Evaluation through literature data of the amount and amino acid composition of basal endogenous crude protein at the terminal ileum of pigs

Proteomic Identification and Quantification of Basal Endogenous Proteins in the Ileal Digesta of Growing Pigs

The accurate estimation of basal endogenous losses (BEL) of amino acids at the ileum is indispensable to improve nutrient utilization efficiency. This study used a quantitative proteomic approach to identify variations in BEL in the ileal digesta of growing pigs fed a nitrogen-free diet (NFD) or a casein diet (CAS). Eight barrow pigs (39.8 ± 6.3 kg initial body weight (BW)) were randomly assigned to a 2 × 2 crossover design. A total of 348 proteins were identified and quantified in both treatments, of which 101 showed a significant differential abundance between the treatments (p < 0.05). Functional and pathway enrichment analyses revealed that the endogenous proteins were associated with intestinal metabolic function. Furthermore, differentially abundant proteins (DAPs) in the digesta of pigs fed the NFD enriched terms and pathways that suggest intestinal inflammation, the activation of innate antimicrobial host defense, an increase in cellular autophagy and epithelial turnover, and reduced synthesis of pancreatic and intestinal secretions. These findings suggest that casein diets may provide a more accurate estimation of BEL because they promote normal gastrointestinal secretions. Overall, proteomic and bioinformatic analyses provided valuable insights into the composition of endogenous proteins in the ileal digesta and their relationship with the functions, processes, and pathways modified by diet composition.

SNAPIG: a model to study nutrient digestion and absorption kinetics in growing pigs based on diet and ingredient properties

Current feed formulation and evaluation practices rely on static values for the nutritional value of feed ingredients and assume additivity. Hereby, the complex interplay among nutrients in the diet and the highly dynamic digestive processes are ignored. Nutrient digestion kinetics and diet × animal interactions should be acknowledged to improve future predictions of the nutritional value of complex diets. Therefore, an in silico nutrient-based mechanistic digestion model for growing pigs was developed: "SNAPIG" (Simulating Nutrient digestion and Absorption kinetics in PIGs). Aiming to predict the rate and extent of nutrient absorption from diets varying in ingredient composition and physicochemical properties, the model represents digestion kinetics of ingested protein, starch, fat, and non-starch polysaccharides, through passage, hydrolysis, absorption, and endogenous secretions of nutrients along the stomach, proximal small intestine, distal small intestine, and caecum + colon. Input variables are nutrient intake and the physicochemical properties (i.e. solubility, and rate and extent of degradability). Data on the rate and extent of starch and protein hydrolysis of different ingredients per digestive segment were derived from in vitro assays. Passage of digesta from the stomach was modelled as a function of feed intake level, dietary nutrient solubility and diet viscosity. Model evaluation included testing against independent data from in vivo studies on nutrient appearance in (portal) blood of growing pigs. When simulating diets varying in physicochemical properties and nutrient source, SNAPIG can explain variation in glucose absorption kinetics (postprandial time of peak, TOP: 20-100 min observed vs 25-98 min predicted), and predict variation in the extent of ileal protein and fat digestion (root mean square prediction errors (RMSPE) = 12 and 16%, disturbance error = 12 and 86%, and concordance correlation coefficient = 0.34 and 0.27). For amino acid absorption, the observed variation in postprandial TOP (61 ± 11 min) was poorly predicted despite accurate mean predictions (58 ± 34 min). Recalibrating protein digestion and amino acid absorption kinetics require data on net-portal nutrient appearance, combined with observations on digestion kinetics, in pigs fed diets varying in ingredient composition. Currently, SNAPIG can be used to forecast the time and extent of nutrient digestion and absorption when simulating diets varying in ingredient and nutrient composition. It enhances our quantitative understanding of nutrient digestion kinetics and identifies knowledge gaps in this field of research. Already useful as research tool, SNAPIG can be coupled with a postabsorptive metabolism model to predict the effects of dietary and feeding-strategies on the pig's growth response.

Standardized ileal digestibility of amino acids in soybean meal fed to non-pregnant and pregnant sows

BACKGROUND

Two studies were designed to determine standard ileal crude protein (CP) and amino acid (AA) digestibility of soybean meal (SBM) from different origins fed to non-pregnant and pregnant sows. Seven solvent-extracted SBMs from soybeans produced in the USA, Brazil, and China were selected. In Exp. 1, eight different diets were created: a nitrogen (N)-free diet and 7 experimental diets containing SBM from different origins as the only N source. Eight non-pregnant, multiparous sows were arranged in an 8 × 8 Latin square design (8 periods and 8 diets). In Exp. 2, the diet formula was the same as in Exp. 1. Eight gestating sows (parity 3) were assigned to 4 different diets in a replicated 4 × 3 Youden square design (three periods and four diets) in mid-gestation and again in late-gestation stages.

RESULTS

When fed to non-pregnant and late-gestating sows, the standardized ileal digestibility (SID) of CP and most AAs from different SBM were not significantly different (P > 0.05). When fed to mid-gestating sows, the SID values for Arg, His, Lys, Phe, Cys, Gly, Ser, and Tyr in SBM 1 were lower than in SBM 4 and 5 (P < 0.05), whereas SID for Leu from SBM 5 was higher than in SBM 1 and 4 (P < 0.05). SID values for Ile, Ala, and Asp from SBM 4 were lower than in SBM 1 and 5 (P < 0.05). Sows had significantly greater SID values for Lys, Ala, and Asp during mid-gestation when compared with late-gestation stages (P < 0.05). Mid-gestating sows had greater SID value for Val and lower SID value for Tyr when compared with non-pregnant and late-gestating sows (P < 0.01), whereas non-pregnant sows had significantly greater SID value for Met when compared with gestating sows (P < 0.01).

CONCLUSIONS

When fed to mid-gestating sows, the SID values for most AAs varied among SBM samples. The SID values for Lys, Met, Val, Ala, Asp, and Tyr in SBM were affected by sow gestation stages. Our findings provide a cornerstone for accurate SBM use in sow diets.

High amylose to amylopectin ratios in nitrogen-free diets decrease the ileal endogenous amino acid losses of broiler chickens

This study explored the variation of ileal endogenous amino acid (IEAA) losses and its influencing factors in chickens offered nitrogen-free diets (NFD) containing different ratios of amylose to amylopectin (AM/AP). A total of 252 broiler chickens at 28 d old were randomly allocated into 7 treatment groups for a 3-d trial. The dietary treatments included a basal diet (control), a NFD containing corn starch (CS), and 5 NFD with AM/AP ratios of 0.20, 0.40, 0.60, 0.80, and 1.00, respectively. As the AM/AP ratio increased, the IEAA losses of all AAs, starch digestibility and maltase activity linearly decreased (P < 0.05), but the DM digestibility linearly and quadratically decreased (P < 0.05). Compared with the control, the NFD increased the number of goblet cells and its regulatory genes mucin-2 and krüppel-like factor 4 (KLF-4) while decreasing serum glucagon and thyroxine concentrations, ileal villus height, and crypt depth (P < 0.05). Additionally, NFD with lower AM/AP ratios (0.20 and 0.40) decreased the ileal microbiota species richness (P < 0.05). In all NFD groups, the number of Proteobacteria increased whereas the abundance of Firmicutes dropped (P < 0.05). However, the broilers in the AM/AP 0.60 group were closer to the digestive physiological state of chickens fed the control diet, with no significant change in maltase activity and mucin-2 expression (P < 0.05). In conclusion, increasing AM/AP ratio in a NFD decreased the IEAA losses and the apparent ileal digestibility of starch but inevitably resulted in malnutrition and disruption of gut microbiota homeostasis. This study recommends AM/AP in NFD at 0.60 to measure IEAA of broiler chickens.

Use of Isotope-Labeled Body or Dietary Proteins to Determine Dietary Amino Acid Digestibility

Amino acid (AA) digestibility in humans has been determined conventionally based on oro-ileal AA disappearance. With this approach, it is necessary to account for undigested AAs of body origin (endogenous AAs) found in the ileal digesta. Determination of the endogenous AAs under physiological conditions is not straightforward, and the use of isotopes (labeled foods or body tissues) has been pivotal to advancing our understanding. The application of isotopes for determining gut endogenous AAs and AA digestibility is discussed as well as the types of digestibility coefficient generated (apparent, true, real) dependent upon methodology. Recently a new dual isotope-based method for determining ileal AA digestibility in humans has been developed that obviates the collection of ileal digesta. The dual isotope method, which awaits full validation, offers considerable promise for making noninvasive measures of AA digestibility in humans of different ages and physiological states.

Presence of Unabsorbed Free Amino Acids at the End of the Small Intestine Indicates the Potential for an Increase in Amino Acid Uptake in Humans and Pigs

BACKGROUND

Unabsorbed free amino acids (AAs) at the end of the small intestine result in a potential preventable nutritional loss.

OBJECTIVES

This study aimed to quantify free AAs in terminal ileal digesta of both humans and pigs to investigate its relevance for the nutritional value of food proteins.

METHODS

Two studies with three diets were performed: a human study-ileal digesta from eight adult ileostomates were collected over 9 h after ingestion of a single meal unsupplemented or supplemented with 30 g zein or whey; pig study-12 cannulated pigs were fed for 7 d with a diet containing whey or zein or no-protein diet, and ileal digesta were collected on the last 2 d. Digesta were analyzed for total and 13 free AAs. True ileal digestibility (TID) of AAs was compared with and without free AAs.

