Estimates of dietary threshold levels for crude protein and amino acids to obtain plateau values of apparent ileal crude protein and amino acid digestibilities in newly weaned pigs

Influence of dietary crude protein on growth performance and apparent and standardized ileal digestibility of amino acids in corn-soybean meal-based diets fed to broilers

This study aimed to examine the influence of dietary CP on the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids (AA) and test the additivity of AA digestibility in corn-soybean meal-based diets fed to broilers. Six experimental diets comprising a nitrogen-free diet and five corn-soybean meal-based diets containing 6.0%, 9.5%, 13.0%, 16.5%, and 20.0% CP were prepared. Increments in CP and AA concentrations were achieved by increasing the inclusion rate of corn and soybean meal at the expense of cornstarch. All diets contained 0.5% chromic oxide, which was included as an indigestible index. A total of 960 Ross 308 male broilers 19-day-old male broilers (Ross 308), with a mean BW of 628 g (SD = 58.0), were allocated to six dietary treatment groups in a randomized complete block design, with each treatment group have eight replicate cages and 20 birds per cage. All birds were fed the experimental diets for 4 days. On d 23, individual BW and feed intake were recorded, followed by collection of ileal digesta samples from the distal ileum. Regarding growth, the final BW, weight gain, feed intake, and gain to feed ratio increased linearly (P < 0.001) as dietary CP concentrations increased. With the increase in dietary CP concentrations from 6.0% to 20.0%, the AID of all AA, except Arg, increased linearly (P < 0.05). However, the SID of all AA, except Arg, Cys, and Pro, remained unaffected by CP concentrations in the diets. This study indicated that dietary CP concentrations from 6.0% to 20.0% have an effect on the growth performance of birds and the AID of most AA; however, the SID of most AA was not affected by dietary CP concentrations in the corn-soybean meal-based diets. In conclusion, the SID of AA is more additive than the AID of AA in poultry diets containing CP in the range of 6.0% to 20.0%.

Crystalline amino acids do not influence calculated values for standardized ileal digestibility of amino acids in feed ingredients included in diets for pigs

An experiment was conducted to test the hypothesis that addition of crystalline amino acids (AA) to diets during the adaptation or collection periods will not influence calculated values for apparent ileal digestibility (AID) or standardized ileal digestibility (SID) of AA in corn and soybean meal (SBM). Seven ileal-cannulated barrows (initial body weight: 77.9 ± 2.6 kg) were allotted to a 7 × 7 Latin Square design with 7 dietary treatments and 7 periods. Dietary treatments included feeding diets based on corn or SBM without or with crystalline AA for the entire 7-d period or with crystalline AA during the adaptation period, but without crystalline AA during the collection period. An N-free diet was also used. Each experimental period consisted of 5 d of adaptation to the diets followed by 2 d of ileal digesta collection, with digesta being collected for 9 hr/d starting after feeding the morning meal. Thus, the entire experiment lasted 49 d. The AID and SID of crude protein (CP) and AA were calculated using values determined in corn or in SBM without or with crystalline AA to determine if crystalline AA influenced calculated values for AID or SID of CP and AA. Results indicated that addition of crystalline AA to diets fed during the entire 7-d period increased (P < 0.05) AID of some AA in corn and SBM. However, no differences in SID of CP and AA were observed between pigs fed the diets without crystalline AA and pigs fed the diets with crystalline AA if dietary crystalline AA were ignored in calculations of SID values. This indicates that crystalline AA were 100% absorbed before the distal ileum and did not affect calculated values for SID of AA if calculations were based only on the AA in corn or SBM. Therefore, it is concluded that crystalline AA may be added to experimental diets in digestibility experiments before and during collection periods without affecting results, if crystalline AA are disregarded in the calculation of AID or SID of AA in ingredients.

