Effects of carriers for oils in compound feeds on growth performance, nutrient digestibility, and gut microbiota in broiler chickens

Carrier materials for oils in compound feeds may be used in animal nutrition to supply liquid feed additives. However, implications of such carriers for the digestibility of the contained oil are unknown. This study investigated the potential of oil carriers in compound feed and their effect on performance, metabolizable energy, fatty acid (FA) retention, amino acid (AA) digestibility, and gut microbiota in broiler chickens. Six experimental diets were formulated following a 2 × 3 factorial arrangement with 20 g/kg or 40 g/kg of rapeseed oil supplied with no carrier or bound in a silica-based (SC) or lignocellulose-based (LC) carrier in a 1:1 mass ratio. The diets were assigned to 48 metabolism units with 15 animals each based on a randomized complete block design and fed from d 18 to 28 of the trial. Total excreta were collected from d 24 to 27 and used to determine total tract retention (TTR) of FA and MEn. On d 28, AA digestibility both by the distal half of the jejunum and the distal half of the ileum was determined, and microbiota of ileal and cecal digesta was analyzed using 16S ribosomal RNA sequencing. There were significant interactions for ADG, ADFI, the gain:feed ratio (G:F), MEn, and the TTR of crude fat and most fatty acids (P ≤ 0.046) except for C18, C18:2, and C22:0. Addition of SC decreased ADG, ADFI, and G:F (P < 0.001), while LC at 40 g/kg oil inclusion increased G:F and MEn (P < 0.001) for both inclusion levels. The TTR of crude fat and the FA C18:1, C18:2, C18:3, and C22:0 was increased by the addition of SC (P ≤ 0.016), while LC increased the TTR of the FA C18:1 and C18:2 as well as the TTR of C18:3 at 20 g/kg oil inclusion (P ≤ 0.016). Adding SC and LC increased the digestibility of 7 and 2 AA by the distal half of the jejunum, respectively, and the digestibility of 8 and 13 AA by the distal half of the ileum, respectively (P ≤ 0.039). The β-diversity and abundance of some taxa were altered by addition of LC and SC in the ceca while no treatment effect on the ileal microbiota was found. The results give no indication of an incomplete release of the oil from the carriers because the TTR of most FA was increased upon addition of SC and LC. LC may be used to supply liposoluble feed additives without drawbacks for nutrient digestibility and growth while SC requires further examination.

Investigation on adaptations of broiler chickens to high dietary free amino acid levels in nitrogen utilisation and plasma amino acid concentrations

1. A reduction in crude protein (CP) in feed for broiler chickens necessitates elevated free amino acid (AA) levels to meet the requirement of each AA. This study investigated adaptations following a change to diets with increasing free AA concentrations and possible reasons for the limitation caused by the inclusion of more free AA.2. Male Ross 308 broiler hatchlings received a starter diet (164 g CP/kg containing 80 g/kg soy protein isolate (SPI)) until d 7. From d 7-22, birds received a diet almost identical to the starter diet or two other diets, where 50% or 100% of digestible AA in SPI were substituted with a free AA mixture. Birds were allocated to metabolism units located in the same barn to determine performance (n = 7 units) and blood traits (n = 14 birds). Total excreta collection was performed on d 7-8, 8-9, 9-10, 11-12, 14-15 and 21-22. Blood samples were collected on d 7, 8, 9, 11, 14 and 21.3. Average daily weight gain (ADG) and average daily feed intake (ADFI) was unaffected at 50% AA substitution but decreased at 100% AA substitution on d 7-22 (p ≤ 0.001). The 100% substitution led to a decline in ADG and ADFI consistently on all days (p ≤ 0.037) except on d 11-12. A 50% AA substitution resulted in lower ADFI on d 7-8 and 14-15 (p ≤ 0.032). Nitrogen utilisation efficiency (NUE) was on a level of ~ 0.74 and was only affected by treatment up to d 11-12 (p ≤ 0.008). Concentrations of 10, 9, 8, 10 and 4 plasma free AA were affected on d 8, 9, 11, 14 and 21, respectively (p ≤ 0.037).4. Following a change to diets containing high levels of free AA, NUE and free AA concentrations in the circulation became more balanced within 3 to 7 d. The results suggested that peptide-bound and free AA did not cause different NUE, particularly 3 and 7 d after the diet change.

The influence of substituting dietary peptide-bound with free amino acids on nitrogen metabolism and acid-base balance of broiler chickens depends on asparagine and glutamine supply

Reducing dietary crude protein (CP) concentration while maintaining adequate amino acid (AA) supply by free AA inclusion can contribute to attenuate the negative environmental effects of animal farming. This study investigated upper limits of dietary free AA inclusions without undesirable effects including the dependence on asparagine (Asn) and glutamine (Gln) supply. Ten broilers were allocated to sixty-three metabolism units each and offered nine experimental diets from day (d) 7-21 (n 7). One diet (167 g CP/kg) contained 80 g soya protein isolate (SPI)/kg. In the other diets, 25, 50, 75 and 100 % of the digestible AA from SPI were substituted with free AA. Digestible Asn+aspartic acid (Asp) and Gln+glutamic acid (Glu) were substituted with Asp/Glu or 50/50 mixes of Asp/Asn and Glu/Gln, respectively. Total excreta were collected from d 11-14 and from d 18-21. Growth and nitrogen accretion were unaffected by 25 and 50 % substitution without and with free Asn/Gln, respectively, but decreased at higher substitution (P ≤ 0·024). Circulating concentrations of Asp, Glu and Gln were unaffected by treatment, while Asn decreased at substitution higher than 50 % when Asn/Gln were not provided (P ≤ 0·005). Blood gas analysis on d 21 indicated a compensated metabolic acidosis at substitution higher than 50 and 75 % without and with free Asn/Gln, respectively (P ≤ 0·017). Results suggest that adding Asn/Gln increased an upper limit for proportion of dietary free AA from 10 to 19 % of dietary CP and enabled higher free AA inclusion without affecting the acid-base balance.

True mineral digestibility in C57Bl/6J mice

Data on mineral digestibility is key to understand mineral homeostasis and refine the recommendations for the dietary intake of these nutrients. In farm animals and pets, there is plenty of data on mineral digestibility and influencing factors. In laboratory mice, however, there is a lack of information on mineral digestibility under maintenance conditions, although this should be the basis for studies on mineral homeostasis under experimental conditions. The aim of the present study was to analyse data on intake, faecal excretion, and apparent digestibility of calcium, phosphorus, sodium, potassium, and magnesium in C57BL/6J mice fed different maintenance diets with varying voluntary dry matter intake. Lucas-tests were used to quantify true digestibility and describe correlations between dietary intake and excretion/absorption of the nutrients. Calcium, phosphorus, and magnesium showed a linear correlation between intake and faecal excretion (R2: 0.77, 0.93 and 0.91, respectively). Intake and apparently digested amounts of sodium and potassium were correlated linearly (R2: 0.86 and 0.98, respectively). These data show that intake is the major determinant of absorption in the minerals listed above. Faecal calcium and phosphorus excretion were correlated as well (R2 = 0.75).

Amino acid digestibility of insect meals and effects on key bacterial groups in excreta of caecectomised laying hens

The chemical composition and amino acids (AA) digestibility were determined in insect meals from mealworms, crickets, black soldier fly (BSF) larvae and BSF prepupae, and soybean meal. Six caecectomised laying hens were individually housed in metabolism cages and fed either a basal diet or one of five assay diets. Diets and hens were arranged in a 6 × 6 Latin square design with 6 subsequent periods. In each period, the laying hens were fed their respective diet for 9 d, and excreta samples were quantitatively collected twice daily from day 5 to 8. On day 9, a sterile plastic bag was attached to the cloaca of each hen to collect excreta for microbiota analysis. The AA digestibility of the insect meals and soybean meal were calculated using a linear regression approach. Crude protein (CP) concentrations in crickets and mealworms were higher than the value in soybean meal, BSF prepupae and BSF larvae. Ether extract concentrations were high in the insect meals and low in the soybean meal. The digestibility of most essential AA in soybean meal was higher (p < 0.05) than in crickets and BSF prepupae and not different from AA digestibility in mealworms and BSF larvae (except for arginine and histidine). The gene copy number of Escherichia coli in excreta from hens fed with BSF prepupae was lower (p < 0.05) than those fed with BSF larvae, whereas the gene copy number of Bacillus spp. and Clostridium spp. in excreta from hens fed with crickets was lower (p < 0.05) than those fed with BSF larvae. In conclusion, the chemical composition and AA digestibility varied among insect meals based on insect species and life stage. The high level of AA digestibility of insect meals supports the assessment that insect meals are a suitable feed component for laying hens, but differences in AA digestibility should be considered in diet formulation.