RESULTS

All terminal ileal digesta samples contained free AAs. The TID of AAs in whey was 97% ± 2.4% (mean ± SD) in human ileostomates and 97% ± 1.9% in growing pigs. If the analyzed free AAs would have been absorbed, TID of whey would increase by 0.4%-units in humans and 0.1%-units in pigs. The TID of AAs in zein was 70% ± 16.4% in humans and 77% ± 20.6% in pigs and would increase by 2.3%-units and 3.5%-units, respectively, if the analyzed free AAs would have been fully absorbed. The largest difference was observed for threonine from zein: if free threonine was absorbed, the TID would increase by 6.6%-units in both species (P < 0.05).

CONCLUSIONS

Free AAs are present at the end of the small intestine and can potentially have a nutritionally relevant effect for poorly digestible protein sources, whereas the effect is negligible for highly digestible protein sources. This result provides insight into the room for improvement of a protein's nutritional value if all free AAs are to be absorbed. J Nutr 2023;xx:xx-xx. This trial was registered at clinicaltrials.gov as NCT04207372.

Effect of increasing dietary fermentable fiber on diet nutrient digestibility and estimation of endogenous phosphorus losses in growing pigs

Fermentable fiber may increase endogenous losses of phosphorus (EPL) and amino acids (AA), thereby reducing apparent nutrient digestibility. Acacia gum with medium-to-high fermentability and low viscosity was increasingly included in diets to investigate its effect on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients, gross energy (GE), and standardized total tract digestibility (STTD) of P in growing pigs. A control diet (49% cornstarch; 18% bovine plasma protein) was formulated to measure basal EPL. Three additional diets were formulated to include 2.5%, 5.0%, or 7.5% acacia gum at the expense of cornstarch. Diets contained 16.1% to 17.4% CP and 0.31% to 0.33% total P (DM-basis). The four diets were fed to eight ileal-cannulated barrows (initial BW, 54.6 kg) for four 9 d periods in a double 4 × 4 Latin square. Apparent hindgut fermentation (AHF) was calculated as ATTD minus AID. Feeding increasing acacia gum quadratically affected (P < 0.05) AID of DM, GE, linearly decreased (P < 0.05) ATTD of DM, crude protein (CP), GE, digestible (DE) and predicted net energy (NE) value of diets, and linearly increased (P < 0.001) AHF of DM and GE. Increasing acacia gum did not affect AID and standardized ileal digestibility (SID) of CP and AA. Basal EPL was 377 mg/kg DM intake (DMI) and increasing acacia gum linearly increased (P < 0.05) total tract EPL. Increasing acacia gum linearly decreased (P < 0.05) diet ATTD of P, and STTD of P based on either the calculated EPL or NRC (2012) recommended value (190 mg P/kg DMI). Increasing acacia gum did not affect AID and ATTD of Ca of diets. In conclusion, feeding increasing dietary fermentable, low-viscous acacia gum decreased diet AID and ATTD of DM and GE, but did not affect AID or SID of CP and AA. Increasing acacia gum decreased ATTD of P, which might have been due to increased specific endogenous losses of P in the total tract of growing pigs.

Effects of feeding levels on ileal amino acid digestibility of extruded full fat soybeans in nongestating sows

The objectives of this study were to investigate the effect of feeding levels on amino acid (AA) digestibility of extruded full fat soybeans (EFSB) fed to nongestating sows and to provide a reference for setting feed intake level when evaluating the quality of nutrients in the feed ingested by sows. Twelve nongestating sows (parity 3 to 5) were fitted with a T-cannula at the distal ileum. After recovery, sows were assigned to a replicated 6 × 3 incomplete Latin square design using two diets (nitrogen-free and EFSB) and three levels of feed intake (1.3, 2.0, and 3.4 times the maintenance requirement for metabolizable energy (ME)). The design included six dietary treatments and three periods, and each period contained two replicates for a total of six replicate sows per treatment. All diets contained 0.3% chromic oxide as an indigestible marker. In each period, ileal digesta samples were collected continuously for 12 h on days 6 and 7 after 5 d of acclimation to the experimental diet. Results of the experiment indicated that different feeding levels (1.3, 2.0, and 3.4 times the maintenance requirement for ME) had no effects on apparent ileal digestibility (AID) of AA and standardized ileal digestibility (SID) of AA, but feeding level did affect the endogenous AA loss estimated using the nitrogen-free diet method. Endogenous phenylalanine excretion was greater with 1.3 times than with 3.4 times the maintenance requirement for ME (P = 0.03), and endogenous tyrosine excretion was greater with 1.3 and 2.0 times than with 3.4 times the maintenance requirement for ME (P = 0.01). Increasing feed consumption resulted in greater loss of total endogenous AAs and crude protein (CP). In conclusion, feeding levels of 1.3 to 3.4 times the maintenance requirement for ME did not affect the AID and SID of AA of EFSB fed to nongestating sows.

Standardized ileal digestibility of amino acids in extruded full-fat soybean fed to non-gestating, gestating, and lactating sows

This study was conducted to determine and compare the apparent ileal digestibility and standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) in extruded full-fat soybean (EFSB) fed to nongestating, midgestating, late-gestating, and lactating sows. Six EFSB samples were collected from different sources. Fourteen nongestating sows (Landrace × Yorkshire; parity 3 to 5) were fitted with a T-cannula at the distal ileum. After recovery, sows were assigned to a replicated 7 × 3 incomplete Latin square design. The diets included a nitrogen-free (NF) diet and six experimental diets (EFSB 1 to 6). Eight midgestating sows (Landrace × Yorkshire; parity 3; day 48 of gestation), eight late-gestating sows (Landrace × Yorkshire; parity 3; day 90 of gestation), and eight lactating sows (Landrace × Yorkshire; parity 3; day 6 of lactation) were all assigned to four dietary treatments in a repeated 4 × 3 incomplete Latin square design. The diets included a NF diet and three experimental diets (EFSB 4 to 6). Results showed that there were significant differences in the AID and SID of CP and other AA in nongestating sows (P < 0.05), the AID and SID values of EFSB 1 to 3 were higher than those of EFSB 4 to 6, and the value of EFSB 5 was the lowest. For midgestating sows, there were differences in the AID of methionine (EFSB 5 had a lower value than EFSB 4 and 6) (P < 0.01). For late-gestating sows, only the AID of methionine (EFSB 5 had a lower value than EFSB 4 and 6), tryptophan (EFSB 5 had a higher value than EFSB 4 and 6), and proline (EFSB 5 had a higher value than EFSB 4) was different (P < 0.05), and the SID of methionine (EFSB 4 had a higher value than EFSB 5) and tryptophan (EFSB 5 had a higher value than EFSB 4 and 6) was different (P < 0.05). The SID of histidine and valine was greater in lactation than in nongestation (P = 0.045 and P = 0.02, respectively). The SID of isoleucine was greater in lactation than in nongestation and gestation (P < 0.01). The SID of methionine in nongestation was lower than in gestation and lactation (P < 0.01). The SID of cysteine was the lowest in midgestation (P = 0.045), and the SID of proline was greater in midgestation than in lactation and nongestation (P < 0.01). In conclusion, the AA ileal digestibility of six EFSB samples from different sources was different, and the ileal digestibility of CP and most AA was not affected by the physiological stage of sows.

Comparison of standardized ileal digestibility of amino acids in faba beans and field peas in broiler chickens and pigs

An experiment, using the same set of five diets was conducted to determine and compare the standardized ileal digestibility (SID) of amino acids (AA) in faba beans and three cultivars of field peas in broiler chickens and pigs. Four test diets were prepared to contain faba beans, DS-Admiral field peas, Hampton field peas, or 4010 field peas as the sole source of nitrogen. A nitrogen-free diet (NFD), as the fifth diet, was prepared to estimate the basal endogenous losses of AA to determine the SID of AA in the test ingredients. A total of 416 male broiler chickens with an initial body weight (BW) of 951 ± 111 g were allotted to five diets in a randomized complete block design with BW as a blocking factor on day 21 posthatching. There were 8 replicate cages with 10 birds per cage for diets containing test ingredients and 12 birds per cage for NFD. All birds were allowed ad-libitum access to feed for 5 days. On day 26 posthatching, all birds were euthanized by CO2 asphyxiation and digesta contents were collected from the distal two-thirds of the ileum. Twenty barrows with an initial BW of 30.2 ± 1.58 kg, surgically fitted with T-cannulas in the distal ileum, were divided into four blocks according to BW and each block was assigned to a 5 × 2 incomplete Latin Square design that consisted of five dietary treatments and two experimental periods. For each experimental period, there was a 5-day adaptation period followed by a 2-day collection of ileal digesta samples. The data were analyzed as a 2 × 4 factorial treatment arrangement with the effect of species (i.e., broiler chickens and pigs) and test diets (i.e., four test ingredients). For broiler chickens, the SID of Lys in faba beans, DS-Admiral field peas, and Hampton field peas were above 90% but in 4010 field peas, it was 85.1%. The SID of Lys in faba beans, DS-Admiral field peas, and Hampton field peas for pigs was above 80% but was 78.9% in 4010 field peas. The respective SID of Met in faba beans, DS-Admiral field peas, Hampton field peas, and 4010 field peas were 84.1%, 87.3%, 89.8%, and 72.1% for broiler chickens, and 71.5%, 80.4%, 81.8%, and 68.1% for pigs. The SID of AA in 4010 field peas was the least (P < 0.05) for chickens, but in pigs, it was comparable with faba beans. In conclusion, the SID of AA in faba beans and field peas was greater in broiler chickens compared with pigs and there was a cultivar effect.

