Influence of dietary calcium and phytase on phytate phosphorus hydrolysis in broiler chickens

Ileal phosphorus digestibility of soybean meal for broiler chickens remains consistent across institutions in a collaborative study regardless of non-phytate phosphorus concentration in the pre-experimental starter diet

The same experimental protocol was used in 4 institutions to evaluate the impact of non-phytate phosphorus (nPP) concentration in the starter diet on regression method-derived ileal P digestibility of soybean meal (SBM) during the subsequent grower phase. A total of 1,536 Ross 308 male broiler chickens on d 0 post hatching were allotted to 2 pre-experimental starter diets that contained 3.5 or 4.5 g nPP/kg (96 replicate cages per diet, 8 birds per cage) for 18 d. Subsequently, 576 birds from each starter diet were selected and allocated to 3 experimental semi-purified grower diets containing 400, 510, or 620 g SBM/kg (32 replicate cages per diet, 6 birds per cage) for 3 d until collection of ileal digesta. Statistical analysis was conducted as a randomized complete block design with the starter period as whole plot and the grower period as split-plot. The only significant 2-way interaction was between grower diet and experimental institution (P < 0.05) on BW gain and gain to feed ratio. The main effect of institution and grower diet impacted (P < 0.05) feed intake, the digestibility of DM, P, and calcium, and disappearance of inositol hexakisphosphate (InsP6) in the grower diets. Birds fed the 3.5 g nPP/kg starter diet had lower (P < 0.05) BW gain and feed intake during the grower period, but presented higher (P < 0.05) digestibility of P and disappearance of InsP6 compared with the birds that were fed the 4.5 g nPP/kg starter diet. Regression method-derived ileal P digestibility of SBM was determined to be 46 or 42% for the respective 3.5 or 4.5 g nPP/kg pre-experimental starter diet and was not affected by the nPP concentration or by the institution. In conclusion, the experimental protocol used in the current study resulted in similar estimates across multiple institutions and is thus endorsed for future application in studies that aim to expand the database of digestible P content in plant source feed ingredients.

Digestible calcium equivalency of phytase and nutrient utilization of broiler chickens fed graded levels of limestone or phytase during the starter phase

The current study aimed to quantify the digestible calcium (Ca) equivalency of a new phytase (HiPhorius) in broiler chickens. A total of 1,152 male Cobb 500 broiler chickens were used in an experiment in which 8 diets consisting of graded levels of Ca supplied with limestone or graded levels of the phytase were fed. The 8 dietary treatments were based on a corn-soybean meal diet containing 5.1 g/kg of Ca and 5.1 g/kg of phosphorus (P) as negative control (NC); the NC + 1.3, 2.6, or 3.9 g/kg of Ca from limestone; and the NC + 500, 1,000, 2,000, or 4,000 FYT/kg of phytase. Birds were fed the experimental diets for 3 d (from d 7 to 10) or 14 d (from d 7 to 21) to determine apparent ileal digestibility (AID) and apparent total tract retention (ATTR) of dry matter (DM), CP, Ca, and P. In the 10-day-old birds, increasing the levels of Ca decreased the AID of P and Ca (linear, P < 0.05). Increasing the levels of phytase quadratically improved (P < 0.05) the AID of Ca and P. The AID of DM and CP in the younger birds quadratically increased (P < 0.05) as the levels of Ca increased. There were linear and quadratic effects (P < 0.05) of increasing phytase level for the AID of DM and a linear effect (P < 0.05) for the AID of CP. In the 21-day-old birds, increasing Ca levels resulted in a linear decrease (P < 0.05) in the AID of CP and P, and a quadratic decrease (P < 0.05) in the ATTR of CP. Increasing phytase levels linearly and quadratically (P < 0.05) improved the AID and ATTR of CP, P, and the ATTR of Ca. The analyzed phytase activity in the diets supplemented with phytase ranged from 1,520 to 7,661 FYT/kg. The digestible Ca equivalence for dietary phytase at 1,520 to 7,661 FYT/kg ranged from 1.55 to 2.02 g/kg in the 10-day-old birds fed for 3 d and from 0.52 to 0.64 g/kg in 21-day-old birds fed for 14 d. The results showed the reduction in Ca level that could be accommodated by phytase supplementation, which is markedly different between the younger and older birds. Feeding duration influenced the impact of phytase supplementation on Ca and P digestibility, with better efficacy of phytase observed in the 10-day-old birds fed for 3 d. Also, the results showed the extra-phosphoric effects of phytase on the utilization of other essential nutrients such as protein and Ca.

Calcium Nutrition of Broilers: Current Perspectives and Challenges

Calcium (Ca) plays an essential role in poultry nutrition as 99% of Ca is located in birds' skeletal system. However, oversupply of Ca rather than deficiency of Ca is the current concern in commercial broiler diets. Calcium is an inexpensive dietary nutrient due to the cheap and abundant availability of limestone, the major Ca source; therefore, little attention was given to the oversupply of Ca in the past. The recent shift in the use of digestible P in broiler feed formulations has necessitated a closer look at digestible Ca, as Ca and P are interrelated in their absorption and postabsorptive utilisation. In this context, data on ileal digestibility of Ca and P in ingredients has been determined. Preliminary data on the digestible Ca and digestible P requirements for the different growth stages of broilers have also recently become available. The present review focusses on these recent advances in Ca nutrition. In addition, aspects of homeostatic control mechanisms, different Ca sources and factors influencing Ca digestibility in poultry are covered.

Effect of Bacterial Phytase on Growth Performance, Nutrient Utilization, and Bone Mineralization in Broilers Fed Pelleted Diets

The influence of a bacterial 6-phytase on growth performance, coefficient of apparent ileal digestibility (CAID) of nutrients, blood parameters, and bone mineralization in broilers was evaluated. A total of 630 one-day-old male broilers were allocated to 7 dietary treatments, including positive control (PC) diet containing dicalcium phosphate, the PC marginally reduced in available P (avP) by 0.1% and calcium (Ca) by 0.2% vs. PC (NC1) or moderately reduced by 0.15 and 0.3% vs. PC (NC2), respectively, and four further diets comprising the NC1 and NC2 supplemented with 500 or 1000 FTU/kg of phytase in starter and finisher phases. A constant Ca to avP ratio was maintained across all diets. The body weight gain (BWG) and feed per unit gain (FCR) of birds fed NC1 and NC2 diets supplemented with phytase (500 and 1000 U/kg) was equivalent to that of birds fed the PC diet at 35 days. Phytase supplementation in the NC1 diet linearly increased the CAID of nitrogen (N) (p < 0.01), phosphorus (P) (p < 0.01), and Ca (p < 0.05). Additionally, phytase reduced (p < 0.01) excreta P concentration by approximately 27%, improved (p < 0.001) toe ash, and tended to increase tibia ash (p = 0.08), comparable with the PC. In conclusion, the addition of bacterial 6-phytase dosed in the range of 500-1000 FTU/kg was effective in replacing 1.5 g/kg avP and 3 g/kg Ca in broilers fed pelleted diets, using bone quality, BWG, and FCR as outcome measures.

Effect of phytase and limestone particle size on mineral digestibility, performance, eggshell quality and bone mineralization in laying hens

The effect of microbial phytase and limestone particle size (LmPS) was assessed in Lohmann Tradition laying hens from 31 to 35 wk of age. Seventy-two hens were used in a completely randomized trial according to a 2 × 2 factorial arrangement with 2 levels of phytase/basal available P (aP); 0 FTU/kg with 0.30% aP or 300 FTU/kg with 0.15% aP, and 2 limestone particle sizes; fine particles (FL, <0.5 mm) or a mix (MIX) of 75% coarse limestone (CL, 2-4 mm) and 25% FL. Diets contained equivalent levels of Ca (3.5%), phytic P (PP; 0.18%), and aP (0.30%) considering the P equivalency of phytase. Thus, dietary treatments were FL0 and MIX0 without phytase, and FL300 and MIX300 with 300 FTU/kg phytase. Performance were recorded daily and eggshell quality (eggshell weight proportion, weight, thickness, and breaking strength) was measured weekly. At the end of the trial, bone parameters (tibia breaking strength, elasticity, and ash) and the apparent precaecal digestibility (APCD) of P and Ca were determined. No differences were observed between treatments in feed intake, FCR and bone parameters. Addition of MIX increased the eggshell proportion, weight and thickness in groups receiving no phytase (+6.5, +6.9, and +4.5%, respectively) while no effect was observed in groups receiving phytase (Phytase × LmPS, P < 0.05). In hens receiving FL, the APCD of P was lower in diets supplemented with phytase (-14 percentage points; Phytase × LmPS, P < 0.001). A higher phytate disappearance was observed in hens fed diets with phytase in combination with MIX (Phytase × LmPS, P = 0.005). Phytase and MIX together increased the APCD of Ca by 7.3 percentage points (Phytase × LmPS, P < 0.001). In conclusion, addition of CL could limit the formation of Ca-phytate complex thus improving the response of the birds to phytase compared to FL.

