Optimum Ratio of Histidine in the Piglet Ideal Protein Model and Its Effects on Body Metabolism

A 4 ‐ 4 Latin square design was used to determine ileal apparent digestibility of amino acids (AAs) in corn, soybean meal, feather meal and dried whey in young pigs. The data were then to be used in formulating a basal diet for studies on AA metabolism in young pigs. Eight castrates T-cannulated at terminal ileum (average initial body weight 12.5 ± 0.62kg) were divided into 4 groups on the basis of body weight and transferred to individual metabolism crates. They were then fed four experimental diets containing the four feedstuffs to be tested (corn, soybean meal, feather meal and dried whey). The trial lasted 20 days, which included 4 five-day periods for ileal digesta collection. It was found that the digestibility of the AAs was similar to that reported in literature. Based on the findings a basal diet for this research was formulated according to an ideal protein model for the 10 to 20kg piglet, on the basis of digestible AAs and containing 14.13MJ/kg digestible energy, 18.22% crude protein, 1.04% digestible lysine and 0.23% digestible histidine.     

Exogenous and endogenous contributions to nitrogen fluxes in the digestive tract of pigs fed a casein diet. II. Ileal and faecal digestibilities and absorption of amino acids.

The present work aimed at quantifying nitrogen (N) and amino acid (AA) fluxes in the digestive tract of growing pigs fed a casein diet. In this paper we report on digesta passage at the terminal ileum, on apparent balances at the ileal and faecal levels, and on nutrients appearance in the portal vein. Digesta flow-rate at the terminal ileum was maximum between 6 and 12 h after the meal. About 10% of N and 5% of total AA ingested were recovered within 24 h. AA absorption started 30 min after the meal, and was measurable until 13 to 14 h. The total AA absorbed in 24 h accounted for 128% of the AA ingested. The AA composition of ileal digesta was very different from that of casein, closely resembling that of endogenous proteins. The AA composition of faeces was very close to that of bacterial proteins. The ileal digestibilities of AA, though lower than their faecal values, were very high. This was confirmed by AA absorption balances greater than 100%. These data suggest that casein was almost totally digested by the terminal ileum, and that endogenous AA were substantially reabsorbed. These findings are supported by data on endogenous N recycling (15N), reported in a following paper.     

Endogenous ileal losses of nitrogen and amino acids in pigs and piglets fed graded levels of casein

In order to determine ileal losses of nitrogen (N) and amino acids (AA) and the coefficients of apparent and true ileal digestibility (AID, TID) of N and AA from casein in piglets and pigs, two experiments were conducted. In Experiment 1, 24 piglets were used. The piglets were weaned at 17 days of age, weighing 6.4 kg and cannulated at terminal ileum. Ileal digesta was collected at 28-29 and 35-36 days of age in period 1 and 2, respectively. Feed intake was 150 and 300 g x d(-1) during the first and second period. In Experiment 2, 16 castrates weighing 52.5 kg and cannulated at terminal ileum were used. The intake level of digestible energy was 2.5 times their maintenance requirement. The experiment lasted 7 days and ileal digesta was collected on day 6-7. Treatments consisted of four levels of N from casein: 8, 16, 24 and 32 g N x kg(-1) feed, respectively. Results showed that N level did not increase N or AA ileal losses. In piglets, N and AA ileal losses were similar between periods, except for period 2, where losses per kg DMI were about 47 and 64% higher for glycine and proline, respectively (p < 0.05). When ileal losses from pigs and piglets were compared, piglets had higher (p < 0.05) ileal losses of N and AA (excepted glutamic acid and alanine). A lower (p < 0.05) AID was observed in piglets in period 2 for N, methionine, glutamic acid, glycine and proline. With exception of glycine in pigs, all values for TID of N and AA of casein were superior to 0.90. Piglets had higher TID of N, leucine, isoleucine, valine and phenylalanine. These results showed that piglets have higher ileal losses than pigs.     