Amino acid digestibility and metabolizable energy of soybean meal of different origins in cecectomized laying hens

This study investigated the variation in amino acid (AA) digestibility and MEn of 18 samples of solvent-extracted soybean meal (SBM; 6 European, 7 Brazilian, 2 Argentinian, 2 North American, 1 Indian) in cecectomized laying hens. The experimental diets contained either 300 g/kg of cornstarch or one of the SBM samples. Pelleted diets were fed to 10 hens in two 5 × 10 row-column designs so that 5 replicates were obtained from each diet during 5 periods. A regression approach and the difference method were used to determine AA digestibility and MEn, respectively. The variation in the digestibility of SBM differed among AA with ranges in digestibility of 6 to 12%-units for most AA. Among the first-limiting AA, the digestibility was 87 to 93%, 63 to 86%, 85 to 92%, 79 to 89%, and 84 to 95% for Met, Cys, Lys, Thr, and Val, respectively. The range of MEn for the SBM samples was 7.5 to 10.5 MJ/kg DM. Indicators of SBM quality (including trypsin inhibitor activity, KOH solubility, urease activity, and in vitro N solubility) and analyzed SBM constituents were significantly correlated (P ≤ 0.05) with AA digestibility or MEn only in a few cases. No differences were observed in AA digestibility and MEn between countries of origins, except low digestibility of some AA and MEn for the 2 Argentinian SBM samples. These results suggest that the precision of feed formulation benefits from considering the variations in AA digestibility and MEn. Often used indicators for SBM quality and analyzed constituents were not suitable to explain variations in AA digestibility and MEn, suggesting that AA digestibility and MEn are determined by other factors.

Research Note: Influence of monocalcium phosphate and phytase in the diet on phytate degradation in cecectomized laying hens

This study investigated the effects of phytase and monocalcium phosphate supplementation on the dephosphorylation of phytic acid [myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate); InsP₆] in cecectomized laying hens using total excreta collection. Four corn-soybean meal-rapeseed meal-based diets were mixed with or without 6 g of monocalcium phosphate/kg, with or without supplementation of 1,500 FTU phytase/kg, and had the same calcium concentration at 39 g/kg of feed. Each diet was tested in 5 replicates using a row-column design with 10 cecectomized laying hens in 2 periods. The hens received 120 g/d of feed while being housed individually in metabolism units, and total excreta were collected for a period of 4 d. The monocalcium phosphate × phytase interaction was not significant for InsP₆ degradation (P = 0.054). Phytase increased InsP₆ disappearance from 13% to 83% (P < 0.001), whereas monocalcium phosphate had no effect. Concentrations of most of the lower inositol phosphate isomers in excreta were higher when monocalcium phosphate was added to the diets. The concentration of Ins(1,2,5,6)P₄ in excreta was the highest among the studied partially dephosphorylated inositol phosphates with phytase supplementation and was higher than in diets without phytase supplementation (P < 0.001). Supplementation with phytase increased myo-inositol concentration in excreta (P = 0.002), whereas monocalcium phosphate had no effect. Phosphorus utilization ranged from 4% to 18% and was not significantly affected by the treatments. These results suggest that phytase supplementation markedly increased InsP₆ degradation in laying hens. The cecectomized laying hen assay may be suitable for studying the effects of phytase supplementation on phytate dephosphorylation under dietary conditions when performance and phosphorus excretion are unlikely to be affected.

Amino acid digestibility and metabolisable energy of spring and winter faba beans grown on two sites and effects of dehulling in caecectomised laying hens

BACKGROUND

The variation in amino acid (AA) digestibility and metabolisable energy (ME_N ) in four spring and four winter faba bean genotypes differing in vicine/convicine (V/C) concentrations grown on two sites was investigated in caecectomised LSL-Classic laying hens. Effects of dehulling one faba bean genotype were also examined. Diets containing one out of 17 faba bean variants each and a basal diet were fed to ten caecectomised laying hens in a row-column design to achieve five replicates per diet.

RESULTS

Ranges and levels of digestibility of the hulled variants differed widely among AA with the lowest and highest range determined for Arg (90-93%) and Cys (-12-65%), respectively. ME_N ranged between 10.3 and 12.3 MJ kg^-1 dry matter. Lower ME_N and digestibility of Cys, Glx, Phe, Pro, Tyr, and Val (P < 0.050) was determined for the winter genotypes grown in Nimtitz compared to the other variants. Digestibility of Ser was lower for the spring than for the winter genotypes (P < 0.050). Negative correlations with AA digestibility were determined for phytate, but not for tannin and V/C concentrations (P < 0.050). Negative correlations between tannin fractions and ME_N were weak (P = 0.082-0.099). Dehulling increased ME_N by 1.8 MJ kg^-1 dry matter and raised the digestibility of Pro, His, and Glx (P < 0.050).

CONCLUSIONS

The results indicated that the digestible AA and ME_N supply of laying hens was increased by using low phytate faba beans while breeding for low V/C genotypes did not affect AA digestibility or ME_N . Dehulling increased ME_N and the digestibility of some AA. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Phytase Supplementation Effects on Amino Acid Digestibility in Broiler Chickens are Influenced by Dietary Calcium Concentrations but not by Acid-Binding Capacity

BACKGROUND

Responses to dietary calcium (Ca) and supplemented phytase on prececal amino acid digestibility (pcAAD) in broiler chickens vary among studies. The variation may arise from the dietary acid-binding capacity (ABC) that influences the activity of enzymes in the digestive tract and from microbial activity.

OBJECTIVE

This study aimed to investigate whether the ABC influences phytase effects on pcAAD and whether microbial activity contributes to this.

METHODS

Male Ross 308 broiler chickens were provided 1 of 12 diets in 72 pens (15/pen) from day 16 of age until the end of the experiment on days 21 or 22. In a 3 × 2 × 2-factorial arrangement, the ABC was varied by replacing calcium carbonate (CaCO3) with Ca-formate or by adding formic acid to CaCO3-containing diets, and contained 5.6 or 8.2 g Ca/kg and 0 or 1500 phytase units/kg. The ileum content was collected for pcAAD measurement and microbial community composition was used to investigate whether changes in pcAAD are related to the microbiota.

RESULTS

Three-factor ANOVA showed that reducing the ABC increased pcAAD (average 1.1 percentage points) and no significant interaction of the ABC with Ca concentration and phytase supplementation including 3-way interactions. Without phytase, increasing dietary Ca concentration decreased pcAAD (average 3.1 percentage points). Phytase supplementation increased pcAAD (average 2.1 and 5.0 percentage points at low and high Ca concentrations, respectively), to reach the same level for both Ca concentrations. Microbial functional predictions pointed towards an influence of the microbiota in the crop and ileum content on amino acid concentrations, as indicated by different relative abundances of predicted genes related to amino acid biosynthesis, degradation, and metabolism.

CONCLUSIONS

Dietary Ca concentrations but not the ABC modulates the effect of supplemented phytase on pcAAD in broiler chickens. The microbiota might contribute to differences in pcAAD by changing the amino acid composition of the digesta. The extent of this effect is still unknown.

Meta-analysis-based estimates of efficiency of calcium utilisation by ruminants

The most abundant mineral in the body of animals is Ca, which has crucial importance for the regulation of various processes. The maintenance of Ca balance has become more challenging, especially in lactating ruminants, owing to the increased milk yields and thus Ca requirement. To determine the Ca requirement, factors such as Ca secretion via milk or Ca deposition in body tissues and conception products are summed up to the net Ca requirement. Nevertheless, dietary Ca cannot be completely utilised by the animal to cover the net Ca requirement, therefore a value for the efficiency of Ca utilisation is applied, which is the maximum proportion of Ca from the feed that the animal can use for covering the net requirement. However, current estimates for the efficiency of Ca utilisation are inconsistent. Therefore, the objective of the present meta-analysis was to estimate the efficiency of Ca utilisation for ruminants, considering the Ca supply of the animal. A data set of 223 observations was compiled from 37 studies, including data on cattle and small ruminants. Standardised Ca digestibility was calculated from data on Ca intake and faecal Ca excretion, corrected for faecal endogenous losses. Furthermore, a data subset on only lactating ruminants was created. For this subset, Ca excretion via faeces and urine and standardised Ca digestibility were related to the Ca supply of the animal. An exponential function was fitted to standardised digestibility data in response to Ca concentration in the diet and Ca supply, revealing that standardised Ca digestibility decreased with increasing dietary Ca concentration and Ca supply. The median for standardised Ca digestibility was 40%, with a remarkable variation between 9% and 88%. In response to Ca supply, faecal Ca excretion increased in a strong linear manner (slope = 0.76, R² = 0.96). Excretion of Ca via urine was very low even when Ca supply was very high. To conclude, Ca digestibility is a suitable indicator for the efficiency of Ca utilisation, since excessive Ca is almost completely excreted in faeces; however, Ca digestibility has to be determined at a Ca supply level below the requirement of the animal. To date, only very limited number of data have been reported for such supply conditions. Comparative studies using various Ca sources are suggested for future studies but should be conducted using a marginal Ca supply level.

