Intact Protein Diet Research Articles

Antioxidant Enzymes and Growth of Broiler Fed Microparticle Protein Diet with Inulin or Lactobacillus acidophillus Supplementation

The effect of dahlia tuber extract or Lactobacillus acidophilus inclusion on intestinal physiology, antioxidant enzymes, and growth performance of broiler chicken given a microparticle protein-composed diet was evaluated in the present study. Three dietary treatments were applied, Control: 21% intact protein diet without additive, MP-DTE: 21% microparticle protein diet + 1.2% dahlia tuber extract as inulin source, and MP-La: 21% microparticle protein diet + 1.2 mL L. acidophilus (1 mL L. acidophilus /La equal to 108 cfu). Microparticle proteins were obtained from common protein source ingredients for poultry, fish meal, and soybean meal. A completely randomized design was assigned with 3 treatments and replicated 8 times, 10 broilers in each replication. Experimental animals were 240 broilers for treatment and 10 birds for endogenous correction. Digestibility of protein and essential amino acids, villi height, intestinal bacterial counts (LAB and Eschericia coli ), short chain fatty acids/SCFA (acetate, propionate, and butyrate), antioxidant enzymes (GSH-Px and SOD), and growth performances (meat protein/MPM and fat mass/MFM, feed consumption, body weight gain/BWG, and feed conversion ratio/FCR) were variables measured. Data were statistically processed based on analysis of variance and continued to the Duncan test (p<0.05). Supplementation of dahlia inulin extract or L. acidophilus to the micropaticle protein diet significantly (p<0.05) increased N retention, villi height, LAB population, SCFA, antioxidant enzymes, and improved MPM and BWG, but decreased E. coli count, MFM, and FCR. However, feed consumption was not affected by any treatment. It can be concluded that L. acidophilus supplementation to the microparticle protein diet (MP-La) improves antioxidant enzymes, and growth performance with high meat protein and low fat mass.

9 What Would Be the Next Feed Amino Acid Based on a Microbial Point of View?

Abstract Global Amino acids market is estimated as $15billion in 2020 and 60% of those volume is used for feed additives. Amino acids are converted to protein efficiently and have a benefit of lowering feeding cost and reducing the nitrogen content of the waste output compared to intact protein diet. Most amino acids are produced using microbial fermentation. Traditionally, amino acids used for feed additives are Lysine, threonine, tryptophan and methionine. Among them methionine was produced only by chemical process, but now methionine can also be produced by microbial fermentation, which can enlarge the choice of methionine from DL-form to L-form. Use of L-form methionine as feed additives reveals new nutritional value of L-methionine compared to DL-methionine. Recently, valine, arginine, isoleucine, and histidine are also included in feeds as functional nutrients thanks to their commercial availability and lower price. Technical progress in microbiology and bioengineering has been made more diverse amino acid to be used as feed additives. Then what would be the next amino acid as feed additivities based on microbial point of view? Leucine, glutamine, tyrosine and phenylalanine could be next possible amino acids based on metabolic pathways of microorganism. These amino acids share the pathways with former feed amino acids such as valine or tryptophan, which means that these can be produced with way that is more economical. In addition, these amino acids could be produced as mixed forms like glutamic acid/glutamine mixture, Tryptophan/tyrosine/phenylalanine mixture, or BCAA forms with cheaper price. Dried fermentation product such as lysine sulfate made by drying of microbial culture broth, could be one of the option for the combination of several new amino acids. Crude protein reduction in feed is one of the big nutritional trend to reach the ideal protein diet and environmental clean situation. Considering the use of new synthetic amino acids in feeds would be a potential way to realize the ideal protein diet.