Lysine synthesized by the gastrointestinal microflora of pigs is absorbed,mostly in the small intestine

This study used a digesta transfer protocol to determine the site of absorption of lysine synthesized by the gastrointestinal microflora of pigs. Eight pigs were used, four with reentrant cannulas in the terminal ileum, two with simple T cannulas in the terminal ileum, and two intact. All pigs were given, for 5 days, the same low-protein diet that included fermentable carbohydrates. The diet of two pigs with reentrant cannulas (donor) and of the two intact (control) pigs was supplemented with (15)NH(4)Cl. The two other pigs with reentrant cannulas (acceptor pigs) and those with simple cannulas (used to supply unlabeled digesta) were given the same diet but unlabeled NH(4)Cl. Ileal digesta were collected continuously from all of the reentrant cannulas and kept on ice. All digesta from each donor pig were reheated and returned to the distal cannula of its companion acceptor, whose ileal digesta were discarded. Unlabeled ileal digesta from the pigs with simple cannulas were instilled into the distal cannulas of the donor pigs. At the end of the experiment, the average (15)N enrichment in the plasma free lysine of control pigs was 0.0407 atom % excess (APE); that of donor pigs was 0.0322 APE (79% of controls), whereas that of acceptor pigs was only 0.0096 APE (24% of controls). Due to nitrogen recycling, acceptor pigs had labeled lysine in the digesta of the stomach and small intestine, and donor pigs had labeled lysine in the digesta of the large intestine. If account is taken of the higher (15)N enrichment of microbial lysine in the large compared with the small intestine, it can be estimated that >90% of the absorption of microbial lysine took place in the small intestine.     

Endogenous ileal losses of nitrogen and amino acids in pigs and piglets fed graded levels of casein

Abstract

In order to determine ileal losses of nitrogen (N) and amino acids (AA) and the coefficients of apparent and true ileal digestibility (AID, TID) of N and AA from casein in piglets and pigs, two experiments were conducted. In Experiment 1, 24 piglets were used. The piglets were weaned at 17 days of age, weighing 6.4 kg and cannulated at terminal ileum. Ileal digesta was collected at 28 – 29 and 35 – 36 days of age in period 1 and 2, respectively. Feed intake was 150 and 300 g · d^?1 during the first and second period. In Experiment 2, 16 castrates weighing 52.5 kg and cannulated at terminal ileum were used. The intake level of digestible energy was 2.5 times their maintenance requirement. The experiment lasted 7 days and ileal digesta was collected on day 6 – 7. Treatments consisted of four levels of N from casein: 8, 16, 24 and 32 g N · kg^?1 feed, respectively. Results showed that N level did not increase N or AA ileal losses. In piglets, N and AA ileal losses were similar between periods, except for period 2, where losses per kg DMI were about 47 and 64% higher for glycine and proline, respectively (p < 0.05). When ileal losses from pigs and piglets were compared, piglets had higher (p < 0.05) ileal losses of N and AA (excepted glutamic acid and alanine). A lower (p < 0.05) AID was observed in piglets in period 2 for N, methionine, glutamic acid, glycine and proline. With exception of glycine in pigs, all values for TID of N and AA of casein were superior to 0.90. Piglets had higher TID of N, leucine, isoleucine, valine and phenylalanine. These results showed that piglets have higher ileal losses than pigs.     

Effect on digestion and performance of dietary protein content and of increased substitution of lucerne hay with soya-bean protein concentrate in starter diets for young rabbits

The aim of this work was to study the effect of protein source / availability on the intestinal microbiota, digestive traits and nutritional performance of early-weaned rabbits. The effects of supplemental antibiotics in the drinking water were also evaluated. Four isoenergetic and isofibrous diets were formulated: a control diet with a high protein (207 g/kg dry matter (DM)) and lucerne hay content (HPHL), a diet with low crude protein (CP) (179 g/kg DM) and high lucerne hay content (LPHL) and low protein diets in which the lucerne hay in diet LPHL was replaced partially (LPML) or totally (LPLL) with soya-bean protein concentrate. Rabbits, weaned at 25 days (52 per diet), were fed the experimental diets for a 2-week period and thereafter received a commercial diet until 56 days of age. The incidence of mortality was investigated using 70 animals per diet without supplemental medication. The profile of the ileal microbiota was studied at 35 days of age in rabbits treated (18 per diet) or not (12 per diet) with antibiotic. As expected, supplementation with antibiotics effectively reduced fattening mortality rate and microbial biodiversity. However, lowering of also the dietary CP content led to a reduction in the mortality rate ( P < 0.05), both in animals treated with (by 80%) or without (by 39%) antibiotics. In addition, there was a reduction ( P < 0.05) in the frequency of Clostridium perfringens in non-medicated animals. Neither jejunal morphology nor growth performance, over the whole fattening period, was affected by dietary CP content of the experimental diets. However, with HPHL, feed efficiency was higher (by 4.8%; P < 0.01) than with LPHL diets. Substitution of lucerne hay with soya-bean meal in low protein diets did not affect apparent faecal or ileal digestibility of DM and CP. However, the ileal digestibility of cystine, alanine, aspartic acid, and proline was lowered ( P < 0.05) with increasing substitution by soya bean. Nevertheless, ileal CP flow, incidence of mortality and presence of C. perfringens were unaffected. Our results suggest that a reduction in dietary CP, resulting in reduced lumenal flows of nitrogen through the ileum, may be beneficial for young rabbits and limit the numbers of potentially harmful bacteria in the lower gut. Modulation of dietary CP should be contemplated as a strategy to increase the intestinal health in rabbits.     

