Toe Ash Research Articles

PSVI-15 Assessing the implications of a silymarin-enriched diet on the performance and blood absorption rate of broiler and laying hen

Abstract This experiment was executed to assess the impacts of silymarin on different aspects of broiler and laying hen, including growth, digestibility, excreta score, footpad lesion score, tibia ash, meat quality, and blood absorption rate. In Experiment 1: 1-d-old Ross 308 broilers (mixed sex; n = 576) were arbitrarily assigned with an average body weight of 42 ± 0.3 g for a 32-d trial. The broilers were sorted into eight repetition pens with 18 birds per pen and four research treatments (basal diet as the control and basal diet included 0.02, 0.04, and 0.06% micelle silymarin). Experiment 2: 61-wk-old Hy-line brown laying hens (n = 16) were divided into 2 treatment groups (TRT1, basal diet + powdered silymarin 4%; TRT2, basal diet + micelle silymarin 4%), with 8 numbers per repetition. Feeding broilers with a graded dose of micelle silymarin (MS) increased body weight gain linearly during d 1–9, 9–21, 21–32, and overall (P = 0.021, 0.011, 0.019, and 0.002, respectively). Furthermore, there was a linear increase in feed intake (P = 0.017) during d 1–9, and the enhancement of dry matter utilization (linear, P = 0.011) was exhibited as the amount of MS inclusion in the diet increased. Tibia ash content enhanced linearly (P = 0.038), and meat quality traits also revealed a linear improvement in breast muscle color (yellowness) (P = 0.045) and linear decrease (P = 0.004) in pH level with the increasing levels of MS in the broiler diet. Nonetheless, both the excreta score and the footpad lesion score showed no significant alteration (P > 0.05). Moreover, a greater absorption rate of silymarin was observed in the blood of laying hens 2 h (P < 0.0001) and 4 h (P < 0.0001) after feeding with micelle-type silymarin as compared with powdered-type silymarin. Briefly, MS can be a favorable supplement for poultry production as it can increase the growth, digestibility, toe ash, and meat quality of broilers and the blood absorption rate of laying hens.

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.

Determination of non-phytate phosphorus requirement for slow-growing feather-frizzled broilers from 1 to 21 days of age

The influence of dietary non-phytate phosphorous (NPP) on growth performance, carcass characteristics, bone quality and serum parameters were investigated to determine the NPP requirement of slow-growing feather-frizzled broilers aged from 1 to 21 days. A total of 480 1-day-old indigenous slow-growing male feather-frizzled broilers were assigned to 1 of 6 treatments with 8 cage replicates of 10 birds each using a completely randomized design. They were fed with corn-soybean meal-based basal diet (containing 0.13 % of NPP) supplemented with 0.00 %, 0.08 %, 0.16 %, 0.24 %, 0.32 %, and 0.40 % of inorganic phosphorus (CaHPO4.2 H2O), respectively. The experimental diets contained a constant 0.90% calcium. Results showed that body weight gain, feed intake, eviscerated carcass ratio, tibia breaking strength, tibia and toe ash or phosphorous concentrations, femoral strength and serum inorganic phosphorous concentration were affected (P < 0.010) by dietary NPP level, and showed significant quadratic responses (P < 0.030) to dietary NPP levels. The estimates of dietary NPP requirements were 0.25–0.36 % based on the best fitted broken-line or quadratic models (P < 0.029) of the above performance, serum and bone parameters. In conclusion, the NPP requirements would be about 0.25 % to obtain the optimum growth performance and carcass yield, and 0.36 % to meet bone development and P metabolism for such slow-growing feather-frizzled broilers fed a conventional corn-soybean meal diet from 1 to 21 days of age.

Feeding broiler chicks with Schizosaccharomyces pombe-expressed phytase-containing diet improves growth performance, phosphorus digestibility, toe ash, and footpad lesions.

