Teaching the principles of least-cost poultry feed formulation utilizing the Solver function within a computer software workbook

A Microsoft Excel workbook, User-Friendly Feed Formulation with Data from Australia (UffdAu.xlsm), has been developed for teaching feed formulation techniques to tertiary level, university students. It runs under both Microsoft Windows and Apple iOS operating systems. The example ingredient composition matrix is based on the Australian Feed Ingredient Database to illustrate the biological and econometric principles of least-cost feed formulation. The nutrient data are based roughly on recent primary breeder company recommendations. The workbook is easily adapted to appropriate ingredients, nutrients, and prices most relevant to the students, wherever it is used. The workbook uses the linear routines of Excel's Solver add-in under the Data heading in the header Ribbon. There is a worksheet illustrating how to adapt non-linear responses such as exogenous enzymes to typical linear models using a step function. Additional worksheets illustrate how proximate analysis can be interpreted in modern analytical chemistry terms and, how various feed energy measures are related to feed composition. UffdAu.xlsm is available free of charge from the Poultry Hub Australia website (https://www.poultryhub.org).

Influence of two levels of phytic acid and particle size of oyster shell on the performance, calcium digestibility, gastrointestinal pH, and bone traits in broilers

1. Phytic acid (PA) is an antinutritional factor in poultry diets. The effect of high dietary PA in chicken diets might be exacerbated when the particle size of oyster shell (OS) is too fine. Thus, this study investigated the hypothesis that high PA with fine OS particle size would impair growth in broilers.2. Two hundred and eighty Cobb 500 broilers were assigned to four diets in a 2 × 2 factorial arrangement in a CRD. The factors were PA (low or high) and OS particle size (fine or coarse) in starter, grower and finisher diets. Data collected were performance, Ca digestibility, gastrointestinal pH and bone traits.3. On d 21, high PA increased intake (P < 0.05), gain (P = 0.099) and body weight (BW; P = 0.093) compared to low PA. On d 42, high PA increased BW (P = 0.086) and gain (P = 0.089) compared to low PA. High PA increased intake (P = 0.063), BW (P = 0.054) and gain (P = 0.056) compared to low PA on d 56. High PA improved liveability on d 56 (P < 0.05) compared to low PA. In birds fed coarse OS, crop and ileal pH were reduced (P < 0.05) by high PA on d 28. The OS × PA interaction was observed for ileal pH (P < 0.05) on d 56, where in birds fed coarse OS, low PA increased ileal pH. Fine OS increased crop (P = 0.056) and proventriculus pH (P < 0.05) on d 56. There were no treatment effects on calcium digestibility. In birds fed fine OS, high PA decreased the BS (P < 0.05).4. Overall, the study showed that a combination of high PA and coarse OS particle size improves the production performance of broilers, while low PA and coarse OS improve their bone health.

Xylo-oligosaccharide-based prebiotics upregulate the proteins of the Sus-like system in caecal Bacteroidetes of the chicken: evidence of stimbiotic mechanism

The present study was conducted to investigate the stimbiotic mechanism of xylo-oligosaccharide (XOS) in degrading the complex polysaccharides by the caecal bacteria of the chicken, by applying a proteomic approach. A total of 800 as-hatched Ross 308 broiler chicks were equally divided into 4 experimental pens (200 chicks per pen) at a commercial poultry barn, allocating 2 pens per treatment. Birds were fed ad libitum with 2 dietary treatments; CON (without XOS) and XOS (with 0.1g XOS/kg diet) from d 0 to 35. From each pen, 60 Individual birds were weighed weekly whereas caecal content was obtained from 5 birds cervically dislocated on d 35. The caecal bacteria were lysed and their proteins were quantified using label-free quantitative proteomic mass spectrometry. The results showed that XOS significantly increased (P < 0.05) bird weight on d 7, 14, 21, and 28, and body weight gain on d 7, 14, 21, and 35 compared to CON. However, no difference (P > 0.05) in body weight gain was observed from d 0 to 35 between CON and XOS. The proteomic analysis of caecal bacteria revealed that 29 proteins were expressed differently between the CON and the XOS group. Out of 29, 20 proteins were significantly increased in the XOS group compared to CON and 9 of those proteins belonged to the starch-utilizing system (Sus)-like system of the gram-negative Bacteroidetes. Bacteroides thetaiotaomicron (Bt) is a significant constituent of the human gut microbiota, known for its remarkable ability to hydrolyze most glycosidic bonds of polysaccharides. This microorganism possesses a 5-protein complex in its outer membrane, named the starch utilization system (Sus), responsible for adhering to, breaking down, and transporting starch into the cell. Sus serves as an exemplar system for numerous polysaccharide utilization loci that target glycans found in Bt and other members of the Bacteroidetes phylum. The proteins of the Sus-like system are involved in the degradation of complex polysaccharides and transportation of the oligosaccharides into the periplasm of the caecal bacteria where they are further broken down into smaller units. These smaller units are then transported into the cytoplasm of the cell where they are utilized in metabolic pathways leading to potential generation of short-chain fatty acids, thus improving the nutritive value of residual feed. In conclusion, XOS supplementation upregulates the expression of the proteins of the Sus-like system indicating its role as a stimbiotic.

Broiler chicken response to xylanase and fermentable xylooligosaccharide supplementation

A study was conducted to determine the effect of dietary fiber (DF), xylanase (XYL), xylooligosaccharides (XOS), and a combination of XYL and xylooligosaccharides (STBIO) on chicken growth performance, N-corrected apparent metabolizable energy (AMEn), and nutrient availability, characteristics of the gastrointestinal tract (GIT), and cecal content of short-chain fatty acids (SCFA). A 35-day experiment was performed on 1,920 as hatched Ross 308 broiler chicks, reared in 96 pens and fed ad libitum. Experimental diets were split into 2 phases: starter (0-21 d) and finisher (22-35 d). There were 2 basal diets, first contained 54% maize and in the second, 5% of the maize was replaced by wheat bran as DF. The diets were split into 4 batches: one of them was used as a control, and each of the others were supplemented either with XYL or XOS or with the STBIO. Each diet was fed to 12 pens following randomization. The data were analyzed in GenStat (20th edition) by ANOVA using a 2 × 4 factorial design. The addition of STBIO improved feed conversion ratio (FCR) and increased weight gain (WG) from 21 to 35 d and from 0 to 35 d (P < 0.05). The inclusion of DF had a negative effect on N and fat retention coefficients at 35 d as well as AMEn and dry matter retention at 21 and 35 d. At 21 d, neutral detergent fiber (NDF) retention was increased when xylanase and STBIO were added to the diet (P < 0.001) and at d 35 the highest retention was noted when the diet was supplemented with DF and XYL or STBIO (P = 0.001). There was no dietary effect on jejunum histomorphometry (P > 0.05). The addition of DF increased the concentration of cecal SCFA in particular valeric and propionic acid at 35-day-old birds (P < 0.05). It can be concluded that addition of STBIO in diet could provide benefits in terms of fiber degradation, WG, and feed efficiency.

The effect of different wheat varieties and exogenous xylanase on bird performance and utilization of energy and nutrients

The aims of the present study were to first, determine the xylan fractions of 10 different wheat cultivar samples and their response to treatment by the same commercial xylanase enzyme preparation. Second, use information obtained to select 5 of the wheats for use within a feeding experiment to determine whether the rate of xylan release can be used to predict the feeding value of the wheats when diets have been supplemented with xylanase. Treatment of 10 different wheat varieties by the same enzyme resulted in varying levels of hydrolysis. Soluble xylan content ranged from 7.85 to 14.40 and 3.20 to 5.13 (mg/g) when treated with and without xylanase, respectively. Oligosaccharide content ranged from 0.34 to 1.58 and 0.05 to 0.54 (mg/g) when treated with and without xylanase, respectively. Five of the 10 wheats were then selected based on the determined xylan fractions to use within a feeding experiment. A total of 360 male Ross 308 broilers were randomly allocated to 60 raised floor pens. A soybean meal (SBM) balancer feed was formulated to contain 12.07 MJ/kg apparent metabolizable energy (AME) and 392.9 g/kg crude protein (CP). Five diets were prepared by mixing 630 g/kg of each of the 5 experimental wheats with 370 g/kg of the balancer. Each diet was split into 2, one of which was supplemented with 100 g/MT of Econase XT (223,000 BXU/g), resulting in a total of 10 diets. The birds were fed the diets from 0 to 28 d of age. Wheat cultivar had an effect (P = 0.044) on feed intake (FI), while the addition of xylanase increased (P < 0.05) weight gain (WG) and improved feed conversion ratio (FCR). Various interactions were observed (P < 0.05) between wheat cultivars and xylanase for AME and nutrient utilization. This study suggests that wheats treated with the same xylanase, differ in their susceptibility to release soluble xylan and oligosaccharides, which may partially explain the varying performance and nutrient digestibility responses noted in the literature.

Effects of adaptation diet and exogenous enzymes on true metabolizable energy and cecal microbial ecology, short-chain fatty acid profile, and enzyme activity in roosters fed barley and rye diets

Three experiments evaluated effects of adaptation diet and exogenous β-glucanase and xylanase on TME_n of barley and rye. Single Comb White Leghorn roosters were fed adaptation diets based on corn/soybean meal (SBM), barley/SBM with and without β-glucanase, or rye/corn/SBM with and without xylanase for 4 wk. In Experiments 1 and 2, after the adaptation period, TME_n was determined using a 48 h precision-fed rooster assay for 100% barley or 100% rye diets with or without β-glucanase or xylanase, respectively. Experiment 3 consisted only of feeding adaptation diets for 4 wk. Cecal samples were collected at the end of experiments for microbial ecology, short-chain fatty acid (SCFA) profiles, and enzyme activity analyses. In Experiments 1 and 2, β-glucanase increased (P < 0.05) TME_n of barley, and there was no significant effect of adaptation diet on TME_n values. Total cecal Eubacteria and Ruminococcaceae were decreased (P < 0.05) and Escherichia coli were increased (P < 0.05) at the end of the TME_n assay compared with the end of the adaptation period (with no TME_n assay). There was a large decrease (P < 0.05) for most cecal SCFA at the end of the TME_n assay compared with the end of the adaptation period. Both cecal β-glucanase and xylanase activity were increased for birds fed adaptation diets containing the respective enzyme. In Experiment 3, there were no consistent effects of adaptation diet on cecal microbial profiles or SCFA but cecal β-glucanase activity was increased (P < 0.05) by exogenous β-glucanase for barley and cecal xylanase activity was increased (P < 0.05) by exogenous xylanase for rye. Overall, the results indicated that TME_n of barley was increased by exogenous β-glucanase, adaptation diet did not significantly influence the TME_n response to the dietary enzymes, and cecal fermentation (based on cecal SCFA) was greatly reduced by the TME_n assay. Cecal β-glucanase and xylanase activity, however, were often increased by feeding high barley and high rye diets containing exogenous enzymes.