Heat-treatment, phytase and fermented liquid feeding affect the presence of inositol phosphates in ileal digesta and phosphorus digestibility in pigs fed a wheat and barley diet

The aim was to evaluate the effect of heat-treatment, microbial phytase addition and feeding strategy (dry feeding v. fermented liquid feeding) on degradation of phytate (myo-inositol hexakisphosphate, InsP6) and formation and further degradation of lower inositol phosphates (myo-inositol pentakisphosphate-myo-inositol bisphosphate, InsP5-InsP2) at the distal ileum of pigs. Furthermore, the apparent ileal digestibility/degradability (AID) of phosphorus (P), InsP6-P and calcium (Ca) and the apparent total tract digestibility (ATTD) of P and Ca were studied. Pigs were fitted with a T-shaped ileal cannula for total collection of digesta at 2 h intervals during an 8 h sampling period after feeding the morning meal. Each period lasted for 2 weeks: 8 days of adaptation followed by 3 days of total collection of faeces and 3 days of total collection of ileal digesta. The experiment was designed as a 4 × 4 Latin square with four pigs fed four diets. A basal wheat/barley-based diet was fed either as non-heat-treated or heat-treated (steam-pelleted at 90°C). The heat-treatment resulted in an inactivation of plant phytase below detectable level. Diet 1 (non-heat-treated basal diet fed dry); diet 2 (heat-treated basal diet fed dry); diet 3 (as diet 2 but with microbial phytase (750 FTU/kg as fed) fed dry); diet 4 (as diet 3 fed liquid (fermented for 17.5 h nighttime and 6.5 h daytime at 20°C with 50% residue in the tank)). Chromic oxide (Cr2O3) was included as marker and ATTD was determined both by total collection of faeces (ATTDTotal) and Cr2O3 (ATTDCr). InsP6 was completely degraded in diet 4 before feeding resulting in no InsP6-P being present in ileal digesta. InsP6-P concentration in ileal digesta decreased with increasing dietary levels of plant or microbial phytase in pigs fed the dry diets. Consequently, AID and ATTD of P and Ca were greatest for pigs fed diet 4 followed by diets 3, 1 and 2. The ATTD of P depended on the used method as ATTDTotal of P was 72%, 61%, 44% and 34%, whereas ATTDCr of P was 65%, 52%, 38% and 23% for diets 4, 3, 1 and 2, respectively. In all pigs the ileal concentration of InsP5-InsP2-P was extremely small, and thus unimportant for maximisation of ATTD of plant P. In conclusion, fermented liquid feeding with microbial phytase seems to be an efficient approach to improve ATTD of plant P compared with dry feeding. This opens up for further reductions in P excretion.     

Comparative Study on the Effect of Variable Phosphorus Intake at two Different Calcium Levels on P Excretion and P Flow at the Terminal Ileum of Laying Hens