Total amino acid level affects the results of standardized ileal digestibility assays for feed ingredients for swine

It has been demonstrated that the fiber content of oilseed meals and total amino acids (AA) in distillers' grains products affects standardized ileal digestibility (SID) values from swine assays and that total protein concentration affects the AA digestibility in assays using chickens. This analysis was conducted to test the hypothesis that the total AA content of test samples affects the SID assay results. Databases containing total AA profiles and SID values of 20 feedstuffs commonly fed to pigs from 2 sources, AMINODat 5.0 (Evonik Industries, 2015) and the Nutrient Requirements of Swine, 12th edition (NRC, 2012) were used to compare AA concentration effects on standardized ileal digestibility coefficients. Databases were compared with AA and SID available in both data sets. The total AA values were similar for the 2 databases with an R ² of 0.979 (P < 0.001). The linear relationship between digestibility coefficients from the 2 databases was highly significant, an R ² of 0.810 (P < 0.001). Both databases had increased SID values with increasing AA contents within and across feed ingredients. The SID = f(AA concentration) relationship was confirmed with an individual paper. Since SID, as typically measured, is a function of both digestion and absorption, both processes following Michaelis-Menten kinetics, SID = f(AA concentration) may simply be a natural phenomenon. Other reasons for the relationship were explored. Methods of estimating endogenous AA losses and misapplication statistical procedures may contribute to variation in results and at least partially explain why SID = f(AA concentration).

Comparison of True Ileal Amino Acid Digestibility between Adult Humans and Growing Pigs

BACKGROUND

It is not feasible to determine the true ileal amino acid (AA) digestibility of protein sources in humans on a routine basis, and the growing pig has been recommended as an animal model for this purpose but requires further validation.

OBJECTIVES

To determine and compare true ileal AA digestibility between adult human ileostomates and growing cannulated pigs for a range of food proteins.

METHODS

Seven protein sources (black beans, bread, collagen, pigeon peas, wheat bran, whey protein isolate, and zein) that spanned the range of digestibilities typically seen in foods were evaluated. Six female growing pigs received each of the protein sources, as well as a protein-free diet, and digesta were collected via ileal T-cannula. Adult human ileostomates consumed the same protein sources (5-8 ileostomates, depending on the protein source), as well as a protein-free diet, and digesta were collected. Titanium dioxide and celite were included in the diets as indigestible markers. True ileal AA digestibility coefficients were determined.

RESULTS

There was a significant effect of protein source (P ≤ 0.001) for all AAs. The effect of species was not significant (P > 0.05) except for total lysine (but not for available lysine). When analyzed within diets, the statistically significant species effect for true lysine digestibility was found for black beans only. Pig and human digestibility values were generally highly and significantly (P ≤ 0.05) correlated. A linear regression equation derived for true ileal AA digestibility (given as coefficients) determined in the human and pig for the overall mean of all AAs was (y = human, x = pig) y = 1.00x - 0.010, with the slope not statistically significant (P > 0.05) from unity and the intercept not different (P > 0.05) from zero.

CONCLUSIONS

True ileal AA digestibility values determined in the growing pig can be directly used for predicting digestibility in adult humans.

Evidence on the potential effects of halal meat on sleep/wake cycles and mood state profile: A pilot study

Nowadays, halal meat is attracting consumers as a healthier product. However, little is known about its nutritional content and possible health effects. A comparative analysis of the protein and amino acid contents between halal and non-halal meats (beef and lamb) was carried out in the present work. Additionally, a pilot study was also simultaneously performed to analyse the impact of their consumption on sleep/wake cycles and mood state profile in general population. Participants (n = 25) were asked to exclusively consume halal meats (1,000 g of gross weight/week) for 30 days. Objective and subjective sleep qualities, mood state profile, and levels of the urinary metabolites of serotonin and melatonin were assessed at baseline and post-intervention. Significantly higher contents of proteins and some amino acids were observed in halal-lamb and halal-beef, respectively. The consumption of halal meats for 30 days caused a slight improvement in men’s diurnal activity and mood state profile, as well as in women’s subjective sleep quality. Significantly higher urine levels of serotonin were also reported, particularly in men. Halal meat consumption seems to have a positive impact on sleep/wake cycles and mood state profile, likely due to the higher protein and amino acid contents. Additional scientific research is needed to support consumer trends in the coming years.

Comparison of endogenous amino acid losses in broilers when offered nitrogen-free diets with differing ratios of dextrose to corn starch

The nitrogen-free diet (NFD) method is widely used to determine the ileal endogenous amino acids (IEAAs) losses in broiler chickens. Starch and dextrose are the main components of NFD, but the effects of their proportion in the NFD on the IEAAs and the digestive physiology of broilers are still unclear. This preliminary study aims to explore the best proportion of glucose and corn starch in NFD to simulate the normal intestinal physiology of broilers, which helps to improve the accuracy of IEAAs determination. For this purpose, 28-day-old broiler chickens were allocated to five treatment groups for a 3-day trial, including a control group and four NFD groups. The ratios of dextrose to corn starch (D/CS) in the four NFD were 1.00, 0.60, 0.33, and 0.14, respectively. Results noted that NFD significantly reduced serum IGF-1, albumin, and uric acid levels compared with the control (P < 0.05), except there was no difference between group D/CS 0.33 and the control for IGF-1. The increased Asp, Thr, Ser, Glu, Gly, Ala, Val, Ile, Leu, His, Tyr, Arg, and Pro contents of IEAAs were detected in broilers fed the NFD with a higher ratio of D/CS (1.00 and 0.60) compared to the lower ratio of D/CS (0.33 and 0.14). Moreover, ileal digestibility of dry matter and activity of digestive enzymes increased as the D/CS elevated (P < 0.001). Further investigation revealed that the number of ileal goblet cells and Mucin-2 expression were higher in the group with D/CS at 1.00 when compared with group D/CS 0.33 and the control (P < 0.05). Microbiota analysis showed that NFD reshaped the gut microbiota, characterized by decreased microbial diversity and lower abundance of Bacteroidetes, and increased Proteobacteria (P < 0.05). Our results indicate that a higher D/CS ratio (1.00 and 0.60) in NFD increases IEAAs by promoting digestive enzymes and mucin secretion. However, the excessive proportion of starch (D/CS = 0.14) in NFD was unsuitable for the chicken to digest. The chickens fed with NFD with the D/CS ratio at 0.33 were closer to the normal digestive physiological state. Thus, the ratio of D/CS in NFD at 0.33 is more appropriate to detect IEAAs of broiler chickens.

Effect of feeding acidified or fermented barley using Limosilactobacillus reuteri with or without supplemental phytase on diet nutrient digestibility in growing pigs

Fermentation of cereal grains may degrade myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP6) thereby increasing nutrient digestibility. Effects of chemical acidification or fermentation with Limosilactobacillus (L.) reuteri with or without phytase of high β-glucan hull-less barley grain on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients and gross energy (GE), standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AAs), and standardized total tract digestibility (STTD) of P were assessed in growing pigs. Pigs were fed four mash barley-based diets balanced for water content: 1) unfermented barley (Control); 2) chemically acidified barley (ACD) with lactic acid and acidic acid (0.019 L/kg barley grain at a ratio of 4:1 [vol/vol]); 3) barley fermented with L. reuteri TMW 1.656 (Fermented without phytase); and 4) barley fermented with L. reuteri TMW 1.656 and phytase (Fermented with phytase; 500 FYT/kg barley grain). The acidification and fermentation treatments occurred for 24 h at 37 °C in a water bath. The four diets were fed to eight ileal-cannulated barrows (initial body weight [BW], 17.4 kg) for four 11-d periods in a double 4 × 4 Latin square. Barley grain InsP6 content of Control, ACD, Fermented without phytase, or Fermented with phytase was 1.12%, 0.59%, 0.52% dry matter (DM), or not detectable, respectively. Diet ATTD of DM, CP, Ca, and GE, digestible energy (DE), predicted net energy (NE) value, and urinary excretion of P were greater (P < 0.05) for ACD than Control. Diet ATTD of DM, CP, Ca, GE, DE and predicted NE value, urinary excretion of P was greater (P < 0.05), and diet AID of Ca and ATTD and STTD of P tended to be greater (P < 0.10) for Fermented without phytase than Control. Diet ATTD of GE was lower (P < 0.05) and diet ATTD and STTD of P, AID and ATTD of Ca was greater (P < 0.05) for Fermented with phytase than Fermented without phytase. Acidification or fermentation with/without phytase did not affect diet SID of CP and AA. In conclusion, ACD or Fermented without phytase partially degraded InsP6 in barley grain and increased diet ATTD of DM, CP, and GE, but not SID of CP and most AA in growing pigs. Fermentation with phytase entirely degraded InsP6 in barley grain and maximized P and Ca digestibility, thereby reducing the need to provide inorganic dietary P to meet P requirements of growing pigs.