Supplementation with Bovine Milk or Soy Beverages Recovers Bone Mineralization in Young Growing Rats Fed an Insufficient Diet, in Contrast to an Almond Beverage

ABSTRACTBackgroundNondairy beverages, produced from soy, rice, oat, almond, or coconut, are increasingly being used as alternatives to dairy milk, with the perception that they are healthier and/or more sustainable products than dairy products.ObjectiveThe aim of this study was to compare the effects of supplementing either bovine milk, soy, or almond-based beverages to young, growing rats fed an intact-protein diet or a diet that had protein substituted with amino acids (AA-diet).MethodsThree-week-old male Sprague-Dawley rats were randomly assigned to 5 groups (n = 10/group) and fed ad libitum for 4 wk. Two control groups were fed either standard AIN-93G food [20% casein (CN) protein] or AIN-93G with amino acids (AAs) equivalent to CN protein, and water to drink. Three treatment groups were fed AIN-93G AA and supplemented with either bovine ultra-heat treatment (UHT) milk or soy or almond UHT beverages. Rat weight gain and food intakes were recorded. During week 4, body composition was assessed using DEXA to determine lean soft tissue, fat, and bone mass. At trial end, bone biomechanical properties and blood plasma mineral concentrations were measured.ResultsAt the end of the trial, animals supplemented with almond beverage were lightest (P > 0.05), with higher plasma calcium concentrations (P > 0.05) and lower bone mineral content (BMC) and bone density (P > 0.05) than animals supplemented with milk or soy beverage. Soy-supplemented animals had similar BMC and bone density compared with milk-supplemented animals, although the soy group gained most weight (P > 0.05) and had the highest fat:lean ratio (P > 0.05) compared with other groups.ConclusionsIn the model tested, supplementing rats with bovine UHT milk and soy UHT beverage provided favorable bone health outcomes. Conversely, almond UHT beverage was not an effective supplement and could be detrimental to bone mineralization and strength outcomes.

A preliminary study assessing cytokine production following ex vivo stimulation of whole blood with diet in dogs with chronic enteropathy

BackgroundEx vivo whole blood stimulation assays (WBSA) have been used to characterize the cytokine response to diet in cats. The present study aimed to use this assay to determine the cytokine response to diets being fed at the time of diagnosis to dogs with chronic enteropathy (CE) and to compare this to a control group of dogs presented for non-gastrointestinal (GI) causes.ResultsDogs with chronic GI signs and dogs presented for non-GI causes were prospectively recruited. For each case, residual blood following diagnostic sampling was placed into heparin. WBSAs were performed using crude extracts of the diet currently being fed and provided by the owner. Supernatants were collected and analyzed for tumor necrosis factor (TNF)-alpha, interleukin (IL)-10 and IL-4 using an enzyme-linked immunosorbent assay. The case group consisted of 22 dogs with CE diagnosed on histopathology of GI biopsy and 9 with suspected CE. The non-GI group consisted of 18 dogs. Of the diets being fed at or prior to diagnosis, hydrolyzed protein diets elicited significantly lower IL-10 and TNF-alpha concentrations compared to commercial intact protein diets in dogs with confirmed or suspected CE (P-value 0.004 and < 0.001, respectively). Six out of 15 dogs with detectable IL-4 concentrations in the confirmed CE group had IL-4 to IL-10 ratios that exceeded the 95% confidence interval (CI) of the mean of the non-GI group (non-GI: 95% CI of IL-4:IL-10 = 0.64–2.71; confirmed CE: IL-4:IL-10 in 6 dogs = mean 22.40, range 2.77–89.11).ConclusionsHydrolyzed protein diets elicited a significantly reduced cytokine response when incubated with patient whole blood ex vivo compared to commercial intact protein diets in dogs with CE. The IL-4 to IL-10 ratio as a marker of dietary responsiveness warrants further investigation, together with assessment of the cytokine response to diet at the intestinal mucosal surface.