A 3 ‐ 2-factorial balance trial was conducted with dietary concentrations of P below the requirement (3.6, 4.3 and 5.0g/kg DM) and Ca below or at the requirement (28 and 37g/kg DM) adjusted by monobasic calcium phosphate (MCP, Ca(H₂PO₄)₂) and calcium carbonate (CaCO₃). The diets were mainly based on maize and soybean meal. Six 18-week old laying hens were allocated to each of the diets, and excreta were quantitatively collected for 21 days from week 22 of age onwards. Feed allowance was 95 g/d according to pre-treatment ad libitum intake of the hens receiving the lowest P concentration. After the balance trial was terminated, ileal digesta was obtained from each hen, and the flow at the terminal ileum was calculated using TiO₂ as indigestible marker. Linear regression analysis was applied to determine the effect of supplementary P. Hens were in a negative energy balance, indicated by a loss in BW across all treatments. Intake and excretion of both N and energy were not significantly affected by the P or Ca content of the diet. P from supplemented MCP was almost completely recovered in excreta, irrespective of dietary Ca concentration. At the terminal ileum, however, the P flow was not significantly affected by the MCP supplementation. Net absorption of P from MCP was almost complete until the terminal ileum, but P was re-directed into the excreta, likewise via the urine. The supplementation of Ca reduced praecaecal net absorption and utilisation of P from the basal diet, likewise due to a reduced phytate hydrolysis. It is suggested by the data, that comparative measurements of P availability for laying hens should be conducted on the basis of praecaecal net absorption rather than on total excretion measurements.     

Apparent Precaecal Digestibility of Nutrients and Level of Endogenous Nitrogen in Digesta of the Small Intestine of Growing Pigs as Affected by Various Digesta Viscosities

Sixteen male growing pigs of about 24kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine+cystine, threonine and tryptophan. Additionally, [¹⁵N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of ¹⁵N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276mg per 12h per kg^0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150mg per 12h per kg^0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.     

Using the dual isotope method to assess cecal amino acid absorption of goat whey protein in rats,a pilot study

Measurement of ileal amino acids (AA) bioavailability is recommended to evaluate protein quality. A dual isotope tracer method, based on plasma isotopic enrichment ratios, has been proposed to determine true digestibility in humans. In a pilot study, we aimed to evaluate whether this method could be implemented in rats to determine AA bioavailability based on isotopic enrichment ratios measured in cecal digesta or plasma samples. Goat milk proteins were intrinsically labeled with ¹⁵N and ²H. Wistar rats were fed a meal containing the doubly labeled goat whey proteins and a tracer dose of ¹³C-spirulina. Blood samples were collected 0, 1 h and 3 h after meal ingestion from the tail vein. The rats were euthanized 4 h (n?=?6) or 6 h (n?=?6) after meal to collect plasma and intestinal contents. True orocecal protein digestibility and AA bioavailability were assessed by means of ¹⁵N and ²H enrichment in cecum content and compared with absorption indexes determined at the plasma or cecum level using isotopic ratios. Plasma kinetics of isotopic enrichment could not be completed due to the limited quantity of plasma obtained with sequential blood collection. However, the absorption indexes determined from cecal ¹⁵N or ²H/¹³C ratios gave coherent values with true orocecal AA bioavailability. This dual isotope approach with measurements of isotopic ratios in digestive content could be an interesting strategy to determine true AA bioavailability in ileal digesta of rats.

     

Flow rates of components in digesta of pigs prepared with re-entrant cannulas in the proximal duodenum and terminal ileum, and fed semipurified, hard wheat, and soft wheat diets.

Four pigs prepared with re-entrant cannulas in the proximal duodenum and terminal ileum were used to study flow rates of total digesta, insoluble dry matter, nitrogen, and amino acids entering and leaving the small intestine. The pigs received a semipurified diet, a hard wheat diet, or a soft wheat diet. These were approximately isonitrogenous. A higher rate of passage of digesta through the proximal duodenum and terminal ileum were measured in pigs receiving the hard wheat diet. Peak flow of digesta at the duodenum of all pigs occurred at 1 h post feeding. Peak flow of digesta at the ileum occurred at 9 h post feeding on the soft wheat diet, but somewhat earlier on the hard wheat and semipurified diet. More nitrogen and essential amino acids flowed in the solid fraction of duodenal digesta during the first 2 h post feeding for the wheat diets and 4 h post feeding for the semipurified diet. It was concluded that flow rate of most nutrients from the stomach and through the small intestine of pigs is modified by the composition and texture of the food ingested. It is postulated that efficiency of mixing of digesta with digestive secretions in the stomach is a major factor influencing rate of flow.     