ObjectiveThe objective of this study was to evaluate the effects of dietary supplementation of Schizosaccharomyces pombe (S. pombe) -expressed phytase on growth performance, apparent ileal digestibility, organ indexes, meat quality, toe ash, and footpad lesions score in broiler chicks.MethodsA total of 390 one-day-old broiler chicks were randomly assigned to 5 groups based on the initial body weight (42.15±0.17 g), there were 6 replicate cages per treatment and 13 birds (mixed sex) per cage. The experimental period was 45 days, including 4 periods (starter, days 1 to 10; grower, days 11 to 24; finisher 1, days 25 to 38; finisher 2, days 39 to 45). Dietary treatments were based on a corn-soybean meal-basal diet and supplemented with 500, 750, 1,000, and 1,500 FTU/kg S. pombe-expressed phytase. One phytase unit (FTU) was defined as the amount of enzyme that catalyzes the release of one micromole phosphate from phytate per minute at 37°C and pH 5.5.ResultsThe inclusion of increasing levels of phytase in the diet linearly increased the body weight gain during days 1 to 10 (p = 0.001), 25 to 38 (p = 0.016), 39 to 45 (p = 0.018), and 1 to 45 (p = 0.004), feed intake during days 25 to 38 (p = 0.032), feed conversion ratio during days 1 to 10 (p = 0.001), 39 to 45 (p = 0.038), and 1 to 45 (p = 0.012), carcass weight (p = 0.035), toe ash (p<0.001), and apparent ileal phosphorus digestibility (p = 0.049). However, the footpad lesions score (p = 0.040) decreased linearly with the increase in phytase levels in the diet.ConclusionDietary supplementation of S. pombe-expressed phytase was beneficial to the growth performance, toe ash, apparent ileal phosphorus digestibility, and footpad lesions of broiler chicks in a dose-dependent manner.

PSIV-14 Feeding Broiler Chicks with S. Pombe-Expressed Phytase-Containing Diet Improves Growth Performance, Phosphorus Digestibility, Toe Ash, and Footpad Lesions

Abstract A total of 390 1-day-old broiler chicks with an average initial body weight of 42.15 ± 0.17 g were used to evaluate the effects of dietary supplementation of S. pombe-expressed phytase on growth performance, apparent ileal digestibility, organ indexes, meat quality, toe ash, and footpad lesions score. All birds were randomly assigned to 5 groups based on the initial body weight (42.15 ± 0.17 g), there were 6 replicate cages per treatment and 13 birds (mixed sex) per cage. The experimental period was 45 d, including 4 periods (starter, d 1-10; grower, d 11-24; finisher 1, d 25-38; finisher 2, d 39-45). Dietary treatments were based on a corn-soybean meal-basal diet and supplemented with 500, 750, 1,000, and 1,500 FTU/kg S. pombe-expressed phytase. One phytase unit (FTU) was defined as the amount of enzyme that catalyzes the release of 1 micromole phosphate from phytate per minute at 37°C and pH 5.5. The inclusion of increasing levels of phytase in the diet linearly increased the body weight gain during d 1-10 (P = 0.001), 25-38 (P = 0.016), 39-45 (P = 0.018), and 1-45 (P = 0.004), feed intake during d 25-38 (P = 0.032), feed conversion ratio during d 1-10 (P = 0.001), 39-45 (P = 0.038), and 1-45 (P = 0.012), carcass weight (P = 0.035), toe ash (P &amp;lt; 0.001), and apparent ileal phosphorus digestibility (P = 0.049). However, the footpad lesions score (P = 0.040) decreased linearly with the increase in phytase levels in the diet. Therefore, dietary supplementation of S. pombe-expressed phytase was beneficial to the growth performance, toe ash, apparent ileal phosphorus digestibility, and footpad lesions of broiler chicks in a dose-dependent manner.

