N. Sauer

Meta-Analysis of the Relative Efficiency of Methionine-Hydroxy-Analogue-Free-Acid Compared with dl-Methionine in Broilers Using Nonlinear Mixed Models

The purpose of this paper was to perform a meta-analysis to compare the biological efficiency of DL-methionine with methionine-hydroxy-analogue-free-acid in broiler chickens. A database was developed which contained dose-response studies of these 2 methionine sources. Criteria for entry into the database were defined before the meta-analysis was initiated. Data from 46 dose-response experiments, extracted from a total of 27 peer-reviewed papers, were used for the analysis with the Statistical Analysis System. Initially, the NLIN procedure was applied to fit an exponential model of the form y = alpha + beta*[1 - exp (-Gamma*dose)] + e. Thereafter, meta-analysis was conducted by means of nonlinear mixed models, which were fitted by a full maximum likelihood method as implemented in the NLMIXED procedure. The nonlinear model used for the analysis allowed for separate plateaus or different efficiencies of the methionine sources. Mixed modeling was applied to account for heterogeneity among the studies in all regression parameters for both sources of methionine via random effects. Statistical hypotheses were tested by the asymptotic Wald test. In addition, potential co-variables were tested for inclusion as linear regressors for the nonlinear model parameters. In conclusion, the null hypothesis of equal plateaus of the 2 methionine sources was not rejected. The analyses of the response variables average daily gain (ADG) and gain to feed ratio (GF) showed a highly significant difference between the tested methionine sources. The covariate age at start of experiment significantly affected the intercept term alpha for the response variables ADG and GF, respectively. The meta-analysis showed that biological efficiencies of DL-methionine-hydroxy-analogue-free-acid were 81 and 79% of the values for DL-methionine, on an equimolar basis, for ADG and GF, respectively.

Standardised ileal crude protein and amino acid digestibilities in protein supplements for piglets

Standardised ileal digestibilities (SID) of crude protein and amino acids (AA) originating from 24 different feed ingredients, including 11 feed ingredients produced from soybeans, seven by-products of starch processing, four whey products and two fish meals, were determined in piglets by means of the difference method. For the indispensable AA, the highest SID values were obtained in three out of four whey proteins (SID ≥90% for most indispensable AA), one out of two fish meals (SID ≥86%), soy protein concentrate, hydrolysed soy protein isolate (SID ≥86% for most indispensable AA), and by-products of starch processing (SID ≥84% for most indispensable AA). The lowest SID values were obtained in extruded soybeans and microbially fermented soy protein (SID ≤78% for most indispensable AA), whereas the SID values for high-protein soybean meal were intermediate (SID 80–89% for indispensable AA except for Thr). The SID values in the three enzymatically fermented soy proteins (SID 80–94% for most indispensable AA) were similar to those in high-protein soybean meal and soy protein concentrate. The results of the present study indicate that SID values of AA in feed ingredients for piglets differ considerably from those reported for grower-finisher pigs, thus there may be a need for separate feed tables for piglets.

The effects of pure nucleotides on performance, humoral immunity, gut structure and numbers of intestinal bacteria of newly weaned pigs1

Weaning is often stressful for piglets and accompanied by morphological, histological, microbial, and immunological changes along the digestive tract. Dietary nucleotides are bioactive compounds which have the potential to diminish weaning-associated challenges. The experiment was carried out with 5 litters each of 7 pigs (mixed sex), weaned at 20 d of age. One baseline pig per litter was slaughtered at d 0. The remaining 30 pigs were housed individually and randomly allocated to 2 dietary treatments: the control diet or the control diet supplemented with a mixture of nucleotides. Measurements of growth performance traits included ADFI, ADG, G:F, and BW. At d 17, fresh fecal samples were taken to determine bacterial numbers. On d 19 and 20, pigs were slaughtered and blood samples were analyzed for plasma immunoglobulins and intestinal samples were assessed for morphological traits. Digesta from the jejunum and cecum were collected for analysis of the microbiome. The ADFI was greater in the nucleotide treatment compared with the control treatment (P < 0.05), but ADG, G:F, and BW did not differ between treatments. Plasma IgA concentrations increased with age and were greater in the nucleotide (P < 0.05) compared with the control group. There were no treatment differences in plasma IgG and IgM, gut morphology, or intestinal and fecal bacterial counts. Supplemental nucleotides may increase ADFI but without having any impact on growth performance of the pigs. Greater plasma IgA concentrations indicate that adding nucleotides in the weaning diet supported humoral immunity. However, there was no effect of dietary nucleotide supplementation on the composition of the bacterial community in parts of the small and large intestine. Further research is warranted before the use of nucleotide as a feed additive in pig diet can be recommended.