The effect of different patterns of thermal processing of potatoes on their digestibility by growing pigs

The effects of three patterns of thermal processing of potatoes on the sites and efficiency of their digestion were examined using pigs cannulated at the terminal ileum. The potatoes were processed in each of the following ways: (I) steamed for 1 h at 100°C, slowly cooled during 24 h to 40°C and then rapidly equilibrated with ambient temperature; (II) steamed for 20 min at 100°C, then rapidly cooled; (III) steamed at 70°C for 20 min, then rapidly cooled. They were given with a mineral and vitamin supplement in three meals per day and the allowance of feed was 70 g of organic matter/kg W^0.75 (～ 9.6 kg “fresh” potato per pig/day). Ileal digesta and faeces were collected during 12-h periods, sub-divided for ileal samples into three periods of 4 h, each commencing after a meal.The results indicate that Treatment I was undesirable; the prolonged heating caused rupture of the cell walls with release of gelatinized starch and resulted in potato protein of low digestibility, particularly anterior to the ileo-caecal junction. Treatment II gave the best results. Treatment III did not cause complete gelatinization of the potato starch and did not effectively denature the anti-nutritive protein present in the raw potato, contrary to the results of laboratory studies. Coefficients of digestibility of organic matter and nitrogen, measured at the terminal ileum, were reduced by 13 and 48% compared with those obtained in Treatment II. Corresponding reductions over the whole gut were 3 and 19%, respectively.     

Effective Recovery of Bacterial DNA and Percent-Guanine-Plus-Cytosine-Based Analysis of Community Structure in the Gastrointestinal Tract of Broiler Chickens

A DNA-based, direct method for initial characterization of the total bacterial community in ileum and cecum of the chicken gastrointestinal (GI) tract was developed. The efficiencies of bacterial extraction and lysis were >95 and >99%, respectively, and therefore the DNA recovered should accurately reflect the bacterial communities of the ileal and cecal digesta. Total bacterial DNA samples were fractionated according to their percent G+C content. The profiles reflecting the composition of the bacterial community were reproducible within each compartment, but different between the compartments of the GI tract. This approach is independent of the culturability of the bacteria in the consortium and can be used to improve our understanding of how diet and other variables modulate the microbial communities of the GI tracts of animals.     

Effect of microbial phytase on apparent ileal amino acid digestibility of phosphorus-adequate diets in growing pigs

Six ileally cannulated pigs (mean initial body weight 34.8 kg) were used to study the effect of microbial phytase on apparent ileal digestibility of P, total N and amino acids. Three P-adequate diets (digestible P concentration 2.3 g kg(- )l) containing barley (B), soyabean meal (S) or a mixture of the two (BS) with or without phytase supplement (1000 FTU x kg(-1)) were fed to pigs using a 6 x 6 Latin square design. The addition of phytase increased (p < 0.05) apparent ileal P digestibility of diets B, S and BS by 16.5, 19.2 and 19.2%, respectively. There was no effect of phytase on the ileal digestibility of total N. Apparent ileal digestibility of amino acids tended to increase in the BS diet supplemented with phytase (mean improvement of 2.2%); but no significant difference was found for any amino acid as compared with the unsupplemented diet. To asses the additivity of apparent amino acid digestibility, the determined values for the BS diet were compared to those calculated from digestibilities found in diets B and S. There were no significant differences between the determined and calculated values. It is concluded that the addition of microbial phytase to P-adequate diets does not affect ileal amino acid digestibility in growing pigs and that the apparent amino acid digestibility values determined in single ingredients may be additive when included into a complex diet.     