PSIV-16 Phytase Expressed from Schizosaccharomyces Pombe Ameliorates Footpad Lesions in Cage-Reared Broiler Chicks

Abstract Footpad lesion is a problem that plagued the poultry industry, because it occurs in birds that are either reared in the cage or on the floor. Reports from previous studies about amelioration of footpad lesions by feeding phytase to floor-reared broiler chicks via reduction in litter moisture content is inconclusive. Therefore, phytase supplementation may have other potential mechanisms to improve the footpad lesions. The cage-reared broiler chicks were used in this study because they are divided with litter. A total of 234 1-d-old broiler chicks were randomly assigned to 3 groups based on the initial body weight (42.22 ± 0.18 g) with 6 replicate cages and 13 birds (mixed sex) per cage. The experimental period was 45 d. Dietary treatments were based on a corn-soybean meal-basal diet and supplemented with 500 and 750 FTU/kg S. pombe-expressed phytase. The unit of phytase (FTU) was defined as the amount of enzyme that catalyzes the release of one micromole phosphate from phytate per minute at 37°C and pH 5.5. Orthogonal contrasts were used to examine the linear and quadratic effects in response to increasing the dietary supplementation of phytase. We found that dietary supplementation of S. pombe-expressed phytase increased (P &amp;lt; 0.05) the apparent ileal calcium and phosphorus digestibility and toe ash in a dose-dependent manner, whereas decreased (P &amp;gt; 0.05) the footpad lesions score. From this, we considered that footpad lesions ameliorated by phytase supplementation were related to the improvement of calcium and phosphorus digestibility and toe ash.

Supplementation of phytase and its combination with xylanase, amylase and protease (XAP) on performance and bone mineralization of broiler chicken

Abstract Phytase is the most common enzyme used in broiler diet mainly to improve phosphorus (P) digestibility and reduce P excretion to environment, but its effectiveness together with other enzymes such as xylanase, amylase and protease (XAP) is not widely evaluated. Current study was conducted to evaluate the efficacy of Buttiauxella spp. phytase supplementation at 1000 FTU/kg alone and its combination with XAP (2000 U/kg xylanase, 200 U/kg amylase and 4000 U/kg protease) on broiler performance and bone mineralization. A total 2849 male broilers Lohmann Indian River (LIR) were randomly assigned to 7 treatments with 11 replications. Treatments were positive control (PC) using standard diet followed LIR recommendation, negative control 1 (NC1) with nutrient reduction of 0.19% units available P, 0.2% units calcium (Ca), 0.41% units crude protein (CP) and 69 kcal/kg AME, NC2 applied similar reduction except for AME which was 105 kcal/kg, and on top of NCs was phytase and/or XAP supplementation. NC1 and NC2 significantly (P&lt;0.05) reduced body weight, mortality-corrected feed conversion ratio (McFCR) and toe ash percentage compared to PC. Phytase alone on top of NCs significantly (P&lt;0.05) improved body weight, McFCR and toe ash percentage. Further, combination of phytase with XAP numerically showed better weight gain, McFCR and broiler index (BI). These data suggest phytase and/or XAP supplementation is effective to maintain broiler performance and toe ash under nutrient deficiency, this because enzymes able to reduce the anti-nutritional effect and lead to better nutrient digestibility.

Evaluation of optimal dietary calcium level by bone characteristics and calcium metabolism-related gene expression of broilers from 22 to 42 d of age.

The current dietary Ca recommendation of broilers is primarily based on the previous studies carried out more than 30 yr ago. However, the modern commercial broilers are quite different from those more than 30 yr ago. The present experiment was conducted to evaluate an optimal dietary Ca level by bone characteristics and Ca metabolism-related gene expression of broilers fed a corn-soybean meal diet from 22 to 42 d of age. A total of 252 22-d-old Arbor Acres male broilers were randomly assigned to 1 of 7 treatments with 6 replicate cages of 6 birds per cage for each treatment. Broilers were fed the corn-soybean meal diets containing 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, 1.00%, or 1.10% Ca for 21 d, and each diet contained 0.31% non-phytate P. The results showed that the mineral contents in tibia and middle toe bone, mineral density in tibia and middle toe bone, middle toe ash percentage, middle toe ash Ca percentage, and tibia alkaline phosphatase mRNA expression level of broilers were influenced (P < 0.04) by dietary Ca level and increased quadratically (P < 0.05) as dietary Ca level increased. The estimates of optimal dietary Ca levels were 0.55%, 0.60%, 0.70%, 0.72%, 0.63%, 0.66%, and 0.70%, respectively, based on the best fitted broken-line, quadratic, or asymptotic models (P < 0.02) of the above sensitive indices. These results indicate that the optimal dietary Ca level would be 0.72% to support all of the Ca metabolism and bone development of broilers fed the corn-soybean meal diet from 22 to 42 d of age.

