Effect of various kinds of dietary protein and supplementation with limiting amino acids on growth,haemolymph components and uric acid excretion in the silkworm, Bombyx mori

Effects of various kinds of dietary protein on growth of the silkworm, Bombyx mori, were determined using semi-synthetic diets. Also, the ingestion, digestion and utilization of dry matter and of nitrogen were measured. Nutritive effects of dietary proteins and supplementation of limiting amino acids on haemolymph protein and amino acids pattern were also investigated. Larval growth was largely dependent on the dietary proteins. When the larvae were reared on a diet containing weakly nutritive proteins such as gluten and zein, haemolymph protein was decreased and uric acid excretion was markedly accelerated. The free amino acid composition of the haemolymph manifested characteristic patterns according to the kinds of dietary protein.The supplementation of gluten and zein with their limiting amino acids resulted in a rise of haemolymph protein and a drop in uric acid excretion. The amino acid patterns in the haemolymph were greatly changed according to supplementation.     

Physiological and biochemical responses to dietary protein in the omnivore passerine Zonotrichia capensis (Emberizidae)

We studied the physiological, biochemical and morphological responses of the omnivore sparrow Zonotrichia capensis, a small opportunistic passerine from Central Chile acclimated to high- and low-protein diets. After 4 weeks of acclimation to 30% (high-protein group) or 7% (low-protein group) dietary casein, we collected urine and plasma for nitrogen waste production and osmometry analysis, and measured gross renal morphology. Plasma osmolality and hematocrit were not significantly affected by dietary treatment, but urine osmolality was higher in the high-protein group than in the low-protein group. Kidney and heart masses were higher in animals acclimated to the high-protein diet. Mean total nitrogen waste was significantly higher in the high-protein group, but the proportions of nitrogen excreted as uric acid, urea and ammonia were unaffected by diet. Our data suggest that the response of Z. capensis to an increase in dietary protein content is through greater amounts of total nitrogen excretion and hypertrophy of kidney structures, without any modification of the proportion of excretory compounds.     

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

ABSTRACT

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

Effect of low-protein corn and soybean meal-based diets on nitrogen utilization,litter quality,and water consumption in broiler chicken production: insight from meta-analysis

The growing demand for high-value animal protein must be met using sustainable means that optimize the utilization of nutrients, especially nitrogen (N) so that excreta do not over-fertilize fields and end up causing soil acidification, waterway eutrophication and greenhouse gas emissions. Malodorous N compounds can cause respiratory diseases and poor growth in livestock. The increasing availability of feed-grade amino acids makes it possible to formulate low-protein diets for broilers and thereby reduce N excretion. However, published studies of the effects of such diets on broiler growth performance have been based on reducing CP contents gradually in a variety of ways that have given inconsistent results. Since the amount of published data is now large, a meta-analysis was performed in order to categorize diet formulation strategies and quantify their impact on N balance, water consumption, litter moisture, plasma uric acid. This showed that lowering the CP content of broiler diets generally means replacing some soybean meal with corn and hence increasing the starch content. However, since soybean meal is also a source of potassium, this reduces electrolyte balance. Lowering the CP content from 19% to 17% is associated with a 29% reduction of N excretion in broilers aged 0–21 d, and a 7% increase in N efficiency (N retention/N intake). Reducing the CP content from 19% to 17% decreases daily water consumption by 20.6 mL/bird, litter moisture by 2.2% and plasma uric acid by 0.56 mg/dL. This meta-analysis improves our understanding of the low-protein strategy and allows us to quantify its impact on N balance, litter quality and uric acid. It shows that managing N excretion is wholly beneficial and reduces litter wetness.     

Effect of adenosine 3',5'-monophosphate on serine metabolism in chick tissues.