Healthy meat production of broiler fed microparticle-protein diet with inclusion of inulin derived from dahlia tuber extract

The present study was conducted to evaluate the healthy edible meat characteristic of broiler due to feeding effect of microparticle-protein diet with inclusion of inulin from dahlia tuber extract. Fish and soybean meal were exposed to ultrasonic bath to obtain microparticle prior to feeding trial. 160 broilers (2- week old) were allocated into 4 treatment. Treatments were tested as follows T0: 21% intact protein diet, T1: 18% intact protein diet, T2: 18% microparticle-protein diet, T3: diet T2 + 1.2% dahlia inulin extract. A completely randomized design with 4 treatments and 5 replications (8 birds each) was arranged. Intestinal Escherichia coli, heterophyl-lymphocyte (H/L) ratio, meat protein and fat mass, meat cholesterol, and carcass weight were the parameters observed. Analysis of variance was applied, and continued to Duncan test. Results showed that all parameters, except carcass weight, were significantly (P<0.05) affected by dietary treatments. Escherichia coli count, H/L ratio, meat cholesterol, were significantly (P<0.05) decreased by T2 and T3 treatments. Meat fat mass was reduced by T3 treatment, but carcass weight was not affected by any treatmnets. In conclusion, diet composed of 18% microparticle protein with inclusion of 1.2% inulin extract produces healthy edible meat of broiler characterized by lower meat fat mass and cholesterol with higher meat protein mass.

The Effect of Maternal Intact Protein- and Amino Acid-Based Diets on Development of Food Intake Regulatory Systems and Body Weight in Dams and Male Offspring of Wistar Rats.

The objective of this study is to examine the effect of maternal and weaning intact protein- and amino acid-based diets on regulation of food intake, intake regulatory hormones, and body weight in dams and their male offspring. Pregnant Wistar rats were allocated to two groups (n = 12) and were fed either an intact protein diet (IPD) or mixed amino acid diet (AAD) from day 3 of gestation throughout gestation and lactation. Male offspring were weaned to either an IPD or AAD for 18 weeks. Food intake (FI) and body weight (BW) were measured weekly. Results: In dams, the AAD group had lower FI and BW in the post-partum period compared with the IPD group. In pups born to AAD dams, birth weight and BW were lower. However, the percentage of fat and lean mass were not affected. Food intake was influenced by maternal diet and was higher in pups born to IPD dams throughout post-weaning. Short-term FI in response to protein preloads was lower in pups born to AAD dams in 1 h. Fasting plasma concentrations of glucose, insulin, and ghrelin were not influenced by either maternal or weaning diet. However, peptide YY (PYY) was higher in pups born to IPD dams at weaning. Conclusions: The physicochemical properties of proteins fed during pregnancy and lactation had determining effects on the body weight and development of food intake regulatory systems in offspring. Maternal AAD resulted in lower BW in dams and lower birth weight and post-weaning BWs in pups compared with maternal IPD which was consistent with their lower FI.

Effects of Polymeric Formula vs Elemental Formula in Neonatal Piglets With Short Bowel Syndrome

Intestinal adaptation is important for recovery in short bowel syndrome (SBS). This process is dependent on the presence of enteral nutrition (EN) and trophic factors, such as glucagon-like peptide-2 (GLP-2). In clinical practice, elemental formula is often used to feed neonates with SBS, whereas animal studies suggest polymeric formula promotes better intestinal adaptation. In neonatal piglet models of SBS, with or without ileum, we compared the elemental with the polymeric formula, including the effect on endogenous GLP-2. Forty-eight piglets underwent 75% mid-intestinal resection with jejunoileal anastomosis, 75% distal-intestinal resection with jejunocolic anastomosis (JC), or sham without resection. Parenteral nutrition (PN) started postoperatively, tapering as EN was increased, according to clinical criteria, based on diarrhea and weight. Within groups, piglets were randomized to an isocaloric/isonitrogenous elemental (amino acid) or polymeric (intact protein) diet. Plasma GLP-2 and histology for adaptation were measured at 14 days. Within both SBS and control groups, no difference in adaptation was observed according to diet. A difference was observed only within the JC piglet group with regard to clinical outcomes. In these piglets, compared with elemental formula, the polymeric formula was associated with more diarrhea ( P = .023) and longer duration of PN support (P = .047). An overall benefit of the polymeric formula over the elemental formula on gut adaptation was not observed. Furthermore, SBS piglets without ileum had less ability to tolerate polymeric formula, contributing to more days of PN support.

