Bone characteristics, pre-caecal phytate degradation, mineral digestibility and tissue expression were marginally affected by zinc level and source in phytase-supplemented diets in 21-day-old broiler chickens

1. This study determined the effect of dietary Zn concentration and source in phytase-supplemented diets on bone mineralisation, gastrointestinal phytate breakdown, mRNA-level gene expression (in jejunum, liver and Pectoralis major muscle) and growth performance in broiler chickens.2. Male Cobb 500 broilers were housed in floor pens (d 0-d 21) to test seven treatments with six replicate pens (12 birds per pen). Diets were arranged in a 2 × 3 + 1-factorial arrangement. The experimental factors were Zn source (Zn-oxide (ZnO) or Zn-glycinate (ZnGly) and Zn supplementation level (10, 30 or 50 mg/kg of diet). A maize-soybean meal-based diet without supplementation and formulated to contain 28 mg Zn/kg (analysed to be 35 mg Zn/kg), served as a control.3. Zinc source and level did not influence (p > 0.05) bone ash concentration and quantity or mineral concentrations in bone ash. Tibia thickness was greater in the treatment ZnO10 than in the treatments ZnO30 and ZnGly50 (Zn level × Zn source: p = 0.036), but width and breaking strength were not affected.4. Pre-caecal P digestibility and concentrations of phytate breakdown products in the ileum, except for InsP5, were not affected by Zn source or level. Only the expression of EIF4EBP1 (eukaryotic translation initiation factor 4E-binding protein 1) and FBXO32 (F-box only protein 32) in Pectoralis major muscle was affected by source, where expression was increased in ZnO compared to ZnGly diets (p < 0.05).5. In conclusion, Zn level and source did not affect gastrointestinal phytate degradation and bone mineralisation in phytase-supplemented diets. The intrinsic Zn concentration appeared to be sufficient for maximum bone Zn deposition under the conditions of the present study but requires validation in longer-term trials.

Growth, not digestibility, in chickens receiving reduced-protein diets is independent of non-specific amino-nitrogen sources when the essential-to-total-nitrogen ratio is constant and lower than 50

1. A 21 d experiment was conducted to investigate whether growth performance and coefficients of amino acids digestibility (cAID) in broilers receiving reduced-protein diets supplemented with different non-essential amino acids (NEAA) were dependent on supplemented NEAA in diets with the same essential-to-total N (eN-to-tN) ratio kept at <50%.2. The experiment used 240 male broiler chicks, allocated to eight treatments with six replicate pens per treatment, and five chicks per replicate. The diets were either adequate in protein diet (PC), reduced protein (NC) diet or the NC diet supplemented with Gly, Gln, Ser, Ala, Gly + Ser or Ala + Ser. Digesta from the distal half of the ileum were collected on d 21. Tissue samples were collected for analysis for gene expression of protein synthesis and degradation (pectoralis major and liver) and peptide and AA transporters (jejunum).3. The treatments had no effects on growth performance. Generally, cAID was greater (P < 0.05) in NC compared to the PC diet. Individual supplementation of the NC diet with Gly, Gln, Ser, Ala or Ala+Ser increased (P < 0.01) cAID of Cys compared to the PC diet. There were no treatment effects on mRNA levels for the AA or peptide transporters in the jejunum. Supplementation of the NC diet with Gln, Ser, Ala, or Gly + Ser produced an upward expression (P < 0.05) of S6 kinase in the liver compared to PC and NC. In addition, there was greater (P < 0.05) expression of TRIM36 in the pectoralis major of broiler chickens receiving the NC diet supplemented with Gly.4. When reduced-protein diets have an eN-to-tN ratio of <50% and the ratio is kept constant in all the diets, growth performance response was independent of the source of non-specific amino-N, but the treatments may influence ileal digestibility of individual AA.

Determination of standardised ileal digestibility of amino acids in high-fibre feedstuffs and additivity of apparent and standardised ileal amino acids digestibility of diets containing mixtures of maize, sorghum, and soybean meal

1. Two experiments were conducted to determine the coefficients of standardised ileal amino acid digestibility for selected high-fibre feedstuffs (Expt.1) and to assess the additivity of coefficients of apparent (cAIAAD) and standardised (cSIAAD) ileal amino acid digestibility for diets containing combinations of sorghum, maize and soybean meal.2. In Expt. 1, broiler chickens (324) were allocated to 54 metabolism cages (nine diets with six replicates). In Expt. 2, broiler chickens (315) were allocated to 63 metabolism cages (seven diets with nine replicates). The diets in Expt. 1 were a nitrogen-free diet plus eight semi-purified diets in which soybean meal (SBM), low-protein SBM (LPSBM), soybean hull, wheat bran, maize bran, rice bran, dried sugarbeet pulp or maize gluten feed were the only sources of protein in the respective diets. In Expt. 2, the seven diets were a nitrogen-free diet, and six semi-purified diets consisting of individual feedstuffs (SBM, maize, or sorghum) or combinations (maize and SBM; sorghum and SBM; or maize, sorghum, and SBM) as the only sources of protein.3. In both experiments, all the broiler chickens received the same maize-SBM diet formulated to meet nutrient requirements according to the breeder's recommendations from d 0 to 16. Allocated experimental diets were provided on d 16, and ileal digesta were collected on d 21.4. In Expt. 1, SBM and LPSBM had greater (P < 0.01) cSIAAD for indispensable and dispensable amino acids than the other feedstuffs. The rice bran had greater (P<0.01) cSIAAD values than wheat bran and maize bran, except for Leu, Cys, and Pro.5. In Expt. 2, predicted cAIAAD values for maize-SBM and maize-sorghum-SBM were generally lower (P<0.01) than actual values. The actual and predicted cSIAAD values for maize-SBM, sorghum-SBM and maize-sorghum-SBM combinations were not significantly different.6. It was concluded that the standardised amino acid digestibility of sorghum, when combined with other feedstuffs, was additive and that approximately three-quarters of total amino acids in the assayed high-fibre feedstuffs, except for dried sugarbeet pulp and maize gluten feed, were digestible.