Aus der Versuchsstation für Tierernährung,Perchtoldsdorf/Wien

This study aimed to compare the effects of organic (proteinate) and inorganic (sulphate) copper (Cu) and zinc (Zn) supplements, in presence or absence of a mannan oligosaccharide (MOS) supplement, on mineral solubility and digestibility in pigs. Twenty-eight barrows (25 ± 4 kg) assigned randomly to four treatment groups were fed a corn-wheat-soya bean meal diet with 10 mg/kg of Cu and 100 mg/kg of Zn supplied as organic or inorganic supplement, and supplemented or not with 0.1% MOS. After an adaptation period, total faeces and urine were collected for a period of 6–7 days. Pigs were then euthanatised and digesta from ileum and caecum were collected. Apparent digestibility was calculated in ileum and caecum using titanium dioxide. The organic mineral supplement improved total (faecal) digestibility and retained/ingested ratio of Cu (p < 0.05) while reducing apparent digestibility of Zn in the ileum (p < 0.05) without effect on total digestibility of Zn. Solubilities of Cu and Zn in liquid fraction of ileum and caecum were not affected by mineral sources. Although MOS supplement increased Cu solubility in the ileum (p < 0.05), it had no effect on digestibility of Zn and Cu in ileum, caecum and faeces, retained/ingested ratio of Zn and Cu, or pH and volatile fatty acid concentration in ileal and caecal digesta. In conclusion, organic mineral supplement improved total digestibility and retained/ingested ratio of Cu in pigs but this cannot be attributed to its solubility in ileal and caecal digesta. The MOS supplement did not interfere with digestibility or dietary utilisation of Zn and Cu in pigs fed above the Zn and Cu requirements.     

Fermented soybean meal increases nutrient digestibility via the improvement of intestinal function,anti-oxidative capacity and immune function of weaned pigs

The nutritional components of fermented soybean meal (FSBM) vary because of the complex process of microbial fermentation. The objective of this study was to investigate the nutritional value of FSBM from two sources and explore the mode of actions of FSBM on the improvement of nutrient digestibility with the measurements of digestive enzymes and serum biomarkers. Eight weaned barrows (initial BW: 14.12 ± 0.24 kg) equipped with T-cannula in the distal ileum were allotted to a duplicated 4 × 4 Latin-square design with four experimental diets and four periods. Four experimental diets included a soybean meal control diet, two FSBM diets, and a nitrogen-free diet. The two sources of FSBM increased the contents of CP, amino acid and lactic acid, while decreased the levels of anti-nutritional factors, including glycinin, β-conglycinin and trypsin inhibitors. Compared to soybean meal control diet, both FSBM diets significantly increased the apparent and standardised ileal digestibility of CP and amino acids (P < 0.05), increased the activities of lipase, maltase and invertase in digesta (P < 0.05), increased total antioxidant capacity, activities of glutathione peroxidase and superoxide dismutase, the levels of interleukin-4, IgA, IgG and IgM in serum (P < 0.05), while decreased the levels of diamine oxidase, malondialdehyde, interleukin-6, and interleukin-2 in serum (P < 0.05). Additionally, the standardised ileal digestibility of amino acids were highly correlated with the aforementioned digestive enzymes and health-related serum biomarkers. In summary, FSBM diets showed an improved nutritional value evidenced by the higher nutrient digestibility, which may be partially derived from its beneficial effects on intestinal integrity, anti-oxidative capacity and immune function.     

Determination of standardized ileal crude protein and amino acid digestibilities in protein supplements for piglets

The objective of the study was to determine standardized ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) in six ingredients commonly used in weanling pigs diets. The ingredients consisted of extruded soybeans (SBe), high-protein soybean meal (SBMhp), soy protein concentrate (SPC), hydrolyzed wheat gluten (WGh), conventional fish meal 1 (FM1) and extracted fish meal 2 (FM2e). Each assay feed ingredient was added to a purified cornstarch-based basal diet supplemented with casein and crystalline AA, and SID of CP and AA of assay ingredients were estimated using the difference method. A total of 12 3-week-old barrows were surgically fitted with T-cannulas at the distal ileum. The piglets were allocated to four simultaneous 3 × 3 Latin-square designs with three animals and three periods each, resulting in six observations per assay diet. After 3 to 5 days recovery from surgery, each assay diet was fed at a level of 30 g/kg body weight. Each experimental period consisted of 5 days for adaptation to the assay diets and 2 days for ileal digesta collection. The SID of CP, Lys, Met, Thr and Trp were 73%, 78%, 76%, 66% and 71% in SBe; 80%, 84%, 87%, 75% and 81% in SBMhp; 86%, 89%, 89%, 78% and 83% in SPC; 87%, 60%, 88%, 76% and 79% in WGh; 87%, 92%, 94%, 86% and 86% in FM1; and 79%, 86%, 89%, 80% and 74% in FM2e, respectively. The greatest SID of indispensable AA were observed for FM1 and SPC (SID 85% for most indispensable AA), followed by WGh, FM2e and SBMhp (SID 80% for most indispensable AA) and the smallest SID were obtained for SBe (SID < 80% for most indispensable AA). The SID of CP and indispensable AA in both types of fish meal, SBMhp and WGh were similar to SPC (P = 0.063 to 0.855), except for Arg (P = 0.010) and Lys (P = 0.001) in WGh, and Phe (P = 0.044) and Trp (P = 0.037) in FM2e. The SID of CP and indispensable AA were smaller in SBe compared with SPC (P < 0.001 to P = 0.017), except for Lys (P = 0.136). The SID of CP and indispensable AA were consistently smaller in FM2e compared with FM1 with significant differences for CP (P = 0.035), Phe (P = 0.028) and Trp (P = 0.008). Digestibility values measured in the present study can be used to formulate diets for piglets based on standardized ileal digestible contents of CP and AA.     