The effect of cyclic 3',5'-AMP and supplemental dietary glycine upon de novo synthesis of serine metabolic enzymes in chick livers were examined. Chicks fed crystalline amino acid diets containing 2% glycine had approximately twofold the activity in liver for 3-phosphoglycerate dehydrogenase and phosphoserine phosphatase compared to liver tissue from chicks fed diets lacking in dietary glycine. Chicks subjected to daily intraperitoneal injections of cyclic 3',5'-AMP and fed diets containing no dietary glycine contained biosynthetic enzyme activity similar to glycine-fed chicks suggesting a correlation between glycine and cyclic AMP for serine enzyme induction. The elevated enzyme activity in liver of chicks fed dietary glycine or injected with cyclic AMP was inhibited when chicks were also injected with actinomycin D indicating de novo synthesis of 3-phosphoglycerate dehydrogenase and phosphoserine phosphatase. Dietary glycine or cyclic AMP, however, did not change serine dehydratase and glycerate dehydrogenase activities in chick liver.     

The effect of roughage to concentrate ratio in the diet on nitrogen and purine metabolism in dairy cows

Four lactating dairy cows were used in two experiments to study the effects of the roughage to concentrate ratio in the diet on nitrogen balance, plasma urea, urinary urea, milk urea and urinary purine derivatives. The use of the allantoin to creatinine ratio in spot samples of urine as an index of the urinary allantoin excretion was also evaluated. Four isoenergetic and isonitrogenous diets were formulated according to a 2 × 2 factorial arrangement. Factor I was concentrate content. The roughage to concentrate ratios were 65:35 and 35:65 for the high roughage and high concentrate diets, respectively. Factor II was fat content, which was 2.8% and 5.8% for the low and high fat diets, respectively. In Experiment 1 cows were fed diets with low fat content, and in Experiment 2 cows were fed diets with high fat content. In both experiments, diets were fed according to a change-over design. Nitrogen balance was not affected by the treatments. In cows fed high concentrate diets the amount and the proportion of nitrogen excreted in milk, as well as milk production was higher than in cows fed the high roughage diets. In both experiments, as an overall effect, the urea levels in plasma, urine and morning milk were higher, although the total urinary excretion of urea was lower, for the high concentrate diets. Urinary allantoin excretion was higher, although not significantly in Experiment 1, for the high concentrate diets. The allantoin to creatinine ratio in spot samples of urine showed the same pattern as the total allantoin excretion. Urinary creatinine excretion appeared to be affected by the diet.     

Bacterial protein meal in diets for pigs and minks: comparative studies on protein turnover rate and urinary excretion of purine base derivatives

The effect of increasing the dietary content of bacterial protein meal (BPM) on protein turnover rate, and on nucleic acid and creatinine metabolism in growing minks and pigs was investigated in two experiments. In each experiment, 16 animals were allocated to four experimental diets. The diets containing no BPM served as controls, i.e. for minks diet M1, for pigs P1; the experimental diets contained increasing levels of BPM to replace fish meal (minks) or soybean meal (pigs), so that up to 17% (P2), 20% (M2), 35% (P3), 40% (M3), 52% (P4), and 60% (M4) of digestible N was BPM derived. Protein turnover rate was measured by means of the end-product method using [15N]glycine as tracer and urinary nitrogen as end-product. In minks, protein flux, synthesis, and breakdown increased significantly with increasing dietary BPM. In pigs, diet had no observed effect on protein turnover rate. The intake of nucleic acid nitrogen (NAN) increased from 0.15 g/kg W0.75 on M1 to 0.26 g/kg W0.75 on M3 and M4 in the mink experiment, and from 0.08 g/kg W0.75 on P1 to 0.33 g/kg W0.75 on P4 in the pig experiment. Increased NAN intake led, in both experiments, to increased allantoin excretion. Analysis of species effects showed that minks excreted 1.72 mmol/ kg W0.75 of allantoin, significantly more than the 0.95 mmol/kg W0.75 excreted by pigs. In minks, approximately 96% of the excreted purine base derivatives consisted of allantoin, whereas in pigs approximately 93% did. Thus, increasing the dietary content of BPM increased protein turnover rate in minks but not in pigs, and allantoin excretion increased with increasing dietary BPM although it seemed that mink decomposed purine bases to their end-product more completely than pigs did. Collectively these data show that BPM is a suitable protein source for pigs and mink, and recorded differences between species were to a large extent due to differences in protein retention capacity and muscle mass.     