Investigating possible impact, and interaction, of phytase supplementation during pre-experimental and experimental phases on assay of true phosphorus pre-caecal digestibility and total tract retention

1. Two experiments were conducted to investigate whether the use of phytase in the pre-experimental or experimental phases of true pre-caecal phosphorus digestibility (TPD) assay influenced the assayed TPD values. In experiments 1 and 2, broiler chickens were randomly allocated to 12 treatments in a 2 × 2 × 3 factorial arrangement. The factors were pre-experimental phytase supplementation (+ or -), experimental phase phytase supplementation (+ or -) with varying soybean meal inclusion levels (450, 560, or 670 g/kg).2. The diets in the pre-experimental phase were based on maize-soybean meal, whereas the diet used during the experimental phase was semi-purified, with soybean meal as the only source of P. Both TPD and true phosphorus retention (TPR) were determined using regression for the P output (g/kg, dry matter basis), pre-caecal or total tract, against P intake (g/kg). Data for TPD and TPR were analysed as a 2 × 2 factorial (with or without pre-experimental or experimental phase phytase).3. In both experiments 1 and 2, there were no significant effects for pre-experimental phytase supplementation nor interaction of pre- and experimental phytase supplementation on any of the pre-caecal digestibility responses. Phytase supplementation during the experimental phase increased (P < 0.01) pre-caecal P digestibility and retention, as well as digestible and retained P intake, and decreased (P < 0.01) P output.4. In experiment 1, pre- and experimental phytase supplementation increased (P < 0.01) the coefficient of TPR. In experiment 2, there was no significant effect of pre-experimental phytase supplementation on coefficient of pre-caecal TPD. However, phytase supplementation in the experimental phase increased (P < 0.01) the coefficient of pre-caecal TPD.5. In conclusion, whether or not phytase was supplemented to a P-adequate diet in the pre-experimental phase of the TPD assay, it had no influence on assayed TPD or TPR value.

Investigation of the effects of substitution levels, assay methods and length of adaptation to experimental diets on determined metabolisable energy value of maize, barley and soya bean meal

1. Two experiments were carried out to investigate the influence of substitution levels, assay methods and adaptation length of broilers to experimental diets on metabolisable energy of corn and barley (Experiment 1) and soya bean meal (Experiment 2). In each experiment, the test feedstuffs proportionately replaced the reference diet at the rates of 150, 300 or 450 g/kg. Each treatment had 8 or 7 replicate cages containing three birds per cage. Broiler chickens were adapted to experimental diets for either 7 or 4 d prior to excreta collection on d 20 and 21.2. Metabolisable energy was determined using the difference method at each substitution level and the regression method, using the 4 combinations of the substitution levels.3. In Experiment 1, AME and AMEn were lower (P < 0.01) for barley than for maize, irrespective of the assay method and there was a trend for an adaptation × cereal grains interaction (P < 0.10) for AME determined by the difference regression method. For maize, AME and AMEn calculated using regression or the difference method were not significantly different, whereas barley AME and AMEn values were greater (P < 0.01) when derived using regression analysis.4. In Experiment 2, there was no significant adaptation length × substitution levels interaction. The AME and AMEn values were lowest (P < 0.01) at 150 g/kg SBM inclusion level when calculated using the difference method. On the other hand, AME and AMEn values determined by the regression method were not influenced by substitution levels.5. It was concluded that the influence of substitution levels on assayed metabolisable energy is feedstuff-dependent and that the regression method produced more consistent metabolisable energy values in a feedstuff-independent manner.

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 graded concentrations of phytase in high-phytate diets on growth performance, apparent ileal amino acid digestibility, and phytate concentration in broilers from hatch to 28 D post-hatch

An experiment was conducted to evaluate graded doses of phytase in high-phytate diets. Ross 308, male broilers (n = 600) were assigned to one of 4 diets, with 10 replicate pens/diet and 15 birds/replicate pen. Diets were a nutrient adequate positive control (PC), a negative control (NC) diet with a reduction of Ca by 0.22%, available P by 0.20%, energy by 120 kcal/kg, and amino acids by 1 to 5% compared with the PC. The NC diet was supplemented with 0, 2,000, or 4,000 phytase units (FTU)/kg. Phytase increased (linear, P < 0.05) weight gain from hatch to day 18. Birds fed the NC + 4000 FTU/kg ate and gained more (P < 0.05) than birds fed the PC. The apparent ileal digestibility (AID) of all nutrients and amino acids were reduced (P < 0.05) in birds fed the NC compared with birds fed the PC. Phytase increased (linear, P < 0.10) AID of most nutrients. Digestibility was lower (P < 0.10) in birds fed the NC + 4000 FTU/kg compared with birds fed the PC. Using daily intake and AID to determine digestible nutrient intake resulted in no differences between birds fed the PC or NC + 4000 FTU/kg diets. Digestible intake of methionine or glutamate was better correlated with BW gain (P < 0.0001) than AID (P > 0.10). Phytase reduced (linear, P < 0.01) phytate concentration and increased inositol (linear, P < 0.01), phytate hydrolysis (linear, P < 0.05), and jejunal expression (linear, P < 0.05) of SNAT-1 and LAT-4 transporters. Supplementation of increasing doses of phytase in high-phytate, low-nutrient dense diets improved gain and digestibility through nearly complete phytate destruction. Digestible nutrient intake may be a better indication of broiler gain than AID alone.