Relative bioavailability of l-lysine sulfate is equivalent to that of l-lysine HCl for nursery piglets

Supplementary l-lysine sources include l-lysine HCl and l-lysine sulfate. l-Lysine sulfate contains at least 50% l-Lys and other components as residues from the fermentation process, other amino acids, and other organic and inorganic substances, being an alternative to l-Lys HCl. The aim of this study was to evaluate the relative bioavailability (RBV) of l-Lys sulfate in comparison with l-Lys HCl and its effects on performance, blood parameters, intestinal functionality, and the apparent total tract digestibility in nursery piglets. A total of 168 female piglets (DB90 × PIC337), weaned at 22 d (BW = 6.29 ± 0.41 kg), were distributed in seven dietary treatments and eight replicates, with three pigs per pen. The experimental period of 42 d was divided into two phases (phase 1, days 0-21; phase 2, days 21 to 42). The basal diet (CON) was lysine-deficient formulated to meet 73% of standardized ileal digestible Lys requirements. For the other diets, the CON was supplemented with three levels (80%, 90%, and 100% of standardized ileal digestible Lys requirements) of l-Lys sulfate (70% l-Lys) or l-Lys HCl (79% l-Lys). There were no significant differences (P > 0.05) in the performance and concentrations of plasma urea and creatinine between the l-Lys sources. The RBV of l-Lys sulfate relative to l-Lys HCl was 106%, 119%, and 117% for effects on ADG, G:F, and plasma urea, respectively. Lys deficiency resulted in a greater (P < 0.05) incidence of diarrhea, while pigs supplemented with Lys sulfate or Lys HCl showed greater (P < 0.05) villus height in the jejunum when compared to those receiving the CON. Diets supplemented with l-Lys sulfate had greater (P < 0.05) apparent total tract digestibility of dry matter, gross energy, and crude protein. In conclusion, the RBV of l-Lys sulfate for effects on ADG, G:F, and plasma urea is equivalent to that of l-Lys HCl for nursery piglets.

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.

Effect of processing of rapeseed under defined conditions in a pilot plant on chemical composition and standardized ileal amino acid digestibility in rapeseed meal for pigs

Five rapeseed meals (RSM) were produced from a single batch of rapeseed in a large-scale pilot plant under standardized conditions. The objective was to evaluate the effect of residence time in the desolventizer/toaster (DT) on chemical composition and standardized ileal digestibility (SID) of AA in RSM. Four RSM, with 48, 64, 76, and 93 min residence time and using unsaturated steam in the DT, referred to as RSM48, RSM64, RSM76, and RSM93, respectively, and 1 low-glucosinolate RSM, which was subjected to sequential treatment with unsaturated steam, saturated steam, and dry heat in the DT, referred to as low-GSL RSM, were assayed. Six barrows (average initial BW = 22 ± 1 kg) were surgically fitted with a T-cannula at the distal ileum. Pigs were allotted to a 5 × 6 row × column design with 5 diets and 5 periods. The 5 RSM were included in a cornstarch-casein-based basal diet. In addition, basal ileal endogenous losses and SID of AA originating from casein were determined at the conclusion of the experiment in 2 additional periods by means of the regression method and using 3 graded levels of casein. The SID of AA in the 5 RSM was determined in difference to SID of AA originating from casein. The glucosinolates (GSL) were efficiently reduced, whereas NDF, ADF, ADL, and NDIN contents increased and reactive Lys (rLys) and Lys:CP ratio decreased as the residence time in the DT was increased from 48 to 93 min. The SID of most AA in RSM linearly decreased (P < 0.05) as the residence time in the DT increased from 48 to 93 min. Moreover, there was a linear decrease (P < 0.05) in SID of AA with increasing NDF, ADF, ADL, and NDIN contents in these RSM, whereas SID of AA linearly decreased (P < 0.05) with decreasing levels of GSL and rLys and a decreasing Lys:CP ratio. The decrease (P < 0.05) in SID of AA amounted from 3 up to 6 (percentage units) for most AA, except for SID of Cys and Lys, which decreased by 10 and 11%-units (P < 0.05), respectively, as the residence time in the DT was increased from 48 to 93 min. The SID in low-GSL RSM was for CP and most AA similar to RSM93 but lower ( < 0.05) compared to RSM48. It can be concluded that time and energy-intensive heat treatment results in lower contents of SID AA in RSM together with a reduction in GSL levels. The feed industry would most likely benefit from a rapid and accurate prediction of SID of AA, for example, based on content of NDIN, GSL, rLys or on Lys:CP ratio, in different batches of RSM used for feed manufacturing.