The influence of nutrition on intestinal disease with emphasis on coccidiosis

Ever since the poultry industry began to intensify early last century, coccidiosis has been a significant problem with which it has had to contend. Losses due to mortality and morbidity can be significant and before the advent of control agents there were several practices, some of which were nutritional, which were implemented to limit these losses. The development of coccidiostats reduced these problems considerably and as a result some of the more extreme intervention measures were no longer necessary. Modern day interpretation of what may have been happening with some of these early interventions provide interesting insights into what may be possible today should cocciodiostats be removed. More recent research has also indicated that the diet has a significant influence on the ability of poultry to resist and resolve an infection through direct and indirect effects on the pathogen, the immune system and on the litter. This paper reviews the role of dietary ingredients and nutrients on the pathogen to establish and the host to resist such an infection. There is clearly no panacea, but the combination of a few practices may reduce the overall challenge experienced by the poultry producer.

Rapeseed meal processing and dietary enzymes modulate excreta inositol phosphate profile, nutrient availability and production performance of broiler chickens

This study aimed to assess the effect of rapeseed meal (RSM) processing method, where solvent extraction occurred under standard industry conditions (ST) or cold-pressed hexane extraction was employed (MT), and exogenous enzyme supplementation (phytase [PHY] and xylanase [XYL]) alone or in combination on key nutritional factors of broiler chickens. A randomized control experiment was performed using 144 male Ross 308 broilers in a 2 × 2 × 3 factorial arrangement. Three diets including a nutritionally complete wheat-based basal diet (BD), a diet containing 200 g/kg of RSM extracted under ST and another diet containing 200 g/kg of RSM extracted under MT were produced. Each diet was then split into 4 parts and was fed as is, or supplemented with PHY at 1,500 FTU/kg or XYL at 16,000 BXU/kg, alone or in combination, resulting in 12 diets in total. Response criteria: feed intake (FI), weight gain (WG), and feed conversion ratio (FCR), from 7 to 21 d age, AMEn, retention coefficients for dry matter (DMR), nitrogen (NR), fat (FR), and the profile of inositol phosphate esters (IP2-6) and myo-inositol (MI) in excreta. Diets containing MT had higher AMEn compared to ST diets (P < 0.05). There was RSM by PHY interaction for FI, as only birds fed MT diet responded to PHY supplementation with reduced FI and FCR (P < 0.001). Feeding XYL reduced overall FI and FCR (P < 0.05). Feeding PHY reduced IP6 and increased MI in excreta (P < 0.001). Feeding XYL and PHY in combination reduced MI in excreta compared to PHY only (P = 0.05). Compared to BD, birds fed RSM diets had an increased IP6 (P < 0.05) and MI concentration in excreta (P < 0.01). This may be due to IP ester differences in RSM and BD.

Dietary soluble non-starch polysaccharide level and xylanase influence the gastrointestinal environment and nutrient utilisation in laying hens

1. The objective of this study was to examine the influence of dietary soluble non-starch polysaccharide (sNSP) level and xylanase supplementation on productive performance, viscosity and pH along the gastrointestinal tract in laying hens. Excreta moisture content, ileal and caecal microbiota and short chain fatty acid (SCFA) composition and apparent total tract nutrient utilisation was measured.2. Hyline Brown laying hens (n=144) were housed individually at 25 weeks of age and allocated to one of four wheat-based dietary treatments in a 2 × 2 factorial arrangement, consisting of two levels of sNSP (High 13.40 g/kg or Low 11.22 g/kg), with or without xylanase (0 or 12,000 BXU/kg). Birds were fed the dietary treatments for 56 days.3. Increasing dietary sNSP increased jejunum viscosity, degradability of total NSP, total tract flow of insoluble arabinose, and succinic acid concentration in the caeca (P<0.05). Feeding high sNSP decreased excreta moisture content, total tract energy retention and free oligosaccharide, total tract flow of soluble and insoluble galactose and insoluble rhamnose and fucose, and ileal acetic and lactic acid concentrations (P<0.05), and tended to reduce egg production (P=0.058).4. Supplementation with xylanase resulted in reduced jejunum and ileum viscosity, caecal pH, excreta moisture, flow of soluble arabinose and glucose and insoluble arabinose and xylose, caecal concentration of Lactobacillus sp. and isobutyric and succinic acid, and ileal concentration of Bacillus sp. and total anaerobic bacteria (P<0.05). Xylanase application also increased energy retention and insoluble and total NSP degradation, and caecal abundance of Bifidobacteria sp. and valeric acid (P<0.05).6. These results reiterated the ability of xylanase to improve nutrient digestibility and reduce excreta moisture content in laying hens, and highlighted the importance of considering dietary sNSP level in laying hen diets.

Effect of sodium sources and exogenous phytase supplementation on growth performance, nutrient digestibility, and digesta pH of 21-day-old broilers

The effect of sodium chloride (NaCl) and NaCl+sodium hydrogen carbonate (NaHCO3) and supplemental phytase (0, 500, 1,000, and 2,000 FTU/kg) on performance, nutrient digestibility and utilization, and digesta pH of male broiler chickens were investigated in a 2 × 4+1 factorial arrangement of treatments in a completely randomized design with 6 replicate cages of 8 birds per replicate. Data were analyzed as a 2 × 4 factorial with contrast between the positive control and the diets containing 0 FTU phytase. Phytase supplementation linearly improved (P < 0.05) average body weigh gain (BWG) and feed intake (d 0-14 and 0-21). Apparent jejunal dry matter (DM) digestibility and digestible energy in birds fed diets containing only NaCl increased (linear and quadratic; P < 0.05) with phytase supplementation whereas quadratic (P < 0.05) effect was observed in birds fed diets containing a combination of NaCl and NaHCO3. Phytase supplementation improved (linear and quadratic; P < 0.05) apparent ileal nitrogen and P digestibility. Apparent utilization of DM, nitrogen, energy, and metabolizable energy increased (linear; P < 0.05) with increasing level of phytase supplementation. Apparent P utilization increased (linear and quadratic; P < 0.05) for both sodium sources but calcium utilization only increased (linear; P < 0.05) with the combination of NaCl and NaHCO3. Bone breaking strength (linear and quadratic) and bone ash (linear) increased (P < 0.05) with phytase supplementation. The combination of NaCl and NaHCO3 resulted in lower (P < 0.05) pH of digesta in the proximal ileum whereas the pH of the digesta in the distal ileum (linear) and the average pH of ileal contents (linear and quadratic) increased (P < 0.05) with phytase supplementation. Results from this study showed that birds' performance and utilization of nutrients and energy by broilers in the presence of phytase was, in general, not influenced by the source of sodium in the diet. Data from this study showed that NaHCO3 can replace a portion of NaCl in the diet of broilers supplemented with phytase without any significant negative effect on performance and that the 2,000 FTU phytase level resulted in better BWG and feed intake as well nutrient and energy utilization.

Requirement of digestible calcium at different dietary concentrations of digestible phosphorus for broiler chickens. 1. Broiler starters (d 1 to 10 post-hatch)

An experiment was conducted to determine the digestible calcium (Ca) and digestible phosphorous (P) requirements of 10-day-old broiler chickens. Fifteen corn-soybean meal-based diets containing 3.3, 3.9, 4.4, 5.0, and 5.5 g/kg standardized ileal digestible (SID) Ca and 4.0, 5.0, and 6.0 g/kg SID P was fed to broilers from d 1 to 10. Each experimental diet was randomly allocated to 6 replicate cages (12 birds per cage). Body weight and feed intake were recorded at the start and end of the experiment and the feed conversion ratio was calculated. On d 10, birds were euthanized to collect ileal digesta, toes and tibia for the determination of digestible Ca and P, toe ash concentration and the concentrations of ash, Ca, and P in tibia. Titanium dioxide (5 g/kg) was included in all diets as an indigestible indicator for apparent ileal digestibility measurements. Total excreta were collected from d 1 to 10 for the measurement of total tract retention of Ca and P. Fixed effects of the experiment were dietary concentrations of SID Ca and SID P and their interaction. If the interaction or main effects were significant (P < 0.05), the parameter estimates for second-order response surface model were determined using General Linear Model procedure of SAS software. The growth performance, bone mineralization and mineral utilization of broiler starters were found to be optimized at 5 g/kg SID P concentration. Required SID Ca for maximum weight gain and bone mineralization was determined to be 3.32 and 4.36 to 4.78 g/kg, respectively, at 5 g/kg SID P concentration, which correspond to SID Ca to SID P ratios of 0.66 and 0.87 to 0.96, respectively. The estimated SID Ca requirement for weight gain is lower than the current Ca recommendation (9.6 g/kg total Ca or 4.4 g/kg SID Ca) for broiler starters. However, bone mineralization is maximized around the current total Ca recommendation at 8.9 to 9.8 g/kg (4.36-4.78 g/kg SID Ca) and indicates that bone mineralization requires more Ca than growth performance.

Effects of phytase supplementation and increased nutrient density on growth performance, carcass characteristics, and hypothalamic appetitive hormone expression and catecholamine concentrations in broilers from 1 to 43 days of age

Two experiments were conducted to evaluate extra-phosphoric effects of phytase and nutrient density on growth performance, meat yield, and hypothalamic appetitive hormone expression and catecholamine concentrations of broilers. Experiment 1 determined differences of digestible amino acid concentrations and AME_n using 256 Yield Plus × Ross 708 broilers (32 cages, 8 birds/cage) fed diets without or with 4,500 phytase units (FTU)/kg inclusion (16 reps/treatment). In Experiment 2, 832 Yield Plus × Ross 708 broilers (32 pens; 26 birds/pen) were provided diets in a 2 × 2 factorial arrangement consisting of 2 nutrient contents (without or with increased density) and 2 phytase inclusions (0 or 4,500 FTU/kg). Increased nutrient density was formulated to contain 0.007, 0.015, 0.013, 0.021, 0.024%, and 61 kcal/kg higher digestible SAA, Lys, Thr, Val, Ile, and AME_n (from Experiment 1) respectively, compared with the control diet. Growth performance was determined at 14, 28, and 40 d of age and carcass characteristics at 41 d of age. At 43 d of age, plasma inositol, hypothalamic appetitive hormone expression, and catecholamine concentrations were determined from 4 birds/pen. Additive effects of phytase inclusion and increased nutrient density resulted in the lowest (P < 0.05) feed conversion from 1 to 40 d of age and the heaviest (P < 0.01) breast meat weights among dietary treatments. Phytase addition numerically increased feed intake (P = 0.06) and BW gain (P = 0.051) compared with birds fed diets without phytase from 1 to 40 d of age. Plasma inositol and dopamine concentrations were 2.3- and 1.2-fold higher (P < 0.01), respectively, in broilers fed phytase-added diets than birds fed diets without phytase inclusion. However, mRNA expression of neuropeptide Y, agouti-related peptide, proopiomelanocortin, cholecystokinin A receptor, ghrelin, and serotonin concentration were not different (P > 0.05) among treatments. These data indicated additive effects of phytase supplementation and increased nutrient density on growth performance and meat accretion of broilers. However, the influence of phytase on feed intake warrants future research.