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.

Investigations of the nutritive value of meals of double-low rapeseed and its influence on growth performance of broiler chickens

Four experiments were carried out to study the possible differences in metabolizable energy (ME) of meals (RSM) or expeller meals (RSE) from double-low rapeseed (Expt. 1), the influence of processing on ME (Expt. 2) and on relative phosphorus (P) bioavailability (Expt. 3) in RSM, and effect of RSM inclusion on growth performance of broilers (Expt. 4). For Expt. 1, diets with 300 g/kg RSM from 11 RSM and 4 RSE varieties were fed to broilers from d 14 to 21, with excreta collection on d 19 to 21. Each treatment had 8 replicates and 3 birds per replicate. Energy metabolizability of RSM of a specialized high glucosinolate variety (V275OL) was greater (P < 0.05) than all the other varieties. In Expt. 2, two RSM varieties were processed with mild or conventional processing condition. There were no variety effects on ME, but ME and MEn were greater (P < 0.01) for RSM processed by mild processing condition. In Expt. 3, P bioavailability of RSM was determined, relative to MSP, using growth performance and tibia ash as responses. Phosphorus relative bioavailability values were greater (P < 0.05) in RSM of DK Cabernet variety processed using the mild processing condition. In Expt. 4, two RSM varieties were added to wheat-soybean meal-based diet at the rates of 50, 100, 150, or 200 g/kg and fed to broilers from d 0 to 42. Inclusion of 150 and 200 g/kg of RSM resulted in reduced weight gain and increased feed conversion ratio (FCR) compared (P < 0.01) with the lower inclusion levels during the starter phase. For the entire trial (d 0 to 42), weight gain was greater (P < 0.01) for birds receiving diets with RSM from PR46W21 variety. It was concluded from the experiments that apart from the residual ether extract content, variety differences had no impact on ME of RSM, conventional processing reduced ME and relative bio-availability of P; and that the maximum level of RSM inclusion depends on maximum growth performance level desired.

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.

Results of an international phosphorus digestibility ring test with broiler chickens

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

Effects of exogenous proteases without or with carbohydrases on nutrient digestibility and disappearance of non-starch polysaccharides in broiler chickens

The objective of the current study was to evaluate the effect of a subtilisin protease, without or with inclusion of carbohydrases, on digestibility and retention of energy and protein, as well as the solubilization and disappearance of non-starch polysaccharides (NSP) from corn-soybean meal based diets fed to broiler chickens. Two hundred eighty-eight Ross 308 male broiler chickens were used for the experiment. On d 14, the birds were weighed and allocated to 6 treatments and 8 replicates per treatment with 6 birds per replicate. Treatments were: 1) corn-soybean meal based control diet; 2) control diet plus supplemental protease at 5,000 (P5000) protease units (PU)/kg); 3) control plus 10,000 PU/kg protease (P10000); or control plus an enzyme combination containing xylanase, amylase, and protease (XAP) added to achieve protease activity of: 4) 2,500 PU/kg (XAP2500); 5) 5,000 PU/kg (XAP5000); or 6) 10,000 PU/kg (XAP10000). The enzymes in XAP were combined at fixed ratios of 10:1:25 of xylanase:amylase:protease. Data were analyzed by ANOVA and specific orthogonal contrasts between treatments were performed. Addition of xylanase and amylase increased (P < 0.05) the ileal digestibility of protein by 4.2% and 2.1% at XAP5000 and XAP10000, respectively (relative to P5000 and P10000, respectively), exhibiting a plateau after the XAP5000 dose. Increment (P < 0.05) in AME due to protease was evident, particularly in P10000. At the ileal level, XAP reduced (P < 0.05) the flow of insoluble xylose and arabinose, which indicates an increase in the solubilization of arabinoxylan polymers in the small intestine. Protease on its own reduced (P < 0.05) the flow of insoluble arabinose but did not affect the flow of insoluble xylose. XAP reduced (P < 0.05) the pre-cecal flow of insoluble and total glucose and galactose. It was concluded that whereas protease by itself improved nutrient utilization and increased solubilization of NSP components, at the lower dose, a combination of xylanase, amylase, and protease produced effects greater than those of protease alone.

Apparent or Standardized Ileal Digestibility of Amino Acids of Diets Containing Different Protein Feedstuffs Fed at Two Crude Protein Levels for Growing Pigs

The current study determined the apparent or standardized ileal digestibility of amino acids (AID or SID of AA) in growing pigs fed diets containing three protein feedstuffs with different fiber characteristics at two dietary crude protein (CP) levels. Twenty boars (Yorkshire×Landrace) with average initial body weight of 35 (±2.6) kg were fitted with a simple T-cannula at the distal ileum. These pigs were offered six diets containing soybean meal (SBM), canola meal (CM) or corn distillers dried grains with solubles (corn-DDGS) that were either adequate (19%) or marginal (15%) in CP using a triplicated 6×2 Youden Square Design. Except for Met, Trp, Cys, and Pro, AID of AA was greater (p<0.05) in the SBM diet compared with the CM diet. Apparent ileal digestibility for Gly and Asp was greater (p<0.05) in the SBM diet compared with the corn-DDGS diet. The AID of Ile, Leu, Phe, Val, Ala, Tyr, and Asp was greater (p<0.05) in the corn-DDGS diet compared with the CM diet. Standardized ileal digestibility of AA was greater (p<0.05) in the SBM diet compared with the CM diet for all AA except Trp and Pro. The SID of Ile, Leu, Val, Ala, Tyr, and Asp was greater (p<0.05) in the corn-DDGS diet compared with the CM diet. It was concluded that protein feedstuff affects ileal AA digestibility and is closely related to dietary fiber characteristics, and a 4-percentage unit reduction in dietary CP had no effect on ileal AA digestibility in growing pigs.