Comparison of mucosal phosphatase activity, phytate degradation, and nutrient digestibility in 3-week-old turkeys and broilers at different dietary levels of phosphorus and phytase

A comparison between 3-wk-old female turkeys (B.U.T. 6) and broilers (Ross 308) was performed to study the effects of species, dietary P, Ca, and phytase levels on gut mucosal phosphatase activity, myo-inositol hexakisphosphate (InsP₆) degradation along the digestive tract, digestibility of P, Ca, and amino acids, and concentrations of myo-inositol in the digesta and blood. The experimental diets were corn-soybean meal-based and identical for both species. Two dietary P and Ca concentrations (CaP-: 4.1 g P/kg, 5.5 g Ca/kg and CaP+: 9.0 g P/kg, 12.0 g Ca/kg) and 2 levels of phytase supplementation (0 and 1,500 FTU/kg) were used in a 2 × 2 factorial design and fed to the animals for 7 d in their third week of age. Each diet was randomly assigned to 6 broiler and 6 turkey pens, with 10 birds each. After slaughter, blood, digesta from the crop, gizzard, duodenum, lower ileum, and mucosa from the jejunum were collected. When fed CaP- without phytase supplementation, there were no differences between species in gut mucosal phosphatase activity, prececal InsP₆ disappearance, and P and Ca digestibility, indicating a similar intrinsic capacity for phytate degradation in both species. When fed CaP+ without phytase supplementation, turkeys showed higher prececal InsP₆ disappearance than broilers. Phytase supplementation increased prececal InsP₆ disappearance and digestibility of P and Ca in both species. However, the phytase-induced increase in prececal InsP₆ disappearance was more pronounced in broilers than in turkeys, possibly due to more adequate conditions for phytase activity in the broiler crop. In broilers, phytase supplementation increased amino acid digestibility overall, whereas, in turkeys, it increased with CaP+ and decreased with CaP-. In addition, the relationship between myo-inositol concentration in the ileum and blood differed between species, indicating differences in myo-inositol metabolism. It was concluded that 3-week-old turkeys and broilers differ in nutrient digestibility and InsP degradation in some segments of the digestive tract but have similar endogenous InsP₆ degradation when fed low P and Ca diets.

Effects of limestone solubility on the efficacy of a novel consensus bacterial 6-phytase variant to improve mineral digestibility, retention, and bone ash in young broilers fed low-calcium diets containing no added inorganic phosphate

This study evaluated the effect of limestone solubility on the capacity of a novel consensus bacterial 6-phytase variant (PhyG) to improve phosphorus (P) and calcium (Ca) digestibility, retention, and utilization in low-Ca broiler diets containing no added inorganic phosphate (Pi). Male Ross 308 broilers (n = 1,152) were fed one of 16 experimental diets from 11 to 21 d of age in a randomized complete design (12 birds/cage, 6 cages/treatment). Diets comprised three positive controls (PC3, PC2, and PC1) containing 1.8, 1.2, or 0.6 g/kg MCP-P and 7.7, 7.0, or 6.2 g/kg Ca, respectively, and a negative control (NC) containing no added Pi (4.4 g/kg P; 2.8 g/kg phytate-P) and 5.5 g/kg Ca from either low or high solubility limestone (LSL or HSL, respectively, [with 42% and 97% solubility after 5 min at pH 3.0]), supplemented with 0, 250, 500, 1,000, or 2,000 FTU/kg of PhyG. Fecal samples collected on days 18 to 20 and ileal digesta collected on day 21 were analyzed for titanium dioxide, Ca, P, and phytate (IP6, inositol hexakisphosphate). Tibias (day 21) were analyzed for ash content. Data were analyzed by factorial analysis (2 limestone solubilities × 4 MCP-P levels and 2 limestone solubilities × 5 phytase dose levels) and exponential regression. Increasing dose levels of PhyG resulted in an exponential increase (P < 0.01) in the apparent ileal digestibility (AID) of P, ileal digestible P content of the diet, ileal IP6 content, and IP6 disappearance in birds fed either HSL or LSL diets, but AID Ca and ileal digestible Ca were exponentially increased by the phytase only in HSL diets (P < 0.01). Relative to HSL, the LSL increased AID P, ileal digestible P, and IP6 disappearance (P < 0.05) but reduced AID Ca, ileal digestible Ca, and retainable Ca (P < 0.05), resulting in reduced retainable P and tibia ash. Phytase exponentially increased the apparent total tract digestibility of P, retainable P, and tibia ash in HSL and LSL diets, but at or above 500 FTU/kg values were higher in HSL than LSL (interaction P < 0.05). The findings highlight that phytase dose-response effects on mineral digestibility and utilization are different for high- and low-solubility limestones, and it is therefore recommended to use digestible rather than total Ca content during diet formulation to ensure an optimal balance of Ca and P, especially in low-Ca diets. In diets containing HSL, higher phytase dose levels may be needed to compensate for the low digestible P content of the basal diet.

Apparent digestibility of energy and nutrients and efficiency of microbial phytase is influenced by body weight of pigs

An experiment was conducted to test the hypothesis that regardless of pig body weight (BW), increasing dietary phytase results in increased phytate degradation and improved digestibility of minerals, amino acids (AA), and gross energy (GE). Eighteen pigs were equipped with a T-cannula in the distal ileum and allotted to a triplicated 6 × 3 Youden square design with six diets and three collection periods of 7 d, for a total of nine replicate pigs per diet. This design was repeated four times to simulate four production phases, and there was a 7-d resting period before each collection phase started (BW at start of collections: 29.3, 53.6, 85.1, and 114.4 kg for phases 1, 2, 3, and 4, respectively). Six corn-soybean meal diets were formulated by including 0, 250, 500, 1,000, 2,000, or 4,000 phytase units/kg feed (FTU). The six diets were used throughout the experiment. Samples of feces and ileal digesta were collected in each period. Results indicated that regardless of pig BW, increasing inclusion of phytase increased (quadratic; P < 0.05) apparent ileal digestibility (AID) of crude protein (CP) and most AA, increased apparent total tract digestibility (ATTD) of Ca, P, K, Mg (linear and quadratic; P < 0.05), and Na (linear; P < 0.05), but decreased (linear and quadratic; P < 0.05) AID and ATTD of GE. In all phases, ileal concentrations of inositol phosphate (IP) 6, IP5, IP4, and IP3 decreased (linear and quadratic; P < 0.05), whereas ileal inositol increased (linear and quadratic; P < 0.05) with increasing dietary phytase. However, as pig BW increased, AID of GE, CP, and AA increased (linear, P < 0.05), and the AID of a few AA (Met, Phe, Thr, Trp, Ala, Asp, Gly, and Ser) also increased quadratically (P < 0.05). The ATTD of GE, K, and Mg increased (linear and quadratic; P < 0.05), but ATTD of Ca and Na (linear; P < 0.05) and of P (linear and quadratic; P < 0.05) decreased as pig BW increased. Ileal IP6 and IP3 (linear and quadratic; P < 0.05) and ileal IP5 and IP4 (linear; P < 0.05) increased, whereas ileal inositol decreased (linear; P < 0.05) as pig BW increased. In conclusion, regardless of pig BW, increasing dietary phytase increased phytate degradation and inositol release in the small intestine, and consequently increased mineral and AA digestibility. Older pigs have reduced Ca, P, and Na digestibility, but increased K, Mg, AA, and GE digestibility compared with younger pigs. The efficiency of dietary phytase to degrade phytate appears to decrease as pigs get older.

Effects of phytase and coccidial vaccine on growth performance, nutrient digestibility, bone mineralization, and intestinal gene expression of broilers

A study was conducted to evaluate effects of phytase and coccidial vaccine on growth performance, bone mineralization, nutrient digestibility, and intestinal gene expression of broiler chickens. The experiment was conducted in a 2 × 4 completely randomized factorial arrangement with 6 replicates per treatment and 10 birds each. Applications of coccidiosis vaccine and different dietary treatments were the 2 main factors in the current study. The dietary treatments included 1) a positive control (PC; 0.90% Ca and 0.45% available P: avP); 2) a negative control (NC; 0.75% Ca and 0.30% AvP); 3) NC + 500 FTU/kg of phytase (NC + 500PHY); and 4) NC + 1500 FTU/kg of phytase (NC + 1500PHY). Data were analyzed using SAS by 2-way ANOVA via GLM procedure. The statistical significance was set at P ≤ 0.05, and means were further separated using Tukey's Test. The results indicated that vaccination had no effect on growth performance except for feed intake from 0 to 14 d but negatively (P < 0.05) regulated bone ash and Ca digestibility. Birds fed with the Ca and P-reduced diet (NC) showed a lower BWG and bone ash compared to birds fed with the normal diet (PC), but supplementing phytase mitigated the negative effects on those birds. Broilers fed the NC diet had higher (P < 0.05) total Ca and P digestibility, and phytate degradation; supplementing phytase further increased P digestibility and phytate degradation of the broilers. A significant interaction (P < 0.05) between phytase and vaccination was observed, suggesting the vaccinated birds fed the PC diet and the unvaccinated birds fed the NC + 1500PHY increased calcium-sensing receptor gene expression compared with the unvaccinated birds fed the PC diet. In conclusion, in spite of coccidiosis vaccine, supplementing phytase at 1,500 FTU/kg alleviated the negative effects on growth performance, bone mineralization, and apparent ileal digestibility of P and phytate.