Comparison of the apparent ileal calcium digestibility of limestone in broilers and layers

1. The apparent ileal calcium (Ca) digestibility coefficients of two limestone sources in growing broilers and layers were determined in two separate experiments.2. In each experiment, two maize-based diets were developed with two limestone sources (A, experiment 1 and B, experiment 2) to contain either 8.0 g/kg Ca for broilers or 40 g/kg Ca for layers. The two sources differed in particle size, with limestone A being finer and limestone B being coarser. Each experimental diet was randomly allotted to six replicate cages and offered for 3 days from 19 to 21-day post-hatch to broilers and during 40 weeks of age to layers. The total tract Ca retention was also measured using the indicator ratios in the diet and excreta.3. In both experiments, the apparent ileal Ca digestibility, gizzard pH and gizzard Ca concentration were higher (P < 0.05) in layers than in broilers. The apparent ileal digestibility coefficient of limestone A for broilers and layers was 0.50 and 0.62, respectively. The corresponding values for limestone B were 0.43 and 0.70, respectively. The apparent total tract retention of Ca was similar (P > 0.05) between broilers and layers in both experiments, and between the two sources.4. The data show that the layers are more efficient in absorbing Ca from limestone than broilers.

Growth performance, real-time gizzard pH and calcium solubility in the gut of broiler chickens is dependent on the interaction between dietary calcium concentration and limestone particle size

1.The purpose of this study was to determine the effect of limestone particle size and dietary Ca concentration on performance, real-time gizzard pH, and Ca and P solubility in the gastrointestinal tract of 21d broiler chickens.2. A total of 576, one-day-old Ross 308 male broilers were randomly allocated among 4 treatments, with 8 replicate pens, and 18 birds per pen. Treatments were arranged as a 2 × 2 factorial consisting of two particle sizes of limestone (coarse, CL, 1200 µm; fine, FL, 44 µm) and two Ca concentrations (9.6 or 6.0 g/kg). On d 19 and 20, four birds per treatment were administered Heidelberg pH capsules and readings monitored for 3 h.3. Reducing Ca concentration from 9.6 to 6.0 g/kg had no effect on d 21 weight gain or FCR of birds fed CL; however, feeding FL at 9.6 g/kg Ca increased weight gain by 10% and reduced FCR by 5% compared to FL at 6.0 g/kg Ca (P < 0.001).4. Average gizzard pH readings ranged from pH 0.67 to 3.01 across all treatments. Birds fed CL at 6.0 g/kg Ca had lower average gizzard pH compared to birds fed 9.6 g/kg Ca, while birds fed FL at 6.0 g/kg Ca had higher gizzard pH than birds fed CL at both Ca concentrations, but was comparable to birds fed FL at 9.6 g/kg Ca (P < 0.001).5. For birds fed CL at 6.0 g/kg Ca, soluble Ca in the gizzard was approximately 40% lower (P < 0.05) than all other treatments, and reduced by 44% (P < 0.05) in the small intestine compared with birds fed FL at 6.0 g/kg Ca.6. These findings demonstrated that the effect of Ca concentration on gizzard pH, Ca solubility and broiler performance was dependent on limestone particle size and suggested that solubility per se had little relevance to performance.

Growth performance and total tract digestibility in broiler chickens fed different corn hybrids

The aim of the present study was to investigate the variability in nutrient digestibility associated with corn genetic background and its influence on the feeding value for broiler chickens. A total of 960 1-day-old male broiler chicks (Ross 308) were distributed in eight treatments, with 12 pens per treatment and 10 birds per pen in a 42-day study. Eight corn samples (Variety 1 to Variety 8) were selected based on their nutrient composition. A fixed amount of each corn (577 g/kg in the starter diets and 662 g/kg in the finisher diets) was used to formulate feeds. Diets were offered ad libitum in pellet form. Performance parameters were determined at d 21 and d 42, and excreta samples collected at d 21 to determine energy, organic matter and dry matter (DM) whole-tract digestibility. The results revealed a decrease (P < 0.05) in body weight (BW) and feed intake in birds fed variety 8 compared to other varieties at d 21. The lowest whole tract DM and energy apparent digestibility were also observed for the variety 8 diet (P < 0.05), together with varieties 3 and 5. Energy digestibility was higher in varieties 2, 4 and 7 (P < 0.05). Multivariate analysis revealed that corn protein concentration was positively correlated with vitreousness (r = 0.60, P = 0.054) and the arabinose:xylose ratio (r = 0.67, P < 0.05) and negatively correlated with starch (r = -0.62, P < 0.05). Soluble non-starch polysaccharide content was negatively correlated with the protein solubility index (r = -0.88, P < 0.05). In addition, corn protein concentration was negatively correlated (P < 0.05) with 21-d BW (r = -0.71) and weight gain (r = -0.62). In conclusion, the corn genetic background influenced the nutrient digestibility and growth performance of broiler chickens. The content and nature of the non-starch polysaccharides were found to be two of the main factors affecting the solubility and availability of nutrients in corn, and could be the reason for the negative effects on the performance of broiler chickens as shown in the present study.

True ileal calcium digestibility in soybean meal and canola meal, and true ileal phosphorous digestibility in maize-soybean meal and maize-canola meal diets, without and with microbial phytase, for broiler growers and finishers

1. Published data on the ileal Ca digestibility in soybean meal (SBM) and canola meal (CM), and the effect of microbial phytase on the Ca digestibility of these ingredients are limited. Therefore, two experiments were conducted, with the primary objective of determining the true ileal digestibility of calcium (Ca) in SBM and CM, without and with microbial phytase, during broiler grower (Experiment 1) and finisher (Experiment 2) periods. A secondary objective was to investigate the influence of microbial phytase on the true ileal digestibility of phosphorus (P), apparent digestibility of nitrogen (N) and minerals, and phytate disappearance in maize-SBM and maize-CM diets. Six experimental diets based on SBM and CM, with three phytase doses (0, 500 and 2000 FTU/kg), were fed to broilers from day 18 to 21 (Experiment 1) or 39 to 42 (Experiment 2) post-hatch. A Ca- and P-free diet, with no added phytase, was also developed to determine the endogenous Ca and P losses. Titanium dioxide was incorporated in all diets as an indigestible indicator. Each experimental diet was randomly allocated to six replicate cages (eight birds per cage). Apparent ileal digestibility was calculated using the indicator method and the true ileal digestibility was calculated by correcting for endogenous losses. Apparent total tract retention (ATTR) of Ca and P was also measured.2. Ileal endogenous losses of Ca and P were determined to be 236 and 310 mg/kg of dry matter intake (DMI), respectively, in broiler growers and 29 and 130 mg/kg of DMI, respectively, in broiler finishers. True ileal Ca digestibility coefficients of SBM and CM, without added phytase, were determined to be 0.51 and 0.53, respectively, in broiler growers and 0.33 and 0.22, respectively, in broiler finishers. Increasing phytase doses increased (P < 0.05) the true ileal Ca digestibility of CM in both broiler growers and finishers, but Ca digestibility of SBM increased (P < 0.05) only at the superdose (2000 FTU/kg) in broiler finishers. The ATTR of Ca (P < 0.001) in growers was higher in CM than in SBM and was increased in both ingredients by increasing phytase doses. In finishers, the ATTR of Ca was increased (P < 0.001) by both phytase doses in CM, but only by the superdose in SBM, resulting in an ingredient × phytase interaction (P < 0.001).3. True ileal P digestibility coefficients of maize-SBM and maize-CM diets, without added phytase, were determined to be 0.89 and 0.66, respectively, in broiler growers and 0.82 and 0.57, respectively, in broiler finishers. Supplemental phytase increased (P < 0.05) the true ileal P digestibility of the maize-CM diet in both broiler growers and finishers. However, the P digestibility of the maize-SBM diet was increased (P < 0.05) in broiler finishers only at the superdose (2000 FTU/kg). The ATTR of P was higher (P < 0.001) in the maize-SBM diet during both periods.4. The apparent ileal digestibility of N, Mg, K and Mn was higher (P < 0.001) in the maize-SBM diet for broiler growers and finishers. Phytase addition had no effect (P > 0.05) on the apparent digestibility of N and minerals in growers and finishers.5. Increasing phytase doses increased IP6 disappearance in the maize-CM diet, but not in the maize-SBM diet, resulting in an ingredient × phytase interaction (P < 0.001) for growers and finishers.6. In conclusion, true ileal Ca digestibility coefficients of SBM and CM for broilers were determined in this study. The findings confirmed the influence of broiler age of Ca digestibility. Superdosing of phytase increased the digestibility and ATTR of Ca in CM and SBM by two-fold compared to the normal phytase dose.

The effects of the fiber source and xylanase supplementation on production, egg quality, digestibility, and intestinal morphology in the aged laying hen

This study was conducted to evaluate the effects of the fiber source (wheat bran [WB] or sugar beet pulp [SBP]) and xylanase supplementation on production, egg quality, ileal digestibility, intestinal morphology, and gastrointestinal pH in aged laying hens. A total of 540 laying hens (Lohman LSL Lite; 70 wk of lay) were randomized into 10 treatments (6 replicate cages of 9 birds) consisting of a corn soy control supplemented with 0, 3, or 6% WB or SBP with or without xylanase (100 mg of xylanase preparation per kg) for a period of 9 wk in a 5 × 2 factorial arrangement. Hens fed with the diets containing either of the levels of SBP or 6% WB had lower hen-day production, and addition of the enzyme improved hen-day production (P < 0.05), but it could not compensate for the lost production due to the higher levels of either of the fiber sources. Supplementation of 6% SBP to the control diet decreased egg mass (P < 0.05). All fiber-supplemented diets significantly decreased ADFI, which was restored on enzyme addition, with the exception of 3% WB diet. Treatments had no effects on egg weight, feed conversion ratio, egg quality, and serum and carcass traits, except for ileum weight, which was greater in hens fed with the 6% SBP diet (P < 0.05). Adding 3% SBP increased ileal DM digestibility (P < 0.05). Addition of 3% WB improved jejunal villus height, villus height-to-crypt depth ratio, and villus surface area (P < 0.05). Villus surface area, DM, organic matter, and protein digestibility increased as a result of enzyme supplementation (P < 0.05). Cecal pH was reduced on feeding diets containing 3% WB, containing 3% SBP, and with enzyme supplementation (P < 0.05). In conclusion, addition of 3% WB in a corn soy control diet has the potential to improve small intestine morphology in older hens without adverse effects on performance, especially if accompanied by the use of an enzyme, which simultaneously improved morphological traits and nutrient digestibility.