Glycine-serine interrelations in the chick.

Glycine and serine are involved in numerous important functions in the body in addition to protein synthesis. Glycine is synthesized by higher animals; however, the rate is not adequate to support maximal growth of the chick. Studies indicate that chicks fed a glycine-serine free crystalline amino acid diet grow at approximately 80% the rate of chicks fed the same diet supplemented with glycine. An equimolar quantity of L-serine has been shown to support equal chick performance as glycine, thus indicating that serine conversion is adequate to meet the dietary need for glycine. The serine-glycine interconversion is catalyzed by the folic acid containing enzyme sering hydroxymethyltransferase, and a deficiency of this vitamin decreases the effectiveness of serine in meeting the chick's dietary need for glycine. Studies with chicks fed normal and high levels of a crystalline amino acid mixture devoid of glycine and serine indicate that the chick has the metabolic potential to synthesize more of these two amino acids than should be required for normal growth. The observed dietary response to glycine or serine or both indicates, however, that this synthetic potential is not being utilized.     

Effect of Dietary Addition of Amino Acids and Proteins on the Activities of Some Urea Cycle Enzymes in Rat Liver

The activities of ornithine transcarbamylase, arginine synthetase and arginase in the liver of rats receiving basal diets containing 25% casein supplemented respectively with arginine, aspartic acid, glutamic acid, glycine, a mixture of arginine, aspartic acid and glutamic acid, egg albumin, casein, wheat gluten and gelatin have been determined.

These urea cycle enzymes in rats receiving diets supplemented with the various nitrogen sources were generally increased, but the increments were due to the increase of the ingested amount of nitrogen, and not the specific effect of the individual amino acids or proteins. The excretion of urinary urea in general was increased proportionally with the elevations of these enzyme activities, independent of the nature of the dietary nitrogen.     

The utilization of nitrogen for growth in mice fed blends of purified proteins

Reasons for differences in growth of weanling mice fed different blends of purified proteins in diets apparently adequate in indispensable amino acids were investigated. Dietary nitrogen provided at increasing levels from a mixture of casein, gelatin, and zein, or from these plus gliadin and lactalbumin resulted in similar weight gains and efficiency of feed utilization in weanling mice. These responses were always lower (P less than 0.05) than for mice fed the control diet. When diets were based on true digestible nitrogen and amino acids, weight gains and feed efficiency decreased (P less than 0.05) as the dietary nitrogen level increased. High plasma glycine concentrations and high phenylalanine to tyrosine ratios were associated with high dietary glycine levels provided by gelatin. When a mixture of constant proportions of protein sources, predominantly casein, supplied most of the dietary nitrogen, small increases in weight gains and feed efficiency were observed as the nitrogen level in the diet increased. Varying the proportions of sources, which increased the percentage of gelatin, resulted in decreased gains in response to more dietary nitrogen. Replacing the amino acids found in gelatin by crystalline L-amino acids and replacing glycine by glutamic acid improved gains and feed efficiency (P less than 0.05) compared with gelatin-containing diets. These studies demonstrated that glycine at dietary concentrations of approximately 1-2%, either from gelatin or as the free amino acid, inhibited growth and feed utilization of growing mice.     

Time course of urinary excretion of intraportal ammonia as uric acid and ammonia in chickens fed low- or high-protein diet

15N-ammonia was intraportally infused for 6 hr into chickens fed 5% or 20% protein diet to examine the time course of urinary excretion of intraportal ammonia and dietary effects on it. Urinary ammonia increased linearly for the first hour to the same extent in both dietary groups and thereafter further in the low-protein group. Urinary uric acid derived from the intraportal ammonia adaptively increased and reached a steady state level within 1.5 hr. This level was four times higher in the high-protein group. The infused ammonia was excreted into urine as both ammonia and uric acid, in relatively high proportions in the chickens fed the low-protein diet but was almost all excreted as uric acid in those fed the high-protein diet.     