Histidine optimal supply in dairy cows through determination of a threshold efficiency

Two His deletion studies were conducted to examine the mechanisms used by dairy cows to support milk true protein yield (MTPY) when His supply is altered. The potential mechanisms involved in how the efficiency of utilization of His varied included reduced catabolism, more efficient mammary usage, and use of His labile pools. For the first study, 5 multicatheterized cows were used in a 4 × 4 Latin square plus 1 cow with 14-d periods. Treatments were abomasal infusion of increasing doses of His (0, 7.6, 15.2, and 20.8 g/d) in addition to a mixture of AA (595 g/d; casein profile excluding His). Cows were fed the same protein-deficient diet throughout the study. The MTPY increased linearly with a quadratic tendency with increasing doses of His. Muscle concentrations of carnosine, a His-based dipeptide, tended to increase in a quadratic manner with increasing His supply, suggesting that the 0- and 7.6-g doses were insufficient to cover His requirement. Liver catabolism of His decreased as His supply decreased. Mammary fractional removal of His was considerably greater at low His supply, but the ratio of His mammary net uptake to milk output was not affected by the rate of His infusion, averaging 1.02. The mechanisms to face a reduced His supply included reduced His hepatic catabolism, more efficient His mammary use of lowered arterial supply, and, to a lesser extent, use of His labile pools. Two independent estimates of His efficiency were calculated, one based on the sum of exported proteins (measured MTPY plus estimated metabolic fecal protein and scurf; i.e., the anabolic component, Eff_MTPY) and the other based on liver removal (i.e., the catabolic component). These 2 estimates followed the same pattern of response to His supply, decreasing with increasing His supply. The Eff_MTPY at which MTPY peaked was 0.785. For the second study, 6 cows were used in a 6 × 6 Latin square with 7-d periods. Two greater doses of His (30.4 and 38.0 g/d) were added; otherwise, the nutritional design was similar to the first study. In this second study, the indicator AA oxidation technique was used instead of the multiorgan approach, with labeled Leu as the indicator of His utilization. The MTPY peaked and Leu oxidation reached the nadir at an average Eff_MTPY of 0.763. Combined across both studies, the data indicate that optimal usage of His would occur at a threshold Eff_MTPY of 0.77. The agreement between experimental approaches across both studies indicates that the biological optimal supply of His expressed in grams per day could be calculated as the sum of exported proteins divided by this Eff_MTPY plus estimated endogenous urinary excretion.

Multi-criteria assessment of pea protein quality in rats: a comparison between casein, gluten and pea protein alone or supplemented with methionine

The objective of this study was to assess the nutritional quality of pea protein isolate in rats and to evaluate the impact of methionine (Met) supplementation. Several protein diets were studied: pea protein, casein, gluten, pea protein-gluten combination and pea protein supplemented with Met. Study 1: Young male Wistar rats (n 8/group) were fed the test diets ad libitum for 28 d. The protein efficiency ratio (PER) was measured. Study 2: Adult male Wistar rats (n 9/group) were fed the test diets for 10 d. A protein-free diet group was used to determine endogenous losses of N. The rats were placed in metabolism cages for 3 d to assess N balance, true faecal N digestibility and to calculate the Protein Digestible-Corrected Amino Acid Score (PDCAAS). They were then given a calibrated meal and euthanised 6 h later for collection of digestive contents. The true caecal amino acid (AA) digestibility was determined, and the Digestible Indispensable Amino Acid Score (DIAAS) was calculated. Met supplementation increased the PER of pea protein (2·52 v. 1·14, P < 0·001) up to the PER of casein (2·55). Mean true caecal AA digestibility was 94 % for pea protein. The DIAAS was 0·88 for pea protein and 1·10 with Met supplementation, 1·29 for casein and 0·25 for gluten. Pea protein was highly digestible in rats under our experimental conditions, and Met supplementation enabled generation of a mixture that had a protein quality that was not different from that of casein.

Progress in ileal endogenous amino acid flow research in poultry

The progress in our understanding of the endogenous protein concept over the past century is reviewed. Non-dietary proteins found in the digesta at the terminal ileum of poultry, known as endogenous protein loss, are comprised of digestive secretions, mucus and sloughed gut epithelial cells. The measurement of this loss is of fundamental importance because it is an indicator of gut metabolism and is essential to adjust apparent estimates of ileal amino acid digestibility. The ileal endogenous amino acid losses comprise of two components, namely basal and specific losses. The basal losses are fixed and associated with feed dry matter intake, whereas the specific losses are variable and induced by the presence of dietary components such as fibre and anti-nutrients. Currently there is no methodology available to directly measure the specific endogenous losses and these losses are calculated by determining the basal and total (basal plus specific) losses and, then subtracting the basal losses from total losses. The seminal features, specific applications and shortcomings of available methodologies are briefly outlined as well as the practical challenges faced in using the published endogenous amino acid loss values for true digestibility corrections. The relevance of taurine as a component of endogenous protein flow in poultry is identified for the first time.

Digestibility of Amino Acids in Protein-Rich Feed Ingredients Originating from Animals, Peanut Flour, and Full-Fat Soybeans Fed to Pigs

Standardized ileal digestibility (SID) of amino acids (AA) in alternative protein sources for growing pigs was determined in this study. Diets containing egg albumen (EA), casein, blood meal (BM), and blood plasma meal (BPM) and a nitrogen-free diet (NFD) were fed to 20 barrows in a quadruplicate 5 × 2 incomplete Latin square design with two periods in experiment 1. The SID of AA was greater in casein than other ingredients (p < 0.05), except Pro. The SID of Arg, Ile, and Met was lower (p < 0.05) in EA than BM and BPM. The SID of Trp in BM was greater (p < 0.05) than EA but not different from BPM. In experiment 2, 20 pigs were fed diets containing peanut flour (PF) or full-fat soybeans (FFSB) or NFD in a randomized complete block design with body weight as a blocking factor but providing six observations for NFD. The SID of Arg, Ileu, Leu, Met, Phe, and Val was greater (p < 0.05) in PF than FFSB. The SID of Lys was greater (p < 0.05) in FFSB than PF. In summary, the test ingredients contain readily digestible AA and could serve as alternative protein sources for growing pigs.

Review: Impact of protein and energy supply on the fate of amino acids from absorption to milk protein in dairy cows

Making dairy farming more cost-effective and reducing nitrogen environmental pollution could be reached through a reduced input of dietary protein, provided productivity is not compromised. This could be achieved through balancing dairy rations for essential amino acids (EAA) rather than their aggregate, the metabolizable protein (MP). This review revisits the estimations of the major true protein secretions in dairy cows, milk protein yield (MPY), metabolic fecal protein (MFP), endogenous urinary loss and scurf and associated AA composition. The combined efficiency with which MP (EffMP) or EAA (EffAA) is used to support protein secretions is calculated as the sum of true protein secretions (MPY + MFP + scurf) divided by the net supply (adjusted to remove the endogenous urinary excretion: MPadj and AAadj). Using the proposed protein and AA secretions, EffMP and EffAA were predicted through meta-analyses (807 treatment means) and validated using an independent database (129 treatment means). The effects of MPadj or AAadj, plus digestible energy intake (DEI), days in milk (DIM) and parity (primiparous v. multiparous), were significant in all models. Models using (MPadj, MPadj × MPadj, DEI and DEI × DEI) or (MPadj/DEI and MPadj/DEI × MPadj/DEI) had similar corrected Akaike's information criterion, but the model using MPadj/DEI performed better in the validation database. A model that also included this ratio was, therefore, used to fitting equations to predict EffAA. These equations predicted well EffAA in the validation database except for Arg which had a strong slope bias. Predictions of MPY from predicted EffMP based on MPadj/DEI, MPadj/DEI × MPadj/DEI, DIM and parity yielded a better fit than direct predictions of MPY based on MPadj, MPadj × MPadj, DEI, DIM and parity. Predictions of MPY based on each EffAA yielded fairly similar results among AA. It is proposed to ponder the mean of MPY predictions obtained from each EffAA by the lowest prediction to retain the potential limitation from AA with the shortest supply. Overall, the revisited estimations of endogenous urinary excretion and MFP, revised AA composition of protein secretions and inclusion of a variable combined EffAA (based on AAadj/DEI, AAadj/DEI × Aadj/DEI, DIM and parity) offer the potential to improve predictions of MPY, identify which AA are potentially in short supply and, therefore, improve the AA balance of dairy rations.

Effects of copper hydroxychloride and distillers dried grains with solubles on intestinal microbial concentration and apparent ileal and total tract digestibility of energy and nutrients by growing pigs1

An experiment was conducted to test the hypothesis that Cu hydroxychloride improves nutrient digestibility and alters the concentration of microbial protein in the small intestine or large intestine by pigs fed a corn-soybean meal diet or a diet based on corn, soybean meal, and distillers dried grains with solubles (DDGS). Twenty-four barrows (33.3 ± 3.4 kg) that had a T-cannula installed in the distal ileum were allotted to a 2 × 2 factorial design with 2 levels of DDGS (0% or 45%) and 2 levels of supplemental Cu from Cu hydroxychloride (0 or 150 mg/kg). A 2-period switch back design with the 4 diets and 6 replicate pigs per diet in each period was used resulting in 12 replicate pigs per diet for the 2 periods. The initial 9 d of each period was considered an adaptation period to the experimental diets. For each period, feces were collected on days 10, 11, and 12, and ileal digesta were collected for 8 h on days 13 and 14. Results indicated that inclusion of 45% DDGS to diets reduced (P < 0.05) the apparent ileal digestibility (AID) of AA and the AID and the apparent total tract digestibility (ATTD) of dry matter, gross energy, and crude protein. In contrast, inclusion of DDGS to diets increased (P < 0.05) the AID and the ATTD of acid hydrolyzed ether extract and the concentration of microbial protein in the hindgut (P < 0.05). However, the total concentration of volatile fatty acids (VFA) in ileal digesta and in feces from pigs fed the DDGS diets were not different from concentrations in pigs fed diets without DDGS. The AID and ATTD of dry matter, gross energy, and crude protein were not affected by dietary Cu concentrations, but the AID and ATTD of acid hydrolyzed ether extract were greater (P < 0.05) in diets supplemented with Cu hydroxychloride compared with diets without Cu hydroxychloride. There was also a reduction (P < 0.05) in the concentration of microbial protein and a tendency for a reduction (P < 0.10) in the total concentration of VFA in feces when diets were supplemented with Cu hydroxychloride. In conclusion, supplementation of Cu hydroxychloride to diets improved AID and ATTD of acid hydrolyzed ether extract and reduced the concentration of microbial protein in the large intestine and this effect was observed in diets containing DDGS as well as in diets without DDGS.