Metabolizable energy content of wheat distillers' dried grains with solubles supplemented with or without a mixture of carbohydrases and protease for broilers and turkeys

In this study, 2 experiments were conducted to determine the AME and AMEn of wheat distillers' dried grains with solubles (DDGS) without or with supplementation of an enzyme mixture containing xylanase, amylase, and protease (XAP) in broilers and turkeys. One hundred twenty-six male Ross 308 broilers (Experiment 1) or 126 male BUT 10 turkeys (Experiment 2) were offered a nutrient-adequate diet from d 1 to 14. On d 14, birds in each experiment were allocated to 6 treatments consisting of 3 levels of wheat-DDGS (0, 300, or 600 g/kg) and 2 levels of XAP (0 or 250 mg/kg diet) in a randomized complete block design. The AME or AMEn content of wheat-DDGS was determined from the slope of regression of wheat-DDGS-associated energy intake (kilocalories) against wheat-DDGS intake (kilograms). In Experiment 1, wheat-DDGS inclusion in the diets linearly decreased (P<0.05) DM retention, AME, and AMEn, irrespective of XAP supplementation. The AME of wheat-DDGS without or with XAP for broilers was 3,587 or 3,700 kcal/kg DM, respectively, and AMEn was 3,356 and 3,459 kcal/kg DM for wheat-DDGS without and with XAP, respectively. In Experiment 2, wheat-DDGS inclusion in the diet linearly decreased (P<0.05) DM retention irrespective of XAP supplementation. Diet AME and AMEn linearly decreased (P<0.05) as the level of wheat-DDGS increased in the diets without added XAP, whereas there was no effect of increasing wheat-DDGS level on dietary AME or AMEn in the XAP-supplemented diets. The AME of wheat-DDGS without and with supplemental XAP for turkeys were 3,355 and 3,558 kcal/kg DM, respectively, and AMEn was 3,109 and 3,294 kcal/kg DM, respectively, for wheat-DDGS without and with XAP. Supplemental XAP increased (P>0.05) the AME and AMEn of wheat-DDGS for broilers and turkeys by up to 6%. It was concluded that wheat-DDGS is a valuable source of AME for broilers and turkeys.

The interplay of dietary nutrient specification and varying calcium to total phosphorus ratio on efficacy of a bacterial phytase: 1. Growth performance and tibia mineralization

A 14-d experiment was conducted to study the effects of 2 dietary variables on efficacy of a 6-phytase from Citrobacter braakii on broiler growth performance and tibia mineralization. Diets were formulated with or without nutrient matrix values for phytase as negative or positive control (NC or PC, respectively) and with 2 Ca:total P (tP; 2:1 or 2.5:1). The diets were supplemented with 0, 1,000, or 2,000 phytase units (FYT)/kg, thus producing a 2 × 2 × 3 factorial arrangement. Birds and feed were weighed on d 7 and 21, and tibia bones were collected from all the birds on d 21. The main effects of nutrient matrix, Ca:tP, and phytase supplementation were significant (P < 0.05) for all the growth performance responses (except for G:F for which there was no effect of matrix). The Ca:tP × phytase and matrix × phytase interactions were significant (P < 0.05) for weight gain. In the PC diets, phytase increased weight gain (P < 0.05) relative to the control only in diets with 2,000 FYT/kg, whereas in NC diets weight gain increased (P < 0.01) only from 0 to 1,000 FYT/kg levels. Broilers consuming diets with 2.5:1 Ca:tP had lower (P < 0.05) tibia ash, whereas phytase increased (P < 0.01) tibia ash, Ca, P, and Zn but decreased (P < 0.01) tibia K. Phytase supplementation of diets with 2:1 Ca:tP increased (P < 0.05) tibia P in birds receiving 1,000 FYT/kg relative to the control with no further increase at 2,000 FYT/kg, whereas each level of phytase supplementation increased (P < 0.05) tibia P in the diets with 2.5:1 Ca:tP. It was concluded that the best response to lower phytase supplementation (1,000 FYT/kg) was in NC diets with narrow Ca:tP, whereas the best response to higher level of phytase supplementation (2,000 FYT/kg) was achieved in diets in PC diets with wide Ca:tP.

The interplay of dietary nutrient level and varying calcium to phosphorus ratios on efficacy of a bacterial phytase: 2. Ileal and total tract nutrient utilization

A 14-d broiler experiment was conducted to assess the effects of 2 dietary variables on efficacy of a bacterial 6-phytase from Citobacter braakii on nutrient and phytate P (PP) utilization. Diets were formulated with or without nutrient matrix values (matrix) for phytase as negative control (NC) or positive control (PC), respectively, and with 2 Ca:total P (tP) levels (2:1 or 2.5:1). The diets were supplemented with 0, 1,000, or 2,000 phytase units (FYT)/kg of diet, thus producing a 2 × 2 × 3 factorial arrangement. Excreta were collected on d 19 to 21 and ileal digesta on d 21. There was no 3-way interaction on digestibility of any nutrient. There was matrix × phytase (P < 0.01) interaction for Ca and DM digestibility and Ca:tP × phytase interaction (P < 0.05) for acid hydrolyzed fat and Ca and P digestibility. Prececal flow of Mn, Zn, and Na was greater (P < 0.05) in NC diets, whereas phytase increased (P < 0.05) prececal flow of Mg, Fe, Mn, and Zn but decreased (P < 0.05) prececal Na flow. Total tract PP disappearance and total tract Ca retention increased (P < 0.05) with phytase supplementation in diets with 2:1 Ca:tP, whereas there was no effect of phytase supplementation on PP disappearance or Ca retention in diets with 2.5:1 Ca:tP. Total P and Ca retention were reduced (P < 0.05) in PC and NC diets when Ca:tP increased to 2.5:1, but the depression was more pronounced in the NC diet. In addition, PP disappearance decreased (P < 0.05) with increasing Ca:tP in the PC diets, but there was no effect of widening Ca:tP on PP disappearance in NC diets. It was concluded from the current study that the effect of phytase supplementation on P utilization is reduced when diets contain adequate P as exemplified in the PC diets and that the negative impact of wide Ca:tP is more pronounced in diets with phytase matrix allowance as exemplified in the NC diets.