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.

Effects of betaine, organic acids and inulin as single feed additives or in combination on bacterial populations in the gastrointestinal tract of weaned pigs.

A study was carried out to investigate whether blends of betaine, organic acids and inulin may improve their efficacy to modulate intestinal bacterial populations in weaned pigs compared with the single application of these additives. Moreover, potential postprandial diurnal variations in ileal bacterial numbers were determined in piglets fed the control diet. Twenty-four piglets in two consecutive experiments received a wheat-barley-soybean meal control diet (Con) or the Con diet supplemented with betaine (BET; 0.2%), an organic acid blend (AC; 0.4%) or inulin (IN; 0.2%) as single additives or in combination. Ileal bacterial numbers of total bacteria, lactobacilli, bifidobacteria (p < 0.05) and enterobacteria (p < 0.10) showed a postprandial diurnal variation, thus spot sampling of ileal digesta for the determination of bacterial numbers may not be representative. There were only small effects of BET, AC and IN on ileal and faecal bacterial populations. BET + AC increased total ileal bacterial numbers compared to the Con and AC treatments. BET reduced lactobacilli numbers in faeces, whereas BET + IN increased ileal numbers of bifidobacteria compared to AC and IN. There is evidence that BET, AC, IN and their combinations may affect proliferation of beneficial bacterial populations, although this has to be confirmed in further studies.

Standardized ileal digestibility of amino acids in eight genotypes of soft winter wheat fed to growing pigs.

A study with growing pigs was conducted to determine the chemical composition and standardized ileal digestibility (SID) of CP and AA of 8 wheat genotypes that have recently been added to the German Descriptive Variety List. These genotypes included Tabasco, KWS Erasmus, Tobak, Skalmeje, Mulan, Event, Tommi, and Adler. The 8 genotypes were grown under identical environmental conditions on the same site, and they were harvested and processed under the same conditions. Nine barrows with an initial BW of 32 ± 2 kg were surgically fitted with simple ileal T-cannulas and allotted to a row-column design with 9 pigs and 8 periods of 6 d each. Wheat was the sole dietary source of CP and AA. Among the 8 wheat genotypes, contents of CP ranged from 10.9 to 13.3% (as-fed basis), whereas contents of total nonstarch polysaccharides ranged from 8.0 to 9.4% (as-fed basis). The SID of CP in the 8 genotypes ranged from 83 to 87%, with greatest ( = 0.01) values for Event and lowest ( = 0.01) for all other wheat genotypes. Intermediate SID of CP values were obtained for Adler and KWS Erasmus. For Lys, greater ( < 0.05) SID was observed in Adler (73%) and KWS Erasmus (74%) in comparison to Tommi, Tobak, and Mulan (69%). Adler had greater SID of Met (88%; = 0.01) when compared to Tabasco (86%); Tobak, Skalmeje, and Mulan (85%); and Tommi (84%). Among the 8 wheat genotypes, standardized ileal digestible content (cSID) of CP followed total CP content and ranged from 9.1 to 11.3% (as-fed basis). Standardized ileal digestible content of both CP and AA were greater ( < 0.001) in Adler compared to all other genotypes. For most AA, Tabasco had the lowest ( < 0.001; except for His, Trp, Asp, and Cys) cSID values of all wheat genotypes. The cSID of CP decreased ( < 0.001) as the starch content in the 8 wheat genotypes increased, but cSID of CP increased ( < 0.001) as the CP content in the 8 genotypes increased. Because SID and cSID of CP and most AA increased ( < 0.05) with lower test weight and falling number, these variables may aid to predict SID and cSID in wheat batches, whereas other nutrients such as fiber fractions are not suitable due to low variation among the 8 genotypes. The present study provides a comprehensive database on nutritional composition and SID of CP and AA of 8 wheat genotypes grown under identical conditions. Because the SID values in these genotypes are lower when compared to literature data, digestibility values in actual feed tables for wheat may overestimate their protein values and need to be updated.