Amino acid requirements in horses

Evaluating amino acid requirements, specifically threonine requirements, in horses will enable better feed formulation and result in economic production, improved animal health, and reduced environmental pollution. However, the current knowledge of protein and amino acid requirements in horses is still limited. Because horses have a unique digestive system and consume a variety of feed ingredients, their protein digestibility may be affected than other species by different feed composition, and thus amino acid requirements are susceptible to vary between situations. Therefore, a careful evaluation of amino acid requirements with a proper method is needed for various conditions. This review will also provide comprehensive information that needs to be considered when designing an amino acid requirement study in horses.

Intact and hydrolyzed casein lead to similar ileal endogenous protein and amino acid flows in adult humans

BACKGROUND

Endogenous amino acids (AAs) contribute to terminal ileal digesta and must be corrected for in determining coefficients of true ileal digestibility. Such estimates are also needed for the factorial calculation of AA requirements.

OBJECTIVE

The effect of the form of delivery of dietary AAs on endogenous nitrogen and AA flows at the end of the ileum was studied.

METHODS

Isotopically labeled 15N-casein (33-34 g), in either a hydrolyzed (HC) or intact (C) form, was included as the sole source of nitrogen in a mixed meal (320 mmol N) consumed by healthy adult humans equipped with a triple-lumen sampling tube in the small intestine. Ileal endogenous AA flows were determined by isotope dilution. An additional meal (A) containing a free AA mixture (306 mmol N) simulating the AA composition of casein was included. Serine was omitted from the AA mixture to allow direct determination of its ileal endogenous flow.

RESULTS

Endogenous N and AA flows did not differ (P > 0.05) for diets C and HC, with mean respective N flows of 728 and 617 mg/8 h (± pooled SD: 144 mg/8 h). Endogenous serine flow was similar (P > 0.05) for diets C, HC, and A [181, 169, and 191 mg/8 h (± 56 mg/8 h)]. Recycling of the 15N marker was determined to be ∼11%, suggesting that the 15N endogenous loss values could underestimate endogenous protein and AA losses by ∼6% (the proportion of recycled 15N divided by the sum of endogenous N and recycled 15N).

CONCLUSIONS

The 3 different forms of dietary AA delivery (free AAs, HC, or C) elicited similar ileal endogenous AA flows in the adult human.This study was registered at clinicaltrials.gov as NCT00873951.

Forage cactus (Opuntia ficus-indica Mill) meal in rabbit diets in the growth phase

ABSTRACT Two experimental tests were carried out to evaluate the inclusion of forage cactus meal in diets for rabbits during the growth phase. In the first test 14 male New Zealand red rabbits were used, housed in metal cages, and distributed in a completely randomly design with two treatments and seven replicates with one animal per experimental unit. The digestibility of the nutrients and the digestible energy of the forage cactus meal were determined by the total feces collection method. The forage cactus meal presented 92.24% of DM, 5.63% of CP and 2,347 kcal of DE/kg. In the second test the inclusion of 0, 10, 20 and 30% forage cactus meal in the rabbit diet was tested for productive performance, carcass characteristics, viscera and economic viability. Thus, 40 male rabbits of the New Zealand red breed were used, distributed in metal cages, completely random designed with four treatments, five replicates and two animals per experimental unit. No influence of inclusion levels (P>0.05) on performance variables, housing characteristics or economic viability was observed. The forage cactus meal can be included in up to 30% in the diets of growing rabbits.

The Effect of Processing on Digestion of Legume Proteins

The domestic processing methods, soaking, cooking (traditional, microwave, pressure), and baking and the industrial processing, autoclaving, baking, and extrusion are used to improve consumption of legumes. The growing awareness of both health and sustainability turns the focus on protein (bio)availability. This paper reports the effect of these processing methods on the legume protein digestibility. Overall, the protein digestibility increases after processing by the different methods. However, since both the type of legume and the applied methods differ it cannot be concluded which specific method is best for the individual legume type.

Impact of dietary fiber and immune system stimulation on threonine requirement for protein deposition in growing pigs

High dietary fiber (DF) and immune system stimulation (ISS) are thought to limit amino acid availability for protein deposition (PD) in growing pigs. A nitrogen-balance study was conducted to determine Thr requirement for optimal PD when DF and ISS were present alone and in combination. A total of 90 barrows (20.5 kg initial BW; SD = 0.75 kg) were randomly assigned to one of 10 dietary treatments (n = 9) in nine blocks. Diets consisted of a low fiber (LF; 12.5% total DF) or high fiber (HF; 18.5% total DF by adding 10% sugar beet pulp and 5% wheat bran to the LF diet) with graded levels of Thr (0.49%, 0.57%, 0.65%, 0.73%, and 0.81% standardized ileal digestible [SID]) fed at 2.2 × maintenance ME requirements. After an 8-d adaptation, two 4-d nitrogen balance collection periods (pre-ISS and ISS) were conducted. ISS was induced by repeated injections (i.m.) of increasing doses of Escherichia coli lipopolysaccharide. Blood samples were taken during both periods to assess acute phase proteins and complete blood cell count. Data were analyzed by PROC MIXED with fixed effects of period, Thr, fiber, and their interactions, with block as a random effect. Nitrogen balance was analyzed separately for each period. Threonine requirement was estimated using PROC NLIN quadratic break-point model. Serum concentration of albumin, haptoglobin, fibrinogen, whole blood white blood cell, and platelet count were affected by ISS (P < 0.001) confirming successful ISS. During pre-ISS, PD increased linearly (P < 0.01) as Thr concentration in the diet increased, with a significant interaction (P < 0.05) between fiber and Thr. During ISS, PD increased linearly (P < 0.05) as Thr concentration in the diet increased. Quadratic break-point model estimated SID Thr required to maximize PD of pigs fed LF and HF diets during pre-ISS period was 0.68% (R2 = 0.88) and 0.78% (R2 = 0.99), respectively. During ISS, the SID Thr requirement was estimated at 0.76% (R2 = 0.76) for LF diet and 0.72% (R2 = 0.95) for HF fed pigs. HF and ISS independently increased Thr requirement for maximum PD, but these effects were not additive. HF may therefore mask the effects of ISS on Thr requirement for immune response and PD.

Additivity of apparent and standardized ileal digestibility of amino acids in wheat, canola meal, and sorghum distillers dried grains with solubles in mixed diets fed to broiler chickens

An experiment was conducted to investigate which method, apparent ileal digestibility (AID) or standardized ileal digestibility (SID), more accurately predicts the digestibility of crude protein (CP) and amino acids (AA) in mixed diets fed to broiler chickens. Male Ross 308 broiler chickens received a standard starter diet from d 0 to 16 post hatching, thereafter grouped into 8 blocks, based on body weight (BW), of 10 birds/cage, and randomly allotted to 6 diets in a randomized complete block design. The 6 diets consisted of a nitrogen-free diet, 3 semi-purified diets, and 2 mixed diets to test the additivity of AID and SID in mixed diets. On d 21 post hatching, digesta from two-thirds of the distal ileum was collected. Using the determined AID or SID for CP and AA in wheat, canola meal (CM), or sorghum distillers dried grains with solubles (DDGS), the AID or SID for 2 mixed diets based on wheat-CM or wheat-CM-DDGS were predicted and compared with determined AID or SID, respectively. The results revealed that the predicted SID of CP and AA in the wheat-CM mixed diet were consistent with determined values except for Asp and Ser, and all the predicted SID of CP and AA were consistent with the determined values in the wheat-CM-DDGS mixed diet. The determined AID of Ile, Met, Thr, Val, Ala, Cys, Ser, and Tyr in the wheat-CM mixed diet were greater (P < 0.05) than predicted AID values. For the wheat-CM-DDGS mixed diet, the determined AID of Trp, Cys, and Glu were greater (P < 0.05) than the predicted AID values. However, there were more inconsistencies between the determined and predicted values in AID values for wheat-CM than the wheat-CM-DDGS mixed diet than SID values for both diets. In conclusion, the present study confirmed that the SID of CP and AA was more additive than the AID of CP and AA when a mixed diet contained wheat, CM, and DDGS as protein sources in broiler chickens.