Inositol and gradient phytase supplementation in broiler diets during a 6-week production period: 2. Effects on phytate degradation and inositol liberation in gizzard and ileal digesta contents

An experiment was conducted to evaluate effects of dietary phytase and inositol supplementation on phytate degradation in gizzard and ileal digesta contents of broilers from 1 to 43 d of age. One thousand nine hundred and twenty Yield Plus × Ross 708 male chicks were placed in 64 floor pens (30 birds/pen). Each pen received 1 of 8 dietary treatments from 1 to 43 d of age. Treatment 1 was formulated to contain 0.165 and 0.150% lower calcium and phosphorus, respectively, than treatment 7. Treatments 2 to 6 were formulated by adding phytase at 500, 1,500, 4,500, 13,500, and 40,500 phytase units (FTU)/kg, respectively, to treatment 1. Treatment 8 was established by adding inositol to treatment 7 based on the maximum inositol liberation in treatment 6. At 15, 29, and 43 d of age, gizzard contents, ileal digesta, and blood were collected for analysis of inositol and inositol phosphate (IP) 2, 3, 4, 5, and 6 concentrations. Increasing phytase from 0 to 40,500 FTU/kg resulted in log-quadratic reductions (P < 0.01) of inositol pentaphosphate and inositol hexakisphosphate concentrations in the gizzard and ileal digesta contents of broilers at 15, 29, and 43 d of age. The increase in phytase doses in treatments 1 to 6 reduced IP3 and IP4 concentrations in a log-quadratic manner (P < 0.05) at each collection period in gizzard contents but only at 43 d of age in the ileal digesta of broilers (P < 0.01). Log-quadratic increases (P < 0.05) of inositol concentrations were observed in gizzard and ileal digesta contents when increasing phytase activity from 0 to 40,500 FTU/kg at each collection period, which translated to a log-quadratic increase (P < 0.01) in plasma inositol concentration of broilers at 15, 29, and 43 d of age. Phytase supplementation up to 40,500 FTU/kg may benefit broilers by reducing phytate concentrations in the gizzard and ileal digesta contents. Moreover, inositol release in the ileal digesta may translate to increased plasma inositol concentration.

Inositol and gradient phytase supplementation in broiler diets during a 6-week production period: 1. effects on growth performance and meat yield

An experiment was conducted to evaluate effects of inositol and gradient phytase supplementation on growth performance and meat yield of broilers from 1 to 41 d of age. A total of 1,920 Yield Plus × Ross 708 male chicks were placed in 64 floor pens (30 birds per pen). Each pen received one of the 8 dietary treatments (8 replicate pens) from 1 to 15, 16 to 29, and 30 to 40 d of age. Treatment 1 was formulated to contain 0.165 and 0.150% lower calcium and phosphorus, respectively, than treatment 7 (positive control). Phytase was added to treatment 1 at concentration of 500, 1,500, 4,500, 13,500, and 40,500 phytase units (FTU)/kg to establish treatments 2 to 6, respectively. Treatment 8 was formulated by adding inositol to treatment 7 based on the expected inositol liberation in treatment 6. Feed and birds were weighed at 1, 15, 29, and 40 d of age to determine BW gain, feed intake, and feed conversion. Twelve birds per pen were processed at 41 d of age to determine carcass characteristics. From 1 to 40 d of age, log-quadratic effects of phytase (treatments 1–6) were observed for BW gain (P = 0.002) and feed conversion in broilers (P = 0.018), whereas feed intake increased log-linearly (P = 0.045). The addition of 40,500 FTU/kg of phytase increased cumulative BW gain (P = 0.001) and decreased cumulative feed conversion (P = 0.005) by 4.7 and 2.6%, respectively, compared with birds subjected to treatment 8. Log-quadratic effects of phytase additions were observed for carcass (P < 0.001) and breast meat weights (P = 0.004). Growth performance and carcass characteristics of broilers subjected to treatment 7 were similar (P > 0.05) to those of birds subjected to treatment 8. These data demonstrate that the extraphosphoric effects of phytase may be associated with increased feed intake of broilers. Inositol supplementation did not provide additional benefits to broilers in this study.

Interactive effect of dietary calcium and phytase on broilers challenged with subclinical necrotic enteritis: part 2. Gut permeability, phytate ester concentrations, jejunal gene expression, and intestinal morphology

Calcium has the capacity to interact with phytate-P to form Ca-phytate complexes and decrease the ability of exogenous phytase to degrade phytic acid. This study investigated the hypothesis that high dietary Ca would impair gut permeability, phytate esters (inositol x-phosphate, IPx: IP3, IP4, IP5, and IP6) degradation, jejunal gene expression, and intestinal morphology. Ross 308 day-old male broilers (n = 768) were distributed into 48-floor pens each housing 16 birds in a factorial arrangement. Factors were NE challenge-no or yes; phytase level of 500 or 1,500 FTU/kg, and Ca level 0.6 or 1.0% starter, 0.5 or 0.9% grower, 0.4 or 0.8% finisher with available P in each phase. Challenged birds were gavaged with 3 field strains of Eimeria on day 9 and 108 CFU per mL of Clostridium perfringens Strain EHE-NE18 on day 14 and day 15. A phytase × Ca interaction was observed in the ileum for IP3 (P < 0.01), IP4 (P < 0.05), and IP6 (P < 0.01). The IP3 and IP4 concentrations were similar for both doses of phytase in the presence of low Ca, but with high Ca, both increased significantly but to a greater extent when the high dose of phytase was used. While IP6 concentrations were low and similar between both doses of phytase at low Ca levels, increasing dietary Ca levels increased IP6 concentrations regardless of phytase dose, but the effect was greater in the low phytase diet. A phytase × Ca interaction was detected for vitamin D receptor (VDR) (P < 0.05) expression where bird fed low phytase and low Ca recorded the highest expression of VDR, all other treatments being equivalent. The challenge decreased crypt depth to villus height ratio (P < 0.001). Challenge birds had higher fluorescein isothiocyanate dextran (P < 0.05) in blood compared with unchallenged birds. Thus, high Ca and high phytase, while not the best for IP6 destruction, did not lead to huge reductions in indicators of gut health.

The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance. 2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days. 3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age). 4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction). 5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present. 6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.

Efficacy and stability of a novel silica supplement for improving bone development in broilers

1. The essentiality of silicon for skeletal development has been established, but the adequacy of bioavailable silicon supply in broiler diets has not been considered for 30 years, despite average daily weight gain of birds increasing by almost a third over that time. Therefore, two studies were undertaken to investigate whether modern strains of broiler chicken benefit from diet supplementation with bioavailable silica. 2. Trial 1 was a 2x2x2 factorial study where six replicate pens of seven chicks were fed one of the eight freshly prepared diets from hatch to 21 days of age, with bodyweight gain and feed intake recorded weekly. Diets combined the following factors: silicon supplement fed at 0 ppm or 1000 ppm, phytase levels of either 0 FTU/kg or 1500 FTU/kg and either 0.6% or 0.7% Ca. Tibia were analysed for bone breaking strength, extent of tibial dyschondroplasia and feet measured for bone ash and pododermatitis score. 3. Trial 2 used a 0.7% Ca with 1500 FTU phytase diet as the control and compared this with the same diet containing either 1000 ppm silicon (MONO-Si) freshly added each week or 1000 ppm silicon added in a single, advance-prepared batch per feeding phase. Each diet was fed to nine pens of seven birds from 0 to 35 d with feed consumption and weight recorded weekly. Two birds per pen were euthanised on d 14, 21 and 35 and tibias collected for measurement of bone breaking strength, ash and mineral content. Serum was collected for Si content. 4. Univariate analysis of means from each trial showed that silica supplementation improved bird weight gain over the starter phase, though there was no effect on feed conversion. 5. Bone strength improved with added silica in both studies, without affecting bone mineral content; indicating that modern strains of broiler may require dietary supplementation with bioavailable silicon.

Interactive effect of 2 dietary calcium and phytase levels on broilers challenged with subclinical necrotic enteritis: part 1-broiler performance, gut lesions and pH, bacterial counts, and apparent ileal digestibility

This study investigated the hypothesis that high dietary calcium (Ca) would stimulate necrotic enteritis (NE) and reduce performance, gut health, and nutrient digestibility, and if increased, phytase would reduce NE. Ross 308 male broilers (n = 768) were randomly distributed to 8 treatments in a factorial arrangement. Factors were NE challenge (no or yes), phytase level (500 or 1,500 FTU/kg using 500 FTU/kg matrix values), and Ca level (0.6 or 1.0% starter, 0.5 or 0.9% grower, 0.4 or 0.8% finisher) with the same level of available P (0.40 S, 0.35 G, and 0.35 F). There were 48 pens, 16 birds per pen and 6 replications. Half of the birds were challenged with Eimeria spp on day 9 and 10⁸ CFU per mL of Clostridium perfringens strain EHE-NE18 on day 14 and 15. Gain was higher in birds fed high phytase on day 14 (P < 0.01), day 21 (P < 0.01), day 28 (P < 0.01), and day 35 (P < 0.01). Birds fed high phytase had greater livability on day 21 (P < 0.01). Ca was more digestible in high-Ca diets on day 16, and an NE × Ca interaction (P < 0.05) showed this effect to be more pronounced in unchallenged than in challenged birds. A challenge × Ca interaction for apparent ileal digestibility (AID) of crude protein (CP) (P < 0.05) indicated lower AID of CP in challenged birds fed high Ca. The challenge decreased AID of Ca (P < 0.01). Ca level had no impact on C. perfringens count, but it decreased Lactobacillus (P < 0.05) and Bifidobacteria (P < 0.05) populations in the ceca. High dietary Ca decreased feed conversion ratio. Overall (42 D), the highest WG was observed in unchallenged birds fed high Ca and high phytase with the lowest WG observed in NE-challenged birds fed low Ca and low phytase. The results suggest that full matrix values for high doses of phytase may be appropriate during NE challenge.