Multi-Omics Reveals Different Strategies in the Immune and Metabolic Systems of High-Yielding Strains of Laying Hens

Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) are two commercially important laying hen strains due to their high egg production and excellent commercial suitability. The present study integrated multiple data sets along the genotype-phenotype map to better understand how the genetic background of the two strains influences their molecular pathways. In total, 71 individuals were analyzed (LB, n = 36; LSL, n = 35). Data sets include gut miRNA and mRNA transcriptome data, microbiota composition, immune cells, inositol phosphate metabolites, minerals, and hormones from different organs of the two hen strains. All complex data sets were pre-processed, normalized, and compatible with the mixOmics platform. The most discriminant features between two laying strains included 20 miRNAs, 20 mRNAs, 16 immune cells, 10 microbes, 11 phenotypic traits, and 16 metabolites. The expression of specific miRNAs and the abundance of immune cell types were related to the enrichment of immune pathways in the LSL strain. In contrast, more microbial taxa specific to the LB strain were identified, and the abundance of certain microbes strongly correlated with host gut transcripts enriched in immunological and metabolic pathways. Our findings indicate that both strains employ distinct inherent strategies to acquire and maintain their immune and metabolic systems under high-performance conditions. In addition, the study provides a new perspective on a view of the functional biodiversity that emerges during strain selection and contributes to the understanding of the role of host–gut interaction, including immune phenotype, microbiota, gut transcriptome, and metabolome.

Growth performance, carcass and meat quality, bone strength, and immune response of broilers fed low-calcium diets supplemented with marine mineral complex and phytase

Influence of marine mineral complex (CeltiCal) as a partial substitute for limestone on growth efficiency, carcass traits, meat quality, bone strength, calcium (Ca) retention, and immune response was investigated in broilers fed low-Ca diets with or without phytase (PHY) addition for a 35-d trial period. A total of 300 one-day-old Ross 308 straight-run broilers were randomly allocated to: T1 (positive control), recommended Ca levels + PHY; T2 (negative control), 0.2% below the recommended Ca levels + PHY; T3, 0.1% below the recommended Ca levels + 0.2% CeltiCal + PHY; T4, 0.2% below the recommended Ca levels + 0.4% CeltiCal + PHY; T5, 0.2% below the recommended Ca levels + 0.4% CeltiCal. PHY was added at 500 phytase units/kg diets. Each dietary treatment had 10 replications of 6 chicks each. Results revealed that production efficiency factor was greater for T4 compared to T2 and T5 during 22-35 d and for T1, T3, and T4 compared to T2 during 0 to 35 d (P < 0.05). Feed conversion ratio was lower for T3 and T4 compared to T2 and T5 during 0 to 35 d (P < 0.05). T4 had a greater (P < 0.05) dressing percentage than T2, which had a lighter (P < 0.01) small intestinal relative weight than all other treatments. Breast meat temperature at 15 min postmortem was highest for T1 and lowest for T3 (P < 0.001). Breast meat pH was greater for T1 compared to T5 at 15 min postmortem and for T3 compared to T4 at 24 h postmortem (P < 0.05). T5 had a lower breast meat redness than all other treatments at 15 min postmortem and then T1 and T3 at 24 h postmortem (P < 0.01). Tibia and femur weights were greater (P < 0.05) for T3, T4, and T5 compared to T2, which had the lowest tibia ash content (P < 0.05) and femur geometric properties (P < 0.001). Greater antibodies to infectious bronchitis virus (P < 0.01) and Ca retention (P < 0.001) were observed for T3 and T4 in comparison to T2. Based on the findings of this research, CeltiCal can adequately replace a considerable portion of limestone in broiler reduced-Ca diets containing PHY.

Global survey of limestone used in poultry diets: calcium content, particle size and solubility

Limestone is used in poultry diets as a calcium (Ca) source. Feed formulation is often based on an estimate of limestone Ca content or, less frequently, wet chemistry analysis. However, limestone composition may vary, which has not previously been studied on a large scale. In this study, 641 limestone samples supplied to poultry feed mills in 40 countries across eight global regions were collected and analysed for macro- and micromineral content, particle size (geometric mean diameter, GMD), and in vitro solubility. Mean Ca content of fine limestone (GMD<1000 μm, n=566) was 37.8% (range 33.3-39.7%) and for coarse limestone (GMD>1000 μm, n=75) was 38.0% (range 34.7-40.0%). There was marked variation among and within regions in the concentration of other macro minerals and microminerals. Particle size (GMD) of fine limestone was 288 μm (range 37.7-991.9 μm) and 1,689 mm for coarse limestone (range 301.6-3,067.9 μm). In vitro solubility of fine limestone (5 min incubation, pH=3.0) was 68.4% (range 18.8 to 99.4%). Particle size only explained 52% of the variation in 5 min incubation solubility (R2=0.52). For coarse limestone, mean solubility (30 min incubation) was 65.5% (range 23.2-96%) which was not correlated (R2=0.09) with particle size. Particle size and solubility rate of limestone have been shown to alter Ca and phosphorus utilisation in broilers and laying hens. Hence, better understanding of variation in mineral analysis, particle size and solubility rate would enable more accurate feed inclusion and subsequently digestibility to support health and performance.

Effects of a novel consensus bacterial 6-phytase variant on the apparent ileal digestibility of amino acids, total tract phosphorus retention and tibia ash in young broilers

The effect of a novel consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID) of amino acids (AA) and phosphorus (P) utilization in young broilers when added to diets with high phytate-P (PP) content without added inorganic phosphate (Pi) and deficient in digestible (dig) AA and metabolizable energy (ME) was investigated. A total of 256 Ross 308 male broilers were assigned to 4 treatments (8 birds/cage, 8 cages/treatment) in a completely randomized design. Treatments comprised a positive control (PC, 2,975 kcal/kg ME, 3.7 g/kg dig P, 2.83 g/kg PP, 8.4 g/kg Ca, 10.6 g/kg dig lysine), a negative control (NC) without added Pi (ME −68 kcal/kg, crude protein −10 g/kg, dig AA −0.1 to −0.4 g/kg, Ca −2.0 g/kg, dig P −2.2 g/kg, Na −0.4 g/kg vs. PC), and NC plus 500 or 1,000 FTU/kg of PhyG. Test diets were corn/soy/rapeseed-meal/rice-bran-based and fed from 5 to 15 d of age. Ileal digesta and tibias were collected on day 15. Excreta was collected during days 12 to 15 to determine P retention. The NC (vs. PC) reduced (P < 0.05) P retention (−10.4% units), tibia ash (−14.3% units), weight gain (−109 g), feed intake (−82 g) and increased FCR (from 1.199 to 1.504), confirming that the NC was extremely deficient in nutrients and energy. Phytase addition to the NC linearly (P < 0.001) improved performance, but did not fully recover it to the level of the PC due to the severe nutrients/energy reduction in NC. Phytase linearly increased P retention (P < 0.001), tibia ash (P < 0.001), AID of dry matter (P < 0.05), nitrogen (P < 0.01), gross energy (P < 0.05), and all 17 individual AA (P < 0.01). At 1,000 FTU/kg, phytase increased (P < 0.05) P retention vs. PC and NC (+14.5 and +24.9% units, respectively) and increased tibia ash vs. NC (+13.8% units), equivalent to PC. The NC decreased AID of Cys, Gly, Thr, and Met vs. PC (P < 0.05). At 1,000 FTU/kg, phytase increased AID of all 17 AA vs. NC (P < 0.01), equivalent to PC. At 1,000 FTU/kg, AID AA responses (above NC) ranged from +4.5% (Met) to +15.0% (Cys), being maximal for essential Thr (+10.4%) and Val (+8.2%) and non-essential Cys (+15.0%) and Gly (+10.4%). The results highlight the efficacy of PhyG at a dose level of 500 to 1,000 FTU/kg in young broilers for improving the ileal digestibility of nitrogen, AA, and energy alongside P retention and tibia ash. The performance data emphasize the need to consider digestible nutrient intake as a response variable in exogenous enzyme studies.

Microbial phytase is widely used in commercial broiler diets to improve digestion of phosphorus (P) and reduce its excretion into the environment. Phytase improves the digestion of phosphorus and other nutrients including amino acids (AA). This study evaluated the effect of a novel consensus bacterial 6-phytase variant (PhyG) added to a nutrient-reduced diet without any added inorganic P on the digestibility of nutrients including P and AA in the ileum of young broilers. Effects on P retention and bone mineralization were also assessed. Compared to an unsupplemented negative control diet, PhyG improved growth performance, P retention, bone mineralization (tibia ash), digestibility of dry matter, nitrogen, gross energy, and all 17 individual AA during 5 to 15 d post-hatch, in a dose-dependent manner (dose range 0 to 1,000 phytase units [FTU] per kilogram of feed). For some AA, the increases in digestibility with PhyG at 1,000 FTU/kg were substantial (cysteine: +15.0%, threonine:+10.4%), and for all AA were equivalent to the responses produced by a nutritionally adequate positive control (unsupplemented) diet. The results demonstrate the efficacy of PhyG to improve AA digestibility alongside growth performance, P retention, and bone mineralization in young broilers.