Real-time quantitative PCR measurement of ileal Lactobacillus salivarius populations from broiler chickens to determine the influence of farming practices

A real-time quantitative PCR assay targeting a 16S-23S intergenic spacer region sequence was devised to measure the sizes of populations of Lactobacillus salivarius present in ileal digesta collected from broiler chickens. This species has been associated with deconjugation of bile salts in the small bowel and reduced broiler productivity. The assay was tested as a means of monitoring the sizes of L. salivarius populations from broilers fed diets with different compositions, maintained at different stocking densities, or given the antimicrobial drugs bacitracin and monensin in the feed. Stocking densities did not influence the numbers of L. salivarius cells in the ileum. A diet containing meat and bone meal reduced the size of the L. salivarius population relative to that of chickens given the control diet, as did administration of bacitracin and monensin in the feed. These changes in the target bacterial population were associated with improved broiler weight gain.     

Studies on the intestine section to be sampled in broiler studies on precaecal amino acid digestibility

Measurements of precaecal amino acid digestibility with digesta sampled from slaughtered animals may be affected by the chosen length of the sampled section. The length needs standardization, therefore, when digestibility is understood to be a measure of feedstuff potential. It was our objective to study the change in the net disappearance of amino acids from the lower small intestine of broiler chicken. The section between Meckel's diverticulum and 2 cm anterior of the ileo-caeco-colonic junction was cut into three subsections of equal length: proximal, medial, and terminal. The contents of each subsection were pooled within the birds of each pen (12 in Experiment 1 and 10 in Experiment 2). TiO2 was used as an indigestible marker. Prior to digesta sampling, broilers had been fed the experimental diets for seven days. In Experiment 1, two diets with either soybean meal or a mix of soybean meal and peas as the main protein sources were used. Each diet was allocated to eight pens and feeding commenced on day 14 of age. Net disappearance was significantly affected by diet only in regard to aspartic acid and methionine. No significant interaction between diet and subsection occurred. Net disappearance was significantly affected by subsection for all amino acids. It ranged from 74-92% for individual amino acids without significant differences in the medial and terminal subsections. Net disappearance was, however, between 3% and 9% lower in the proximal subsection. In Experiment 2, diets contained soybean meal as the main protein source and were given to 18 pens from day 22 of age. Again, the effect of subsection on net disappearance was significant for all amino acids. Net disappearance was significantly lower in the proximal than in the middle subsection, and differences ranged from 5-10%. Significant differences in the net disappearance were also found for most of the amino acids between the middle and the terminal subsection ranging from 2-4%. In conclusion, when precaecal amino acid digestibility should be used as a measure for a protein source's potential, digesta sampling should not consider the proximal third of the section between Meckel's diverticulum and the end of the ileum.     

Magnesium binding in the digesta of the chicken.

Two experiments involving laying hens and mature roosters were carried out to determine the effect of pH on the ultrafilterable fraction of Mg((Mg)u) present in the digesta along the gastrointestinal tract. Concurrently, the approximate molecular weight of the (Mg)u was determined. The average pH's for laying hens were: crop 4.88, proventriculus 5.27, ventriculus 4.77, duodenum 5.57, jejunum 6.15, ileum 7.82, and colon 6.65. Similar pH values were obtained for mature roosters. The (Mg)u fraction decreased significantly in the ileum where the pH was greater than 7.00. However, treating the ileal digesta with an acid pH buffer released about 70% of the nonfilterable Mg. The molecular weight of the (Mg)u was found to be less than 700, suggesting that the Mg was present in digesta as an inorganic salt or as an organic complex of low molecular weight.