Effects of calcium level and source, formic acid, and phytase on phytate degradation and the microbiota in the digestive tract of broiler chickens

BACKGROUND

Diet acidification, dietary calcium (Ca) level, and phytase supplementation are known influences on the microbial community in the digestive tract and on phosphorus (P) utilization of broiler chickens. Effects of dietary factors and microbiota on P utilization may be linked because microorganisms produce enzymes that release P from phytate (InsP6), the main source of P in plant feedstuffs. This study aimed to detect linkages between microbiota and InsP6 degradation by acidifying diets (i.e., replacing Ca carbonate (CaCO3) by Ca formate or adding formic acid to CaCO3-containing diets), varying Ca levels, and supplementing phytase in a three-factorial design. We investigated i) the microbial community and pH in the digestive tract, ii) prececal (pc) P and Ca digestibility, and iii) InsP6 degradation.

RESULTS

All factors under investigation influenced digesta pH and the microbiota composition. Predicted functionality and relative abundance of microorganisms indicated that diets influenced the potential contribution of the microbiota on InsP degradation. Values of InsP6 degradation and relative abundance of the strains Lactobacillus johnsonii and Lactobacillus reuteri were correlated. Phytase supplementation increased pc InsP6 disappearance, with differences between Ca levels, and influenced concentrations of lower inositol phosphate isomers in the digestive tract. Formic acid supplementation increased pc InsP6 degradation to myo-inositol. Replacing CaCO3 by Ca-formate and the high level of these Ca sources reduced pc InsP6 disappearance, except when the combination of CaCO3 + formic acid was used. Supplementing phytase to CaCO3 + formic acid led to the highest InsP6 disappearance (52%) in the crop and increased myo-inositol concentration in the ileum digesta. Supplementing phytase leveled the effect of high Ca content on pc InsP6 disappearance.

CONCLUSIONS

The results point towards a contribution of changing microbial community on InsP6 degradation in the crop and up to the terminal ileum. This is indicated by relationships between InsP6 degradation and relative abundance of phosphatase-producing strains. Functional predictions supported influences of microbiota on InsP6 degradation. The extent of such effects remains to be clarified. InsP6 degradation may also be influenced by variation of pH caused by dietary concentration and solubility of the Ca in the feed.

Relative phytase efficacy values as affected by response traits, including ileal microbiota composition

The objective of this study was to compare the effects of graded inclusions of 2 phytase products and a mineral P source in broiler chickens using different response traits, including ileum microbiota composition. Eleven experimental diets were used. These were a low-P basal diet and diets supplemented with increasing levels of dicalcium phosphate (DCP), Natuphos E 5000 G (NE), or Natuphos 5000 G (N). The performance traits, prececal P digestibility, and tibia and foot ash results were subjected to regression analysis and slope ratios were used to compare the supplements based on the measured evaluation traits. In the microbiota analysis, total nucleic acids were extracted and the 16S rRNA gene was targeted for use in the amplicon sequencing process. Phylogenetic analysis was performed using Mothur, followed by a multivariate statistical analysis. The various response traits caused different estimates of relative efficacy. The mean results of all the response traits showed that a 1.75-fold increase in the activity of N was needed to achieve the same response as NE and the variability among the detected traits ranged from 1.59 (prececally digestible P intake) to 1.91 (amount of tibia ash). The mean slope ratio between DCP and NE was 311 and varied between 208 (ADG) and 349 (foot ash concentration). The mean slope ratio for phytase N with DCP was 552 and varied from 357 (ADG) to 640 (tibia ash concentration). The ileum microbiota composition was not different among the diets. A similar composition was driven in the abundance of Lactobacillus crispatus, Lactobacillus salivarius, and Lactobacillus gallinarum. The results suggest that different response traits cause markedly different estimates of relative phytase efficacy.

Effect of low-temperature drying on the nitrogenous compounds and inositol phosphates in broiler chickens and cecectomized laying hen excreta

We investigated how the chemical composition of broiler chicken and cecectomized laying hen excreta is affected by drying in a forced-air drying chamber at low temperatures. Excreta that was immediately frozen after voiding provided the reference values. The excreta were dried in drying chambers for 4 hr, 6 hr, and 12 hr at 23°C or 33°C in the broiler experiment and 19°C or 29°C in the cecectomized laying hen experiment. The total N and inositol phosphate concentrations in the excreta of broiler chickens and cecectomized laying hens were not influenced (p > .050), except for one inositol tetrakisphosphate isomer (p = .026) in broilers. Compared to fresh excreta, drying did not affect the ammonia concentrations in the cecectomized laying hen experiment (p > .050), but the ammonia concentration was lower when dried for 12 hr at 33°C in the broiler experiment (p = .002). Amino acid concentrations in cecectomized laying hen excreta decreased until 4 hr of drying and then increased at both drying temperatures (p < .001). The results indicate that the applicability of drying poultry excreta at low temperatures in forced-air drying chambers to determine the chemical compound concentrations is trait-dependent. Future studies are necessary to investigate whether these results are also dependent upon the amount of excreta stored in the drying chambers.

Interactive Effects of Glycine Equivalent, Cysteine, and Choline on Growth Performance, Nitrogen Excretion Characteristics, and Plasma Metabolites of Broiler Chickens Using Neural Networks Optimized with Genetic Algorithms

Simple Summary

The negative effects of nitrogen emissions caused by animal husbandry on the environment can be reduced by lowering the crude protein content in the diets of broiler chickens. The nonessential amino acids glycine and serine, investigated together as glycine equivalent, can limit the growth of broiler chickens fed diets that are low in crude protein. The response of broiler chickens to dietary glycine equivalent is not constant and is affected by endogenous precursors of glycine equivalent and metabolic processes that dissipate glycine equivalent. Choline can be converted to glycine, and glycine equivalent is required to form cysteine from methionine. The present study investigated interactive effects among dietary glycine equivalent, cysteine, and choline in broiler chickens. The results showed that the gain:feed ratio increased with dietary glycine equivalent supplementation. The extent of interactive effects among glycine equivalent, cysteine, and choline on the gain:feed ratio was hardly pronounced. Very high nitrogen-utilization efficiency with low variation among treatments was found. The findings indicate that small differences in nitrogen-utilization efficiency caused low glycine equivalent dissipation for nitrogen excretion, likely resulting in small interactive effects among dietary glycine equivalent, cysteine, and choline. These results contribute to further dietary crude protein reduction in feed for broiler chickens.

Abstract

Responses of broiler chickens to dietary glycine equivalent (Gly_equi) are affected by dietary cysteine and choline. Hence, this study investigated interactive effects among dietary Gly_equi, cysteine, and choline on the growth of broiler chickens. Male Ross 308 broiler chickens were maintained in 105 metabolism units (10 birds/unit) from days 7 to 22. Excreta were collected in 12-h intervals from days 18 to 21. Blood was sampled on day 22 (1 bird/unit). Five levels each of Gly_equi (9–21 g/kg), cysteine (2–5 g/kg), and choline (0.5–1.7 g/kg) were tested under 15 diets in 7 replicates each following a fractional central composite design. Another diet was provided to five metabolism units (15 birds/unit) to measure prececal amino acid digestibility. Data were evaluated using neural networks. The gain:feed ratio (G:F) increased with digestible Gly_equi intake. Differences between low and high digestible cysteine intake were low. Effects of choline intake on G:F were low. Nitrogen-utilization efficiency (NUE) was high (≥77%), with low variation among treatments. Plasma metabolites varied among treatments and indicated that metabolism of Gly_equi, cysteine, and choline was influenced. These findings showed that interactive effects of dietary Gly_equi, cysteine, and choline on growth were small, possibly because NUE was barely influenced.