Assessment of crop usage in ad libitum fed birds and short-term phytase efficiency as affected by acid addition

1. A field assessment was performed to map the extent of crop usage and thus retention time in broiler chickens. In addition, a broiler experiment was carried out to study the short-term effect of acid addition on phytase efficacy in the crop.2. In the field assessment, the crop content of 40 ad libitum fed broiler chickens from four different farms were sampled at 10, 20 and 30 d of age. The dry matter (DM) content varied from zero to 32 g.3. From 11 d of age, 120 individually caged chickens were intermittently fed a high phytate-P diet with either no addition or 500 FYT C. braakii-derived phytase added or both phytase and 1.4 % formic acid added. Excreta were collected for assessment of phosphorus (P) retention. At 20 and 21 d of age, starved birds were fed for 1 h, and thereafter crop and gizzard contents were collected every 20 min until 140 min after start of the feeding. At 60 and 140 min, the contents from the jejunum and ileum were collected.4. All diets reduced the concentration of phytate in the crop, however the combination of acid and phytase resulted in a higher degradation (P<0.05) than the other diets from 20 min after the start of feeding. Simultaneously, the concentration of the smaller inositol phosphate isomers, such as inositol-5-phosphate, increased (P<0.05). Phytase increased (P<0.05) P retention, and the combination of acid and phytase increased jejunal P digestibility (P<0.05) compared to the other diets.5. The results indicated that lower pH in the crop due to acid addition improved phytase efficacy and increased P digestibility in the anterior digestive tract, even with short retention times.

Increased microbial phytase increased phytate destruction, plasma inositol, and feed efficiency of weanling pigs, but reduced dietary calcium and phosphorus did not affect gastric pH or fecal score and reduced growth performance and bone ash

An experiment was conducted to test two hypotheses: 1) reducing dietary Ca and P reduces gastric pH and diarrhea in weanling pigs; 2) negative effects of low Ca and P on pig growth performance may be overcome if phytase is added to the diets. A total of 320 weanling pigs (6.35 ± 0.87 kg) were allotted to eight corn-soybean meal-based diets in a randomized complete block design with five pigs per pen. Two phase 1 (days 1 to 14) control diets containing 100 or 50% of total Ca and digestible P relative to the requirement, and six diets in which 500, 2,000, or 16,000 units of phytase/kg feed (FTU) were added to each control diet were formulated. Phytase was assumed to release 0.16% total Ca and 0.11% digestible P. Common diets were fed in phases 2 (days 15 to 27) and 3 (days 28 to 42). Growth performance data were recorded within each phase. Data for fecal scores and gastrointestinal pH were recorded for phase 1. Colon content (day 14), the right femur (days 14 and 42), and blood samples (days -1, 14, 27, and 42) were collected from one pig per pen. In phase 1, reducing Ca and P did not reduce gastric pH or fecal score, but pigs fed the 50% diets had reduced (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI) compared with pigs fed the 100% diets. In both 50% and 100% diets, phytase above 500 FTU increased (P < 0.05) gain:feed ratio (G:F) and tended (P < 0.10) to reduce gastric pH of pigs. From days 1 to 42, pigs fed the 50% diets tended (P < 0.10) to have reduced ADG and ADFI compared with pigs fed the 100% diets, but among the 100% diets, pigs tended (P < 0.10) to have a linear increase in G:F as phytase level increased. Pigs fed the 50% diets had reduced (P < 0.05) concentrations of inositol phosphate esters (IP) in the colon and reduced bone ash (days 14 and 42) compared with pigs fed the 100% diets. Phytase did not affect bone ash or most blood metabolites. Concentrations of IP in the colon decreased, whereas plasma inositol increased (d 14; P < 0.05) in pigs fed diets with phytase (≥ 500 FTU). In pigs fed the 100% diets, IP in the colon linearly decreased (P < 0.05), but plasma inositol linearly increased (P < 0.05) with increasing levels of phytase. In conclusion, reducing Ca and P in diets for weanling pigs did not influence gastric pH or fecal score, but compromised growth performance and bone ash. However, regardless of dietary Ca and P, high doses of phytase increased phytate degradation and inositol absorption, which consequently increased G:F of pigs.

Supplemental Effects of Phytase on Modulation of Mucosa-Associated Microbiota in the Jejunum and the Impacts on Nutrient Digestibility, Intestinal Morphology, and Bone Parameters in Broiler Chickens

This study aimed to determine supplemental effects of phytase on modulation of the mucosa-associated microbiota in the jejunum, intestinal morphology, nutrient digestibility, bone parameters, and growth performance of broiler chickens. Three hundred and sixty newly hatched broiler chickens (Ross 308) (44 ± 2 g BW) were randomly allotted in 6 treatments with 10 birds per cage based on a completely randomized design and fed for 27 d. The treatments consisted of one negative control (NC), diet formulated meeting the requirements suggested by Ross recommendations (2019), and without phytase supplementation. The other treatments consisted of a positive control diet (PC) formulated with 0.15% deficient Ca and P and split into 5 treatments with different phytase inclusion levels (0, 500, 1000, 2000, 4000 FTU/kg feed). Titanium dioxide (0.4%) was added to feeds as an indigestible marker to measure apparent ileal digestibility (AID) of nutrients. On d 27, 3 birds were randomly selected from each cage and euthanized to collect samples for analyzing the mucosa-associated microbiota in the jejunum, oxidative stress status, AID, and bone parameters. Data were analyzed using the proc Mixed of SAS 9.4. Phytase supplementation tended to have a quadratic effect (p = 0.078) on the overall ADG (maximum: 41 g/d at 2833 FTU/kg of feed). Supplementation of phytase at 2,000 FTU/kg increased (p < 0.05) the relative abundance of Lactobacillus and reduced (p < 0.05) Pelomonas. Moreover, it tended to reduce Helicobacter (p = 0.085), Pseudomonas (p = 0.090) Sphingomonas (p = 0.071). Phytase supplementation increased (p < 0.05) the villus height and the AID of CP; and tended to increase (p = 0.086) the AID of P. Phytase supplementation increased (p < 0.05) breaking strength and P content in the tibia. In conclusion, phytase supplementation showed potential benefits on the modulation of the mucosa-associated microbiota in the jejunum by tending to reduce harmful bacteria (Pelomonas, Helicobacter, and Pseudomonas) and increase beneficial bacteria (Lactobacillus). In addition, it showed positive effects increasing apparent ileal digestibility of CP and P, enhancing intestinal morphology (villus height), and improving the bone parameters (bone breaking strength, ash, and P content). Phytase supplementation at a range of 38 to 59 FTU/d or 600 to 950 FTU/kg of feed provided the most benefits related to nutrient digestibility.

Prediction of calcium and phosphorus requirements for pigs in different bodyweight ranges using a meta-analysis

Several studies have focused on Ca and P requirements for pigs. These requirements are estimated from their retention and bone formation. However, modern pig breeds have different responses to dietary Ca and P than traditional breeds, and their requirements are expected to change on an annual basis. Besides individual Ca and P needs, the Ca to P ratio (Ca/P) is an important factor in determining requirements. This study aimed to implement a linear and quadratic regression analysis to estimate Ca and P requirements based on average daily gain (ADG), apparent total tract digestibility (ATTD) of Ca (ATTD-Ca), ATTD of P (ATTD-P), and crude protein (CP) digestibility. Results show that Ca/P had linear and quadratic effects on ADG in the phytase-supplemented (PS) group in both the 6–11 kg and 11–25 kg categories. In the latter category, the CP digestibility was linearly increased in response to increasing Ca/P in the without-phytase (WP) group. In the 25–50 kg category, there was a linear response of ADG and linear and quadratic responses of CP digestibility to Ca/P in the PS group, while a linear and quadratic increase in CP digestibility and a quadratic effect on ATTD-Ca were observed in the WP group. In the 50–75 kg category, Ca/P had significant quadratic effects on ADG in the PS and WP groups, along with significant linear and quadratic effects on ATTD-Ca. In addition, Ca/P had significant quadratic effects on ATTD-P and led to a significant linear and quadratic increase in the CP digestibility in the WP group. In the 75–100 kg category, analysis showed a significant decrease in ATTD-Ca and ATTD-P in the PS and WP groups; in the latter, ATTD-P and ATTD-Ca were linearly decreased by increasing Ca/P. In conclusion, our equations predicted a higher Ca/P in the 6–25 kg bodyweight categories and a lower Ca/P in the 50-100 kg category than that recommended in the literature.