Effect of dietary protein supply originating from soybean meal or casein on the intestinal microbiota of piglets

Dietary composition is a major factor influencing the intestinal microbial ecosystem of pigs. To alleviate weaning-associated disorders, variations in dietary protein supply may beneficially affect microbial composition in the gastrointestinal tract of piglets. A total of 48 piglets, fitted with simple ileal T-cannulas, was used to examine the effect of protein supply of either highly digestible casein or less digestible, fiber-rich soybean meal (SBM) on the composition of the intestinal microbiota. Gene copies of 7 bacteria groups were determined by real-time PCR in ileal digesta and feces. Ileal counts of total eubacteria, the Bacteroides-Prevotella-Porphyromonas group, Enterobacteriaceae and Clostridium Cluster XIVa were higher (P < 0.001) in the casein-based diets. Fecal counts of all analyzed bacterial groups were higher for the SBM-based diets (P < 0.001), apart from Enterobacteriaceae (P < 0.05) which were higher in the casein-based diets. Ileal counts of lactobacilli linearly increased as the crude protein level was increased up to 335 g/kg (P < 0.01). The Bacteroides-Prevotella-Porphyromonas group linearly decreased in ileal samples (P < 0.01) and increased in fecal samples (P < 0.05) as the crude protein level in the SBM-based diet was increased. Both, protein level and protein source may affect intestinal microbial balance. Higher dietary protein levels in combination with diets low in fiber contents might stimulate proliferation of protein fermenting bacteria in piglet's large intestine. Further studies are warranted to clarify, whether this would be associated with intestinal disturbances.

Amino acid fortified diets for weanling pigs replacing fish meal and whey protein concentrate: Effects on growth, immune status, and gut health

Background

Limited availability of fish meal and whey protein concentrate increases overall feed costs. Availability of increased number of supplemental amino acids including Lys, Met, Thr, Trp, Val, and Ile allows replacing expensive protein supplements to reduce feed costs. This study was to evaluate the effect of replacing fish meal and/or whey protein concentrate in nursery diets with 6 supplemental amino acids on growth performance and gut health of post-weaning pigs. Treatments were 1) FM-WPC: diet with fish meal (FM) and whey protein concentrate (WPC); 2) FM-AA: diet with FM and crystalline amino acids (L-Lys, L-Thr, L-Trp, DL-Met, L-Val, and L-Ile); 3) WPC-AA: diet with WPC and crystalline amino acid; and 4) AA: diet with crystalline amino acid.

Results

Pigs in FM-AA, WPC-AA, and AA had greater (P < 0.05) ADG and gain:feed than pigs in FM-WPC during wk 1 (phase 1). Plasma insulin concentration of pigs in AA tended to be greater (P = 0.064) than that of FM-WPC at the end of wk 1(phase 1). Plasma concentrations of IgG in AA was lower (P < 0.05) compared with WPC-AA and FW, and FM-AA had lower (P < 0.05) IgG concentration than WPC-AA at the end of wk 1 (phase 1). Concentration of acetate in cecum digesta in FM-AA tended to be greater (P = 0.054) than that of FM-WPC and WPC-AA. Concentration of isovalerate in cecum digesta of pigs in FM-AA was greater (P < 0.05) than that of FW and WPC-AA.

Conclusions

This study indicates that use of 6 supplemental amino acids can replace fish meal and/or whey protein concentrate without adverse effects on growth performance, immune status, and gut health of pigs at d 21 to 49 of age. Positive response with the use of 6 supplemental amino acids in growth during the first week of post-weaning may due to increased plasma insulin potentially improving uptake of nutrients for protein synthesis and energy utilization. The replacement of fish meal and/or whey protein concentrate with 6 supplemental amino acids could decrease the crude protein level in nursery diets, and potentially lead to substantial cost savings in expensive nursery diets.