Phytase supplementation effects on amino acid digestibility depend on the protein source in the diet but are not related to InsP6 degradation in broiler chickens

The objective was to determine phytase effects on prececal amino acid (AA) digestibility and phytate (InsP6) breakdown when different oilseed meals were used in broiler chicken diets. The study included 14 diets: a corn-soybean meal (SBM) basal diet and 6 diets that contained SBM, rapeseed meal (RSM), and sunflower meal (SFM) with 2 inclusion levels at the expense of corn starch (150 and 300 g/kg SBM or SFM, or 100 and 200 g/kg RSM). Each diet was mixed with or without a phytase supplement of 1,500 FTU/kg. Diets were provided to broilers for 5 D. Digesta from the posterior half of the ileum were collected on day 21. The average essential AA digestibility, calculated by a regression approach, without and with phytase was 84 and 85% (SBM), 74 and 77% (SFM), and 66 and 73% (RSM), respectively. In the diets, phytase effects on AA digestibility were lower owing to other protein sources also present in the diet, but significant. Prececal InsP6 disappearance was significantly affected by interactions between oilseed meal, inclusion level, and phytase supplementation. Overall, prececal InsP6 disappearance was higher in SBM diets (52%) than in SFM diets (38%) and intermediate in RSM diets (43%). Across diets, phytase supplementation effects on prececal InsP6 degradation linearly increased with the InsP6 concentration of the diet up to 12 g/kg DM. The only exception from linearity was the diet with the high inclusion of SFM, which contained 15.9 g InsP6/kg DM. In the ileal content, the concentration of myo-inositol was significantly increased by phytase supplementation, and this effect was highest in the diets that contained SBM as the only oilseed meal. Concentrations of lower inositol phosphates were increased by phytase supplementation, and this effect was most remarkable for Ins(1,2,3,4)P4 and inositol tetrakisphosphates. The study showed that phytase effects on AA digestibility varied among the 3 tested oilseed meals, but these differences were not detectable in the diets containing these meals. Although phytase effects on ileal content of InsP6 and its degradation products were substantial, they were not related to the effects on AA digestibility.

Evaluation of analytical and statistical approaches for predicting in vitro nitrogen solubility and in vivo pre-caecal crude protein digestibility of cereal grains in growing pigs

Different analytical (enzyme system and near-infrared spectroscopy (NIRS)) and statistical (single and multiple regressions) approaches were used to predict in vivo standardized pre-caecal digestibility (PCD) of crude protein (CP) and amino acids (AA) in cereal grains for growing pigs as well as in vitro nitrogen (N) solubility. Furthermore, different chemical and physical characteristics were categorized (e.g. crude nutrients, AA, minerals, fibre components or combinations of these) and used for generating prediction equations. There were strong linear relationships (p < .05) between in vivo PCD of CP and essential AA and in vitro N solubility when grain species was considered as covariate in the model. Predicting in vivo PCD values using various chemical and physical characteristics produced inconsistent results among different grain species and AA and could therefore not be used for predicting PCD. It is possible to predict in vitro N solubility from chemical and physical characteristics for some grain species. However, the relationships between some of these categories and the in vitro N solubility were not consistent and not always causative or physiologically explainable. The R² of NIRS for predicting in vitro N solubility was at a relatively high level (up to R²  = 0.80). This level of R² indicates that a classification of the grain samples in, for example, high, medium and low in vitro N solubility levels is possible, but it does not allow for a quantitative prediction of the in vitro N solubility. In conclusion, the present database can be used for establishing a ranking of different cereal grain species for PCD of CP and essential AA values. However, it was not possible to create clear prediction equations for in vivo or in vitro digestibility values. Therefore, greater variation within grain species, for example due to different growing and harvesting conditions, is warranted for predicting PCD values of individual grain samples.

Effect of microbial phytase supplementation on P digestibility in pigs: a meta-analysis

The objectives of this meta-analysis were to determine to which extent phosphorus (P) digestibility and digestible P concentration in pig diets were increased by phytase supplementation and to quantify factors that potentially influence effects of phytase supplementation. A data set with a total of 547 data lines was compiled from 88 experiments published in 74 peer-reviewed papers between 2007 and April 2019. An exponential model was determined as more suitable to describe the response of P digestibility to phytase supplementation than a polynomial model. Phytase supplementation increased P digestibility by 25.6 percentage points (standard error (SE) = 1.54) to a plateau at 64.9% (SE = 1.82). The digestible P concentration was increased by phytase supplementation in the order of 1.01 g/kg (SE = 0.102) to a plateau at 2.62 g/kg (SE = 0.122). Goodness-of-fit criteria were R² = 0.780 and root mean square error = 7.55% for P digestibility, and R² = 0.691 and root mean square error = 0.48 g/kg for digestible P concentration. Consideration of further factors such as mineral P supplementation (yes or no), ad libitum vs. restrictive feeding, mixed diets vs. single feed ingredients, sex and age of pigs did not increase the accuracy of prediction in this data set. Some of these traits exhibited responses, but they likely are artefacts generated through the imbalanced structure of the data set. Effects of dietary total P, phytate (InsP₆), InsP₆-P to total P ratio, and Ca on the effect of supplemented phytase were not quantifiable. The present meta-analysis showed that responses to phytase supplementation can be well predicted although variation in P digestibility and digestible P concentration in the data set was high. Overall, predicted effects of phytase on P digestibility well corresponded to predictions made 25 years ago.

Prececal amino acid digestibility and phytate degradation in broiler chickens when using different oilseed meals, phytase and protease supplements in the feed

The purpose of this study was to investigate the effects of phytase and protease supplementation on prececal (pc) amino acid (AA) digestibility, phytate (InsP6) degradation, and MEn concentration in diets using 3 oilseed meals as main protein sources in broiler chicken feed. The broiler chicken diets, which lacked mineral phosphorus, contained either soybean meal (SBM), SBM and rapeseed meal (SBM/RSM), or SBM and sunflower meal (SBM/SFM) as main protein sources. Diets were not supplemented with enzymes or supplemented with 1,500 or 3,000 FTU phytase/kg, or with 1,600 mg protease/kg. For diets containing SBM as the main protein source, the effects of phytase supplementation with and without monocalcium phosphate were also investigated. Data were obtained during 2 subsequent runs from days 14 to 22 and from days 23 to 31. Each diet was tested using 8 replicates with 4 replicates per run. For pc AA digestibility, no significant interactions were observed between main protein sources, enzyme supplementation, or addition of monocalcium phosphate except for Cys. Supplementation of 1,500 FTU phytase/kg increased pc digestibility of all AA. No differences in pc AA digestibility were observed between 1,500 and 3,000 FTU phytase/kg supplementation treatments. Prececal disappearance of InsP6 and pc P digestibility were greater in the high phytase supplementation treatment. Protease supplementation increased pc digestibility of all AA except for Cys when SBM/RSM was the main protein source. Supplementation of protease and 3,000 FTU phytase/kg increased MEn concentrations. The effect of phytase on pc AA digestibility was fully expressed at a lower supplementation level than needed for a maximized pc InsP6 disappearance and MEn concentration.

Effects of protease and phytase supplements on small intestinal microbiota and amino acid digestibility in broiler chickens

The objective of this study was to determine the effects of protease origin and dosage on the prececal (pc) amino acid (AA) digestibility and the influence on composition of the microbial community in the small intestine. In addition, the effects of phytase supplementation were investigated. A total of 8 dietary treatments were included. The basal diet contained mainly corn and soybean meal. Three protease products were added to the basal diet, each at the level recommended by the supplier and at an 8-fold level. Phytase was supplemented in another dietary treatment. Each dietary treatment was allocated to 8 replicates of 15 birds each. The experimental diets were offered from day 15 to 21 for ad libitum consumption. The effect of protease supplementation on the pc AA digestibility depended on the protease product type and the amount supplemented. The pc AA digestibility was significantly increased by 1 protease product when supplemented at high level and when phytase was supplemented. In all the other treatments, protease supplementation had no significant influence or it decreased pc AA digestibility, when compared with the treatment with no enzymes added. In general, Firmicutes was the most abundant phylum among the ileal microbiota across all the treatments. Significant effects on microbiota composition were observed at the genus level for some but not all protease treatments and phytase supplementation. The genera Streptococcus, Lactobacillus, and uncultured Clostridiaceae were responsible for these differences. Furthermore, microbial networks established for each diet showed either high or low number of intergeneric interactions, but without a consistent enzyme effect. We conclude that enzyme supplementation effects were evident in the terminal small intestine microbiota composition, and to a lesser extent, in pc AA digestibility. However, the changes in microbiota composition and pc AA digestibility could not be correlated, indicating absence of a causal relationship.