Bacterial protein meal in diets for pigs and minks: Comparative studies on protein turnover rate and urinary excretion of purine base derivatives

Abstract

The effect of increasing the dietary content of bacterial protein meal (BPM) on protein turnover rate, and on nucleic acid and creatinine metabolism in growing minks and pigs was investigated in two experiments. In each experiment, 16 animals were allocated to four experimental diets. The diets containing no BPM served as controls, i.e. for minks diet M1, for pigs P1; the experimental diets contained increasing levels of BPM to replace fish meal (minks) or soybean meal (pigs), so that up to 17% (P2), 20% (M2), 35% (P3), 40% (M3), 52% (P4), and 60% (M4) of digestible N was BPM derived. Protein turnover rate was measured by means of the end-product method using [¹⁵N]glycine as tracer and urinary nitrogen as end-product. In minks, protein flux, synthesis, and breakdown increased significantly with increasing dietary BPM. In pigs, diet had no observed effect on protein turnover rate. The intake of nucleic acid nitrogen (NAN) increased from 0.15 g/kg W^0.75 on M1 to 0.26 g/kg W^0.75 on M3 and M4 in the mink experiment, and from 0.08 g/kg W^0.75 on P1 to 0.33 g/kg W^0.75 on P4 in the pig experiment. Increased NAN intake led, in both experiments, to increased allantoin excretion. Analysis of species effects showed that minks excreted 1.72 mmol/kg W^0.75 of allantoin, significantly more than the 0.95 mmol/kg W^0.75 excreted by pigs. In minks, approximately 96% of the excreted purine base derivatives consisted of allantoin, whereas in pigs approximately 93% did. Thus, increasing the dietary content of BPM increased protein turnover rate in minks but not in pigs, and allantoin excretion increased with increasing dietary BPM although it seemed that mink decomposed purine bases to their end-product more completely than pigs did. Collectively these data show that BPM is a suitable protein source for pigs and mink, and recorded differences between species were to a large extent due to differences in protein retention capacity and muscle mass.     

Fish protein hydrolysate elevates plasma bile acids and reduces visceral adipose tissue mass in rats

Conjugation of bile acids (BAs) to the amino acids taurine or glycine increases their solubility and promotes liver BA secretion. Supplementing diets with taurine or glycine modulates BA metabolism and enhances fecal BA excretion in rats. However, it is still unclear whether dietary proteins varying in taurine and glycine contents alter BA metabolism, and thereby modulate the recently discovered systemic effects of BAs. Here we show that rats fed a diet containing saithe fish protein hydrolysate (saithe FPH), rich in taurine and glycine, for 26 days had markedly elevated fasting plasma BA levels relative to rats fed soy protein or casein. Concomitantly, the saithe FPH fed rats had reduced liver lipids and fasting plasma TAG levels. Furthermore, visceral adipose tissue mass was reduced and expression of genes involved in fatty acid oxidation and energy expenditure was induced in perirenal/retroperitoneal adipose tissues of rats fed saithe FPH. Our results provide the first evidence that dietary protein sources with different amino acid compositions can modulate the level of plasma bile acids and our data suggest potential novel mechanisms by which dietary protein sources can affect energy metabolism.     