Influence of meat and bone meal, phytase, and antibiotics on broiler chickens challenged with subclinical necrotic enteritis: 2. intestinal permeability, organ weights, hematology, intestinal morphology, and jejunal gene expression

Undigested proteins entering the hindgut may favor the proliferation of Clostridium perfringens. Using phytase to eliminate the need for meat and bone meal (MBM) as a P source may reduce potential infection with C. perfringens. A study was conducted to determine the impact of MBM, phytase, and antibiotics (AB) on intestinal permeability and morphology, organ weights, and jejunal gene expression in Ross 308 chickens challenged with subclinical necrotic enteritis (NE). Male Ross 308-day-old chicks (672 each) were randomly allocated to 8 treatments with 6 replicate pens each housing 14 birds. A 2 × 2 × 2 factorial arrangement of treatments was used: MBM (no or yes); AB (no or yes-Zn bacitracin 100 in S and 50 ppm in G/F and salinomycin Na 60 ppm in all phases); phytase (500 or 1,500 FTU/kg, both using 500 FTU matrix values) using wheat-SBM-canola meal diets. Birds were challenged with Eimeria spp on day 9, and C. perfringens strain EHE-NE18 on day 14 and 15. An AB × MBM interaction (P < 0.05) was detected for relative gizzard weight (with contents) being lower in birds fed MBM and AB compared to those fed MBM and no AB. A MBM × AB interaction (P > 0.01) was detected for lymphocyte counts being lower with MBM and AB compared to MBM without AB. A phytase × AB interaction (P < 0.05) was observed for villi length being increased with high phytase and no AB compared to with AB. Inclusion of MBM increased (P < 0.05) blood FICT-d concentration, whereas AB decreased it (P < 0.05). Antibiotics increased RBC (P < 0.05), Hgb (P < 0.05), and PCV (P < 0.05) and expression of Ca-binding protein, CALB1 (P > 0.05). Inclusion of MBM decreased expression of MUC2 (P < 0.05). Results indicate that dietary MBM has a detrimental effect on gut health of broilers but this may be counteracted using AB.

Arabinoxylan-oligosaccharides kick-start arabinoxylan digestion in the aging broiler

While arabinoxylans (AX), an important dietary fiber fraction of wheat-based broiler diets, are known for exerting antinutritional effects in the gastrointestinal (GI) tract of broilers, the prebiotic potential of arabinoxylan-oligosaccharides (AXOS) is also well-documented. However, inconsistent performance responses as well as the effectiveness of low amounts of AXOS used in diets of previously conducted experiments put into question the classical prebiotic route being the sole mode of action of AXOS. The objective of this study was to investigate the effects of dietary AXOS addition on the rate of AX digestion in the gastrointestinal tract of broilers as a function of broiler age to gain more insight into the mode of action of these oligosaccharides. A feeding trial was performed on 480 one-day-old chicks (Ross 308) receiving a wheat-based diet supplemented with or without 0.50% AXOS, containing no endoxylanases. Digesta samples from ileum and caeca and fecal samples were analyzed for AX content, AX digestibility, intestinal viscosity, and microbial AX-degrading enzyme activities at 6 different ages (day 5, 10, 15, 21, 28, 35). Chicks fed from hatching with 0.50% AXOS demonstrated a higher ileal viscosity (P < 0.05). Also higher levels of AX solubilization and fermentation compared to control birds at 10 D were observed. This was noted by the higher total tract AX digestibility of water-extractable AX (WE-AX) and total AX (TOT-AX) at this age (P < 0.05). Although no significant difference in AX-degrading enzyme activities was observed among the dietary treatments, AXOS supplementation in young broilers was shown to stimulate or "kick-start" dietary AX digestion, thereby speeding up the development of a fiber-fermenting microbiome in the young broiler. This stimulation effect of AXOS could enable greater functional value to be extracted from dietary fiber in broiler feeds.

Interactive effect of dietary calcium and phytase on broilers challenged with subclinical necrotic enteritis: 3. Serum calcium and phosphorus, and bone mineralization

Calcium is chelated by phytic acid and forms phytate-mineral complexes reducing Ca availability and the ability of phytase to hydrolyze phytate. An increased Ca concentration in the gut favors the activity of Clostridium perfringens (C. perfringens). Therefore, it was hypothesized that high dietary calcium with high dietary phytase would decrease serum Ca and P and bone mineralization during necrotic enteritis occurrence. A total of 768 one-day-old Ross 308 male chicks were randomly allocated to 8 treatments with 6 replicate pens, each housing 16 birds. A 2 × 2 × 2 factorial arrangement of treatments was applied: dietary Ca (0.6 or 1.0%), phytase (500 or 1,500 FTU/kg), and challenge (no or yes). Half of the birds (384) were challenged with Eimeria spp. on day 9 and C. perfringens strain EHE-NE18 on day 14 and 15. Blood was collected from 2 birds per pen to determine Ca, P, and parathyroid hormone in the serum. The middle toe, tibia, and femur were excised from 2 birds per pen on day 16 and 29 for determination of ash, breaking strength (BS), and mineral concentration. The challenge decreased (P < 0.05) serum Ca⁺ in birds regardless of dietary Ca level (day 16). There was a challenge × Ca interaction (P < 0.05) for tibial BS (day 16), with challenge being more severe in birds fed high Ca than low Ca diets. A challenge × phytase interaction (P < 0.05) was present for femur ash (day 16), with high phytase only increasing ash in challenged birds. The challenge decreased (P < 0.05) the BS of femur and tibia at each time point. Birds fed high dietary Ca had lower tibial Mg (P < 0.001), Fe (P < 0.001), Na (P < 0.001), and Zn (P < 0.05) concentrations (day 29). Altogether, high dietary Ca and phytase improved bone mineralization showing that attention to Ca and P nutrition and phytase matrix values is warranted when high levels of phytase are used.

Short-chain fatty acids and ceca microbiota profiles in broilers and turkeys in response to diets supplemented with phytase at varying concentrations, with or without xylanase

Two independent studies were performed, each with a 3 × 2 factorial arrangement to compare the response in broilers and turkeys to phytase and xylanase supplementation on cecal fermentation and microbial populations. For both studies, 960 Ross 308 and 960 BUT 10 (1-day-old) were allocated to 1 of 6 experimental treatments: (1) control diet, containing the standard dose (100 g/ton) of phytase (STD-Xyl); (2) the control diet with 100 g/ton of xylanase (STD + Xyl); (3) the control diet supplemented on top with 2 fold the standard dose of phytase (200 g/ton), also referred as superdosing (SD-Xyl); (4) the superdosed diet with 100 g/ton of xylanase (SD + Xyl); (5) the control diet supplemented with 5-fold the standard dose of phytase (500 g/ton), also referred as megadosing (MD-Xyl); and (6) the megadosed diet with 100 g/ton of xylanase (MD + Xyl). Each treatment had 8 replicates of 20 animals. Broiler and turkey diets, based on wheat, soybean meal, rapeseed, and barley, and water were available ad libitum. On day 28, the cecal contents from 5 birds per pen were collected. The profile of short-chain fatty acids (SCFA) and microbiome structure (by % guanidine and cytosine [G + C] method) were analyzed. Selected % G + C fractions were used for 16S rDNA sequencing for the identification of bacteria. No treatment effects were noted on SCFA concentrations in either broilers or turkeys. Broilers fed MD diets had greater proportions of unclassified Clostridiales, Mollicutes (RF9) and Faecalibacterium. Xylanase supplementation in broilers resulted in lower proportions of Lactobacillus but increased Mollicutes (RF9), unclassified Ruminococcus, unclassified Clostridiales, and Bifidobacterium. The microbiome in turkeys was unaffected by phytase supplementation, but xylanase supplementation increased the proportions of Lachnospiraceae (Incertae sedis), Lactobacillus, and Bifidobacterium. Supplementation of turkey diets with increasing doses of phytase did not affect the cecal microbiota in contrast to what was observed in broilers. In contrast, xylanase supplementation in both species led to significant changes in the microbial populations, suggesting a positive influence through the provision of oligosaccharides.

Influence of meat and bone meal, phytase, and antibiotics on broiler chickens challenged with subclinical necrotic enteritis: 1. growth performance, intestinal pH, apparent ileal digestibility, cecal microbiota, and tibial mineralization

This study investigated the influence of meat and bone meal (MBM), phytase, and antibiotics (AB) on the performance, intestinal pH, ileal digestibility, cecal microbiota, and tibial mineralization in Ross 308 broilers challenged with necrotic enteritis (NE). A total of 672-day-old male Ross 308 chicks were allocated to 8 treatments with 6 replicate pens, with 14 birds each. The study employed a 2 × 2 × 2 factorial arrangement of treatments: MBM (no or yes), AB (no or yes, zinc bacitracin + salinomycin), and phytase level (500 or 1,500 FTU/kg; both using 500 matrix recommendations). Diets were based on wheat–soybean meal–canola meal. All birds were challenged with Eimeria spp on day 9 and Clostridium perfringens (C. perfringens) strain EHE-NE18 on day 14 and day 15. On day 21 (postchallenge), birds fed MBM had reduced weight gain (WG; P < 0.05) relative to without MBM. A 2-way phytase × AB interaction for WG on day 14 (P < 0.001) and day 21 (P < 0.001) and feed conversion ratio on day 21 (P < 0.001) and day 42 (P < 0.01) indicated positive effects of high phytase on bird performance in the presence of AB. On day 42, a 3-way MBM × phytase × AB interaction (P < 0.01) was observed for WG, showing high phytase increased WG with AB, relative to the birds without AB in the presence of MBM. A 2-way MBM × phytase interaction (P < 0.01) was observed for apparent ileal digestibility of Ca and P on day 16, whereby there was a notable reduction in Ca and P digestibility in birds fed MBM-free diets and a low phytase level, but with the high phytase level, Ca and P digestibility was not influenced by MBM. In conclusion, in NE challenged birds, high phytase has a beneficial effect on leg health and mineral utilization to the extent that it can replace MBM and has beneficial effects on bird performance in the presence of AB.