Very Low Crude Protein and Varying Glycine Concentrations in the Diet Affect Growth Performance, Characteristics of Nitrogen Excretion, and the Blood Metabolome of Broiler Chickens

BACKGROUND

The minimum to which dietary crude protein (CP) level for broiler chickens can be reduced without decreasing growth and the glycine equivalent (Glyequi) concentration required are not known. The plasma metabolome might reflect dietary influences on physiological processes.

OBJECTIVE

The aim of this study was to investigate the effect of 3 low CP levels with 4 Glyequi concentrations on growth and characteristics of nitrogen excretion, and to identify plasma metabolome variations.

METHODS

Male Ross308 broiler chickens were provided 1 of 12 dietary treatments in 84 metabolism cages (10/cage) from days 7 to 21. Three diets with 163 (CP163), 147 (CP147), and 132 (CP132) g CP/kg were formulated, each containing 12, 15, 18, and 21 g Glyequi/kg. Essential amino acid concentrations were the same in all diets. Animals and feed were weighed on days 7 and 21 to determine average daily gain (ADG) and gain:feed ratio (G:F). Excreta were collected from days 18 to 21 to analyze nitrogenous components, and blood was obtained on day 21 to conduct a metabolome analysis.

RESULTS

Two-factor ANOVA showed significant interaction effects for ADG, G:F, and nitrogen efficiency (P < 0.001). Reduction of CP decreased ADG and G:F, and increased nitrogen efficiency. Glyequi supplementation increased ADG (by 7.9 g/d) and G:F (by 0.07 g/g) at CP132. The ADG (by 2.4 g/d) at CP147 and G:F (by 0.02 g/g) at CP147 and CP163 increased up to 15 g Glyequi/kg. Multivariate statistical analysis showed an influence of Glyequi on plasma acylcarnitine and lysophosphatidylcholine concentrations, and a decrease of plasma phosphatidylcholine and sphingomyelin concentrations with reduced CP.

CONCLUSIONS

These results suggest that a nutrient other than Glyequi limited growth when CP was reduced from CP163 to CP147, and that the response of broiler chickens to Glyequi is dependent on the dietary CP level. Plasma metabolites indicate dietary influences on the physiological state of the animals.

The relevance of glycine and serine in poultry nutrition: a review

1. Dietary glycine equivalents (Gly_equi) for glycine and serine represent the first-limiting non-essential amino acid in poultry diets. Targeted adjustment of essential amino acids and Gly_equi in diets can considerably decrease crude protein (CP) in poultry diets below the limit of CP reduction when only essential amino acids are adjusted. 2. The level to which CP can be reduced in diets adequate in Gly_equi depends on the objective; which includes reducing dietary CP without affecting performance and increasing nitrogen utilisation efficiency. Dietary CP can be reduced to ~15-16% in diets for up to 21 d old broiler chicken without affecting growth performance compared to responses to diets with currently common CP concentrations by considering Gly_equi in the diet formulation. Dietary CP can be further reduced to maximise nitrogen utilisation efficiency; however, this leads to reduced growth performance. 3. The dietary Gly_equi requirement of poultry varies depending on other dietary constituents. In broiler chickens up to 21 days of age, the dietary Gly_equi requirement is estimated to be between 11 and 20 g/kg. This estimate is influenced by the concentrations of Cys and the endogenous Gly_equi precursors, threonine and choline. Urinary nitrogen excretion seems to be a major determinant of the response to dietary Gly_equi, because it is needed for uric acid formation. 4. The variable requirement for dietary Gly_equi means that its static recommendation in poultry diets would lead to high safety margins in Gly_equi supply or the risk of Gly_equi deficiency. Variable recommendations for dietary Gly_equi concentrations would help to supply birds based on their specific requirements and could reduce nitrogen emissions originating from poultry farming.

Variability of amino acid digestibility of lupin and pea grains in caecectomised laying hens

1. The objective of this study was to investigate the variations in amino acid (AA) digestibility of lupin and pea grains in caecectomised laying hens. The relationship between AA digestibility and chemical constituents of the grains was determined. 2. Twelve variants of lupins and peas were each added to a basal diet at a concentration of 300 g/kg, at the expense of maize starch. The lupin and pea variants were separately investigated in two subsequent trials. Each trial consisted of two 7 × 7 Latin squares, each comprising the basal diet and six diets with lupins or peas. 3. Fourteen caecectomised laying hens (LSL-classic) were individually housed in metabolism cages and 120 g/d of experimental diets were provided for eight days. During the last four days, excreta were collected quantitatively and feed intake was recorded. A regression approach was used to determine the AA digestibility of the lupin and pea variants. 4. Amino acid digestibility of the lupins and peas was high, although significant differences in AA digestibility among the lupins and peas were detected. The digestibility of lysine was in the range of 0.87-0.91 and 0.87-0.93 for lupins and peas, respectively. The digestibility of methionine in lupins and peas varied between 0.80-0.88 and 0.72-0.90. Variations in AA digestibility in peas were more pronounced than in lupins. 5. Significant correlations between chemical constituents of lupins, such as alkaloids, and AA digestibility were detected in some cases, without a consistent pattern. In peas, tannin concentration and the insoluble protein fraction were negatively correlated with digestibility of some AAs, but only when one colour flower variant was considered. Trypsin inhibitor activity in peas was negatively correlated with AA digestibility, particularly for the white flower variants.

Influence of feed provisioning prior to digesta sampling on precaecal amino acid digestibility in broiler chickens

A regression approach was applied to determine the influence of feed provisioning prior to digesta sampling on precaecal (pc) amino acid (AA) digestibility in broiler chickens. Soybean meal was used as an example test ingredient. Five feed-provisioning protocols were investigated, four with restricted provision and one with ad libitum provision. When provision was restricted, feed was provided for 30 min after a withdrawal period of 12 h. Digesta were sampled 1, 2, 4 and 6 h after feeding commenced. A diet containing 300 g maize starch/kg was prepared. Half or all the maize starch was replaced with soybean meal in two other diets. Average pc digestibility of all determined AA in the soybean meal was 86% for the 4 and 6-h protocols and 66% and 60% for the 2 and 1-h protocols, respectively. Average pc AA digestibility of soybean meal was 76% for ad libitum feed provision. Feed provisioning also influenced the determined variance. Variance in digestibility ranked in magnitude 1 h > ad libitum > 2 h > 6 h > 4 h for all AA. Owing to the considerable influence of feed-provisioning protocols found in this study, comparisons of pc AA digestibility between studies applying different protocols prior to digesta sampling must be treated with caution. Digestibility experiments aimed at providing estimates for practical feed formulation should use feed-provisioning procedures similar to those used in practice.

Effect of particle size distribution of maize and soybean meal on the precaecal amino acid digestibility in broiler chickens

1. Herein, it was investigated whether different particle size distributions of feed ingredients achieved by grinding through a 2- or 3-mm grid would have an effect on precaecal (pc) amino acid (AA) digestibility. Maize and soybean meal were used as the test ingredients. 2. Maize and soybean meal was ground with grid sizes of 2 or 3 mm. Nine diets were prepared. The basal diet contained 500 g/kg of maize starch. The other experimental diets contained maize or soybean meal samples at concentrations of 250 and 500, and 150 and 300 g/kg, respectively, instead of maize starch. Each diet was tested using 6 replicate groups of 10 birds each. The regression approach was applied to calculate the pc AA digestibility of the test ingredients. 3. The reduction of the grid size from 3 to 2 mm reduced the average particle size of both maize and soybean meal, mainly by reducing the proportion of coarse particles. Reducing the grid size significantly (P < 0.050) increased the pc digestibility of all AA in the soybean meal. In maize, reducing the grid size decreased the pc digestibility of all AA numerically, but not significantly (P > 0.050). The mean numerical differences in pc AA digestibility between the grid sizes were 0.045 and 0.055 in maize and soybean meal, respectively. 4. Future studies investigating the pc AA digestibility should specify the particle size distribution and should investigate the test ingredients ground similarly for practical applications.