A review of limitations to using cassava meal in poultry diets and the potential role of exogenous microbial enzymes

Cassava (Manihot esculenta), a crop grown in the tropics, is increasingly becoming a vital feed resource for human beings and livestock. Traditionally, cassava has been used primarily as a source of food for humans. However, it is becoming an increasingly important ingredient in livestock feed. The use of cassava leaves and roots in poultry diets is limited because of nutrient imbalances and toxins (hydrogen cyanide (HCN)) found in them. High HCN is reduced to innocuous levels by processing the ingredient using a simple sun drying method. Plant fibre content can be reduced and made available for use by poultry through the use of exogenous enzymes. More recent innovative interventions in biotechnology have brought about various exogenous enzymes that can help improve the digestibility of fibrous diets. These include, among others, carbohydrases, proteases and phytases. The extent to which the animals utilise nutrients is influenced by the type of enzyme and the physicochemical properties of the feed ingredient. This review aims to collate information on the current state of knowledge on the use of exogenous microbial enzymes in diets containing cassava and how the enzymes that target carbohydrates might be useful in making nutrient available for poultry.

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.

In vitro assays for evaluating phytate degradation in non-ruminants: chances and limitations

The positive effects of phytases on the environment, animal welfare and animal feed costs have resulted in the continuous development and improvement of these enzymes in the non-ruminant feed market. To test the efficacy of these phytases, a large number of experimental animals are necessary, antagonising the animal welfare aspect of these enzymes. In the present review, we summarise the most prominent available in vitro assays for evaluating phytase enzymes and how far they can reduce the number of in vivo experiments. Several in vitro assays exist that differ in their setup, extent and conditions depending on the animal of interest and the research question. With the in vitro assays described, it is not possible to fully replace in vivo trials. However, for the investigation of phytase effects in feedstuffs, the use of an in vitro assay has several advantages. In vitro assays have the potential to be used for ranking feed enzymes and as screening tools. Applying in vitro protocols will result in a reduction in the number of animals or treatments usually necessary for an in vivo trial, thus acting towards the three Rs. © 2020 Society of Chemical Industry.

Effect of dietary calcium and phosphorus levels on growth, carcass characteristics and liver and kidney functions of growing Egyptian geese

The present study investigated the effect of different dietary levels of calcium (Ca) and non-phytate phosphorus (P) on the growth performance, carcass characteristics, and blood components of growing geese. A total of 120, 4-wk-old Egyptian goslings with similar body weights were randomly distributed to four groups in a 2 × 2 factorial arrangement, which included 2 levels of Ca (0.85% and 0.70%) and 2 levels of non-phytate P (0.45% and 0.35%). Each group was subdivided into 6 replicates of five birds. The experiment lasted 8 wk, from 4 to 12 wk of age. Results show that dietary Ca level had no significant effect on any of the studied growth performance traits over the full experimental period. Dietary P level also had no significant impact on these traits, with the exception of daily body weight gain and feed conversion ratio at 8 to 12 wk of age; these improved significantly with the low P diet. Geese received a diet containing 0.70% Ca + 0.45% P had the lowest body weight values at 12 wk of age and the lowest daily body weight gain, and feed intake at 8 to 12 weeks of age. While, the lowest value of feed conversion ratio was recorded in geese fed low level of Ca with low level of P (0.70% Ca + 0.35% P). There were no significant effects of the different dietary levels of Ca, P, or their interaction on all studied carcass parameters. Low dietary Ca level significantly increased the plasma levels of total protein, albumin, alanine transaminase (ALT), aspartate transaminase (AST), and creatinine and significantly decreased the plasma levels of Ca and P. Different dietary P levels had no significant effect on plasma levels of albumin, AST, ALT, ALP, and urea, whereas the 0.35% P-based diet significantly decreased the plasma contents of total protein, creatinine, Ca, and P. Plasma levels of albumin, creatinine, urea, Ca, and P were not affected by an interaction between Ca and P. Diets containing 0.70% Ca and 0.45% P lead to the highest plasma values for total protein, ALT, AST, and ALP compared with the other dietary Ca and P combinations. In conclusion, dietary Ca and P levels can be simultaneously reduced without negative impacts on growth performance, carcass characteristics, or blood biochemical components. We advise to avoid increasing the dietary Ca: P ratio, as it leads to negative effects on growth performance and blood biochemistry in growing geese. So, the findings of the current study recommended the low levels of Ca (0.70%) and non-phytate P (0.35%) for the performance of Egyptian geese during the fattening period.

A comparison of the release of phosphorus by a phytase enzyme in pigs fed diets deficient or adequate in phosphorus content

Previous research indicated that phytase may release less phosphorus (P) from phytate when it is evaluated using diets with P levels above requirement as compared with diets below requirement. The objectives of this experiment were to further test the hypothesis that the P release values determined for phytase are higher when pigs are fed diets that are deficient (DE) in P compared with when they are fed diets that are adequate (AD) in P, and that phytase will increase the digestibility of dry matter (DM), gross energy (GE), nitrogen (N), and calcium (Ca) independent of dietary P status. Twenty-four barrows (body weight: 23.2 ± 1.8 kg) were randomly assigned to one of eight dietary treatments and housed in individual pens for 21 d and then moved to metabolism crates for 9 d, with the collection of urine and feces occurring on the final 5 d. A basal corn-soybean meal diet (P-AD) was formulated at 0.36% standardized total tract digestible (STTD) P and total calcium:STTD P (Ca:STTD P) of 2:1. A P-DE diet was also formulated to maintain a constant Ca:STTD P of 2:1 in both basal diets. Phytase was added to AD and DE diets at 350, 600, 1,000 phytase units (FYT)/kg. Pig was the experimental unit; diet (P-AD or P-DE), phytase level, and replicate were fixed effects. Orthogonal polynomial contrasts were used to test linear and quadratic effects of phytase within P-AD and P-DE diets. Phytase improved apparent total tract digestibility (ATTD) and STTD of P in both P-AD (linear P < 0.001) and P-DE diets (quadratic P < 0.001). Estimates for STTD P release were 0.07%, 0.09%, and 0.09% for 350, 600, and 1,000 phytase units (FYT)/kg in P-DE diets, and 0.02%, 0.03%, and 0.05% in P-AD diets, respectively. In P-DE diets, phytase improved absorption and retention of P and increased urinary excretion of P (quadratic P < 0.001). In P-AD diets, phytase improved absorption of P (linear P = 0.066), tended to improve retention (linear P = 0.066), and increased urinary excretion of P (quadratic P = 0.021). Phytase improved ATTD of Ca in P-DE diets (quadratic P = 0.002) but not in P-AD diets (P > 0.1). In conclusion, the release of P by phytase is lower in diets that are AD in P than those which are DE. Phytase increased the availability of Ca only in the diets DE in P. Finally, phytase increased the ATTD of DM and tended to increase the ATTD of energy, independent of dietary P status.

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.

Effect of two phytases at two doses on performance and phytate degradation in broilers during 1-21 days of age

The effect of two microbial phytases at two dose-levels on performance and apparent ileal digestibility (AID) of nutrients in broilers fed European-type diets was studied. A total of 1,200 d-old Ross 308 male broilers were randomly assigned to 5 treatments with 30 birds/pen and 8 pens/treatment. A nutritionally adequate positive control (PC) diet was tested against 4 experimental diets containing reduced total P, retainable P, Ca and Na as per the recommended nutritional contribution for Buttiauxella phytase (Phy B) at 1,000 FTU/kg (-1.87 g/kg, -1.59 g/kg, -1.99 g/kg and -0.4 g/kg vs. PC, respectively). Experimental diets were supplemented with Phy B at 500 FTU/kg or 1,000 FTU/kg, or Citrobacter phytase (Phy C) at 1,000 FTU/kg or 2,000 FTU/kg. Diets were based on corn, soybean meal, rapeseed meal and sunflower meal and formulated by phase (starter 1–10 d, grower 11–21 d) in crumbled or pelleted form. Overall (d 1–21), at 1,000 FTU/kg, birds fed Phy C exhibited lower BWG (-2.7%), FI (-3.4%) and tibia ash (-2.2%) vs. PC (P < 0.05), and reduced BWG (-3.6%), FI (-3.9%) and tibia ash (-1.8%) vs. Phy B (P < 0.05). Phy B at 1,000 FTU/kg and Phy C at 2,000 FTU/kg maintained performance equivalent to the PC. Digestibility of Ca did not differ among phytase treatments but at 1,000 FTU/kg AID P was greater with Phy B than Phy C (72.3% vs. 62.7%, P < 0.05). Ileal phytate (myo-inositol hexakisphosphate, IP6) digestibility was greatest with Phy B at 1,000 FTU/kg which was higher than Phy C at 1,000 FTU/kg (87.6 vs. 60.6%, P < 0.05). The findings indicate a higher phytate degradation rate of Phy B than Phy C at equivalent dose-level and this is correlated to the performance of the broilers.