Effects of Dietary Arginine on Hematological Parameters and Innate Immune Function of Channel Catfish

The effects of elevated dietary arginine on the hematology and immune function of juvenile channel catfish Ictalurus punctatus were evaluated by means of in vivo and in vitro experiments. Healthy juvenile channel catfish (average weight, 34.8 g) were fed casein-gelatin-based diets containing 28% crude protein and supplemented with crystalline L-arginine (ARG) at 0.5, 1, 2, or 4% of diet. An intact-protein diet containing 1.3% arginine also was included to investigate the effects of amino acid form (crystalline-free amino acids versus intact protein). Each purified diet was fed to apparent satiation to triplicate groups of fish for 6 weeks. At the end of the experimental feeding period, the fish were injected intraperitoneally with two doses (3 d apart) of 2 mg lipopolysaccharide/kg body weight. Six days after the initial injection, the fish were anesthetized and tissue samples were obtained to evaluate hematological and humoral and cellular immune parameters, including phagocytic activity of peritoneal macrophages, hemoglobin, hematocrit, mean corpuscular volume (MCV), blood cell counts, plasma protein, and hepatic superoxide dismutase activity. High dietary levels (4% ARG) resulted in significantly higher levels of hemoglobin, hematocrit, and circulating erythrocytes. Dietary ARG did not significantly affect MCV and the number of circulating leukocytes, lymphocytes, eosinophils, and monocytes. In vitro, a moderate level (2 mM) of ARG in the culture media was found to be ideal in significantly enhancing phagocytosis. This study demonstrates that some aspects of the immune system of channel catfish are sensitive to changes in dietary ARG.

The effects of inulin supplementation of diets with or without hydrolysed protein sources on digestibility, faecal characteristics, haematology and immunoglobulins in dogs

Dogs with food allergy are often treated by giving a diet with hydrolysed protein sources. Prebiotics might also be successful in prevention and treatment of allergic disease through their effect on the colonic microflora, analogous to studies on probiotics in allergic children. The present study was set up to investigate the effect of supplementing inulin (IN) to commercial hypoallergenic dog diets on apparent nutrient digestibility, faecal characteristics, haematology and Ig in dogs. Supplementation of 3 % IN did not affect faecal pH, food and water intake and urine production. Compared with the intact protein diet with a limited number of ingredients (L), the diet with a hydrolysed protein source (H) resulted in an increased water intake (P<0.001), which could be due to the osmotic effect of free amino acids. Faeces production was increased by IN due to increased faecal moisture content. Increased faeces production on the H diet was mainly due to a higher DM excretion. Subsequently, the apparent digestibility coefficient (ADC) of DM was lower in the H diet group. A similar result was noted for ADC of diethyl ether extract and crude ash. The ADC of crude protein was higher in the H diet group, whereas IN decreased the ADC of crude protein. Differences in the ADC of crude protein among the different diets disappeared after correction for a higher faecal biomass, except for the dogs fed the L+IN diet. Total faecal IgA concentrations were lower in the H group (P<0.05) because of lower antigenic stimulation of hydrolysed protein, which implies that hydrolysed protein is really hypoallergenic. The present study indicates that the use of hydrolysed protein diets for canine food allergy treatment can affect digestibility and that combination with IN affected apparent protein digestibility but not IgA response.