Prececal amino acid digestibility of soybean cake in fast- and slow-growing broiler chickens

The objective of the present study was to determine whether there are differences in prececal amino acid digestibility between commonly used slow- and fast-growing broiler strains when the regression approach is applied. ISA J-275 and Ross 308 were selected as common representatives of slow- and fast-growing broiler strains, respectively. The experimental diets with soybean cake at levels of 0, 100, and 200 g/kg were offered for ad libitum consumption between 22 and 29 d post-hatch. Titanium dioxide was used as an indigestible marker. Each treatment was tested with six pens comprising 10 birds each. Digesta samples were collected on a pen basis from the distal two-thirds of the intestine section between Meckel's diverticulum and 2 cm anterior to the ileocecal-colonic junction. The prececal amino acid digestibility of soybean cake was calculated by linear regression simultaneously for both strains. There was no significant interaction between broiler strain and inclusion level of soybean cake with respect to the prececal CP and amino acid digestibility of complete diets; there was a significant strain effect for 5 out of the 16 measured amino acids. The prececal CP and amino acid digestibility of soybean cake did not differ significantly between strains and was numerically almost identical. The results of the present study provide evidence of the transferability between broiler strains of prececal amino acid digestibility data, determined using the regression approach, thus improving the accuracy of diet formulation without drawbacks.

Results of an international phosphorus digestibility ring test with broiler chickens

The objective of this ring test was to investigate the prececal phosphorus (P) digestibility of soybean meal (SBM) in broiler chickens using the trial protocol proposed by the World's Poultry Science Association. It was hypothesized that prececal P digestibility of SBM determined in the collaborating stations is similar. Three diets with different inclusion levels of SBM were mixed in a feed mill specialized in experimental diets and transported to 17 collaborating stations. Broiler chicks were raised on commercial starter diets according to station-specific management routine. Then they were fed the experimental diets for a minimum of 5 d before content of the posterior half of the ileum was collected. A minimum of 6 experimental replicates per diet was used in each station. All diets and digesta samples were analyzed in the same laboratory. Diet, station, and their interaction significantly affected (P < 0.05) the prececal digestibility values of P and calcium of the diets. The prececal P digestibility of SBM was determined by linear regression and varied among stations from 19 to 51%, with significant differences among stations. In a subset of 4 stations, the prececal disappearance of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate)-P; InsP6-P) also was studied. The prececal InsP6-P disappearance correlated well with the prececal P digestibility. We hypothesized that factors influencing InsP6 hydrolysis were main contributors to the variation in prececal P digestibility among stations. These factors were probably related to the feeding and housing conditions (floor pens or cages) of the birds in the pre-experimental phase. Therefore, we suggest that the World's Poultry Science Association protocol for the determination of digestible P be should extended to the standardization of the pre-experimental period. We also suggest that comparisons of P digestibility measurements among studies are made only with great caution until the protocol is more refined.

Effect of nitrogen fertilisation on the amino acid digestibility of different triticale genotypes in caecectomised laying hens

BACKGROUND

The influence of nitrogen fertilisation and genotype on the amino acid (AA) digestibility of triticale grain was investigated in caecectomised laying hens. Three genotypes, Grenado, EAW6002 and Lasko, were cultivated with and without nitrogen fertilisation at the end of the heading stage. The six triticale variants as well as a basal diet were each used to feed seven laying hens in a 7 × 7 Latin square design.

RESULTS

Nitrogen fertilisation influenced the digestibility of Cys, Glu, Phe and Ser in some triticale genotypes and reduced Ala, Ile, Lys, Met and Val digestibility in all genotypes (P < 0.05). Nitrogen fertilisation increased the concentration of all AAs in the grain. Consequently, the concentration of digestible AAs in the grains was increased for most AAs upon nitrogen fertilisation. Overall, Lys had the lowest digestibility, whereas that of Glu and Pro was the highest. For the triticale genotypes, the level of AA digestibility was highest for EAW6002 followed by Lasko and Grenado, with significant differences (P < 0.05) between genotypes for some but not all AAs.

CONCLUSION

The results indicated that the accuracy of the digestible AA supply for hen feeding might benefit from considering fertilisation and genotype-specific digestibility data in feed formulation. © 2016 Society of Chemical Industry.

Variation in chemical composition and physical characteristics of cereal grains from different genotypes

Genotypes of cereal grains, including winter barley (n = 21), maize (n = 27), oats (n = 14), winter rye (n = 22), winter triticale (n = 21) and winter wheat (n = 29), were assayed for their chemical composition and physical characteristics as part of the collaborative research project referred to as GrainUp. Genotypes of one grain species were grown on the same site, except maize. In general, concentrations of proximate nutrients were not largely different from feed tables. The coefficient of variation (CV) for the ether extract concentration of maize was high because the data pool comprised speciality maize bred for its high oil content. A subset of 8 barley, 20 rye, 20 triticale and 20 wheat samples was analysed to differ significantly in several carbohydrate fractions. Gross energy concentration of cereal grains could be predicted from proximate nutrient concentration with good accuracy. The mean lysine concentration of protein was the highest in oats (4.2 g/16 g N) and the lowest in wheat (2.7 g/16 g N). Significant differences were also detected in the concentrations of macro elements as well as iron, manganese, zinc and copper. Concentrations of arsenic, cadmium and lead were below the limit of detection. The concentration of lower inositol phosphates was low, but some inositol pentaphosphates were detected in all grains. In barley, relatively high inositol tetraphosphate concentration also was found. Intrinsic phytase activity was the highest in rye, followed by triticale, wheat, barley and maize, and it was not detectable in oats. Substantial differences were seen in the thousand seed weight, test weight, falling number and extract viscoelasticity characteristics. The study is a comprehensive overview of the composition of different cereal grain genotypes when grown on the same location. The relevance of the variation in composition for digestibility in different animal species will be subject of other communications.

Impact of genomic risk factors on outcome after hematopoietic stem cell transplantation for patients with chronic myeloid leukemia

BACKGROUND

Non-HLA gene polymorphisms have been shown to influence outcome after allogeneic hematopoietic stem cell transplantation. Results were derived from heterogeneous, small populations and their value remains a matter of debate.

DESIGN AND METHODS

In this study, we assessed the effect of single nucleotide polymorphisms in genes for interleukin 1 receptor antagonist (IL1RN), interleukin 4 (IL4), interleukin 6 (IL6), interleukin 10 (IL10), interferon (IFNG), tumor necrosis factor (TNF) and the cell surface receptors tumor necrosis factor receptor II (TNFRSFIB), vitamin D receptor (VDR) and estrogen receptor alpha (ESR1) in a homogeneous cohort of 228 HLA identical sibling transplants for chronic myeloid leukemia. Three good predictors of overall survival, identified via statistical methods including Cox regression analysis, were investigated for their effects on transplant-related mortality and relapse. Predictive power was assessed after integration into the established European Group for Blood and Marrow Transplantation (EBMT) risk score.

RESULTS

Absence of patient TNFRSFIB 196R, absence of donor IL10 ATA/ACC and presence of donor IL1RN allele 2 genotypes were associated with increased transplantation-related mortality and decreased survival. Application of prediction error and concordance index statistics gave evidence that integration improved the EBMT risk score.

CONCLUSIONS

Non-HLA genotypes were associated with survival after allogeneic hematopoietic stem cell transplantation. When three genetic polymorphisms were added into the EBMT risk model they improved the goodness of fit. Non-HLA genotyping could, therefore, be used to improve donor selection algorithms and risk assessment prior to allogeneic hematopoietic stem cell transplantation.

Cytokine profiles of cord and adult blood leukocytes: differences in expression are due to differences in expression and activation of transcription factors

BACKGROUND

Stem cell transplantation as therapy for hematological disorders is often hampered by severe graft-versus-host-disease. This may be reduced by umbilical cord blood transplantation, an effect that has been attributed to qualitative differences between neonatal and adult T cells. We compared levels of secreted proteins and cytokine mRNA induced in cord blood leukocytes (CBL) and adult blood leukocytes (ABL) by various stimuli.