Additivity of apparent and standardized ileal digestibility of amino acid determined by chromic oxide and titanium dioxide in mixed diets containing wheat and multiple protein sources fed to growing pigs

The aim of this study was to investigate the additivity of apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) in mixed diets containing wheat, canola meal (CM), meat and bone meal (MBM), and sorghum distillers' dried grains with solubles (DDGS) fed to pigs with chromic oxide (Cr2O3) and titanium dioxide (TiO2) as digestibility index markers. Four diets were prepared to contain wheat, CM, MBM, or DDGS as a sole source of nitrogen; three mixed diets were prepared to contain wheat, CM, and MBM; wheat, MBM, and DDGS; or wheat, CM, MBM, and DDGS; also, a nitrogen-free diet was prepared to estimate the basal ileal endogenous losses (BEL) of CP and AA. Both Cr2O3 and TiO2 were incorporated at 5 g/kg into each diet. Sixteen barrows (initial body weight = 34.7 ± 0.6 kg) surgically fitted with T-cannulas at the distal ileum were allotted to a duplicate 8 × 4 Youden square design with eight experimental diets and four periods. During each 7-d period, the ileal digesta was collected for 2 d after a 5-d adaptation, and the AID and SID of CP and AA were determined using Cr2O3 or TiO2 as marker. There was no interaction between diet and marker type for both AID and SID of CP and AA. Similar BEL, AID, and SID of CP and AA were determined by Cr2O3 and TiO2. In the wheat-CM-MBM diet, the measured AID of CP and most AA determined with Cr2O3 or TiO2 were not different from the predicted values, which was determined based on the measured AID values in wheat, CM, and MBM. In the wheat-MBM-DDGS diet, the measured and predicted AID of CP and seven indispensable AA differed (P < 0.05) using Cr2O3 as marker, and the measured and predicted AID of CP and four indispensable AA differed (P < 0.05) using TiO2 as marker. The measured AID of CP and most indispensable AA were greater (P < 0.05) than predicted AID regardless of marker type for the wheat-CM-MBM-DDGS diet. The measured SID of CP and indispensable AA were consistent with the predicted values, except Lys in the wheat-CM-MBM diet using either marker and His in the wheat-MBM-DDGS diet with Cr2O3 as marker. In conclusion, more accurate prediction of ileal digestibility of CP and AA was achieved using SID rather than AID in mixed diets containing wheat, CM, MBM, and DDGS. The determination of endogenous loss, AID, and SID of CP and AA were not affected by marker type in this study. In addition, the additivity of AID and SID of CP and most indispensable AA in mixed diets was not affected by marker type.

A Casein Hydrolysate Does Not Enhance Ileal Endogenous Protein Flows Compared With the Parent Intact Casein When Fed to Growing Pigs

BACKGROUND

The form of dietary nitrogen (free peptides or intact proteins) may influence the amount of endogenous amino acids found at the terminal ileum of the pig, and it has been speculated that hydrolyzed dietary protein may lead to increased endogenous amino acids.

OBJECTIVE

To compare the effect of dietary free peptides on ileal endogenous nitrogen and amino acid flows [ileal endogenous nitrogen flow (ENFL), ileal endogenous amino acid flow (EAAFL)] with that of peptides released naturally from dietary protein during digestion, from the same intact parent protein source.

METHODS

Six pigs (mean body weight: 34 kg) were equipped with a postvalve T-caecum cannula. Semisynthetic test diets contained the same 15N-labeled intact casein (C) or hydrolyzed casein (HC). Pigs received the test diets every sixth day and the corresponding unlabeled diets in the intervening 5-d periods. Digesta were pooled from 4 to 10 h postprandially. EAAFL and ENFL, calculated with reference to the dietary marker titanium dioxide, were determined by isotope dilution for C and HC.

RESULTS

Ileal EAAFL and ENFL (mean flows n = 5 of 1828 and 1912 μg/g of dry matter intake for diets HC and C, respectively) did not differ (P > 0.05) between pigs fed HC and C. Centrifugation and ultrafiltration of the HC digesta allowed an estimation of label recycling into gut endogenous proteins. Some 20% of ileal endogenous protein (diet HC, ultrafiltered digesta) was 15N-labeled due to tracer recycling.

CONCLUSIONS

The administration of a casein hydrolysate had no effect on ileal endogenous protein flows compared with C. There was no evidence of enhanced ileal endogenous protein losses with the HC diet.

Microbial Fermentation of Dietary Protein: An Important Factor in Diet⁻Microbe⁻Host Interaction

Protein fermentation by gut microbiota contributes significantly to the metabolite pool in the large intestine and may contribute to host amino acid balance. However, we have a limited understanding of the role that proteolytic metabolites have, both in the gut and in systemic circulation. A review of recent studies paired with findings from previous culture-based experiments suggests an important role for microbial protein fermentation in altering the gut microbiota and generating a diverse range of bioactive molecules which exert wide-ranging host effects. These metabolic products have been shown to increase inflammatory response, tissue permeability, and colitis severity in the gut. They are also implicated in the development of metabolic disease, including obesity, diabetes, and non-alcoholic fatty liver disease (NAFLD). Specific products of proteolytic fermentation such as hydrogen sulfide, ammonia, and p-Cresol may also contribute to the development of colorectal cancer. These findings are in conflict with other studies showing that tryptophan metabolites may improve gut barrier function and attenuate severity in a multiple sclerosis model. Further research examining proteolytic fermentation in the gut may be key to our understanding of how microbial and host metabolism interact affecting health.

Impact of Brachyspira hyodysenteriae on intestinal amino acid digestibility and endogenous amino acid losses in pigs

Brachyspira hyodysenteriae (Bhyo) induces mucohemorrhagic diarrhea in pigs and is an economically significant disease worldwide. Our objectives were to determine the impact of Bhyo on apparent total tract digestibility (ATTD), ileal digestibility (AID), and ileal basal endogenous losses (BEL) in grower pigs. In addition, we assessed the effect of Bhyo on hindgut disappearance of DM, N, and GE. Thirty-two Bhyo negative gilts (38.6 ± 0.70 kg BW) were fitted with a T-cannula in the distal ileum and individually penned. In replicates 1 and 2, pigs were fed a complete diet (7 Bhyo-, 10 Bhyo+ pigs) or nitrogen-free diet (NFD; 4 Bhyo-, 11 Bhyo+ pigs), respectively. Across multiple rooms, the 21 Bhyo+ pigs (62.6 ± 1.39 kg BW) were inoculated with Bhyo on day post inoculation (dpi) 0, and the 11 Bhyo- pigs were sham inoculated. Feces were collected from 9 to 11 dpi and ileal digesta collected from 12 to 13 dpi. All pigs were euthanized at 14 to 15 dpi and intestinal tract pathology assessed. Within the complete diet and NFD treatments, data were analyzed to determine pathogen effects. All Bhyo- pigs remained Bhyo negative, and 5 Bhyo+ pigs in each replicate were confirmed Bhyo positive within 9 dpi. Infection with Bhyo reduced ATTD of DM, N, and GE and increased AID of Gly (P < 0.05). No other AA AID differences were observed. Only BEL of Pro was reduced (P < 0.05) while Arg, Trp, and Gly tended (P < 0.10) to be reduced in Bhyo+ pigs. When calculated from AID and BEL, Bhyo infection reduced standardized ileal digestibility (SID) of N, Arg, Lys, Ala, Gly, Pro, and Ser (P < 0.05) and tended to reduce Thr SID (P = 0.09). In the hindgut of Bhyo+ pigs, there was generally an appearance of nutrients rather than disappearance. In Bhyo+ pigs fed a complete diet, hindgut appearance of N and GE were increased (P < 0.05) by 58 and nine-fold, respectively, and DM tended to be increased two-fold (P = 0.06). Similarly, in NFD fed pigs, hindgut appearance of N and GE was increased by 172% and 162%, respectively, although high variability led to no significance. Altogether, Bhyo infection decreases ATTD but has minimal impact on AID of AA, when corrected for BEL, SID of N, Arg, Lys and some nonessential AA are specifically reduced. Unexpectedly, BEL of several AA involved in mucin production were unaffected by Bhyo infection. This may suggest an increased need for specific AA and energy during a Bhyo challenge.

Comparison of two methods of protein quality evaluation in rice, rye and barley as food protein sources in human nutrition

Different foods differ in their protein quality, which is characterized by the content and digestibility of individual amino acids. The Food and Agriculture Organisation has recommended replacing the method for protein quality evaluation of foods called protein digestibility corrected amino acid score (PDCAAS) with the new method - digestible indispensable amino acid score (DIAAS), in which the values of ileal amino acid digestibility obtained in pigs are used. However, the information about DIAAS values of foods are limited. Therefore, the study on growing pigs was conducted to determine true fecal protein digestibility and standardized ileal amino acid digestibility of rice, rye and barley. Using these values, the PDCAAS and DIAAS were calculated and compared. A total of 18 gilts with a T-cannula inserted in the terminal ileum were allotted to 3 diets with six replicate pigs per diet. Three semi-purified diets were formulated to contain the tested cereal grains (rice, rye, barley) as the sole nitrogen source. Chromic oxide was used as indigestible marker. Each experimental period comprised of a 7-d adaptation period followed by 24 h collection of feces and ileal digesta. The content of nitrogen, dry matter and chromic oxide was analyzed in samples of diets, feces and ileal digesta. Moreover, in the samples of diets and ileal digesta the content of amino acids was determined. Calculated ratio of crude protein to lysine was greatest in rice (4.50) followed by rye (3.65) and the lowest one in barley (3.35). True fecal protein digestibility was greater when compared with ileal amino acid digestibility for all tested samples, thus suggesting an overestimation of protein quality determined by PDCAAS. Calculated PDCAAS values for rice, rye and barley (81, 65 and 61%) were generally greater than the DIAAS values (79, 56 and 55%), especially for the poorer quality protein sources such as rye and barley in comparison with rice. The lysine was the first limiting amino acid in all tested cereal grains. Based on the DIAAS evaluation, rice is better protein source in human nutrition in comparison with rye or barley.

