extraction and alpha-amylase treatment.

The effects of germination, extraction (double extraction with 70% ethanol and water at isoelectric point) and alpha-amylase treatments of chick pea seed flours on crude protein, total carbohydrate, protein efficiency ratio (PER), biological value (BV), true digestibility (TD), net protein utilization (NPU), essential amino acid composition, in-vitro protein digestibility (IVPD) and actual amino acid indices (essential amino acid index or amino acid score) were evaluated. Crude protein content was increased (8-149%), while total carbohydrate was decreased (11-62%) by germination, extraction and alpha-amylase treatments. Alpha-amylase treatment was more efficient in reducing total carbohydrate and increasing the protein content than that of extraction treatment. The protein quality of chick pea flours as measured by PER, BV, TD, NPU, IVPD and corrected amino acid indices (actual amino acid indices x IVPD) was significantly improved by these treatments. The protein quality of germinated-alpha-amylase treatment was comparable with casein, while germinated-alpha-amylase treaded seeds appeared nutritionally superior to casein. The results indicate that the germinated-alpha-amylase and germinated-alpha-amylase-extracted treatments could be used successfully as a source of concentrated high quality protein for baby food production. The corrected amino acid indices gave better prediction of PER, BV, TD and NPU (r = 93 to 97) than actual amino acid indices (r = 45 to 71). PER was highly correlated with corrected amino acid score (r = 0.93). The PER could be predicted from the following simple regression equation: PER = -1.827 + 0.0561 x corrected amino acid score.

Rebalancing essential amino acids intake by self-selection in the rat.

The purpose of the present study was to assess whether rats are capable of selecting the right proportions of two diets that are individually inappropriate in terms of essential amino acid composition to satisfy their amino acid requirements. Rats were offered a choice of one protein-free regimen and another devoid of only one essential amino acid (either threonine or isoleucine) set up in such a way as to provide amino acid balance if they were consumed in 1/3 and 2/3 proportions respectively. Preliminary experiments had established that all our diets were aversive by themselves except for the 60 g casein/kg diet. Rats did reach almost the necessary proportion with, according to published standards (National Research Council, 1978), some excess in isoleucine intake. In addition, given access to two aversive diets that were each nutritionally inadequate, rats showed no aversion and gained body weight when they had the opportunity to consume both of them. Beyond the capacity that rats have of rebalancing their micronutrient intake, the present experiment brings out the idea that the imbalance-induced aversion:preference ratio may be completely upset when this omnivore has access to more than one feed.