Urinary amino acid excretion by marine shrimp, Penaeus monodon, in response to orally administrated intact protein and crystalline amino acids

Oral protein administration was conducted to gain more insight into the ability of the shrimp ( Penaeus monodon) to utilize different protein sources and estimate the urinary amino acid excretion. Both intact protein diet and a corresponding crystalline amino acid diet were administrated orally after the cannulated shrimp were fasted for 24 h. Urine was then collected from the shrimp for 24 h. Each treatment had five replicates. Free amino acid concentrations in urine of shrimp fed the crystalline amino acid diet were significantly higher than those of shrimp fed the intact protein diet. The total amino acids lost in urine was about 6% of the total oral crystalline amino acids in the diet. The individual amino acids lost in urine as a percentage of the crystalline amino acids in the diet were 13.6% for His, 17.6% for Phe, and about 8–10% for Ile, Leu, Lys and Val, respectively. In addition to the high concentration of free amino acids in the plasma which might induce catabolism of the absorbed dietary amino acids, the high percentage of amino acids lost in the urine could be another explanation of poor utilization of crystalline amino acids by shrimp.

Evaluation of crystalline amino acid test diets including pH adjustment with red drum ( Sciaenops ocellatus) and hybrid striped bass ( Morone chrysops × Morone saxatilis)

The red drum and hybrid striped bass are cultured in the United States for both stock enhancement and food production. Based on previous observations in this laboratory, the hybrid striped bass appeared to use pH-adjusted crystalline amino acid test diets more readily than the red drum. Therefore, the present study was conducted to directly compare responses of red drum and hybrid striped bass fed crystalline amino acids with and without neutralization (pH 7) relative to an intact protein diet composed of red drum muscle. Fifteen red drum (initially 1.5–2.5 g each) and 15 hybrid striped bass (4.5–5.5 g each) were placed separately in each of nine 38-l aquaria (18 aquaria total) as part of a brackish water (7‰) recirculation system. Each diet was randomly assigned to three replicate tanks of red drum and hybrid striped bass. After a 55-day feeding period, both red drum and hybrid striped bass fed the intact protein diet had significantly ( P < 0.05) greater weight gain, feed efficiency and protein efficiency ratio values compared to those fed the crystalline amino acid diets. However, hybrid striped bass used the crystalline diets more efficiently than red drum relative to the intact protein diets. In addition, no differences were detected in red drum or hybrid striped bass performance when fed the crystalline amino acid diets regardless of pH adjustment.

Effects of dietary protein level and form on production characteristics and ammonia excretion of red drum Sciaenops ocellatus

The red drum traditionally has been an important commercial and recreational fish species in the Gulf of Mexico; therefore, its aquacultural production for food and for stock enhancement continues to develop. This laboratory has addressed refinements in protein and amino acid nutrition of this species in an effort to increase the efficiency of production while limiting nitrogenous wastes. In the present experiment, control diets at 35% and 45% crude protein (CP) contained only intact protein provided by a 50/50 mixture of red drum muscle and wheat gluten. Two experimental diets at each CP level contained the mixture (60% of CP) and crystalline amino acids (40% of CP) to provide lysine at the same level when expressed as a percent of crude protein. All diets contained 11% lipid by dry weight and an estimated 3.6 kcal digestible energy/g. The culture system consisted of 110-l aquaria in a recirculating mode containing brackish (7‰) water at 27±°C. Twenty acclimated juvenile red drum initially averaging 3.4 g/fish were stocked in each aquarium. Diets were fed to fish in triplicate tanks at a fixed rate approaching apparent satiation twice daily for 6 weeks. At the end of the feeding trial, fish were weighed and three were euthanized for body composition analysis. Fish remaining in each tank were used to determine total ammonia nitrogen (TAN) excretion at 4-h postprandial. Diets supplemented with crystalline amino acids supported similar weight gain (94–98%) as that obtained by fish fed control diets with intact protein; however, fish fed the 45% CP diets had significantly greater weight gain than those fed the 35% CP diets. Fish fed the diets with 45% CP excreted significantly more ammonia than those fed 35% CP diets. The crystalline amino acid diets at each CP level also resulted in elevated ammonia excretion compared to intact protein diets. Thus, crystalline amino acid diets did not appear to be utilized as efficiently based on ammonia excretion, but reduced efficiency was not evident in weight gain or other production characteristics.