Phytase expressed from Saccharomyces pombe ameliorates footpad lesions in cage-reared broiler chicks.

Background/aimThe condition of footpad is an important aspect of poultry welfare. This is a problem that plagues the poultry industry because it occurs whether birds are reared in the cage or on the floor. It is reported that feeding phytase to floor‐reared broiler chicks could ameliorate footpad lesions, which is related to the reduction of litter moisture. However, some studies reported that phytase supplementation could ameliorate footpad lesions, but did not affect litter quality. Therefore, phytase supplementation may have other potential mechanisms to improve the footpad lesions. Cage‐reared broiler chicks were used in this study because they had no access to litter.Material and methodsA total of 234 1‐day‐old broiler chicks were randomly assigned to three groups based on the initial body weight (42.22 ± 0.18 g) with six replicate cages and 13 birds (mixed sex) per cage. The experimental period was 45 days. Dietary treatments were based on a corn–soybean meal‐basal diet and supplemented with 500 and 750 FTU/kg Saccharomyces pombe expressed phytase. The unit of phytase (FTU) was defined as the amount of enzyme that catalyzes the release of one micromole phosphate from phytate per minute at 37°C and pH 5.5.Result and conclusionWe found that dietary supplementation of S. pombe expressed phytase could improve calcium and phosphorus digestibility and subsequent improvement in toe ash, thus ameliorating footpad lesions in broiler chicks with no access to litter.

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

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

Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 3. Bone mineralization and litter quality.

This study was conducted to determine the effect of necrotic enteritis (NE), phytase level and meat and bone meal (MBM) processing on bone mineralization of broilers and litter quality. Ross 308 male broiler chicks (n = 768) were allotted to 48 pens with 16 birds each. There were 8 dietary treatments in a 2 × 2 × 2 factorial arrangement. Factors were NE challenge (no or yes), phytase level (500 or 5,000 FTU/kg), and MBM (as-received or over-processed). Half of the birds were challenged with field strains of Eimeria spp. at d 9 and 108 CFU per mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15. The middle toe, tibia and femur of 2 birds per pen were excised at d 16 and 29 for determination of ash, breaking strength (BS) and bone mineralization. At d 42, all were assessed for hock burns and litter was scored and assessed for dry matter (DM). At d 16, challenged birds had lower toe ash (P < 0.01), femur ash (P < 0.001), tibia ash (P < 0.001) and tibial BS (P < 0.001) than unchallenged birds. At d 16, challenged birds fed high phytase and over-processed MBM had higher toe Mn than those fed low phytase and as-received MBM. At d 29 unchallenged birds fed high phytase and as-received MBM had a higher toe Mn than those fed over-processed MBM. At d 16, a phytase × MBM interaction was detected for femur Zn concentration (P < 0.05), where a higher level of Zn was observed in the high phytase group fed over-processed MBM. At d 16, tibial Ca (P < 0.05) and P (P < 0.05) were lower in the challenged whereas the femur K (P < 0.001), Mn (P < 0.01) and Na (P < 0.001) were higher in the challenged at d 16. At d 42, challenged birds had higher litter DM (P = 0.058) and fewer hock burns than those unchallenged (P < 0.05). In conclusion, NE impaired bone traits but high phytase and over-processed MBM increased bone mineral contents. Cases of hock burns may be lower under NE incidences due to lower livability of birds reducing litter wetness.