Simultaneous determination of cereal monosaccharides, xylo- and arabinoxylo-oligosaccharides and uronic acids using HPAEC-PAD

Xylo- and arabinoxylo-oligosaccharides (XOS and AXOS) are of interest for their prebiotic activity. The production of these oligomers might be accompanied with monosaccharides. The measurement of both oligosaccharides and monosaccharides usually requires two methods. The current work presents an HPAEC-PAD method based on gradient elution of aqueous solvents sodium hydroxide and sodium acetate, in contrast to conventional isocratic elution, for the simultaneous separation of 16 standards of monosaccharides, xylo-oligosaccharides, arabinoxylo-oligosaccharides and uronic acids using CarboPac PA 200 column. The presented method showed a stable baseline and high-resolution separation of the standards. The method showed acceptable accuracy and precision. Limits of Detection and Quantitation (LOD and LOQ) were estimated for all the standards. The method was applied to measure the activity of a commercial endoxylanase on wheat bran; a steady release of xylose monosaccharide was observed. Enzyme action on oligosaccharide standards showed a preference for the larger oligosaccharides.

Application of exogenous enzymes: is digestibility an appropriate response variable?

The use of digestible nutrient values for feedstuffs and non-ruminant diets has resulted in significant improvements in ingredient utilisation, pig and poultry performance and efficiency, and reduced feed costs and environmental waste. The use of exogenous enzymes such as carbohydrases, phytases and proteases in non-ruminant diets has also had a profound effect on meat production, feed efficiency and reduced environmental waste through an improvement in nutrient digestibility. However, the use of nutrient digestibility in the absence of animal growth or efficiency, on individual feed ingredients or complete diets, as an estimate of exogenous enzyme efficacy requires careful consideration. Numerous studies have highlighted a range of factors that will influence the estimated digestibility coefficients. These include but are not limited to: differences in methods employed, the use of a point-in-time measure of nutrient digestion versus growth over the lifetime of the chicken or pig, adjustment (or not) for endogenous losses, age of the animal, production status and nutritional status of the diet. These factors can also be influenced by or have an influence on exogenous enzyme efficacy to yield positive, negative, non-significant, or inconclusive effects on nutrient digestion. In addition, exogenous enzyme supplementation of diets has resulted in improvements in nutrient digestibility in the absence of an effect on productivity or efficiency or vice versa. Therefore, the use of nutrient digestibility as a response variable for exogenous enzyme efficacy is informative but only in the presence of growth performance, intake, or meat yield.

Effect of age on the relationship between metabolizable energy and digestible energy for broiler chickens

A total of 960 male Ross 308 chicks (day-old) were used to investigate the effect of age on the relationship between metabolizable energy (ME) and digestible energy (DE) for broiler chickens. Bird growth variables, nitrogen retention (NR), nitrogen digestibility (ND), as well as the relative weight of liver, pancreas, and the gastrointestinal tract were determined. Practical diets that compared 2 cereals (corn and wheat) and exogenous xylanase (0 or 16,000 BXU/kg) were evaluated at 5 ages (7, 14, 21, 28, and 35 D) in a 2 × 2 × 5 factorial arrangement of treatments with 8 replicates per treatment and started with 30 birds per replicate. A randomized block ANOVA analysis of repeated measures was performed, and a 2 × 2 × 5 factorial structure was used to investigate the 2 dietary treatment factors (cereal type and the presence of xylanase) within the 5 bird ages (7, 14, 21, 28, and 35 D), and their interactions. Apparent metabolizable energy (AME) increased linearly from 7 until 28 D of age, but (P < 0.05) decreased at 35 D of age. Digestible energy was high at 7 D of age, then dropped and remained similar (P > 0.05) from 14 to 35 D of age. The AME: DE ratio was lowest (P < 0.05) at 7 D of age but there were no (P > 0.05) differences thereafter. Cereal type and xylanase supplementation did not (P > 0.05) change the ME: DE ratio. The results indicate that determining ME before 14 D of age may give absolute values that are lower than would be obtained with older birds. ME values that are determined on older broiler chickens may overestimate the energy availability of practical feeds used in broiler starter feeds.

Age-related arabinoxylan hydrolysis and fermentation in the gastrointestinal tract of broilers fed wheat-based diets

Endoxylanases are frequently used in cereal-based broiler feeds to improve the nutritional quality of the feed. It is hypothesized that the age of broilers and the age-related development of their intestinal microbiota influence the efficacy of these enzymes. Hence, the objective of this study was to identify possible age-related changes in arabinoxylan (AX) digestion in the different parts of the gastrointestinal (GI) tract of broilers. A feeding trial was performed with 240 1-day-old chicks (Ross 308) receiving a wheat-based feed containing no supplemented endoxylanase. Digesta samples from every section of the GI tract were collected at 5, 10, 15, 21, 28, and 35 d of age and analyzed for AX content, AX digestibility, intestinal viscosity, and microbial endoxylanase and arabinofuranosidase activities. In the first 2 wk, the microbiota were able to solubilize a part of the water-unextractable arabinoxylan (WU-AX), thereby increasing intestinal viscosity and water-extractable arabinoxylan (WE-AX) concentrations in the GI tract. In these young birds, WU-AX and WE-AX with low arabinose to xylose ratios were able to enter the caeca but were not yet extensively fermented by the caecal microbiota as indicated by the high caecal AX concentrations at 5 and 10 d (P < 0.01). Establishment of a more mature microbial community at 3 wk of age resulted in a further increase in both the solubilization of WU-AX and fermentation of WE-AX at the ileum and caecum (P < 0.10). Furthermore, the increase in AX degrading enzyme activities with age denotes the high AX degrading capacity of the caecal microbiota. Finally, a total tract AX digestion of 24% was achieved at slaughter age (day 35). Our results clearly indicate that the capacity of intestinal microbiota to degrade AX in the hindgut increases as the broiler ages. This suggests that the benefits of endoxylanase supplementation of broiler feeds depend on the interaction of the intestinal microbiota and AX present in the GI tract at specific broiler ages.

Effects of age and supplemental xylanase in corn- and wheat-based diets on cecal volatile fatty acid concentrations of broilers1

An experiment was conducted to evaluate the effects of age and supplemental xylanase in corn- or wheat-based diets on cecal volatile fatty acid (VFA) concentrations of Ross × Ross 708 male broilers during weekly intervals from 14 to 42 d of age. Day-old chicks (1,500) were randomly distributed into 60 floor pens (25 chicks/pen; 0.078 m2/bird) and fed 1 of 4 dietary treatments (TRT) throughout the starter (1 to 14 d of age), grower (15 to 28 d of age), and finisher (29 to 42 d of age) phases with 15 replicates per TRT. Dietary TRT consisted of a 2 × 2 factorial arrangement with 2 diet types (corn- or wheat-based) and 2 xylanase inclusions (0 or 16,000 BXU/kg) as the main factors. At 14, 21, 28, 35, and 42 d of age, cecal contents were collected (4 birds/pen) for VFA analysis. Main effects of cereal grain source (P < 0.05) affected propionic, isobutyric, butyric, isovaleric, valeric, and isocaproic acid concentrations at 14, 21, 28, 35, and 42 d of age. Broilers fed corn-based diets had higher (P < 0.05) propionic, isobutyric, isovaleric, valeric, and isocaproic concentrations than those fed wheat-based diets from 14 to 42 d of age. However, broilers fed wheat-based diets had higher (P < 0.05) butyric acid concentrations at 28, 35, and 42 d of age compared with those fed corn-based diets. Individual and total VFA concentrations increased (P < 0.05) linearly from 14 to 42 d of age. Age and cereal grain interacted (P < 0.05) to affect propionic, isobutyric, butyric, isovaleric, and valeric acid concentrations. These results indicate that broiler cecal VFA concentrations are influenced by cereal grain source and age. In contrast, supplemental xylanase inconsistently influenced broiler cecal VFA concentrations. Therefore, future research evaluating factors affecting supplemental xylanase and cecal VFA production in broilers is warranted. Additionally, research investigating cereal grain source effects on cecal microflora development and fermentative patterns may be beneficial for optimizing cecal VFA production in broilers.

Effect of a high dose of exogenous phytase and supplementary myo-inositol on mineral solubility of broiler digesta and diets subjected to in vitro digestion assay

This study was conducted to evaluate the effect of microbial phytase and myo-inositol supplementation in low non-phytate phosphorus (nPP) diets on pH and the solubility of minerals in an in vitro digestion procedure (IVDP) and to compare this with digesta from birds fed different diets (grower diets) compared to the in vitro test (starter diets). A total of 660 1-day-old broilers were randomly allotted into 11 dietary treatments and fed a corn-soybean-meal-based diet with recommended nPP (positive control; PC), an nPP-deficient diet (negative control; NC), NC diets supplemented with phytase (500; 1,000; 2,000; 3,000; 4,000; 5,000; and 6,000 FTU/kg), an NC diet plus 0.15% myo-inositol, and an NC diet with reduced Ca level (Ca: nPP ratio same as PC) from 1 to 23 D of age. The pH and Ca solubility of the NC diet was increased compared with the PC when subjected to IVDP (P < 0.05). P solubility in the gizzard and jejunal digesta was reduced in the NC compared with the PC diet and this was also reflected in the IVDP. Phytase addition to the NC diets linearly increased (P < 0.05) the pH value and Ca and P solubilities in both digesta and diets subjected to IVDP. Higher doses of microbial phytase increased (P < 0.05) Zn and Fe solubilities in both digesta and IVDP. Myo-inositol supplementation of the NC diet had no effect on mineral solubility, but decreased (P < 0.05) the pH of the IVDP. Lowering the Ca content of the NC diet decreased (P < 0.05) the pH of the in vitro digested diets and Ca solubility in both broiler digesta and IVDP and also increased (P < 0.05) P solubility in both the jejunal digesta and IVDP. Correlations were noted between the solubility of P in the in vitro assay and that in the gizzard and jejunal digesta, and also with bird performance, confirms the usefulness of in vitro assay.