Effect of crop retention time and acidification of the feed on phytase efficacy in broiler chickens

1. An in vitro test to study the effect of pH reduction on phytic acid degradation over time for four commercial phytases was conducted. Changing the pH level affected phytate degradation over time differently for the various phytases (P < 0.05).2. The phytase with the largest response of pH reduction in the in vitro test and a feed pH level of 4.5 was chosen for the broiler experiment. The effect of intermittent feeding, addition of 500 FYT C. braakii-derived phytase and 1% formic acid were tested in a 2 x 2 x 2 factorial arrangement. Ten pens containing 10 birds each were fed each of the treatment combinations from 15 to 36 d of age. Ad libitum fed birds had two 4-h dark periods with 2-h light in-between, while intermittently fed birds in addition had restricted access to the feed through except for four 1-h and one 2-h feeding bouts.3. In addition to assessing performance, excreta were collected on a pen basis. The tibia and contents from jejunum and ileum were collected from one bird per pen. In addition, crop contents were collected from the intermittently fed birds 80, 160 and 240 min after the start of feeding.4. Phytase improved performance, ileal and jejunal P digestibility, P retention and tibia ash and P concentration (P < 0.001). Intermittent feeding increased jejunal P digestibility and P retention (P < 0.001), but ileal P digestibility increased only in the intermittently fed birds compared to the ad libitum fed birds without phytase addition (P = 0.025). Acidification increased jejunal P digestibility only in the ad libitum fed birds (P = 0.019). There was a considerable inositol hexakisphosphate degradation into lower isomers in the crop after 80 min for diets with phytase (InsP_{3 and 4}:P < 0.001), and acidification further increased this degradation (InsP₄:P = 0.007). After 160 min retention time, the effect of phytase and acidification was even higher with more significant (P < 0.05) interactions.5. The current data showed that prolonged retention time in the crop combined with feed acidification increased phytase efficacy by improving the phytate degradation.

Reevaluation of Phytase Action Mechanism in Animal Nutrition

The release of phosphorus from phytates occurs via sequential cleavage of phosphate groups. It was believed that, regardless of the properties of phytases, the rate of phytate dephosphorylation is limited by the first cleavage of any phosphate group. The position of the first cleaved-off phosphate group depending on the specificity of phytase. The inhibition of dephosphorylation initiation is not associated with the action mechanism of the enzyme and can be rather due to the insufficient phytase activity or low availability of phytates. The analysis of the transformations in the inositol hexakisphosphate (IP₆)→inositol (I) reaction chain shows that IP₆ dephosphorylation as a whole limits the phosphate group removal from I(1,2,5,6)P₄ (third reaction from the beginning of hydrolysis of phosphate bonds in PA). The lower availability of nutrients in the presence of phytates is not due to action of phytates, but is caused by PA anions (IP_6-3), which bind positively charged metal ions, amino acids, and proteins. The availability of nutrients increases as a result of the decrease in their binding caused by the decrease in the concentration of IP_(6-3) anions under the action of phytases. Phytases added to feeds play a lesser role in the digestion of phytates compared to natural enzymes and complement their action. The concept of extra-phosphoric effect has no scientific justification, since phytases exhibit only the phosphohydrolase activity and are not able to catalyze other reactions.

Influence of exogenous phytase supplementation on phytate degradation, plasma inositol, alkaline phosphatase, and glucose concentrations of broilers at 28 days of age

Inositol is the final product of phytate degradation, which has the potential to serve as an indicator of phytase efficacy. An experiment was conducted to evaluate effects of supplementing broiler diets with phytase on phytate degradation and plasma inositol concentrations at 28 d of age. Twenty-four Ross × Ross 708 male chicks were placed in battery cages (4 birds per cage) from 1 to 21 d of age and individually from 22 to 28 d of age. At 27 d of age, a catheter was placed in the brachial vein of broilers to avoid repeated puncture of the vein during blood collection. At 28 d of age, broilers received 1 of 3 experimental diets formulated to contain 0, 400, or 1,200 phytase units (FTU)/kg, respectively, in diet 1, 2, and 3. Blood was collected 1 h before feeding experimental diets and from 20 to 240 min after feeding experimental diets at 20-min intervals with a final blood collection at 480 min to determine plasma inositol concentrations. Inositol phosphate (IP) ester degradation was determined in gizzard contents and ileal digesta. Broilers provided the 1,200 FTU/kg phytase diet had 60% less (P < 0.01) IP6 concentration in gizzard content (1,264 vs. 4,176 nmol/g) and ileal digesta (13,472 vs. 33,244 nmol/g) than birds fed the 400 FTU/kg diet. Adding phytase at 1,200 FTU/kg increased (P < 0.01) inositol concentrations in gizzard content and ileal digesta of broilers by 2.5 (2,703 vs. 1,071 nmol/g) and 3.5 (16,485 vs. 4,667 nmol/g) fold, respectively, compared with adding 400 FTU/kg. Plasma inositol concentration of broilers was not different (P = 0.94) among the dietary treatments at each collection time. Inositol liberation in the digesta of broilers fed diets with 1,200 FTU/kg phytase did not translate to increased plasma inositol concentrations, which warrants further investigation.

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.

Effects of limestone particle size, phytate, calcium source, and phytase on standardized ileal calcium and phosphorus digestibility in broilers

Work was carried out to determine the effects of limestone (LM) geometric mean diameter (GMD), phytate, Ca source, and phytase on standardized ileal digestibility (SID) of Ca and P in broilers. Twelve treatments (TRT) were tested. One basal corn and corn germ-based diet was prepared without adding inorganic Ca or P (TRT1, 0.02% Ca). Limestone from the same source (800 or 151 μm GMD) and bone (151 μm GMD) were added to TRT 2–4, (0.7% Ca). TRT5 was a corn/soybean meal (SBM) diet with 800 μm GMD LM (0.77% Ca). Buttiauxella sp. phytase was added (1,000 U/kg) to TRT 1–5 to prepare TRT 6–10, respectively. In addition, 800 or 150 μm GMD LM and monosodium P were added to a nitrogen-Ca-phytate–free diet (TRT 11 and 12, respectively). Treatments were analyzed as a complete block design using SAS mixed procedures and with factorial analysis on subsets of data: 1) LM GMD (151 vs. 800 μm GMD) with or without phytase: TRT 2, 3, 7, and 8; 2) phytate (corn or corn-free) with the same LM at 2 different sizes: TRT 2, 3, 11, and 12; 3) Ca source (LM vs. bone) with or without phytase: TRT 2, 4, 6, 8, and 9; 4) phytate source (corn vs. corn/SBM) with or without phytase: TRT 2, 5, 7, and 10. Broilers (4/pen) were fed mash diets ad lib for 36 h (20–22 d of age). At the end of the trial, distal ileal digesta were collected. Fine LM had lower SID Ca (38.09%) vs. coarse LM (49.18%), irrespective of phytase (P < 0.05). Standardized ileal digestibility of P was lower when the smaller LM was used vs. coarse LM with either 0 or 1,000 phytase U/kg (P < 0.05). Both SID Ca and P were higher without phytate vs. when phytate from corn was present (P < 0.05). Ca from bone was more digestible and its impact on SID P smaller vs. LM regardless of phytase (P < 0.05). In addition, phytate from SBM was more digestible and responsive to phytase as compared to phytate from corn (P < 0.05). In conclusion, dietary factors affected Ca and P digestibility and their response to phytase inclusion.

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.

Phytate Degradation, Transcellular Mineral Transporters, and Mineral Utilization by Two Strains of Laying Hens as Affected by Dietary Phosphorus and Calcium

Laying hens require less phosphorus (P) but markedly more calcium (Ca) in their diet than broilers. These differences may cause more distinct interactions with phytate degradation and utilization of minerals in laying hens than those in broilers. The objective of the study was to characterize intestinal phytate degradation, ileal transcript copy numbers of transcellular Ca and P transporters, and mineral utilization by two laying hen strains fed with standard or reduced levels of dietary Ca and P at the laying peak. The strains showed differences regarding several traits driving Ca and P metabolism along the digestive tract. Thus, the two strains may use different mechanisms to meet their respective P demand, i.e., via effective phytate degradation and transcellular transport. Clear effects of the Ca level on myo-inositol concentrations and mineral utilization revealed the significance of this element for the measured traits. The absence of P-mediated effects confirmed the findings of several studies recommending that P concentrations used in laying hen feeds are too high. Differences were noted between individuals within one treatment. The next step would be to evaluate the data in individual birds to identify birds that better cope with a challenging diet.

Phytate degradation, myo-inositol release, and utilization of phosphorus and calcium by two strains of laying hens in five production periods

The objective of this study was to compare 2 laying hen strains in 5 production periods regarding phytase activity, phytate (InsP₆) degradation, and myo-inositol (MI) release in the digestive tract and phosphorus (P) and calcium (Ca) utilization. One offspring of 10 nonrelated roosters per strain (Lohmann Brown-classic (LB) or Lohmann LSL-classic (LSL)) was placed in one of 20 metabolic units in a completely randomized block design in week 8, 14, 22, 28, and 58 of life. All hens were fed the same corn and soybean meal–based diet at one time, but the diet composition was adjusted to the requirements in the respective period. For 4 consecutive days, excreta were collected quantitatively at 24-hour intervals. In week 10, 16, 24, 30, and 60, the blood plasma, digesta of crop, gizzard, jejunum, ileum, and ceca, and mucosa of the jejunum was collected. The concentration of inorganic P in the blood plasma was higher in LB than in LSL hens (P = 0.026). Plasma Ca concentrations increased with each period (P < 0.001) in both strains. In jejunum digesta, the MI concentration did not differ between strains, but InsP₆ concentration was higher in LB than in LSL hens (P = 0.002) and the highest in week 30 and 60. Total phosphatase and phytase activities were higher in LB than in LSL hens (P ≤ 0.009). Period effects were also significant for these enzymes. Concentrations of some constituents of the cecal content were different between the strains. The MI concentration in the egg albumen and yolk was higher in LB than in LSL hens. Differences in InsP₆- and MI-related metabolism of the 2 hen strains existed. These differences were partly dependent of the period. Especially, week 24 was a period of remarkable change of metabolism. Great differences also existed among individuals, making it worth to have a closer look at the metabolism of individuals in addition to evaluating treatment means. Further studies on metabolic, genetic, and microbiome level may help explain these differences.