Effects of Elevated Dietary Arginine on Resistance of Channel Catfish to Exposure toEdwardsiella ictaluri

An experiment was conducted to assess the effects of elevated dietary arginine on infection resistance to Edwardsiella ictaluri by juvenile channel catfish Ictalurus punctatus. Healthy channel catfish fingerlings were fed casein- and gelatin-based purified diets containing 28% crude protein and supplemented with crystalline L-arginine at 0.5, 1, 2, or 4% of the diet. An intact-protein diet containing 1.3% arginine also was included to investigate the effects of amino acid form (crystalline free amino acids versus intact protein). Each diet was fed to apparent satiation to triplicate groups of fish for 2 weeks. Subsequently, fish were exposed by immersion (1.3 × 108 colony-forming units/mL) to a virulent strain of E. ictaluri. Morbidity, mortality, and cause of death were recorded during a 21-d period. Plasma amino acid concentrations (14 h postprandial) 1 d before and 1 d after the bacterial exposure were analyzed via high-performance liquid chromatography. The dietary concentration of L-arginine significantly (P < 0.05) influenced mortality of fish because maximum survival after exposure to E. ictaluri occurred in fish fed the diet with 2% arginine. There was no additional improvement in survival rates after bacterial exposure by including a purified diet with intact protein. Circulating plasma amino acid concentrations indicated an increased usage of arginine and glutamine in exposed fish. These results demonstrated a positive effect of an arginine-enriched diet on the resistance of channel catfish to infection with E. ictaluri.

Intact Dietary Soy Protein, but Not Adding an Isoflavone-Rich Soy Extract to Casein, Improves Plasma Lipids in Ovariectomized Cynomolgus Monkeys

The dietary consumption of soy protein has been linked to a reduction in coronary heart disease and improvements in a number of related risk factors. Recent investigations have focused on isoflavone components of soy protein. The purpose of this study was to examine plasma lipids and lipoproteins, particularly LDL, with the intake of intact soy protein or casein-lactalbumin diets with and without a semipurified extract of soy, rich in isoflavones. Sixty ovariectomized cynomolgus monkeys were assigned to one of three groups fed diets containing the following: 1) casein-lactalbumin as the protein source (CAS; n = 20); 2) CAS plus a semipurified extract of soy, rich in isoflavones (ISO; n = 20); or 3) intact soy protein (SOY; n = 20) for 12 wk. Lipoproteins were fractionated by combined ultracentrifugation and HPLC. Isolated LDL particles were further subfractionated by dividing the LDL peak into three fractions for compositional analyses. The SOY group had significantly lower plasma total cholesterol, VLDL plus IDL cholesterol and LDL cholesterol, and significantly less HDL cholesterol than the CAS group. LDL particles from the SOY group had a significantly less cholesteryl ester than the CAS group. The semipurified extract of soy, rich in isoflavones, added to casein-lactalbumin protein did not have the same effects as intact soy protein on plasma lipids and lipoproteins. Other components of soy protein, either alone or in combination with isoflavones, may be involved in the effects seen in this study.

Poor utilization of dietary free amino acids by white sturgeon

Three separate experiments were conducted to investigate the utilization of dietary free amino acids by white sturgeon,Acipenser transmontanus. In the first experiment, sturgeon were fed for 8 weeks with isoenergetic and isonitrogenous diets containing either intact protein, an amino acid mixture, or a neutralized amino acid mixture of similar composition. Sturgeon fed the two amino acid diets grew significantly (p<0.05) less, mainly because of reduced feed intake. In the second experiment, postprandial changes in plasma free amino acids of sturgeon force-fed the above diets were monitored at 2, 4, 6, 8, 12, and 24 h Total plasma amino acids in sturgeon force-fed the intact protein diet showed a gradual increase and reached peak levels at 8 h. In contrast, plasma amino acids of fish force-fed the amino acid diets showed a rapid increase and reached maximal levels at 2 h. In the third experiment, free amino acid diets showed a urine of sturgeon force-fed the three diets was monitored at 4, 8, 12, 16, 20, and 24 h. In all dietary groups, peak excretion of indispensable amino acids was detected at 8 h after feeding but with significantly higher levels from fish force-fed the amino acid diets. Sturgeon force-fed the neutralized amino acid diet excreted 35% less amino acids compared to fish force-fed the non-neutralized diet. Sturgeon force-fed the intact protein diet excreted significantly higher amounts of ammonia. Under amino acid feeding conditions, sturgeon excreted more amino acids in its urine, but the urinary excretion of amino acids was not a major route in dealing with the rapid absorption of dietary free amino acids.