Comparative evaluation of standardized ileal amino acid digestibility in protein supplements for piglets

Standardized ileal digestibility (SID) of AA was determined in 6 protein ingredients for piglets. A basal diet based on corn (Zea mays) starch and casein was supplemented with fluid-bed-dried porcine intestinal mucosa hydrolysate, spray-dried porcine intestinal mucosa hydrolysate, soy (Glycine max) protein concentrate, 2 batches of soy protein, or full-fat soybeans. The SID of AA did not differ between the 4 soybean products (P > 0.05). Compared to most SID values in the 4 soybean products, SID of AA were lower in the 2 porcine intestinal mucosa hydrolysates (P ≤ 0.05). In conclusion, although the initial trypsin inhibitor contents in the raw soybeans have not been determined, high SID values in the 4 soybean products indicate that the different processing procedures used to manufacture these products were efficient to inactivate trypsin inhibitors. For most AA in the 2 porcine intestinal mucosa hydrolysates, drying procedure did not affect SID of AA, but SID values were generally lower compared to the 4 soybean products.

Effect of soybean meal origin on standardized ileal amino acid digestibility in piglets

The present study with piglets was conducted to estimate standardized ileal digestibility (SID) of AA in European Union soybean (Glycine max) meal (SBM) imports sourced from Argentina, Brazil, and the United States. Twelve piglets with an average initial BW of 9 kg (47 d of age) were fitted with a simple ileal T-cannula to determine SID of AA in 4 batches of SBM originating either from Argentina (n = 1), Brazil (n = 1), or the United States (n = 2; US1 and US2). A semisynthetic diet based on corn (Zea mays) starch and casein (125 g casein/kg as-fed) was supplemented with 1 of 4 batches SBM at an inclusion rate of 235 g SBM/kg (as-fed) each. The chemical composition did not differ largely, with CP contents ranging from 458 in Argentinean to 461 g/kg (as-fed) in US1 SBM. The SID of indispensable AA ranged from 80% in US2 SBM to 83% in Argentinean SBM and from 74% for Trp in US2 and Brazilian SBM to 91% for Arg in US2, Brazilian, and Argentinean SBM. Most SID values did not differ among the SBM batches (P > 0.05). In conclusion, European SBM imports from Brazil, Argentina, or the United Sates were similar in their chemical composition. For most AA, high and uniform SID values were obtained independent from their source of origin.

Standardized ileal digestibilities of crude protein, amino acids, and contents of antinutritional factors, mycotoxins, and isoflavones of European soybean meal imports fed to piglets

A study with 3 experiments and 3 periods each was conducted to assess the protein value of soybean meal (SBM) batches that were imported into the European Union (EU) from Argentina, Brazil, or the United States (US). Six random SBM batches from each origin were analyzed for contents of CP, AA, ether extract, crude ash, NDF, ADF, oligosaccharides, isoflavones, mycotoxins, trypsin inhibitor activity (TIA), and protein dispersibility index. Piglets were used for determination of standardized ileal digestibilities (SID) of CP and AA in these 18 SBM batches. In each experiment, 12 piglets (initial BW = 5.6 ± 0.7 kg) were surgically fitted with simple T-cannulas at the distal ileum. The piglets were randomly allotted to 18 semisynthetic assay diets, which included 1 of the 18 SBM batches from the 3 origins at an inclusion level of 250 g/kg (as-fed). Average content of CP was 480, 505, and 488 g/kg (as-fed) for Argentinean, Brazilian, and US SBM batches, respectively, and was greater for Brazilian SBM (P ≤ 0.05) compared with the other 2 origins. Contents of most AA were greater (P ≤ 0.05) in Brazilian compared with Argentinean SBM batches. Amino acid contents in US SBM batches ranged between those from Argentina and Brazil. Average TIA were 3.9, 5.1, and 3.4 mg trypsin inhibitor/g CP for Argentinean, Brazilian, and US SBM batches, and were greater (P ≤ 0.05) for Brazilian SBM compared with the other origins. Mycotoxins were detected in 8 out of 18 SBM batches, but all mycotoxin concentrations were less than their critical benchmarks. The contents of individual isoflavones varied considerably and differed (P ≤ 0.05) among SBM origins. The SID of CP, Arg, Phe, Thr, Trp, Asp, Gly, and Ser were greater (P ≤ 0.05) for US compared with Argentinean SBM batches, with intermediate values for Brazilian SBM batches. The obtained SID values were most variable within Argentinean SBM batches and most homogenous within US SBM batches, as indicated by great and small CV, respectively. However, SID of CP and AA were not affected (P > 0.05) by any of the chemical variables measured in this study, according to linear and quadratic regression analyses. Greatest SID values and good homogeneity between individual batches of the same origin were observed for US SBM. The results of this study with piglets will expand the database on SID of CP and AA in SBM from 3 of the major soybean-producing and processing countries.