Effect of two commercial limestone sources with different solubility on the efficacy of two phytases in 0-21 d old broilers

A study evaluated the effects of limestone sources with different solubility on the efficacy of two phytases in broilers. A 2×5 factorial arrangement was employed with two commercial limestone sources and five diet treatments; a positive control (PC) diet with 7.2 g/kg P and 9.6 g/kg Ca, and a negative control diet containing reductions of 1.87 g/kg available P, 1.99 g/kg Ca and 0.4 g/kg Na, supplemented with either Buttiauxella phytase (PhyB) or Escherichia coli phytase (PhyE) at 500 or 1000 FTU/kg diet. The two limestone sources were feed-grade commercial products with different particle sizes and solubility (fast-soluble (FS) 100%; slow-soluble (SS) 26% soluble after 30 minutes at pH 3) containing similar levels of Ca. Diets were fed to one-day-old Ross 308 males (n=2,400) with 30 birds/pen and eight pens/treatment in two phases (starter 0-10 d and grower 10-21 d). On d 21, ileal digesta was collected from 12 birds/pen to determine apparent ileal digestibility (AID) of P and Ca, and myo-inositol hexakisphosphate (IP6) disappearance, and tibias from four birds/pen for ash determination. The SS limestone improved body weight gain (BWG), feed intake (FI) and FCR vs FS limestone in starter/grower phases (P<0.05), and improved AID of P (P<0.05) and IP6 disappearance (P<0.05) at d 21. There was an interaction between limestone and phytase on BWG, FI and FCR in the grower phase (P≤0.05) whereby FS (vs SS) limestone reduced BWG at either dose of PhyE, but only at 500 FTU/kg of PhyB. At an equivalent dose, PhyB had higher BWG and feed intake than PhyE (P<0.05). At 1000 FTU/kg, performance was equivalent (BWG and FI) or superior (FCR) to the PC, PhyB produced greater tibia ash, AID of P and IP6 disappearance (P<0.05). The findings showed that the effects of limestone particle size on phytase efficacy varied with phytase source and dose.

Muscle Metabolome Profiles in Woody Breast-(un)Affected Broilers: Effects of Quantum Blue Phytase-Enriched Diet

Woody breast (WB) myopathy is significantly impacting modern broilers and is imposing a huge economic burden on the poultry industry worldwide. Yet, its etiology is not fully defined. In a previous study, we have shown that hypoxia and the activation of its upstream mediators (AKT/PI3K/mTOR) played a key role in WB myopathy, and supplementation of quantum blue (QB) can help to reduce WB severity via modulation of hypoxia-related pathways. To gain further insights, we undertook here a metabolomics approach to identify key metabolite signatures and outline their most enriched biological functions. Ultra performance liquid chromatography coupled with high resolution mass spectrometry (UPLC-HRMS) identified a total of 108 known metabolites. Of these, mean intensity differences at P < 0.05 were found in 60 metabolites with 42 higher and 18 lower in WB-affected compared to unaffected muscles. Multivariate analysis and Partial Least Squares Discriminant analysis (PLS-DA) scores plot displayed different clusters when comparing metabolites profile from affected and unaffected tissues and from moderate (MOD) and severe (SEV) WB muscles indicating that unique metabolite profiles are present for the WB-affected and unaffected muscles. To gain biologically related molecule networks, a stringent pathway analyses was conducted using IPA knowledge-base. The top 10 canonical pathways generated, using a fold-change -1.5 and 1.5 cutoff, with the 50 differentially abundant-metabolites were purine nucleotide degradation and de novo biosynthesis, sirtuin signaling pathway, citrulline-nitric oxide cycle, salvage pathways of pyrimidine DNA, IL-1 signaling, iNOS, Angiogenesis, PI3K/AKT signaling, and oxidative phosphorylation. The top altered bio-functions in term of molecular and cellular functions in WB-affected tissues included cellular development, cellular growth and proliferation, cellular death and survival, small molecular biochemistry, inflammatory response, free radical scavenging, cell signaling and cell-to-cell interaction, cell cycles, and lipid, carbohydrate, amino acid, and nucleic acid metabolisms. The top disorder functions identified were organismal injury and abnormalities, cancer, skeletal and muscular disorders, connective tissue disorders, and inflammatory diseases. Breast tissues from birds fed with high dose (2,000 FTU) of QB phytase exhibited 22 metabolites with significantly different levels compared to the control group with a clear cluster using PLS-DA analysis. Of these 22 metabolites, 9 were differentially abundant between WB-affected and unaffected muscles. Taken together, this study determined many metabolic signatures and disordered pathways, which could be regarded as new routes for discovering potential mechanisms of WB myopathy.

The effect of reducing dietary calcium in prestarter diets (0-4 D) on growth performance of broiler chickens, tibia characteristics, and calcium and phosphorus concentration in blood

During the incubation period, the Ca-to-P weight (mg/mg) ratio in the yolk increases from 0.26 on day 0 to 0.92 on day 17.5 and to 2.9 at hatch. Moreover, the absolute Ca content in the yolk increases by 41%, whereas P content decreases by 87%, from day 0 to the day of hatching. Thus, at hatch and during the first days after hatching, there are high reserves of Ca relative to P in the residual egg yolk, risking hypercalcemia and hypophosphatemia. A growth performance study was conducted to explore the effects of reducing dietary Ca content in the prestarter phase (0–4 D) on BW and bone mineral deposition during the first days after hatch and at market weight (day 37). Four prestarter (0–4 D) diets were formulated to have 0.4, 0.6, 0.8, and 1.0% Ca content. After the prestarter phase, all birds were fed with the same commercial diets based on a 3-phase feeding program (starter, grower, and finisher). Growth performance (BW, ADG, ADFI, and feed conversion ratio [FCR]) was monitored throughout the study, and blood and tibia bone samples were collected on specific days. On day 4, BW and ADG decreased with dietary Ca contents higher than 0.6% (P < 0.05), but there were no differences in BW on day 14 onward (P > 0.10). For the overall study (0–37 D), there were no differences in ADG and ADFI, but the FCR decreased with lower Ca contents (P < 0.05). On day 4, there were no differences in blood plasma Ca concentration, but P concentration increased in the group treated with diet containing 0.4% Ca compared with the groups treated with diets containing 0.6 and 0.8% Ca (P < 0.05). Tibia ash content decreased in the group treated with diet containing 0.4% Ca (P < 0.05) compared with all other treatments at the end of the prestarter phase. Tibia ash content and tibia breaking strength, on day 37, were not different among the treatments (P > 0.10). In conclusion, during the prestarter phase, BW increased with dietary Ca contents lower than 0.6%, most likely improving Ca–P balance; bone mineral deposition was reduced in this period. On feeding with a diet containing higher Ca content, bone mineral content was rapidly recovered.

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.

Modelling and optimizing of calcium and non-phytate phosphorus requirements of male broiler chickens from 1 to 21 days of age using response surface methodology

The skeleton is the main site of P and Ca deposition; therefore, accurate estimation of Ca and P requirements is necessary to maintaining health and optimum performance of broiler chickens. A response surface methodology (RSM) using a central composite design (CCD) was used for evaluating and optimizing of Ca and non-phytate P (NPP) requirements of broiler chickens for optimal performance, ileal nutrient digestibility and bone mineralization from 1 to 21 days of age. A total of 750 one-day-old male broiler chickens (Ross 308) were randomly distributed into 50 cages including 9 treatments, each replicated 5 times (except central treatment with 10 replicates) and 15 birds in each cage by CCD. The dietary Ca levels of 4.3, 5.6, 8.6, 11.7 and 13.0 g/kg and NPP of 2.5, 2.9, 4.0, 5.0 and 5.4 g/kg were used for nine treatments of CCD. The results indicated that the linear and quadratic effects of NPP, quadratic effects of Ca and Ca × NPP were significant for average weight gain (AWG, P < 0.05), average feed intake (AFI, P < 0.05), feed conversion ratio (FCR, P < 0.05) and Ca and P apparent ileal digestibility (AID, P < 0.05); however, the linear effect of Ca was significant only for FCR (P < 0.05). On the other hand, tibia and toe ash were affected by NPP (linear and quadratic, P < 0.01) and Ca (quadratic, P < 0.01). The second-order polynomial regression model was significant for AWG (R2 = 0.93, P < 0.001), AFI (R2 = 0.88, P < 0.001), FCR (R2 = 0.78, P < 0.001), AID of Ca (R2 = 0.78, P < 0.001) and P (R2 = 0.88, P < 0.001), tibia ash (R2 = 0.86, P < 0.001) and toe ash (R2 = 0.85, P < 0.001). The multi-objective optimization indicated that broiler chickens from 1 to 21 days of age need 7.03 and 4.47 g/kg of Ca and NPP, respectively, to achieve optimal AWG, FCR, tibia and toe ash. However, the dietary Ca and NPP levels can be reduced to 6.57 and 3.95 g/kg with a slight negative impact on performance and bone mineralization, respectively. In conclusion, the findings indicate that using multi-objective optimization model such as RSM provides more information regarding optimum Ca and NPP requirements of broiler chickens, considering the complex interaction between these two minerals. While the NPP levels are in line with current recommended requirements, Ca levels are considerably lower and suggest that current recommended Ca requirements may be in excess of the needs of the broiler.