Casein, hydrolyzed casein, and amino acids that simulate casein produce the same extent of mucosal adaptation to massive bowel resection in adult rats

We determined the effect of the extent of protein polymerization on the intestinal hyperplastic adaptation of adult male Wistar rats after 80% resection of the jejunal-ileal segment. Rats received one of four chemically defined solid diets prepared by using casein, two casein hydrolysates of different peptide size distributions, or free amino acids simulating casein and identical in all other components for 12 d, starting 3 d after surgery. Semipaired feeding was used to ensure that the same quantity of food was ingested by each group and as a consequence, nitrogen and energy intakes were reduced to 63% of that obtained with ad libitum feeding of the casein diet to intact rats. No significant differences were demonstrable in food ingestion, weight gain, nitrogen balance, or morphometric data for the remaining jejunal and ileal segments (number of cells/villus, number of cells/crypt, and crypt cell mitosis rate). These data demonstrate that the extent of polymerization of the protein nitrogen source did not affect the hyperplastic adaptative process of the rat. Additional studies in humans are necessary to determine whether intact protein diets can be used first as a nitrogen source in nutritional support of patients with a nonspecific hyperplastic response to surgical resection before the use of expensive hydrolysates and the more expensive amino acid mixtures.

Absorption and incorporation of dietary free and protein bound (U 14C)-lysine in Atlantic cod ( Gadus morhua)

Atlantic cod ( Gadus morhua) were fed (U- 14C) lysine in an amino acid diet and (U- 14C) lysine bound into an intact protein to study the retention and metabolism of lysine. Fish fed the amino acid diet showed both earlier and higher maximum isotope activity in plasma as compared with fish fed the intact protein diet. Despite the lower values in plasma, the fish fed the intact protein diet showed the greatest retention of lysine in muscle tissue. Fish fed intact protein diet showed a maximum incorporation of 38.4% of the fed isotope into muscle at 24–48 hr postprandially. Those fed the amino acid diet reached a maximum level at 24 hr postprandially with isotope incorporation of 30.4%. Incorporation into the myosin heavy chain was higher in cod fed the intact protein diet as compared with those fed the amino acid diet. The metabolism of lysine into fat was low.

The effects of diets formulated on an ideal protein basis on growth performance, carcass characteristics, and thermal balance of finishing gilts housed in a hot, diurnal environment2