Modification of digesta pH and intestinal morphology with the use of benzoic acid or phytobiotics and the effects on broiler chicken growth performance and energy and nutrient utilization

Two experiments, each consisting of 2 trials, were conducted to investigate the effect of feeding benzoic acid (BA) and turmeric meal (TM) individually or in combination (Exp. 1) or garlic meal (GM) and TM individually or in combination (Exp. 2) on growth performance, digesta pH, gut morphology, and nutrient utilization in broiler chickens. Diets consisted of a nutrient-adequate control diet and the control diet with added BA (2 g/kg), TM (10 g/kg), BA (1 g/kg) plus TM (5 g/kg), and BA (2 g/kg) plus TM (10 g/kg) in Exp. 1. In Exp. 2, in addition to the same control diet as Exp. 1, the control diet with added GM (10 g/kg), TM (10 g/kg), GM plus TM at 5 g/kg each, and GM plus TM at 10 g/kg each were used. Each treatment had 6 replicate floor pens with 10 chickens per replicate. On d 14, 5 broiler chickens from each floor pen were transferred to metabolism cages and continued on their respective diets. Body weight and feed intake data were collected on d 0 and 21, excreta were collected from chickens in metabolism cages on d 19 and 20, and ileal digesta were collected on d 21. Digesta pH was measured at the crop, proventriculus, jejunum, and cecum. Jejunum sections were collected from chickens in Exp. 1 to study gut morphology. In Exp. 1, only the combination of BA and TM tended (P < 0.10) to improve weight gain but there were no effects on G:F. The combination of BA and TM at both inclusion rates decreased (P < 0.05) digesta pH in the crop, jenunum, and ceca. There were no treatment effects on ileal DM or total tract DM retention, but supplementation of BA or TM alone or in combination increased (P < 0.01) apparent ME (AME) and nitrogen-corrected AME (AMEn) relative to the control diet. In Exp. 2, TM alone or combined with GM improved (P < 0.05) weight gain and G:F compared to the control. Supplementation of TM alone or in combination with GM at the rate of 10 g/kg each reduced (P < 0.05) digesta pH in the crop, proventriculus, and ceca but had no effect at the jejunum. The combination of GM and TM improved (P < 0.01) ileal DE, AME, and AMEn. In conclusion, BA, TM, and GM individually or in combination with wheat-soybean meal based diets adequate in nutrients and energy selectively improved growth performance, modified digesta pH and intestinal growth, and increased the efficiency of dietary energy use.

Marker type but not concentration influenced apparent ileal amino acid digestibility in phytase-supplemented diets for broiler chickens and pigs

Two experiments were conducted to investigate whether the choice of digestibility marker or marker concentration in corn-soybean meal diets influence apparent ileal AA digestibility (AIAAD) or the potential phytase-induced improvement in AIAAD in broiler chickens and pigs. One hundred ninety-two, 42-d-old, Ross 708 broilers were used in a 7-d study in Exp 1. The birds were allocated to 6 dietary treatments in a 2 × 3 factorial arrangement of treatments in a split-plot design. The factors were a combination of chromic oxide and titanium dioxide (0.3% or 0.5% of both markers, as-fed basis), and 3 levels of phytase inclusion [0, 500, or 1,000 phytase units (FTU)/kg]. In Exp. 2, 6 barrows fitted with a simple T-cannula at the distal ileum were allocated to 4 diets in a 6 × 4 Youden square design and 2 × 2 factorial arrangement of treatments. The factors were similar to Exp. 1, except the 500-FTU/kg phytase level was not used in Exp. 2. There were no marker type × marker concentration, phytase × marker type, or phytase × marker type × marker concentration interactions for any of the AA in either experiment. On average, AIAAD values calculated using Ti was greater (P < 0.05) than those calculated using Cr, regardless of the phytase inclusion level in both experiments. In Exp. 1, AIAAD values for His, Trp, Cys, and Pro were greater (P < 0.05) at the 0.3% than 0.5% marker concentration. The AIAAD values were consistently greater when calculated using Ti compared with Cr, irrespective of phytase level. It is concluded that the type of marker used does not influence whether a response to phytase supplementation, in terms of AIAAD, is observed.