Allantoin and allantoic acid titre in the faeces and tissues of the developing larva of the moth, Orthaga exvinacea Hampson

Allantoin and allantoic acid are investigated in the faeces and tissues of the developing sixth instar larva of the moth, Orthaga exvinacea. The nitrogen excreted as allantoin and allantoic acid is compared with nitrogen excreted as uric acid and ammonia. The larva excretes 2.35–5.14 μmol/g allantoin and 0.74–1.34 μmol/g allantoic acid which account for 0.83 to 2.39% and 0.23 to 0.53%, respectively, of the excreted total nitrogen. Allantoin and allantoic acid are found to be minor nitrogenous end-products of the larva. Allantoin and allantoic acid are also present in the haemolymph and fat body of the larva in varying concentrations. The level of allantoin in the haemolymph shows a negative correlation with the allantoin concentration of faeces and fat body. The allantoin is found to be stored in the fat body at a low level. The results of the present study also indicate the coexistence of uric acid storage and uricolysis.     

Metabolism and excretion of nitrogen during metamorphosis and egg production in the sawfly, Neodiprion sertifer

Measurements of whole-body dry matter, total nitrogen, water-soluble protein, amino acids, and uric acid were determined at successive stages during metamorphosis in Neodiprion sertifer. The major change was in the uric acid fraction: in females, it increased up to the non-pharate pupa and then decreased during the subsequent stages of adult development and egg production; in males, it continued to increase during adult development. The decline of uric acid could not be explained by the accumulation of allantoin, allantoic acid, urea, or uric acid riboside. Examination of amino acid levels in the gut revealed an accumulation in the pupa followed by a depletion at the onset of adult development. This was followed by an excretory phase marked by the progressive accumulation of large quantities of uric acid and small quantities of urea, ammonia, and amino acids during the formation of the meconium. Amino acid analysis of the meconium revealed the presence of large proportions of proline, hydroxyproline, and histidine in comparison with the other amino acids.     

Influence of incrementally substituting dietary soya bean meal for rapeseed meal on nutrient digestibility, nitrogen excretion, growth performance and ammonia emissions from growing-finishing pigs

A completely randomised design experiment was performed to examine the effects of replacing different levels of soya bean meal (SBM) with rapeseed meal (RSM) on the growth performance, carcass characteristics, apparent nutrient digestibility, nitrogen (N) balance and manure ammonia emissions of growing-finishing pigs. Pigs (n = 336; mean live weight 42.1 kg) were assigned to one of four dietary treatments containing per kg diet: 210 g SBM; 140 g SBM and 70 g RSM; 70 g SBM and 140 g RSM; and 210 g RSM. All diets were formulated on an ileal digestible amino acid, net energy and available phosphorus basis. There was no significant treatment effect on average daily gain, feed intake, feed conversion ratio and carcass characteristics. There was a linear decrease in gross energy digestibility (p < 0.01) as RSM increased at the expense of SBM in the diet. There was a linear decrease in urinary N excretion (p < 0.01), N digestibility (p < 0.05), total N excretion (p < 0.05) and N retention (p < 0.05) with increasing levels of RSM. There was no effect of dietary treatment on manure ammonia emissions. The results of this study indicate that RSM can be used as a direct replacement for SBM with no associated depression in performance, when formulated on an ileal digestible amino acid and net energy basis. Consumption of diets containing incremental levels of RSM linearly decreased urinary N and total N excretion, reflecting the associated decrease in crude protein concentrations.     

Allantoin,the oxidation product of uric acid is present in chicken and turkey plasma

Urate oxidase is not present in birds yet allantoin, a product of this enzyme, has been measured in birds. Studies were designed to compare the concentrations of plasma purine derivatives in chickens and turkeys fed inosine-supplemented diets. The first study consisted of 12 male chicks that were fed diets supplemented with 0.6 mol inosine or hypoxanthine per kilogram diet from 3- to 6-week-old. Study 2 consisted of 12 turkey poults (toms) fed inosine-supplemented diets (0.7 mol/kg) from 6- to 8-week-old. Plasma allantoin and oxypurines concentrations were measured weekly using high performance liquid chromatography. Plasma uric acid (PUA) in chickens fed inosine-supplemented diets increased from 0.31 to 1.34 mM (P<0.05) at the end of week 2. In turkeys, those fed control diet had 0.17 mM PUA concentration compared to 0.3 mM in those fed the inosine diet at week 2 (P<0.05). Allantoin concentration increased in chickens from week 1 to 2 while a decrease was observed in turkeys (P<0.005) for both treatments. These data show that allantoin is present in turkey and chicken plasma. The presence of allantoin in avian plasma is consistent with uric acid acting as an antioxidant in these species.     