RESULTS

While interleukin-2 (IL-2) levels were similar in CBL and ABL, there was less induction of the Th1 cytokine interferon-gamma in CBL. Production of the Th2 cytokines IL-4, IL-5, and IL-13 and the hematopoietic cytokine IL-3 was much lower in CBL versus ABL after T-cell receptor-mediated stimulation, whereas production of GM-CSF was comparable in the 2 cell types. The lower levels of Th1 and Th2 cytokines were maintained in CBL during a 4-day time-course study, while after 12 hours IL-3 and GM-CSF reached in CBL levels similar to those in ABL. For all cytokines except IFN gamma, the IC50 values for inhibition by cyclosporin A were similar in ABL and CBL. In contrast, there was less expression and activation of transcription factors in CBL. Activation of NF-kappaB by TPA/ionomycin was detected in ABL but not CBL. Furthermore, there was less expression of the Th subset-specific transcription factors T-bet and c-maf in CBL versus ABL, whereas GATA-3 expression was similar. Expression of T-bet and c-maf correlated with expression of the Th1 and Th2 cytokines, respectively. Time course experiments revealed that T-bet expression was stimulated in both cell types, whereas c-maf and GATA-3 were induced only in ABL.

CONCLUSION

The diminished capability of CBL to synthesize cytokines is probably due to decreased activation of NF-kappaB, whereas differences in Th subsets are due to differences in regulation of Th lineage-specific transcriptions factors. We propose that the reduced incidence and severity of GvHD after allogeneic transplantation of umbilical CB cells is due to lesser activation of specific transcription factors and a subsequent reduction in production of certain cytokines.

Quantitative expression analysis of HHV-6 cell receptor CD46 on cells of human cord blood, peripheral blood and G-CSF mobilised leukapheresis cells

Human herpesvirus-6 (HHV-6) can infect blood cells and thereby may inhibit hematopoietic stem and progenitor cell expansion and differentiation. In this context, it has been discussed if early progenitor cells can be infected by HHV-6. CD46 was identified as one possible cellular surface receptor for HHV-6. The study presented here had been done to get insight into the susceptibility of various leukocyte subpopulations to HHV-6 (including early hematopoietic progenitors) by determining the amount of CD46 molecules expressed on their surfaces. Human cord blood cells, peripheral blood cells and G-CSF mobilised progenitor cells were analysed by flow cytometry. CD46 molecule number per cell was determined and compared to calibration beads conjugated with known ratio of PE per bead. Highest CD46 expression was detected on B- lymphocytes, whereas T-lymphocytes only showed about half of the amount found on B cells. Hematopoietic progenitors also carried CD46 at intermediate levels. Unexpectedly, CD46 expression on progenitors from G-CSF mobilised leukapheresis products was approximately 20% of that found on comparable cells from untreated cord blood. In conclusion, hematopoietic progenitor cells express CD46 on their surface, thereby fulfilling a basic requirement for the susceptibility of HHV-6 infection.

Activity of thalidomide in patients with platinum-refractory germ-cell tumours

The aim of this study was assess the activity of thalidomide in patients with progressive relapsed or platinum-refractory germ-cell tumours (GCT). Between April 2002 and January 2003, 15 patients with inoperable progressive GCT were treated with escalated daily doses of 200-600 mg thalidomide. All patients had failed first-line and salvage chemotherapy with a median of 6 (range 4-12) cisplatin-based treatment cycles, 13/15 (87%) patients had received high-dose chemotherapy (HDCT) and 8/15 (53%) patients were considered platinum-refractory or absolute refractory; 8/15 (53%) patients had previously received other palliative chemotherapy regimens. No patient achieved a complete remission (CR) or partial remission (PR). However, 5/15 (33%) patients achieved serological PR and 1 additional patient had stable disease for 3 months. The median duration of remissions was 3 months (range 2-12 months) including 2 patients with a progression-free survival of 9 and 12 months. Responses occurred mainly in patients with a low tumour burden, slow disease progression and alpha-foetoprotein (AFP) elevations. Responses to thalidomide were independent from platinum-sensitivity. Toxicity was mild, with lethargy and constipation in the majority of patients. Skin rash grade II developed in 2 patients and peripheral neurotoxicity grade II/III developed in 4 patients. One responding patient died suddenly from an unknown cause. It is concluded that thalidomide shows single-agent activity in patients with heavily pre-treated GCT, AFP elevations and slowly progressive disease.

Evaluation of prognosis in relapsed germ cell tumors: Identification of patients who profit from high dose chemotherapy (HDCT)

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Background: To identify prognostic variables in patients (pts) with metastatic germ cell tumors (GCT) and relapse or progression after first-line chemotherapy (FLC). Methods: In our database of 257 GCT pts treated with HDCT, 176/257 (67.4%) pts with first relapse or progression were identified. All patients had received platinum-based FLC. As salvage treatment all pts had received 1–3 cycles of conventional-dose salvage chemotherapy (CDCT) followed by one cycle HDCT. First, pts were retrospectively classified according to a prognostic score developed for CDCT by Fossa et al. [Br J Cancer 1999,80:1392], based on variables present at the time of relapse. Thereafter, a multivariate analysis was performed to evaluate further risk factors. Results: After a median follow up of 9 years the event-free survival (EFS) and overall survival (OS) for all 176 patients was 34% and 38%, respectively. Patients with good (n= 100/176, 57%) and poor (n = 76/176, 43%) prognosis in accordance to Fossa et al. showed an EFS of 41% and 26% (p < 0.01) and an OS of 47% and 26% (p < 0.01). Thus, in contrast to the data of Fossa et al, long-term survival could be demonstrated even in the poor prognosis subset. In the multivariate analysis, the level of elevated tumor markers alfa-fetoprotein and human chorionic gonadotrophin (p < 0.01), the presence of extrapulmonal visceral metastases (p < 0.01) and refractoriness to cisplatin (p < 0.01) adversely influenced OS after HDCT significantly. Based on these latter factors three different groups with increasingly poor OS could be identified: none factor (n = 39/176, 22%) 4 year OS of 59%, one factor (n = 78/176, 44%) 6 year OS of 42% and more than one factor (n = 59/176, 34%) 4 year OS of 17%. Conclusion: In pts with first relapse or progression after platinum-based FLC high serum tumor markers, presence of extrapulmonal visceral metastases and cisplatin refractoriness proved to be independent prognostic significance for OS after salvage HDCT. However, even in the poor prognosis subset long-term survival could be demonstrated.

No significant financial relationships to disclose.

Infections with human herpesvirus 6 variant B delay platelet engraftment after allogeneic haematopoietic stem cell transplantation

The clinical significance of human herpesvirus (HHV-6) infections after allogeneic stem cell transplantation (SCT) remains controversial. We analysed cryoconserved plasma samples from 82 patients after allogeneic SCT by quantitative polymerase chain reaction for HHV-6 variants A and B. Platelet engraftment was delayed in patients with HHV-6B infections but not with HHV-6A infections detected before day +28. In multivariate analysis early HHV-6B infections and the type of conditioning were associated with platelet engraftment. In conclusion, the two variants of HHV-6 should be studied separately; early infections with HHV-6B may contribute to delayed platelet engraftment after allogeneic SCT.

Sustained complete molecular remissions after treatment with imatinib-mesylate in patients with failure after allogeneic stem cell transplantation for chronic myelogenous leukemia: results of a prospective phase II open-label multicenter study

PURPOSE

In the era of molecular therapy of chronic myelogenous leukemia (CML) applying BCR-ABL tyrosine kinase inhibitors, the usefulness of molecular end points, in particular, quantitative polymerase chain reaction (PCR) for BCR-ABL in monitoring responses has been broadly accepted. Therefore, we have designed a prospective phase II trial in CML, which, for the first time, evaluated the feasibility and safety of molecular end points as surrogate markers to guide through a stratified treatment algorithm within a multicenter trial.

PATIENTS AND METHODS

As a clinical model, we adopted minimal residual disease (MRD) found in relapse after allogeneic stem cell transplantation (SCT) in CML. Forty-four patients were enrolled and received the BCR-ABL tyrosine kinase inhibitor imatinib (IM) at a starting dose of 400 mg/d. The quality of molecular responses achieved then decided on discontinuation of IM or dose escalation up to 800 mg/d, and finally, on application of donor lymphocyte infusions. Results Seventy percent of patients achieved a complete molecular response (CMR), defined as nested PCR-negativity for BCR-ABL in three consecutive samples. Interestingly, in four out of 10 patients who discontinued IM, CMR was durable even after cessation of IM with a median follow-up of 494 days. This suggests the possibility of long-term tumor control in a subset of patients.