Metabolizable energy value of porcine meat and bone meal for broiler chickens

Bolarinwa, O. A., Olukosi, O. A. and Adeola, O. 2012. Metabolizable energy value of porcine meat and bone meal for broiler chickens. Can. J. Anim. Sci. 92: 73–78. Ross 308 broiler chickens at 14 d post-hatch were used in a 7-d experiment to determine the metabolizable energy (ME) value of two meat and bone meal (MBM) samples. Three hundred and thirty-six broiler chickens were grouped by weight into eight blocks of seven cages with six birds per cage. The seven diets consisted of a corn-soybean meal reference diet formulated to meet the NRC (1994) requirement, and six test diets. The reference diet contained four energy sources namely corn, soybean meal, corn starch and soy oil. In the test diets, each of the two MBM samples were added to the reference diet at 30, 60 or 90 g kg−1 diet to partly replace the energy sources such that the ratio of the energy sources to one another was kept constant in all the diets. The ME and nitrogen-corrected ME (MEn) of the MBM samples were determined by the regression method in which the MBM contribution to ME, and MEn of the diets, in kilocalories, were regressed against the amount of MBM intake in grams. Gross energy of MBM1 and MBM2 were 4247 and 4697 kcal kg−1 DM, respectively. The crude protein, ash, and crude fat contents for MBM1 or MBM2 were 567 or 594, 264 or 211, and 106 or 116 g kg−1 DM. Addition of MBM linearly decreased (P<0.05) ileal nitrogen digestibility, total tract utilization of DM, energy and nitrogen as well as ME and MEn of the diets. In conclusion, the respective ME and MEn values were 2512 and 2345 kcal kg−1 DM for MBM1, and 2711 and 2127 kcal kg−1 DM for MBM2; thus MBM can be included in the diets of broiler chickens at less than 10% to provide energy.

Broiler responses to supplementation of phytase and admixture of carbohydrases and protease in maize-soyabean meal diets with or without maize Distillers' Dried Grain with Solubles

1. This experiment investigated growth performance and nutrient utilisation responses of broilers to partial replacement of maize and soyabean meal in broiler diets with 100 g kg(-1) maize Distillers' Dried Grain with Solubles (mDDGS) as well as responses to supplementation of an admixture of carbohydrases and protease (XAP) or phytase individually or in combination in the diets. 2. A total of 288 one-day-old broilers were allocated to 8 treatments in a randomised complete block design and a 2 x 2 x 2 factorial arrangement of treatments. The three factors were two levels each of mDDGS (0 or 100 g kg(-1)), phytase (0 or 1000 FTU kg(-1)), and XAP (0 or 500 mg kg(-1)). 3. Each treatment had 6 replicate cages with 6 birds per replicate cage. The control diets were formulated to meet all nutrient requirements of broilers according to National Research Council recommendations of 1994, but were marginally deficient in non-phytate P and ME. 4. Weight gain and gain:food were higher in broilers receiving diets containing mDDGS. The coefficient of apparent ileal N digestibility was lower in diets with mDDGS. Phytase increased the coefficient of apparent ileal DM digestibility in all diets. 5. Phytase improved the coefficient of the apparent total tract DM retention independently of mDDGS and tended to improve the coefficient of apparent P retention in the diets without mDDGS. The enzymes were additive in their effects in the diets with mDDGS. Overall, the results showed that adding 100 g kg(-1) mDDGS to a maize-soyabean meal diet had no negative effect on growth when energy and nutrient concentrations were similar to the maize-soyabean meal diet, and that phytase or an admixture of carbohydrases and protease individually or in combination modestly improved nutrient utilisation independently of mDDGS addition. Combination of the enzymes did not produce greater benefit than the use of phytase alone.

Estimation of the metabolizable energy content of meat and bone meal for swine

Experiments were conducted to determine apparent ME (AME) and apparent nitrogen-corrected ME (AME(n)) of 21 meat and bone meal (MBM) samples and to develop regression equations for predicting energy value of MBM. One hundred ninety-eight 32-kg of BW barrows were used for the study. The 22 treatments consisted of 1 corn-soybean meal reference diet and 21 test diets in which 21 MBM samples replaced 100 g/kg of corn and soybean meal such that the ratio of corn and soybean meal was the same in the reference and test diets. The DE, AME, and AME(n) of the MBM samples were determined by the difference method in a metabolism study consisting of 5-d adjustment and 5 d of total collection of feces and urine. On a DM basis, GE of MBM ranged from 3,895 to 5,193 kcal/kg, CP ranged from 491 to 641 g/kg, and ash ranged from 142 to 338 g/kg. The AME of the MBM samples ranged from 2,320 to 3,872 kcal/kg, whereas AME(n) ranged from 2,212 to 3,767 kcal/kg. None of the proximate compositions explained >50% of the variation in energy content of the MBM. Fat was positively correlated with GE, DE, AME, and AME(n) (r < or = 0.44), but CP, ash, Ca, and P were negatively correlated with DE, AME, and AME(n). The ratios of the proximate compositions to each other were correlated with the energy contents of the MBM. Crude protein:fat and GE:fat were negatively correlated with DE, AME, and AME(n) of the MBM (r ranged from -0.17 to -0.39), but fat:ash had the greatest positive correlation with AME and AME(n) compared with other ratios tested. When the data from 1 MBM sample that was an outlier were removed from the analysis, R(2) was 0.42 for AME and AME(n). The 4 variables that produced the best prediction equation for AME and AME(n) were GE, CP, P, and ash. The prediction equation for AME using these variables was AME = 13,587 - (1.25 x GE, kcal/kg) - (3.51 x CP, g/kg) + (30.4 x P, g/kg) - (16.4 x Ash, g/kg), and for AME(n), the equation was AME(n) = 13,547 - (1.25 x GE, kcal/kg) - (3.59 x CP, g/kg) + (31.0 x P, g/kg) - (16.5 x Ash, g/kg). It was concluded from this study that MBM is a good energy source for pigs and that, although other extrinsic factors may contribute to the variations in energy content of MBM, proximate compositions should be sufficient to predict the energy value of MBM for pigs.