Nitrogen-economy and synthesis of serine and glycine in reticulocytes

Amino acids constitute the main substrate of the reticulocyte. The amino acid pool of reticulocytes represents a characteristic selection. The composition of the amino acid pool is dependent on maturation. From the preferential oxidation of short-chain amino acids one would expect a ratio about of 5:1 between the oxygen consumption and ammonia formation. If one corrects for NH3-formation by the deamination of nucleotides the ratio between the oxygen consumption and NH3-formation is about an order of magnitude higher than the theoretical ratio. The small liberation of NH3 in energy production from amino acids results from the re-utilization of their alpha-NH2-group for the synthesis of serine and glycine, while the C-skeleton stems from glucose. Serine is formed via OH-pyruvate and OH-pyruvate. Serine and glycine serve preferentially for synthesis of hemoglobin. In reticulocytes there exists a compartmentation of glycine which accounts for differences between serine and glycine in isotopic experiments. From the time dependent change of the specific activities of pulse-labelled serine and glycine one may calculate that the serine synthesis amounts to 15--30% of the glucose utilization.     

The relationship between uric acid and its oxidative product allantoin: a potential indicator for the evaluation of oxidative stress in birds

Uric acid is the main nitrogenous waste product in birds but it is also known to be a potent antioxidant. Hominoid primates and birds lack the enzyme urate oxidase, which oxidizes uric acid to allantoin. Consequently, the presence of allantoin in their plasma results from non-enzymatic oxidation. In humans, the allantoin to uric acid ratio in plasma increases during oxidative stress, thus this ratio has been suggested to be an in vivo marker for oxidative stress in humans. We measured the concentrations of uric acid and allantoin in the plasma and ureteral urine of white-crowned sparrows (Zonotrichia leucophrys gambelii) at rest, immediately after 30 min of exercise in a hop/hover wheel, and after 1 h of recovery. The plasma allantoin concentration and the allantoin to uric acid ratio did not increase during exercise but we found a positive relationship between the concentrations of uric acid and allantoin in the plasma and in the ureteral urine in the three activity phases. In the plasma, the slope of the regression describing the above positive relationships was significantly higher immediately after activity. We suggest that the slope indicates the rate of uric acid oxidation and that during activity this rate increases as a result of higher production of free radicals. The present study demonstrates that allantoin is present in the plasma and in the ureteral urine of white-crowned sparrows and therefore might be useful as an indicator of oxidative stress in birds.     

Effects of combined nitrogen on anapleurotic carbon assimilation and bleeding sap composition in Phaseolus vulgaris L.

Dwarf french beans, Phaseolus vulgaris L., were grown with or without inoculation with rhizobia (strain 3644), and with or without a combined nitrogen source (nitrate or ammonium ions). The distribution of radioactivity into products of dark ¹⁴CO₂ assimilation was studied in roots or nodules from these plants. A detailed study was also made of the distribution and rates of excretion of nitrogen in xylem bleeding sap in 28 day old plants grown on the various sources of nitrogen. Whereas detached nodules accumulated radioactive glycine, serine and glutamate when incubated with ¹⁴CO₂, bleeding sap from plants root fed ¹⁴CO₂ contained low levels of radioactivity in these compounds but higher levels in allantoin. Chemical analysis showed allantoin to be the major compound transported in the xylem of nodulated plants, whether or not they were fed on combined nitrogen. In contrast uninoculated plants accumulated mainly amino acids in the bleeding sap, the amount and chemical composition of which depended on the combined nitrogen source.Abbreviations PEP phosphoenol pyruvate - OAA oxaloacetate