Impact of PRRSV infection and dietary soybean meal on ileal amino acid digestibility and endogenous amino acid losses in growing pigs

Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant disease in the swine industry, and increasing soybean meal (SBM) consumption during this disease challenge may improve performance. Our objectives were to determine the impact of SBM level on apparent total tract (ATTD) and ileal (AID) digestibility during PRRSV infection and to determine ileal basal endogenous losses (BEL) during PRRSV infection. Forty PRRSV negative gilts were fitted with a T-cannula in the distal ileum. Treatments were arranged in a 2 × 2 factorial with high and low SBM (HSBM, 29% vs. LSBM, 10%), with and without PRRSV (n = 6/treatment). The remaining pigs (n = 8/challenge status) were fed a N-free diet. Chromic oxide was used as an indigestible marker. On day post inoculation (dpi) 0, at 47.7 ± 0.57 kg BW, 20 pigs were inoculated with live PRRSV; 20 control pigs were sham inoculated. Infection was confirmed by serum PCR. Feces were collected at dpi 5 to 6 and dpi 16 to 17, and ileal digesta collected at dpi 7 to 8 and dpi 18 to 19. Feed, feces, and digesta were analyzed for DM, N, and GE. Digesta and feed were analyzed for AA. Data were analyzed in a 2 × 2 + 2 factorial design to determine main effects of diet and PRRSV and their interaction. Data from N-free fed pigs were analyzed separately to determine BEL and hindgut disappearance due to PRRSV infection. All control pigs remained PRRSV negative. There were no interactions for AID of AA; however, HSBM reduced DM, GE, Lys, and Met AID and increased Arg and Gly AID during both collection periods (P < 0.05). At dpi 7 to 8 only, PRRSV reduced DM and GE AID (P < 0.05). At 7 to 8 dpi, BEL of Arg, Ala, and Pro were reduced (P < 0.05) due to PRRSV by 64%, 39%, and 94%, respectively. At dpi 18 to 19, BEL of Thr tended (P = 0.06) to be increased in PRRSV-infected pigs; however, no other differences were observed. Pigs fed LSBM had increased Lys, Met, Thr, Trp, and Pro standardized ileal digestibility (SID), primarily at 7 to 8 dpi. At 7 to 8 dpi, PRRSV reduced Arg, Gly, and Pro SID (P < 0.01), and SID Pro continued to be reduced by 17% at dpi 18 to 19. Compared with HSBM pigs, LSBM reduced hindgut disappearance of DM and GE at dpi 5 to 8 and dpi 16 to 19, while N disappearance was reduced at dpi 5 to 8. There were no differences between control and PRRSV N-free fed pigs. Altogether, SBM inclusion impacts SID of AA and hindgut disappearance of nutrients, regardless of PRRSV. In contrast, there is minimal impact of PRRSV on BEL, and therefore, SID of most AA are not different.

Additivity of standardized ileal digestibility of amino acids in mixed diets containing multiple protein sources for growing pigs fed three crude protein levels

This study was conducted to investigate the effect of dietary crude protein (CP) levels of semi-purified diets on the additivity of values for standardized ileal digestibility (SID) of amino acids (AA) in mixed diets from multiple protein sources for growing pigs. A total of 28 barrows (initial BW, 66.4 ± 1.3 kg) were surgically fitted with simple T-cannulas at the distal ileum and assigned to a replicated 14 × 4 incomplete Latin square design with 14 diets and 4 periods. The 14 experimental diets consisted of a nitrogen-free diet; a corn-based diet (80 g CP/kg); nine semi-purified diets containing soya bean meal (SBM), canola meal (CM) or corn distillers dried grains with solubles (cDDGS), each type (protein source) of semi-purified diets supplied 80, 120 or 160 g CP/kg, respectively; three mixed diets based on corn, SBM, CM and cDDGS formulated to contain 120, 160 and 200 g CP/kg respectively. Pigs were fed each of the 14 diets during a seven-day period, and ileal digesta were collected from 08:00 a.m to 6:00 p.m on day 6 and 7. Chromic oxide was added as an indigestible marker. Results indicated that the SID of CP and AA were not affected by CP levels (p > .05). Values for SID of AA were additive (p > .05) with the exception of His and Lys; Arg and Lys; Arg, Lys, Thr, Asp, Cys and Gly in the mixed diets containing 120, 160 and 200 g CP/kg respectively (p < .05). In conclusion, additivity of SID values of AA in the mixed diets at different CP levels was not affected by the CP levels of semi-purified diets for growing pigs. Therefore, it is recommended that SID values of AA should be used to formulate practical diets containing multiple ingredients for pigs.

Dietary protein level affects nutrient digestibility and ileal microbiota structure in growing pigs

This study aimed to determine whether dietary protein content influences pig health as indicated by ileal microbiota structure and coefficients of total tract apparent digestibility (CTTAD) of nutrients. Seventy-two gilts, with an initial body weight of 29.9 ± 1.5 kg, were used in this 42-day feeding study. Pigs were randomly allotted to one of three dietary treatments of corn-soybean meal contained 14, 16 or 18% crude protein (CP). As dietary CP content decreased, the CTTAD of most essential amino acids (AAs), except for arginine and histidine, increased linearly, while those of most nonessential AAs decreased linearly. The concentration of total short-chain fatty acids (SCFA) was higher in pigs fed the diet with 14% CP content than others. Ileal microbiota structure was changed by dietary treatments. In particular, at the phylum level, the relative abundance of Tenericutes in ileal digesta decreased as the dietary protein content reduced, while that of cyanobacteria increased. At the genus level, the relative abundance of Weeksella, Phaseolus acutifolius, Slackia, Sulfurimonas and Aerococcus showed significant differences among the three dietary treatments. In conclusion, ileal microbiota structure was changed by dietary protein content. Moderate reduction of protein intake can benefit gut health by enhancing the gut microbial fermentation and SCFA formation.

Viscous and fermentable nonstarch polysaccharides affect intestinal nutrient and energy flow and hindgut fermentation in growing pigs

Two experiments were conducted to determine the effects of viscosity and fermentability of purified nonstarch polysaccharides (NSP) on intestinal nutrient and energy flow and hindgut fermentation in growing pigs. In Exp. 1, 15 ileal-cannulated pigs (50.5 ± 2.9 kg BW) were allotted to 5 diets in a 2-period incompletely randomized design. Pigs were provided a cornstarch N-free diet (CST) or a diet containing 5% inulin (INU), carboxymethylcellulose sodium (CMC), microcrystalline cellulose (MCC), or Solka-Floc (SFC). Apparent ileal digestibility (AID) of DM, ash, and GE were greater ( < 0.05) in the MCC and SFC diets than in the INU and CMC diets. Apparent total tract digestibility (ATTD) of DM, carbohydrates (CHO), and GE and the DE content in the CST and INU diets were greater ( < 0.01) than in the CMC, MCC, and SFC diets. Hindgut disappearance of DM, CHO, and GE in the INU diet was greater ( < 0.05) than in the other N-free diets. The ileal endogenous flow of His, Ile, Leu, Met, Thr, Val, and all dispensable AA in the CMC diet was greater ( < 0.05) than in the other diets. In Exp. 2, 6 ileal-cannulated pigs were allotted to 3 diets containing either a corn-soybean meal control diet or the control diet with 5% INU or CMC in a replicated 3 × 3 Latin square design. Standardized ileal digestibility (SID) of Ala, Arg, Asp, Cys, Gly, His, Ile, Leu, Lys, Phe, Ser, Thr, and Val were greater ( < 0.05) in the CMC diet than in the control and INU diets. Incorporation of 5% INU or CMC in the control diet reduced ( < 0.01) the AID of arabinoxylan and insoluble and total NSP. The ATTD of NSP and cellulose and the hindgut disappearance of NSP, β-glucan, and cellulose in the CMC diet were less ( < 0.01) than in the control and INU diets. Inclusion of 5% INU in the diet increased ( < 0.01) hindgut fermentation of insoluble and total NSP compared with the control and CMC diets. In conclusion, depending on the viscosity and fermentability of the NSP, different sources will have different effects on nutrient digestibility and hindgut fermentation. Addition of 5% INU to a corn-soybean meal diet reduced digestibility of the NSP component in the ileum and increased hindgut fermentation of total NSP. In contrast, the inclusion of CMC increased the AID and SID of the diet and reduced total tract digestion and hindgut fermentation of NSP component. Carboxymethylcellulose sodium is not recommended as a source of synthetic fiber in a N-free diet to determine the SID of AA of diets.

Pelleting and extrusion can ameliorate negative effects of toasting of rapeseed meal on protein digestibility in growing pigs

Toasting time (TT) of rapeseed meal (RSM), the diet processing (DP) method and the interaction between both on the apparent CP digestion along the gastrointestinal tract and the apparent ileal digestibility (AID) of amino acids of growing pigs were investigated. The experiment consisted of a 3×3 factorial design of TT of RSM (0, 60 and 120 min) and DP method (mash, pelleting and extrusion). In total, 81 boars with a starting BW of 20 kg were euthanized 4 h after their last feeding. The gastrointestinal tract was dissected and the small intestine divided in three sections of similar length. Samples were collected from the stomach, 1.5 m from the ends of each of the three sections of the small intestine, and the rectum. The apparent digestibility (AD) of CP for each of the small intestine sections was used to calculate the rate of CP digestion. Increasing the TT of RSM resulted in lower protein solubility, lower lysine/reactive lysine contents and higher protein denaturation, indicative of the occurrence of protein aggregation and Maillard reactions. There were significant effects (P⩽0.01) of TT on the AD of CP in the different sections of the gastrointestinal tract. The rate of CP digestion of the 0 min toasted RSM diets was 23% and 35% higher than that of the 60 and 120 min toasted RSM diets, respectively. There was a significant interaction (P=0.04) between TT and DP for the AID of CP. Although pelleting of the 0 and 60 min toasted RSM diets did not change the AID of CP with respect to the mash diets, pelleting of the 120 min toasted RSM diet increased the AID of CP by 9.3% units. Extrusion increased the AID of CP of the 0 and 60 min toasted RSM diets by 3.4% and 4.3% units with respect to the mash diets, whereas extrusion of the 120 min toasted RSM diet increased the AID of CP by 6.9% units. Similar positive effects of pelleting and extrusion were obtained for the AID of lysine and reactive lysine, especially in the diets with higher TT. In conclusion, processing (pelleting and extrusion) of RSM containing diets can ameliorate the negative effects of RSM toasting on protein and amino acid digestibility; these effects were larger for the RSM toasted for longer times.