Influence of enzyme supplementation of maize-soyabean meal diets on carcase composition, whole-body nutrient accretion and total tract nutrient retention of broilers

1. Carcase composition, whole body nutrient accretion rates and total tract nutrient retention of broilers in response to supplemental phytase or carbohydrase and protease from 0 to 21 d of age were investigated. 2. A total of 480 broilers were allocated to 4 slaughter groups (SG) of 30, 150, 150 and 150 broilers. Thirty broilers, in 6 replicates of 5 birds, comprised the initial SG killed at d 0; 150 broilers were allocated to each of the d 7, 14 and 21 final SG. Broilers in the final SG were allocated to 5 treatments in a randomised complete block design; each treatment had 6 replicate cages of 5 broilers per replicate cage. 3. The diets were maize-wheat-soyabean based and the treatments were: (1) positive control which met NRC (1994) energy and nutrients requirements for broiler, (2) negative control (NC) deficient in metabolisable energy (ME) and P, (3) NC plus phytase added at 1000 FTU/kg, (4) NC plus cocktail of xylanase, amylase and protease (XAP), and (5) NC plus phytase and XAP. 4. Except for ash and Ca, the treatments had no effect on carcase composition. Phytase or XAP individually or combined had variable effects on body nutrient accretion rates at various age periods of the broilers compared with the NC diet. Phytase alone or combined with XAP consistently improved body accretion rates of DM, protein, fat, ash, Ca, and P. 5. Addition of phytase alone or combined with XAP to the NC diet improved total tract N and P retention compared with the NC diet. Cocktail of XAP alone or combined with phytase improved Ca retention. Combination of phytase and XAP improved metabolisable energy (ME) and dry matter retention. 6. Overall, the results showed that the exogenous enzymes used had greater effects on the rates of nutrient accumulation in the carcase rather than on the proportion of nutrients deposited in the carcase.

Supplementation of carbohydrases or phytase individually or in combination to diets for weanling and growing-finishing pigs1

The overall objective of the studies reported here was to evaluate the growth and nutrient utilization responses of pigs to dietary supplementation of phytate- or nonstarch polysaccharide-degrading enzymes. In Exp. 1, growth performance and nutrient digestibility responses of forty-eight 10-kg pigs to dietary supplementation of phytase or a cocktail of xylanase, amylase, and protease (XAP) alone or in combination were evaluated. The growth response of one hundred fifty 23-kg pigs to dietary supplementation of phytase or xylanase individually or in combination was studied in Exp. 2 in a 6-wk growth trial, whereas Exp. 3 investigated the nutrient digestibility and nutrient retention responses of thirty 24-kg pigs to dietary supplementation of the same enzymes used in Exp. 2. In Exp. 1, the pigs were used in a 28-d feeding trial. They were blocked by BW and sex and allocated to 6 dietary treatments. The treatments were a positive control (PC) diet; a negative control (NC) diet marginally deficient in P and DE; NC with phytase added at 500 or 1,000 phytase units (FTU)/kg; NC with xylanase at 2,500 units (U)/kg, amylase at 400 U/kg, and protease at 4,000 U/kg; and NC with a combination of phytase added at 500 FTU/kg and XAP as above. In Exp. 2 and 3, the 5 dietary treatments were positive control (PC), negative control (NC), NC plus 500 FTU of phytase/kg, NC plus 4,000 U of xylanase/kg, and NC plus phytase and xylanase. In Exp. 1, low levels of nonphytate P and DE in the NC diet depressed (P < 0.05) ADG of the pigs by 16%, but phytase linearly increased (P < 0.05) ADG by up to 24% compared with NC. The cocktail of XAP alone had no effect on ADG of pigs, but the combination of XAP and phytase increased (P < 0.05) ADG by 17% compared with the NC treatment. There was a linear increase (P < 0.01) in Ca and P digestibility in response to phytase. In Exp. 2, ADG was 7% greater in PC than NC (P < 0.05); there were no effects of enzyme addition on any response. In Exp. 3, addition of phytase alone or in combination with xylanase improved (P < 0.05) P digestibility. Phosphorus excretion was greatest (P < 0.01) in the PC and lowest (P < 0.05) in the diet with the combination of phytase and xylanase. The combination of phytase and xylanase improved P retention (P < 0.01) above the NC diet to a level similar to the PC diet. In conclusion, a combination of phytase and carbohydrases improved ADG in 10-kg but not 23-kg pigs, but was efficient in improving P digestibility in pigs of all ages.

Xylanase in diets for growing pigs and broiler chicks

Experiments designed to determine the effects of feeding graded levels of xylanase to 10-kg pigs (exp. 1) and 1-d old broiler chicks (exp. 2) are presented. Pigs received diet composed of corn, rye, wheat, and SBM for 28 d, whereas chickens were fed diet composed of rye, wheat, and SBM for 21 d. Six dietary treatments consisting of a control diet or control plus xylanase (in units kg-1) at 400, 800, 1600, 3200 or 32 000 were fed. Graded levels of xylanase had no effect on growth performance of 10-kg pigs. There were diet and age effects (P < 0.05) on digestibility of DM, CP, and Ca in pigs. Linear and quadratic responses (P < 0.05) in final weight, weight gain, and gain:feed of broiler chicks to graded levels of xylanase were observed in exp. 2. In exp. 2, the effect of xylanase became apparent (P < 0.05) at 800 U kg-1; there were no differences in response to xylanase at 3200 and 32 000 U kg-1. In conclusion, xylanase improved growth performance in 1-d-old broilers fed a diet composed of rye, wheat, and SBM but not in 10-kg pigs that received a diet composed of corn, rye, wheat, and SBM. Key words: Broiler chicks, non-starch polysaccharides, pigs, xylanase

Response of growing pigs toPeniophora lycii- andEscherichia coli-derived phytases or varying ratios of calcium to total phosphorus