Forty-eight finishing gilts (initial BW = 70.6 +/- .95 kg) were randomly assigned to one of eight experimental treatments in a 2 x 2 x 2 factorial arrangement with main effects including dietary lysine (.60 vs 1.00%), source of amino acid fortification (intact protein vs synthetic amino acids formulated on an ideal protein basis), and environmental temperature (thermoneutral [TN]: 20 degrees C vs hot, diurnal [HD]: 27.7 to 35 degrees C). The ideal protein diets were formulated by using corn and soybean meal to meet the fifth-limiting amino acid; synthetic lysine, threonine, tryptophan, methionine, or isoleucine were added to meet the gilts' estimated requirements. The ratios of other total amino acids relative to lysine were as follows: threonine, 66%; tryptophan, 17%; methionine and cystine, 56%; and isoleucine, 63%. Average daily gain, ADFI, and feed efficiency (G/F) were similar for gilts fed the intact and those fed the ideal proteins diets (P > .10). Increasing dietary lysine improved d 0 to 14 ADG (P < .01), but no differences were observed for the overall experiment. Gilts in the HD environment ate less feed and had lower ADG than gilts in the TN environment (P < .01). A temperature x lysine interaction was observed (P < .02) for G/F. Increasing dietary lysine had no effect on G/F of gilts in the TN environment but improved G/F of gilts in the HD environment. Gilts fed the intact protein diets had higher (P < .01) N intake and plasma urea concentrations. Gilts fed the ideal protein diets had lower (P < .05) plasma essential amino acids, with the exception of lysine. Carcass protein and lipid contents were improved (P < .01) for gilts in the HD environment and for those fed 1.00% lysine. Backfat thickness and longissimus muscle area (P < .01) were improved and lipid accretion rate tended to decrease (P < .08) in gilts fed 1.00% lysine. The source of amino acid fortification did not influence carcass characteristics (P > .10). Rectal, skin, and ear temperatures were higher for gilts in the HD environment (P < .05). Metabolic heat production was elevated by feeding gilts the ideal protein diets (P < .03). In conclusion, increased dietary lysine improved G/F and carcass leanness in gilts to a greater extent in HD than in TN environments. However, no improvements in growth performance or carcass traits resulted from feeding ideal protein diets.

Research Note: Effect of Crystalline Lysine and Methionine Intake on Amino Acid Excretion by Precision-Fed Cockerels

A study was conducted to investigate the relationship between increasing intake of crystalline lysine and methionine and excretion of these amino acids in a precision-fed cockerel assay. Birds were deprived of feed for 24h and then given increasing amounts of crystalline L-Lysine-HCl or DL-methionine via crop intubation. The amino acids were given with either 30 g of sucrose or with 30 g of an intact protein diet deficient in the test amino acid. The supplemental dietary levels (percentage of diet) were 0, 1.0, 2.4, and 9.1% for lysine and 0, .2, .45, 1.6, and 7.1% for methionine. Excreta (feces plus urine) were quantitatively collected for 48h postfeeding. The results showed that lysine and methionine excretion were significantly increased (P < .05) only at the highest dietary level. The effect of supplemental dietary lysine on lysine excretion was greater for the sucrose diet than the intact protein diet. Relative lysine balance (intake minus excretion expressed as a percentage of intake) decreased at the 2.4 and 9.1% levels in the sucrose diet and at the 9.1% level in the intact protein diet. Relative methionine balance was high at all intake levels. The results of the present study indicate that crop intubation of moderate levels of crystalline amino acids has little or no effect on amino acid excretion in the precision-fed cockerel assay.

Applications of chemically defined diets to the solution of nutrition problems

Chemically defined amino acid diets have been developed for most laboratory and meat-producing animal species as well as for humans. In many cases, growth performance of animals fed these diets equals that obtained with standard intact-protein diets. The pattern of both essential and nonessential amino acids is critical to obtaining excellent voluntary food intake. Other factors such as carbohydrate and fat type and level, acid-base balance (i.e., cation-anion ratio), and texture are important to the success of purified diets. Chemically defined diets provide amino acids, mineral elements and vitamins in forms that are maximally bioavailable. Also, virtually any nutrient can be manipulated at will for studies of a) requirements, b) bioavailability, c) factors affecting requirements and bioavailability, d) nutrient-nutrient interrelationships, e) nutrientdrug or nutrient-toxin interrelationships, f) absorption phenomena and g) efficiency and priority aspects of nutrient utilization. Requirements for essential nutrients are generally lower with purified diets than for practical diets because the nutrients in the former are more bioavailable, but also because purified diets generally lack antagonizing factors such as phytate and soluble fiber. That chemically defined diets for pigs, rats and dogs yield such excellent rates of growth suggests that a specific peptide requirement many not exist for these species. Also, this suggests that all known nutrients necessary for maximal growth must be present in the diet. Whether additional nutrients, or different levels, may be necessary for optimal health and immunocompetency, or for maximal life span, needs further study.