CONCLUSION

The treatment strategy showed that IM treatment was well-tolerated and highly efficacious in MRD after allogeneic SCT. Moreover, this study demonstrated that evaluation of a molecular end point within a multicenter trial can be a safe and effective tool for clinical decision making.

A randomised trial of high-dose chemotherapy in the salvage treatment of patients failing first-line platinum chemotherapy for advanced germ cell tumours

BACKGROUND

Incomplete remission or relapse from first-line chemotherapy has poor prognosis in male germ cell tumour patients. This phase III randomised trial compares conventional salvage to high-dose-intensification chemotherapy.

PATIENTS AND METHODS

Between February 1994 and September 2001, 280 patients from 43 institutions in 11 countries, were randomly assigned to receive either four cycles of cisplatin, ifosfamide and etoposide (or vinblastine) (arm A), or three such cycles followed by high-dose carboplatin, etoposide and cyclophosphamide (CarboPEC) with haematopoietic stem cell support (arm B).

RESULTS

Similar complete and partial response rates were observed in both treatment arms (56%; 95% CI 50% to 62%). There were 3% and 7% toxic deaths in arms A and B, respectively. No significant improvements with CarboPEC were observed in either 3-year event-free survival (35% versus 42%, P=0.16) or overall survival (53%; 95% CI 46% to 59%). Complete responders with CarboPEC had a significant improvement in disease-free survival (55% versus 75% at 3 years, P <0.04).

CONCLUSIONS

The single cycle of high-dose salvage chemotherapy after three cycles of standard dose chemotherapy had no effect on treatment outcomes. These results suggest that data from uncontrolled studies should not be used to justify routine use of a toxic and expensive treatment without confirmation in a randomised trial.

After major ABO-mismatched allogeneic hematopoietic progenitor cell transplantation, erythroid engraftment occurs later in patients with donor blood group A than donor blood group B

BACKGROUND

Isohemagglutinins directed against the donor blood group frequently delay erythroid engraftment after major ABO-mismatched allogeneic hematopoietic progenitor cell transplantation (HPCT). Graft-versus-host reactions are capable of accelerating the clearance of isohemagglutinins. Whether immunogenicity of the A- and B-antigen is important in this process is unknown.

PATIENTS AND METHODS

Data of 807 patients from three centers were screened for patients with major or bidirectionally ABO-mismatched donors. Clinical data and red blood cell (RBC) transfusion support were analyzed retrospectively.

RESULTS

A total of 158 patients with major or bidirectionally mismatched donors were identified. After major mismatched HPCT, patients with anti-A directed against the donor blood group required RBC transfusion support for a median of 109 days (range, 0-324 days) compared to 21 days (range, 2-98 days) for patients with anti-B directed against donor blood group (log-rank test, p = 0.0001). Other risk factors associated with prolonged RBC transfusion support in univariate analysis were age (p = 0.024), cytomegalovirus infection (p = 0.016), hemolytic anemia (p = 0.027), and chronic bleeding disorders (p = 0.038). The independent influence of donor blood group and recipient age were confirmed in a multivariate analysis.

CONCLUSION

These results indicate that the immunogenicity of the ABO antigen plays an important role for the kinetics of erythroid engraftment after ABO-mismatched HPCT.

Second-line high-dose chemotherapy in patients with mediastinal and retroperitoneal primary non-seminomatous germ cell tumors: the EBMT experience

BACKGROUND

Results of second-line chemotherapy in patients with extragonadal non-seminomatous germ cell tumor (NSGCT) appear inferior to results in testicular NSGCT. Patients with retroperitoneal NSGCT achieve a comparable long-term survival rate of 30%, but the salvage rates of patients with mediastinal primary are less than 10%. We conducted a retrospective analysis on patients with mediastinal and retroperitoneal NSGCT treated with second-line high-dose chemotherapy (HDCT) registered with the European Group for Blood and Marrow Transplantation (EBMT).

PATIENTS AND METHODS

Between 1987 and 1999, 59 registered patients with retroperitoneal (n=37) and mediastinal (n=22) primary NSGCT, median age 28 years (range 18-60), were treated with second-line HDCT. All had received cisplatin-containing chemotherapy as first-line treatment.

RESULTS

Toxic death occurred in three cases (5%). With a median follow-up of 58 months (range 14-114), 18/59 patients (30%) continue to be disease-free. Of three patients who had a disease recurrence after HDCT, one patient achieved a disease-free status with further chemotherapy and surgery. In total, 19 patients (32%) are currently disease-free. Sixteen of 37 patients (43%) with retroperitoneal NSGCT, and three of 22 patients (14%) with mediastinal NSGCT are currently alive and disease-free.

CONCLUSIONS

Second-line HDCT might represent a possible option for patients with retroperitoneal primary NSGCT. New salvage strategies are needed for patients with mediastinal NSGCT.

Reference gene selection for quantitative real-time PCR analysis in virus infected cells: SARS corona virus, Yellow fever virus, Human Herpesvirus-6, Camelpox virus and Cytomegalovirus infections

Ten potential reference genes were compared for their use in experiments investigating cellular mRNA expression of virus infected cells. Human cell lines were infected with Cytomegalovirus, Human Herpesvirus-6, Camelpox virus, SARS coronavirus or Yellow fever virus. The expression levels of these genes and the viral replication were determined by real-time PCR. Genes were ranked by the BestKeeper tool, the GeNorm tool and by criteria we reported previously. Ranking lists of the genes tested were tool dependent. However, over all, β-actin is an unsuitable as reference gene, whereas TATA-Box binding protein and peptidyl-prolyl-isomerase A are stable reference genes for expression studies in virus infected cells.

Inhibition of cord blood cell expansion by human herpesvirus 6 in vitro

To elucidate the role of human herpesvirus 6 (HHV-6) in hematopoiesis, the influence of HHV-6A and HHV-6B on the in vitro expansion and differentiation of cord blood (CB) progenitor cells was investigated in liquid culture. Nonfractionated CB mononuclear cells (CB-MNC) or MACS-enriched CD34+ CB cells were seeded in liquid culture under conditions allowing maximal expansion of nucleated cells. Cells were either incubated with HHV-6A- or HHV-6B-containing cell culture supernatants or a virus-free control. After 7, 14, and 21 days, cells were analyzed for growth by cell count, for differentiation by flow cytometry, and for HHV-6 infection by antigen detection or PCR. Expansion of CB-MNC was significantly inhibited by HHV-6A and HHV-6B for a period of 3 weeks, including reduced proportions of CD34+ and CD33+ cells in HHV-6-treated cultures on day 7. In contrast, when starting with enriched CD34+ cells, the expansion was only affected by HHV-6A. Inhibition of CD34 and CD33 cell development was less pronounced in these cultures compared to CB-MNC cultures. However, HHV-6 antigen and DNA was detectable in these cultures. In conclusion, although HHV-6A inhibited expansion of CD34 progenitor cells, HHV-6B inhibited growth of immature CB cells only in interaction with nonfractionated CB-MNC.

Residual tumor resection after high-dose chemotherapy in patients with relapsed or refractory germ cell cancer

PURPOSE

To assess the role of residual tumor resection performed after high-dose chemotherapy (HDCT) in patients with relapsed or refractory germ cell tumors (GCT).

PATIENTS AND METHODS

Between July 1987 and October 1999, postchemotherapy resections of residual tumors were performed in 57 patients who had been treated with HDCT for relapsed or refractory GCT and who had achieved a partial remission to this treatment.

RESULTS

Complete resections of residual masses were achieved in 52 (91%) of 57 patients who were rendered disease free; in five (9%) of 57 patients, the resections were incomplete. Resection of a single site was performed in 39 (68%) of 57 patients, and the remaining 18 (32%) of 57 patients required interventions at two or more residual tumor sites. Necrosis was found in 22 (38%) of 57 patients, mature teratoma with or without necrosis was found in nine (16%) of 57 patients, and viable cancer with or without additional necrosis or mature teratoma was found in 26 (46%) of 57 patients. Viable cancer consisted either of residual germ cell or undifferentiated cancer in 22 (85%) of 26 patients, with additional non-GCT histologies in the remaining four patients. Patients with viable cancer had a significantly inferior outcome after surgery compared with patients with necrosis and/or mature teratoma even if all cancer was completely resected. Pulmonary lesions with a diameter of more than 2 cm were the only predictive variable for viable cancer in univariate analysis.

CONCLUSION

Resections of all residual tumors should be attempted in patients with relapsed or refractory GCT and partial remissions after HDCT.