Two experiments were conducted to study the effects of phytase derived fromEscherichia coli(ECP) andPeniophora lycii(PLP) on performance, nutrient digestibility, and phosphorus (P) equivalency values of young pigs; and the influence of varying ratios of calcium (Ca) to total phosphorus (Ca:tP) with or without ECP on growth performance of pigs. In each experiment, 48 10-kg pigs were housed in individual pens for 28 days. Experiment 1 was designed to study the efficacy of ECP and PLP in improving growth performance and bone mineralization of young pigs given a low inorganic P (iP) diet. In the experiment, pigs were blocked by weight and sex and randomly allocated to eight dietary treatments. Each treatment had six replicates. The treatments were a positive control with adequate iP (PC); a low iP negative control (NC) diet; NC with supplemental iP in the form of monosodium phosphate added to provide 0·75 or 1·50 g iP per kg diet (as-fed basis); NC with ECP or PLP added at 500 or 1000 FTU per kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 μmol of iP per min, at pH 5·5, from an excess of 15 μmol/l sodium phytate at 37°C). In experiment 2, the objective was to study the effect of varying Ca:tP ratio with or without ECP on growth performance of growing pigs. Pigs (eight replicates) were blocked by weight and sex and randomly assigned to six dietary treatments in a 3×2 factorial arrangement of Ca:tP ratios at 1·2, 1·5, or 1·8; and ECP at 0 or 1000 FTU per kg (as-fed basis). In experiment 1, ECP (P<0·001) and PLP (P<0·05) linearly increased daily gain. There was a positive linear (P<0·05) response to the supplementation of the NC diet with ECP or PLP in the mineralization of the third and fourth metacarpal bones. Phosphorus equivalency values for 500 FTU of ECP or PLP based on mineralization of the third metacarpal bone were 0·77 g or 0·572 g, respectively. There were linear (P<0·001) and quadratic (P<0·05) responses to ECP, and linear (P<0·01) response to PLP in P digestibility. Neither iP supplementation nor either of the two phytases had significant effects on digestibility of dry matter, protein or energy. In experiment 2, reducing Ca:tP ratio linearly improved (P<0·05) daily gain, food intake, and food efficiency in pigs regardless of phytase supplementation. There was an enzyme by Ca:tP interaction on food intake. These studies in young pigs showed that ECP and PLP were efficacious in improving the growth performance and bone mineralization and that reducing the Ca:tP ratio enhanced performance response to phytase supplementation.

Age-Related Influence of a Cocktail of Xylanase, Amylase, and Protease or Phytase Individually or in Combination in Broilers

This 21-d experiment was conducted to determine if the response of chicks to a cocktail of xylanase, amylase, and protease (XAP) or Escherichia coli-derived phytase individually or in combination when fed a nutritionally marginal corn-soybean meal diet is age-dependent. Six hundred 1-d-old chicks were allocated to 5 dietary treatments in a randomized complete block design. The treatments were as follows: 1) positive control with supplemental inorganic P; 2) negative control (NC) marginal in P and ME; 3) NC plus XAP to provide (per kg of diet) 650, 1,650, and 4,000 U of xylanase, amylase, and protease, respectively; 4) NC plus phytase added to provide 1,000 phytase units/kg; and 5) NC plus a combination of XAP and phytase. Low ME and P in the NC diet depressed weight gain and gain:feed (P < 0.001). A cocktail of XAP alone did not improve performance, but phytase supplementation improved (P < 0.001) weight gain. The enzymes were additive in their effects on growth performance. The enzymes had no effect on ileal digestible energy. Ileal N digestibility was higher (P < 0.05) in diet with XAP or phytase individually compared with NC. Both phytase and XAP individually and in combination improved (P < 0.01) ileal P digestibility compared with NC. Total tract nutrient retention and ME increased (P < 0.01) as the birds grew older. There were age x diet interactions (P < 0.001) on total tract retention of P and Ca; improvement in P retention due to phytase use decreased by 50% as the chicks matured. The current study shows that a combination of XAP and phytase improved performance, but the enhancement in performance appears to be mainly from phytase. Both XAP and phytase were effective in improving P digestibility and retention of chicks receiving nutritionally marginal corn-soybean meal. The data also shows that the chicks benefited more from the enzyme addition at a younger age and that the contribution of the enzymes to nutrient retention decreased with age in chickens.

Effects of feeder space allowance on agonistic behaviour and growth performance of broilers (short communication)

Abstract. One hundred and thirty-two 4-weeks old unsexed Anak-2000 broiler strain were used to study the effect of feeder space allowance on agonistic behaviour and growth performance of broilers from weeks 4–8. The feeder space allowance were 2.4 cm/bird, 3.0 cm/bird and 3.6 cm/bird in groups I, II and III. The agonistic behaviour observed included head pecks, steps, pushes, threats and chase during feeding and "non-feeding" periods. There was a decrease in total agonistic behaviour as feeder space per bird increased from 2.4cm/bird to 3.6 cm/bird, both during feeding and non-feeding periods. There was a significant effect (p ≤ 0.05) of feeder space allowance on mean agonistic acts/bird/hour during feeding period being highest in G1 (7.8 acts/bird/hour), and lowest in G3 (4.5 acts/bird/hour). There was no significant effect (p > 0.05) of feeder space allowance on mean agonistic acts/bird/hour during non-feeding period. In G1 and G2, there was a significant effect (p ≤ 0.05) of period of observation on mean agonistic acts/bird/hour being highest in the feeding period and lowest in the non-feeding periods. In G3, there was no significant effect (p > 0.05) of period of day on mean agonistic acts/bird/hour and no significant effect of feeder space allowance on the growth performance parameters measured at p>0.05.