Techniques for evaluating digestibility of energy, amino acids, phosphorus, and calcium in feed ingredients for pigs

Sound feed formulation is dependent upon precise evaluation of energy and nutrients values in feed ingredients. Hence the methodology to determine the digestibility of energy and nutrients in feedstuffs should be chosen carefully before conducting experiments. The direct and difference procedures are widely used to determine the digestibility of energy and nutrients in feedstuffs. The direct procedure is normally considered when the test feedstuff can be formulated as the sole source of the component of interest in the test diet. However, in some cases where test ingredients can only be formulated to replace a portion of the basal diet to provide the component of interest, the difference procedure can be applied to get equally robust values. Based on components of interest, ileal digesta or feces can be collected, and different sample collection processes can be used. For example, for amino acids (AA), to avoid the interference of fermentation in the hind gut, ileal digesta samples are collected to determine the ileal digestibility and simple T-cannula and index method are commonly used techniques for AA digestibility analysis. For energy, phosphorus, and calcium, normally fecal samples will be collected to determine the total tract digestibility, and therefore the total collection method is recommended to obtain more accurate estimates. Concerns with the use of apparent digestibility values include different estimated values from different inclusion level and non-additivity in mixtures of feed ingredients. These concerns can be overcome by using standardized digestibility, or true digestibility, by correcting endogenous losses of components from apparent digestibility values. In this review, methodologies used to determine energy and nutrients digestibility in pigs are discussed. It is suggested that the methodology should be carefully selected based on the component of interest, feed ingredients, and available experimental facilities.

A link between damaging behaviour in pigs, sanitary conditions, and dietary protein and amino acid supply

The tendency to reduce crude protein (CP) levels in pig diets to increase protein efficiency may increase the occurrence of damaging behaviours such as ear and tail biting, particularly for pigs kept under suboptimal health conditions. We studied, in a 2×2×2 factorial design, 576 tail-docked growing-finishing entire male pigs in 64 pens, subjected to low (LSC) vs. high sanitary conditions (HSC), and fed a normal CP (NP) vs. a low CP diet (LP, 80% of NP) ad libitum, with a basal amino acid (AA) profile or supplemented AA profile with extra threonine, tryptophan and methionine. The HSC pigs were vaccinated in the first nine weeks of life and received antibiotics at arrival at experimental farm at ten weeks, after which they were kept in a disinfected part of the farm with a strict hygiene protocol. The LSC pigs were kept on the same farm in non-disinfected pens to which manure from another pig farm was introduced fortnightly. At 15, 18, and 24 weeks of age, prevalence of tail and ear damage and of tail and ear wounds was scored. At 20 and 23 weeks of age, frequencies of biting behaviour and aggression were scored for 10×10 min per pen per week. The prevalence of ear damage during the finisher phase (47 vs. 32% of pigs, P < 0.0001) and the frequency of ear biting (1.3 vs. 1.2 times per hour, P = 0.03) were increased in LSC compared with HSC pigs. This effect on ear biting was diet dependent, however, the supplemented AA profile reduced ear biting only in LSC pigs by 18% (SC × AA profile, P < 0.01). The prevalence of tail wounds was lower for pigs in LSC (13 ± 0.02) than for pigs in HSC (0.22 ± 0.03) in the grower phase (P < 0.007). Regardless of AA profile or sanitary status, LP pigs showed more ear biting (+20%, P < 0.05), tail biting (+25%, P < 0.10), belly nosing (+152%, P < 0.01), other oral manipulation directed at pen mates (+13%, P < 0.05), and aggression (+30%, P < 0.01) than NP pigs, with no effect on ear or tail damage. In conclusion, both low sanitary conditions and a reduction of dietary protein increase the occurrence of damaging behaviours in pigs and therefore may negatively impact pig welfare. Attention should be paid to the impact of dietary nutrient composition on pig behaviour and welfare, particularly when pigs are kept under suboptimal (sanitary) conditions.

Effect of Bacillus subtilis and Bacillus licheniformis supplementation in diets with low- and high-protein content on ileal crude protein and amino acid digestibility and intestinal microbiota composition of growing pigs

Background

Bacillus spp. seem to be an alternative to antimicrobial growth promoters for improving animals’ health and performance. However, there is little information on the effect of Bacillus spp. in combination with different dietary crude protein (CP) levels on the ileal digestibility and microbiota composition. Therefore, the objective of this study was to determine the effect of Bacillus spp. supplementation to low- (LP) and high-protein diets (HP) on ileal CP and amino acid (AA) digestibility and intestinal microbiota composition.

Methods

Eight ileally cannulated pigs with an initial body weight of 28.5 kg were randomly allocated to a row-column design with 8 pigs and 3 periods of 16 d each. The assay diets were based on wheat-barley-soybean meal with two protein levels: LP (14% CP, as-fed) and HP diet (18% CP, as-fed). The LP and HP diets were supplemented with or without Bacillus spp. at a level of 0.04% (as-fed). The apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA was determined. Bacterial community composition from ileal digesta was analyzed by Illumina amplicon sequencing and quantitative real-time PCR. Data were analyzed as a 2 × 2 factorial design using the GLIMMIX procedures of SAS.

Results

The supplementation with Bacillus spp. did not affect both AID and SID of CP and AA in growing pigs. Moreover, there was no difference in AID of CP and AA between HP and LP diets, but SID of cystine, glutamic acid, glycine, and proline was lower (P < 0.05) in pigs fed the HP diets. The HP diets increased abundance of Bifidobacterium spp. and Lactobacillus spp., (P < 0.05) and by amplicon sequencing the latter was identified as predominant genus in microbiota from HP with Bacillus spp., whereas dietary supplementation of Bacillus spp. increased (P < 0.05) abundance of Roseburia spp..

Conclusions

The HP diet increased abundance of Lactobacillus spp. and Bifidobacterium spp.. The supplementation of Bacillus spp. resulted in a higher abundance of healthy gut associated bacteria without affecting ileal CP and AA digestibility, whereas LP diet may reduce the flow of undigested protein to the large intestine of pigs.

Performance of pigs kept under different sanitary conditions affected by protein intake and amino acid supplementation

There is growing evidence that requirements for particular AA increase when pigs are kept under low sanitary conditions. The extent to which reduction in growth performance is related to these increased requirements is unclear. To evaluate this relationship, an experiment (2 × 2 × 2 factorial arrangement) was performed with 612 male pigs (9 per pen) kept under low sanitary conditions (LSC) or high sanitary conditions (HSC) and offered ad libitum access to either a normal CP concentration diet (NP; 17, 15, and 15% CP for the starter, grower, and finisher phase, respectively) or a low CP concentration diet (LP; 20% CP reduced relative to NP for each phase), each of which containing a basal AA profile (AA-B) or a supplemented AA profile (AA-S). The supplemented diet type contained 20% more Met, Thr, and Trp relative to Lys on an apparent ileal digestible basis compared with the basal diet type. Pigs were followed for a complete fattening period and slaughtered at a targeted pen weight of 110 kg. Haptoglobin concentrations in serum (0.92 g/L for LSC and 0.78 g/L for HSC) and IgG antibody titers against keyhole limpet hemocyanin (3.53 for LSC and 3.08 for HSC) collected in the starter, grower, and finisher phases and pleuritis scores at slaughter (0.51 for LSC and 0.20 for HSC) were greater for LSC pigs compared with HSC pigs ( ≤ 0.01), illustrating that sanitary conditions affected health conditions. The ADG and G:F were greater for HSC pigs compared with LSC pigs ( ≤ 0.01). The number of white blood cells (WBC) was higher in (AA-S)-fed pigs compared with (AA-B)-fed pigs when kept at LSC but not at HSC [SS (sanitary conditions) × AA interaction, = 0.04]. Pigs fed NP had a lower number of WBC compared with pigs fed LP ( = 0.02). The number of platelets in pigs fed AA-S diets was higher compared with pigs fed AA-B diets ( ≤ 0.01). A 20% reduction in dietary supplementation of Met, Thr, and Trp relative to Lys decreased G:F more in LSC pigs than in HSC pigs (interaction, = 0.03), illustrating that dietary requirements for these AA differ depending on sanitary conditions. This study, performed under practical conditions, shows that AA requirements are dependent on sanitary conditions. Furthermore, supplementation of diets with particular AA may improve performance, especially under poor hygienic conditions. Dietary protein concentration as well as Met, Thr, and Trp supplementation can modify immune status, which may influence resistance to subclinical and clinical diseases.