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.

In vitro prediction of standardised ileal crude protein and amino acid digestibilities in grain legumes for growing pigs

The study was conducted to validate in vitro prediction of standardised ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) in grain legumes for growing pigs using six different cultivars of faba beans (Vicia faba), six different cultivars of field peas (Pisum sativum), and five different cultivars of lupins (Lupinus spp.). The SID for CP and AA were predicted from in vitro analysis by means of a two-step enzymatic method using pepsin and pancreatin incubations. In vitro predicted SID values of CP and AA were generally higher than the corresponding SID values measured in vivo. There were strong linear relationships (r2 = 0.73 for Lys to r2 = 0.91 for Cys and Trp) between in vivo and in vitro predicted SID values in the assay feed ingredients if grain legume species (i.e. faba beans, field peas and lupins) was included as a covariate in multiple linear regression analysis. However, to rapidly and accurately predict SID of CP and AA in individual batches of various feed ingredients, further studies are warranted.

Short-term effect of dietary yeast nucleotide supplementation on small intestinal enzyme activities, bacterial populations and metabolites and ileal nutrient digestibilities in newly weaned pigs*

In previous studies, dietary nucleotides have been shown to improve performance in single-stomached animals by promoting the renewal of small intestine epithelial cells and by influencing the activity and composition of the microbial community in the digestive tract. The present experiment was carried out with 12 barrows weaned at the age of 18 days and fitted with a simple T-cannula at the distal ileum. To determine short-term effects of dietary yeast nucleotides, the piglets received a grain-soybean meal-based basal diet with or without supplementation of 1 g/kg of a dried yeast product containing free nucleotides. Dietary supplementation with yeast did not affect bacterial numbers in the ileum as well as ileal concentrations of individual short-chain fatty acids (SCFA), total SCFA and total lactic acid (p > 0.05). Moreover, there was no effect of supplemental yeast nucleotides on ileal α-amylase, leucine amino peptidase, maltase and lactase activities (p > 0.05), as well as on ileal dry matter, crude protein and crude fibre digestibilities (p > 0.05). In conclusion, short-term supplementation with dietary yeast nucleotides did not affect microbial metabolite concentrations, bacterial numbers and enzyme activities in the ileal digesta as well as ileal nutrient digestibilities of newly weaned pigs.

Effect of feeding level on the composition of the intestinal microbiota in weaned piglets.

In piglets, the development and composition of intestinal microbiota is influenced by dietary factors. A considerable reduction in feed intake during the transition from liquid to solid feed is often accompanied by postweaning diarrhea. Therefore, it is hypothesized that variations in feeding level during weaning may affect intestinal microbial composition. Forty-eight piglets fitted with simple ileal T-cannulas were used to examine the effects of a high (60 g/kg BW) and a low (30 g/kg BW) feeding level on the composition of the ileal and fecal microbiota. The assay diets contained graded inclusion levels of soybean (Glycine max) meal or casein. Bacterial cell numbers of total eubacteria, Lactobacillus spp., and the mainly proteolytic Clostridium leptum, Clostridium coccoides, Enterobacteriaceae, and Bacteroides-Prevotella-Porphyromonas group (Bacteroides group) of feces and ileal digesta were determined by use of real-time PCR. There were no interactions between feeding level and protein source except for the Bacteroides group in ileal digesta. Ileal cell numbers of lactobacilli were increased (P < 0.001) at the higher feeding level. In contrast, ileal cell numbers of Clostridium coccoides were lower (P < 0.001) at the higher feeding level. There were no differences of bacterial cell numbers in feces. Results indicate that feeding level affects microbial composition in the small intestine. Also, sufficient feed intake during weaning encourages proliferation of beneficial bacteria, thereby contributing to improved gut health.