Effect of fibrous diet and vitamin C inclusion on uniformity, carcass traits, skeletal strength, and behavior of broiler breeder pullets

This experiment studied the effect of broiler breeder nutritional strategies on uniformity, carcass traits, tibia parameters, and behavior during rearing and prebreeder periods (up to 22 wk of age). One-day-old pullets (n = 384) were randomly assigned to 4 treatments arranged as a 2 × 2 factorial, with 2 fiber levels (control vs. fibrous diet, 15% diluted in AMEn and nutrient content) and 2 vitamin C feed inclusions (0 vs. 200 mg/kg). At 6, 15, and 22 wk, blood sampling was carried out (4 birds/replicate) to determine serum alkaline phosphatase (ALP) levels, and behavior was observed by visual scan sampling. At 22 wk, carcass traits, tibia parameters, and intestinal morphology were assessed (2 birds/replicate), and tail- and wing-feather integrity of all birds were scored. Fibrous diet did not modify BW uniformity, mortality, or tibia growth when compared with control diet. Pullets fed the fibrous diet had lower tibia breaking strength, elastic modulus, and ash content values (P < 0.05). They also had lower ALP serum level at 6 and 22 wk (P < 0.05), their breast muscle was less developed (18.5 vs. 19.8%, P < 0.05), and their abdominal fat deposition was higher (1.14 vs. 0.87%, P < 0.05). At 15 and 22 wk, they performed, on average, 97% less grasping feather pecking and 45% less non–food object pecking behaviors, and their wing-feather score was lower (P < 0.05) at 22 wk. Tail- and wing-feather scores of the control treatments were reduced by vitamin C inclusion (tail: 0.30 vs. 1.15, P < 0.05; wing: 0.98 vs. 1.26, P < 0.05) at 22 wk. In conclusion, fibrous diet improves carcass traits (reduces breast muscle and increases abdominal fat deposition), deteriorates bone mineral deposition and thus skeletal strength, and reduces stereotypic behaviors, improving wing-feather integrity. Vitamin C inclusion improves tail- and wing-feather integrity of lower in feed allowance.

Effects of phytase supplementation on eggshell and bone quality, and phosphorus and calcium digestibility in laying hens from 25 to 37 wk of age

Effects of dietary available phosphorus (aP) and Ca levels and an Escherichia coli 6-phytase supplementation were studied in Lohmann LSL-Lite hens from 25 to 37 wk of age. Eighty-four hens were used in a completely randomized design with 7 treatments. The treatments were a positive control (PC) diet with 0.45% aP, 3.70% Ca, and 0.16% Na from 25 to 28 wk and 0.38% aP, 3.73% Ca, and 0.15% Na from 29 to 37 wk; a negative control (NC) diet, similar to the PC diet, with 0.22% aP, 3.00% Ca, and 0.13% Na from 25 to 28 wk and 0.19% aP, 3.02% Ca, and 0.13% Na from 29 to 37 wk; the NC diets supplemented with phytase at 150 (NC + 150), 300 (NC + 300), 600 (NC + 600), or 1,200 (NC + 1,200) phytase unit (FTU)/kg; and the PC diet supplemented with phytase at 1,200 (PC + 1,200) FTU/kg. Hen performance, eggshell, and bone quality were measured on a 4-wk basis. Bone breaking strength and ash and apparent ileal digestibility (AID) of P and Ca were determined at 37 wk. One- and 2-way ANOVA were conducted, and Tukey's range test was used to compare multiple means where P ≤ 0.05. No differences in hen performance, eggshell quality, bone breaking strength, bone ash, and P digestibility were observed between the PC and the NC treatments. The NC hens had lower cortical (P < 0.001) and trabecular + medullary bone mineral density (P = 0.004) and total bone mineral content (P < 0.001) than the PC hens. The PC + 1,200 increased cortical bone mineral density (P < 0.001). The reductions of aP and Ca in the NC diet were not deficient for performance but had a minor impact on bone mineralization. The NC + 600 and NC + 1,200 increased AID of P (P = 0.024), and all phytase treatments except the NC + 150 increased AID of Ca (P = 0.010) compared with the NC diet.

Influence of Dietary Zinc, Copper, and Manganese on the Intestinal Health of Broilers Under Eimeria Challenge

The incidence of enteric infections in broiler chickens may increase worldwide due to mounting pressure to limit the use of sub-therapeutic antibiotics and ionophores for coccidia suppression/prevention in the diets of broilers. For this reason, we need expand our knowledge on the role that micro-minerals have in modulating the intestinal physiology, immunology, and microbiology of broiler chickens. There are issues associated with the use of high doses of some micro-minerals in the diets of animals, such as environmental contamination, bacterial resistance, and gizzard erosion. Therefore, there is a need to maximize the absorption of these minerals by the gastrointestinal tract (GIT) of birds when intestinal function may be compromised. Zinc is an essential micromineral required for growth, and influences intestinal development and/or regeneration during and after enteric disease. Two studies were conducted by our lab to determine the effects of Zn source in broilers under coccidia and Clostridium perfringens challenge. In the first study, Zn proteinate had beneficial effects on the performance of chickens challenged with coccidia plus C. perfringens by enhancing intestinal integrity and partially attenuating the inflammatory response. In the second study, Zn proteinate lowered the expression of pro-inflammatory cytokines and modulated the ileal microbiota. Additionally, the poultry industry has used prophylactic concentrations of dietary Cu for its ability to improve feed conversion for a long time. Copper absorption occurs mainly in the duodenum of chickens and, therefore, injuries to the intestinal epithelium of duodenum would impair Cu absorption and decrease its tissue concentration. Although there is a lack of studies relating Mn supplementation and its different sources on the immune response against coccidiosis in poultry, it is likely that Mn is beneficial during enteric challenges due to its role in the production of mucopolysaccharides. Therefore, the proper evaluation of the role of minerals on mitigating the negative impact of coccidiosis in broilers must consider their properties in modulating the physiology, immunology, and the intestinal microbiota of the host during health and disease situation events.

Phytate degradation in gnotobiotic broiler chickens and effects of dietary supplements of phosphorus, calcium, and phytase

Gnotobiotic broiler chickens were used to study interactive effects of supplemented phosphorus, calcium (PCa), and phytase (Phy) on myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP₆) degradation and release of myo-inositol in the digestive tract. In 2 subsequent runs, the chickens were subjected to 1 of 4 dietary treatments with and without PCa and Phy supplementation. Sanitized eggs were hatched in 8 germfree isolators, and a minimum of 9 male Ross 308 chickens were placed in each pen (total 16 pens). Treatments implemented on day 10 included gamma-irradiated diets without (PCa−; 4.1 g P and 6.2 g Ca/kg DM) or with (PCa+; 6.9 g P and 10.4 g Ca/kg DM) monosodium phosphate and limestone supplementation and without (Phy−) or with (Phy+) 1,500 FTU Phy/kg feed in a factorial arrangement. On day 15, digesta was collected from different sections of the intestinal tract and analyzed for InsP isomers and myo-inositol. The isolators did not remain germfree, but analysis of contaminants and results of InsP degradation indicated no or minor effects of the identified contaminants. Prececal InsP₆ disappearance was 42% with the PCa−Phy− treatment and 17% with PCa+Phy−. No InsP_3–4 isomers were found in the digesta of the terminal ileum in PCa−Phy−. The concentration of myo-inositol in the ileal digesta from PCa−Phy− (6.1 μmol/g DM) was significantly higher than that from PCa+Phy− (1.7 μmol/g DM), suggesting rapid degradation of the lower InsP isomers by mucosal phosphatases and their inhibition by PCa. Phytase supplementation increased InsP₆ disappearance and prevented inhibitory effects of PCa supplements (72% in PCa−Phy+ and 67% in PCa+Phy+). However, PCa supplementation reduced the degradation of lower InsP isomers mainly in the posterior intestinal sections in the presence of Phy, resulting in significantly lower myo-inositol concentrations. It is concluded that mucosa-derived phosphatases might significantly contribute to InsP₆ degradation in broiler chickens. The potential of mucosa-derived phosphatases to degrade InsP₆ and lower InsP is markedly reduced by dietary PCa supplementation.