Determination of protein and amino acid digestibility in foods including implications of gut microbial amino acid synthesis

To meet the protein and amino acid requirements of individuals and of populations requires information not only about their requirements but also about the capacity of available foods to meet those requirements. Most of our current knowledge of the digestibility of food proteins and the methods to estimate it has been derived from work with animals. Because the microbiota of the large intestine alter the amino acid composition of the digesta, and because only trivial quantities of amino acids are absorbed intact from the large intestine, the current method of choice for assessing amino acid digestibility is ileal digestibility corrected for basal endogenous losses, that is, standardized ileal digestibility. For protein as a whole, however, because nitrogen absorbed in forms other than as amino acids can contribute to the nitrogen economy, the absorption of nitrogen over the whole digestive tract is the more appropriate measure. Most of the methods developed for estimating ileal amino acid outflow in animals are not directly applicable to man: the exception is the use of volunteers with an ileostomy. The flow and composition of ileal digesta in human subjects can also be measured by the infusion of a marker and withdrawal of samples through a naso-intestinal tube. However, this method is too demanding for routine use and is likely to be restricted to validating the application to humans of digestibility data obtained either from animals, of which the pig seems most suitable, orin vitromethods. Microbial activity in the gastrointestinal (GI) tract is not confined to the large intestine: the numbers and metabolic activity of the upper GI microbiota lead to substantial amounts of microbial protein leaving the ileum. It appears however that a large proportion of the amino acids used by the upper GI microbiota are preformed - from the diet or from endogenous materials - rather than fromde novosynthesis. Although there are still uncertainties about the impact of microbial activity in the upper GI tract, the amino acid composition of ileal digesta provides the best available basis for estimating the proportion of dietary amino acids available for metabolism.

Effect of feed intake level on ileal digestibilities of crude protein and amino acids in diets for piglets

BACKGROUND

The study was conducted to determine the effect of graded levels of feed intake on apparent (AID) and standardized (SID) ileal digestibilities of crude protein (CP) and amino acids (AA) in diets for piglets. The piglets were surgically fitted with simple T-cannulas at the distal ileum. The cornstarch-casein-soybean meal-based diets were fed at three graded levels of feed intake corresponding to 30, 45 and 60 g kg(-1) body weight (BW) per day.

RESULTS

The AID and SID of most AA were quadratically affected by the feed intake level (P≤0.05). Initially, both AID and SID of most AA increased up to 1.9 percentage units as the feed intake level was increased from 30 to 45 g kg(-1) BW. Thereafter, these AID and SID values decreased by 2.6 and 2.7 percentage units, respectively, as the feed intake level was further increased from 45 to 60 g kg(-1) BW.

CONCLUSION

Because the voluntary feed intake is highly variable in piglets after weaning, comparison of ileal AA digestibilities between and within studies may be confounded by variations in feed intake level. Thus, when designing digestibility studies with piglets, a standardization of feed intake should be taken into consideration.