Response of broiler chickens to xylanase and butyrate supplementation

A 2 × 2 factorial experiment was used to evaluate the effect of xylanase and sodium butyrate supplementation on performance, intestinal fermentation, histology, and morphometry in broiler chickens. A total of 384 Ross 308 broiler chicks (1-day-old) were allocated to 4 experimental treatments: CTR (control diet), XYL (CTR diet with 16,000 BXU/kg of xylanase), BUT (CTR diet with 1 kg/t sodium butyrate), and XYL+BUT (CTR diet plus xylanase and sodium butyrate). Each treatment had 8 replicates of 12 animals. Starter and grower diets, based on wheat and soybean meal, and water were available ad libitum. Body weight gain and feed intake were measured from 0 to 42 D, and feed conversion ratio corrected for mortality (FCR) was calculated. The profile of short-chain fatty acids in the duodenum, jejunum, ileum, and ceca digesta on days 21 and 42 was analyzed in addition to the relative weights of the different portions of the gastrointestinal tract (GIT). The villus height (VH), crypt depth (CD), and villus to crypt (VH: CD) ratio from the ileal tissue on day 42 were also evaluated. Statistical comparisons were performed using a 2-way ANOVA. Xylanase supplementation improved 42-D FCR by 5 points (P = 0.006), while butyrate did not affect 42-D FCR. On day 21, birds fed butyrate had heavier total GIT (P = 0.024), duodenum (P < 0.001), and jejunum (P = 0.025). Xylanase did not influence the relative weights in any intestinal section except the crop which was smaller in xylanase supplemented birds. At day 42, the VH: CD ratio was increased with sodium butyrate (P = 0.005). Supplementation of broiler diets with xylanase improved performance but had little effect on intestinal measures, whereas sodium butyrate influenced many of the intestinal indices with no consequence on animal performance.

The association between faecal host DNA or faecal calprotectin and feed efficiency in pigs fed yeast-enriched protein concentrate

Gut cell losses contribute to overall feed efficiency due to the energy requirement for cell replenishment. Intestinal epithelial cells are sloughed into the intestinal lumen as digesta passes through the gastrointestinal tract, where cells are degraded by endonucleases. This leads to fragmented DNA being present in faeces, which may be an indicator of gut cell loss. Therefore, measuring host faecal DNA content could have potential as a non-invasive marker of gut cell loss and result in a novel technique for the assessment of how different feed ingredients impact upon gut health. Faecal calprotectin (CALP) is a marker of intestinal inflammation. This was a pilot study designed to test a methodology for extracting and quantifying DNA from pig faeces, and to assess whether any differences in host faecal DNA and CALP could be detected. An additional aim was to determine whether any differences in the above measures were related to the pig performance response to dietary yeast-enriched protein concentrate (YPC). Newly weaned (∼26.5 days of age) Large White × Landrace × Pietrain piglets (8.37 kg ±1.10, n = 180) were assigned to one of four treatment groups (nine replicates of five pigs), differing in dietary YPC content: 0% (control), 2.5%, 5% and 7.5% (w/w). Pooled faecal samples were collected on days 14 and 28 of the 36-day trial. Deoxyribonucleic acid was extracted and quantitative PCR was used to assess DNA composition. Pig genomic DNA was detected using primers specific for the pig cytochrome b (CYTB) gene, and bacterial DNA was detected using universal 16S primers. A pig CALP ELISA was used to assess gut inflammation. Dietary YPC significantly reduced feed conversion ratio (FCR) from weaning to day 14 (P<0.001), but not from day 14 to day 28 (P = 0.220). Pig faecal CYTB DNA content was significantly (P = 0.008) reduced in YPC-treated pigs, with no effect of time, whereas total faecal bacterial DNA content was unaffected by diet or time (P>0.05). Faecal CALP levels were significantly higher at day 14 compared with day 28, but there was no effect of YPC inclusion and no relationship with FCR. In conclusion, YPC reduced faecal CYTB DNA content and this correlated positively with FCR, but was unrelated to gut inflammation, suggesting that it could be a non-invasive marker of gut cell loss. However, further validation experiments by an independent method are required to verify the origin of pig faecal CYTB DNA as being from sloughed intestinal epithelial cells.

Xylanase and xylo- oligosaccharide prebiotic improve the growth performance and concentration of potentially prebiotic oligosaccharides in the ileum of broiler chickens

1. The objective of this study was to investigate the effect of supplementing broiler diets with xylanase or xylo- oligosaccharide (XOS) on growth performance, the concentration of non-starch polysaccharide (NSP) hydrolysis products in the ileum and concentration of short chain fatty acids (SCFA) in the caeca of broiler chickens.2. In total, 500 male Ross 308 broilers were used in this 29-day (d) study. The treatments were organised into a 2 × 2 plus 1 factorial arrangement consisting of two additives (xylanase or XOS) at two levels (low or high) plus a control treatment with no additives. This gave five treatments with 100 birds in each treatment group. The diets were slightly deficient in protein by 20 g/kg and energy by 1 MJ/kg.3. On d 14 and 28, two birds per pen were euthanised, the caeca content collected and analysed for short chain fatty acid (SCFA) concentration. On d 29, six birds per pen were euthanised and ileal digesta were collected and analysed for the concentration of NSP fractions.4. On d 14, caecal acetic acid, iso-butyric acid, iso-valeric acid, n-valeric acid and total SCFA concentrations were significantly greater (P ≤ 0.05) when diets were supplemented with XOS compared with xylanase.5. Ileal concentration of arabinose, galactose and glucuronic acid (GlucA2) were significantly greater (P ≤ 0.05) in the insoluble NSP fraction when diets were supplemented with a high level of xylanase, compared with the control treatment. Ileal concentration of fructose was significantly greater (P ≤ 0.05) in the water soluble NSP when a high level of xylanase or low level of XOS were included in the diet compared with the control.6. It was concluded that xylanase and XOS had similar effects on NSP concentration and SCFA in the caeca, although there was little effect on performance. This observation demonstrated further benefits of xylanase supplementation in wheat-based broiler diets beyond digesta viscosity reduction and the release of extra nutrients.

Effects of cereal grain source and supplemental xylanase concentrations on broiler growth performance and cecal volatile fatty acid concentrations from 1 to 40 d of age2

An experiment was conducted to evaluate the effects of feeding diets varying in cereal grain source and supplemental xylanase concentrations on growth performance and cecal volatile fatty acid (VFA) concentrations of Ross × Ross 708 male broilers from 1 to 40 d of age. A total of 1,536 day-old chicks were randomly distributed into 64 floor pens (24 chicks/pen; 0.08 m2/bird) and fed 1 of 8 dietary treatments (TRT) with 8 replicates per TRT. Experimental TRT were of either corn- (TRT 1 to 4) or wheat-based (TRT 5 to 8) origins. The 4 dietary TRT for each cereal grain source consisted of a positive control (PC) reference diet and 3 reduced AMEn diets (AMEn reduced 66 kcal/kg below PC) with supplemental xylanase at either 0 (negative control), 12,000, or 24,000 BXU/kg. Birds and feed were weighed at 1, 14, 26, and 40 d of age to determine BW gain, feed intake, and feed conversion ratio. At 26 and 40 d of age, cecal contents were collected and pooled per pen (7 birds/pen; 5 replicate pens/TRT) for VFA concentrations. No TRT differences (P > 0.05) in cumulative growth performance were observed. Likewise, no TRT differences (P > 0.05) in acetic or total VFA concentrations were observed at 26 or 40 d of age. However, cereal grain source (P < 0.05) influenced propionic, isobutyric, butyric, and isovaleric concentrations at 26 and 40 d of age with birds receiving the corn-based diets having higher (P < 0.05) cecal propionic, isobutyric, and isovaleric concentrations, and lower (P < 0.05) butyric acid concentrations than those fed the wheat-based diets. These results indicate that dietary cereal grain source may influence individual cecal VFA concentrations. However, supplemental xylanase did not affect broiler growth performance or cecal VFA concentrations. Therefore, future research evaluating factors limiting xylanase responses on broiler growth performance and cecal VFA production is warranted.

Wheat sample affects growth performance and the apparent metabolisable energy value for broiler chickens

1. The aim of this study was to examine chemical composition, quality characteristics, apparent metabolisable energy (AME) and nutrient utilisation of wheat samples currently available to the UK poultry industry and their effect on broiler growth performance. 2. Seventeen current UK wheat samples were used to formulate 17 diets, all of which included 670 g/kg of each wheat sample and 330 g/kg of a balancer feed. Eight hundred 1-day-old male Ross 308 broilers were allocated randomly to 160 raised floor pens. Each diet was replicated eight times, fed ad libitum from 0 to 21d age in a randomised complete block design. Excreta were quantitatively collected during the last 3 days for AME determination. 3. The content of protein, ash and gross energy (GE) ranged from 97 to 143 g/kg DM, 12.8 to 19.6 g/kg DM and 17.81 to 18.24 MJ/kg DM, respectively. The amount of starch and total non-starch polysaccharides (NSP) ranged from 671 to 728 and 80.1 to 98.2 g/kg DM, respectively. The quality characteristics of wheat samples were in the expected range. 4. There were differences (P < 0.05) in AME and N-corrected AME (AMEn) of wheat samples. The AME of the wheat had a maximum range of 1.13 MJ/kg DM between samples. Dry matter retention (DMR) and fat digestibility (FD) were significantly different (P < 0.05) between wheat samples. 5. The daily feed intake (FI) and weight gain (WG) of broilers fed two wheat samples were significantly (P < 0.05) lower as compared to other samples and their low FI and WG were not related to their chemical composition and quality characteristics. 6. The ash content of wheat samples was negatively associated with AMEn (r = - 0.489, P < 0.05). The coefficient of FD was positively related to AMEn (r = 0.552, P < 0.05). 7. Chemical composition and quality characteristics of the wheat did not relate (P > 0.05) to FI and WG of broilers. There was no relationship between growth performance of broilers and AMEn of the wheat samples.

Xylo-oligosaccharides display a prebiotic activity when used to supplement wheat or corn-based diets for broilers

It is now well established that exogenous β-1,4-xylanases improve the nutritive value of wheat-based diets for poultry. Among other factors, the mechanism of action of exogenous enzymes may involve a microbial route resulting from the generation of prebiotic xylo-oligosaccharides (XOS) in the birds' gastro-intestinal (GI) tract. In a series of three experiments, the effect of XOS on the performance of broilers fed wheat or corn-based diets was investigated. In experiment 1, birds receiving diets supplemented with XOS displayed an increased weight gain (P = 0.08). The capacity of XOS to improve the performance of animals during a longer trial (42 d) was investigated (Experiment 2). The data revealed that diet supplementation with XOS, tested at two incorporation rates (0.1 and 1 g/kg), or with an exogenous β-1,4-xylanase resulted in an increased nutritive value of the wheat-based diet. An improvement in animal performance was accompanied by a shift in the microbial populations colonizing the upper portions of the GI tract. XOS were also able to improve the performance of broilers fed a corn-based diet, although the effects were not apparent at incorporation rates of 10 g/kg. Together these studies suggest that in some cases the capacity of β-1,4-xylanases to improve the nutritive value of wheat-based diets is more related to their ability to produce prebiotic XOS than to their ability to degrade arabinoxylans. The extremely low quantities of XOS used in this study also challenge the depiction of a prebiotic being a quantitatively fermented substrate. These data also bring into question the validity of the "cell wall" mechanism, as XOS elicited an effect with clearly no action on endosperm cell wall integrity and yet the performance effects noted were equivalent or superior to the added enzymes.

Meta-analysis: explicit value of mono-component proteases in monogastric diets

A meta-analysis was conducted to investigate the effect of mono-component proteases on performance and apparent ileal amino acid digestibility (AIAAD, %) in monogastrics. A total of 67 experimental trials were included in the meta-analysis from published and internal reports, contributing 467 lines of data. Poultry and swine data accounted for 81 and 19% of the dataset, respectively. Forty-four different proteases were included in the meta-analysis, accounting for commercial and non-commercial products. Mixed Model analysis was used to assess protease effect and the influence of inherent characteristics of the control on protease response. The mean performance response to protease was a reduction in feed conversion ratio (FCR) for poultry (1%, P < 0.05) and swine (4%, P > 0.05). The mean relative effect of protease on AIAAD over the control was 1.6 ± 0.3%, ranging from 1.2% for Arg, Phe and Trp to 2.6% for Cys. For the majority of amino acids, inherent AIAAD of control diets influenced (P < 0.05) the magnitude of the protease response such that, as inherent digestibility increased, the effect of protease on amino acid digestibility decreased. The dataset was subsequently divided into 2 subgroups: diets with and without other enzymes, namely non-starch polysaccharide degrading enzymes (NSPase) and phytase. Addition of protease in diets containing no other enzymes significantly (P < 0.05) increased AIAAD for the majority of amino acids and tended (P < 0.10) to improve Met, Trp, Pro, Gly, and Tyr. However, when other enzymes were included in the experiment, the beneficial effect of protease on AIAAD was lost (P > 0.05). These findings suggest that when other enzymes are already included in the diet, addition of protease requires further justification for use in monogastric diets.

Exogenous phytase and xylanase exhibit opposing effects on real-time gizzard pH in broiler chickens

1. The current study was conducted to evaluate the influence of high phytase doses and xylanase, individually and in combination, on performance, blood inositol and real-time gastric pH in broilers fed wheat-based diets. 2. In a 42-d experiment, a total of 576 male Ross 308 broiler chicks were allocated to 4 dietary treatments. Treatments consisted of a 2 × 2 factorial arrangement, with 500 or 2500 FTU/kg phytase and 0 or 16 000 BXU/kg xylanase, fed in two phases (starter 0-21; grower 21-42 d). Heidelberg pH capsules were administered to 8 birds from each treatment group, pre- and post-diet phase change, with readings captured over a 5.5-h period. 3. At 21 and 42 d, birds fed 500 FTU/kg phytase without xylanase had on average 127 and 223 g lower weight gain than all other treatments, respectively (P < 0.05). At 21 d, feed conversion ratio (FCR) was reduced (P < 0.01) by 2500 FTU/kg phytase or xylanase; however, 42-d FCR was unaffected by enzyme treatment. Inositol content of plasma was twice that of the erythrocyte (P < 0.001), with 2500 FTU/kg phytase tending to increase (P = 0.07) inositol content in both blood fractions. 4. Across all treatments, capsule readings ranged from pH 0.54 to 4.84 in the gizzard of broilers. Addition of 2500 FTU/kg phytase to the grower diet reduced (P < 0.05) average gizzard pH from 2.89 to 1.69, whilst feeding xylanase increased (P < 0.001) gizzard pH from 2.04 to 2.40. In contrast, digital probe measurements showed no effect of xylanase on gizzard pH, while addition of 2500 FTU/kg phytase increased (P = 0.05) pH compared to 500 FTU/kg phytase with or without xylanase. 5. These findings suggested that xylanase and high phytase doses have opposite effects on real-time gastric pH, while similarly improving performance of broilers.

The effects of phytase and xylanase supplementation on performance and egg quality in laying hens

1. The aim of this study was to evaluate the effects of phytase and xylanase and their interaction on laying hen performance, egg quality, phosphorus (P) digestibility, phytate breakdown, volatile fatty acid (VFA) production and peptide YY concentration. 2. Two hundred and forty hens were allocated to cages at 22 weeks of age based on a 3 × 2 arrangement with phytase (0, 300 or 1500 FTU/kg) and xylanase (0 or 12 000 BXU/kg) as factors. 3. Phytase increased hen-day production (P < 0.05), daily egg mass (P < 0.05) and P digestibility with increasing levels of phytase (P < 0.001). Phytase fed at 1500 FTU/kg reduced IP6 and IP5 and increased myo-inositol concentration in gizzard digesta (P < 0.05). Phytase fed at 300 FTU/kg reduced IP6 in ileal digesta (P < 0.05); however, IP6 and IP5 were further reduced and myo-inositol increased when phytase was added at 1500 FTU/kg (P < 0.05). 4. Xylanase improved feed efficiency when phytase was fed at 300 FTU/kg (P < 0.05). In the absence of phytase, xylanase reduced dry matter and Ca digestibilities (P < 0.05). 5. Neither phytase nor xylanase had an effect on peptide YY or caecal VFA concentrations.

Superdosing phytase reduces real-time gastric pH in broilers and weaned piglets

1. The current study was conducted to investigate the effect of high phytase doses on growth performance and real-time gastric pH measurements in broiler chickens and pigs. 2. In the first experiment, 576 male Ross 308 broilers were fed in two phases (0-21 and 21-42 d) with 4 treatment groups, with diets meeting nutrient requirements containing 0, 500, 1500 or 2500 FTU/kg phytase. In the second, 64 Landrace weaners were fed on diets meeting nutrient requirements with or without phytase (0 or 2500 FTU/kg) in two phases (0-21 and 21-42 d). Heidelberg pH capsules were administered to 7 broilers and approximately 13 pigs per treatment group, pre- and post-phase change, with readings monitored over several hours. 3. Addition of phytase into an adequate Ca and P diet had no significant effect on broiler performance although phytase tended (P < 0.07) to improve feed conversion in pigs over the entire experimental period. Real-time pH capsule readings in broilers demonstrated an increase (P < 0.05) in gizzard pH when phytase was dosed at 500 or 1500 FTU/kg, while higher doses of 2500 FTU/kg phytase lowered pH to a level comparable to control birds. Gastric pH increased (P < 0.01) when animals were exposed to dietary phase change, signifying a potential challenge period for nutrient digestibility. However, pigs fed 2500 FTU/kg were able to maintain gastric pH levels through diet phase change. In contrast, spear-tip probe measurements showed no treatment effect on gastric pH. 4. These findings demonstrate dietary manipulation of gastric pH and the value of real-time pH capsule technology as a means of determining phytase dose response.

Methodology affects measures of phosphorus availability in growing broilers. 2. Effects of calcium feeding strategy and dietary adaptation period length on phytate hydrolysis at different locations in the gastrointestinal tract1

An experiment was conducted to determine the effects of dietary adaptation period length (DAPL; 0, 24, and 48 h) and Ca feeding strategy (0.35% or 1.4:1 Ca:P ratio) on apparent phytate P (myo-inositol 1,2,3,4,5,6 hexakis dihydrogen phosphate; IP6) hydrolysis (AIP6H) and apparent digestibility (AΣIPD) of the sum of all inositol phosphate esters (ΣIP) of corn-titration diets at 3 locations (proventriculus/gizzard [Pro/Giz], jejunum, and distal ileum) in the gastrointestinal tract (GIT). Four hundred thirty-two Ross × Ross 708 male broilers were placed into 36 battery cages and fed a common starter diet until 18 d of age. Eight semipurified diets and a control diet for DAPL were fed from 19 to 21 d of age. Digesta were collected at each location from 4 birds per pen after each DAPL. Diets formulated with a 1.4:1 Ca:P ratio had higher (P < 0.001) AIP6H and AΣIPD when measured in the jejunum and ileum, but no differences were observed in the Pro/Giz. No interaction effects between DAPL and sampling location were observed for AIP6H and AΣIPD of the control diet. Conversely, interactive effects (P < 0.05) were measured for AIP6H and AΣIPD of the corn-titration diets. The highest values for both AIP6H (73.9%) and AΣIPD (80.7%) were measured in the Pro/Giz after 24 h. Phytate hydrolysis and AΣIPD were similar regardless of DAPL when sampled from the distal ileum. Concentrations of TiO2, IP6 and ΣIP also varied (P < 0.05) in response to DAPL and sampling location. Variability was likely due to inconsistencies in the flow of inositol phosphate esters and TiO2 through the GIT, specifically the Pro/Giz. Therefore, the use of TiO2 as an inert marker may have limitations when determining the hydrolysis and digestibility of phytate esters.

Hydrolysis of phytate to its lower esters can influence the growth performance and nutrient utilization of broilers with regular or super doses of phytase

The aim of the study was to observe the effects of dietary available phosphorus (aP) and calcium (Ca), with regular or super doses of phytase, on phytate hydrolysis and subsequent influences on broiler growth performance and nutrient utilization. In a 2 × 3 factorial design, 384 Ross-308 broilers were allocated to one of 6 dietary treatments with 8 replicates in a randomized complete block design for 21 days. Diets were nutritionally adequate (positive control, PC) or marginally deficient in aP and Ca (negative control, NC), with 0, 500 or 1,500 FTU/kg phytase. Bird and feed weights were recorded on d 0 and 21, excreta were collected on d 19 and 20, and gizzard and ileal contents were collected on d 21. Body weight gain (P < 0.01) increased linearly with phytase in the PC and quadratically in the NC. There was an interactive effect on ileal DM, N, and P utilization, increasing quadratically with phytase supplementation in the NC, but there was no phytase influence in the PC (P < 0.05). Phytase linearly increased copper (P < 0.001) and linearly decreased Ca (P < 0.05) utilization in the ileum. Phytase decreased ileal (IPx, inositol x-phosphate) IP6 and IP5 and increased inositol (quadratic, P < 0.001) but had no effect on IP4 or IP3. The influence of the dietary aP was more apparent on the hydrolysis of phytate and phytate esters after the ileum, with increasing (linear and quadratic, P < 0.05) IP4 and IP3 content in the excreta of birds fed the NC or PC when phytase was added. Phytate hydrolysis improves the growth potential of birds fed NC diets, allowing them to match the growth performance of birds fed PC diets and improve nutrient utilization. These results indicate that dietary Ca and aP concentrations can be reduced when phytase is supplemented. It also may be beneficial to apply the enzyme nutrient matrix to other nutrients in the diet to maintain an optimal balance of nutrients in the digesta.