Effect of different doses of phytase and protein content of soybean meal on growth performance, nutrient digestibility, and bone characteristics of broilers

This study evaluated the effects of high phytase doses and soybean meal (SBM) with different CP content on growth performance, ileal nutrient digestibility, digestible energy, plasmatic myo-inositol, phosphate release in vitro, and bone composition of broiler chickens. One thousand two hundred 1-day-old broilers were distributed in a 2 × 2 completely randomized factorial arrangement, with 2 phytase doses (1,000 and 2,500 phytase units [FYT]/kg of feed) and 2 SBM with different CP concentrations (45 and 47%), totaling 4 treatments with 12 replicates of 25 birds each. The chickens received feed and water ad libitum. Diets were based on corn and SBM, with different inclusions of soybean hull used to dilute the CP content of SBM according to each treatment. The inclusion of 2,500 FYT increased weight gain from 0 to 21 d (P < 0.05), whereas growth performance from 22 to 42 d was not affected, and SBM had no effect on growth performance. At day 21, ileal digestibility of dry matter, ash, and P, and digestible energy were greater in diets with 2,500 FYT/kg (P < 0.05), as well as phosphate in vitro release (P < 0.01) compared to the lower dose. At day 42, diets with SBM 47% CP and 2,500 FYT/kg promoted greater digestibility of dry matter, ash, CP, Ca, P, and digestible energy (P < 0.001), and greater phosphate release (P < 0.05) in comparison to other treatments. myo-inositol level in the plasma at 21 and 42 d was higher with the use of 2,500 FYT compared to 1,000 FYT (P < 0.05). The higher phytase dose increased tibia ash, toe ash, and Seedor Index (P < 0.05) at day 21, and the Ca content in tibia was higher with 2,500 FYT and SBM 47% CP at day 42. In conclusion, higher phytase doses for broilers improve weight gain, myo-inositol provision, and bone mineral composition. Nutrient ileal digestibility can be enhanced by higher phytase doses when in combination with SBM of greater nutritional quality.

Effects of phytase and benzoic acid supplementation on growth performance, nutrient digestibility, tibia mineralization and serum traits in male broiler chickens

This study was conducted to investigate the effects of phytase (Phy), benzoic acid (BA) and their interactions on growth performance, nutrients digestibility and tibia mineralization in broiler chickens fed standard or nutrient,s deficient diets. A total of 768 one-d-old male chicks were divided into 8 treatments for 42 d. The treatments were as follows:positive control (PC), PC diet with 0.5 g/kg of BA, PC diet with 500 FTU/kg of Phy, PC diet with 0.5 g/kg of BA and 500 FTU/kg of Phy, negative control diet (NC) with a nutrient deficiency (ND) equal to matrix value of 500 FTU/kg of Phy, NC diet with 0.5 g/kg of BA, NC diet with 500 FTU/kg of Phy, and NC diet with 0.5 g/kg of BA and 500 FTU/kg of Phy. Broiler chickens received NC diets had lower body weight gain (BWG), feed intake (FI) and higher feed conversion ratio (FCR) in the entire experiment (P ≤ 0.05). Dietary ND negatively influenced tibia and toe ash contents, serum, and tibia P contents as well as ileal P, Ca and CP digestibility at d 28 (P ≤ 0.05). FCR of d 1 to 11 and d 12 to 24 improved when Phy was added to NC rather than PC diets (P ≤ 0.05). Phy supplementation did not affect serum P and Ca content at d 28 (P> 0.05), but reduced serum alkaline phosphatase content in broiler chickens fed PC diets (P ≤ 0.05). Phy supplementation increased tibia and toe ash contents at d 28, especially in broiler chickens fed NC diets (P ≤ 0.05). Inclusion of BA did not influence (P> 0.05) tibia ash, tibia Ca and P contents at d 28, but increased toe ash content (P ≤ 0.05).The interaction between BA and the dietary nutrient level was significant for FCR of d 25–42 and d 1–42 (P ≤ 0.05). Broiler chickens fed PC diets with BA had better FCR compared with those fed PC diets without BA atd 25–42 (P ≤ 0.05). Adding Phy to the diets containing BA improved BWG and FI atd 1–11(P ≤ 0.05). In conclusion, Phy was effective in improving some growth performance traits, and bone mineralization especially when added to NC diets. However, BA had a positive effect on FCR of broiler chickens fed PC diets and had no impact on ileal nutrients digestibility, but improved toe ash content.

Vitamin D3 enhanced intestinal phosphate cotransporter genes in young and growing broilers

The influence of dietary vitamin D3 (VD3) levels on growth, bone performance, and duodenal type IIb sodium-dependent phosphate cotransporter (NaPi-IIb) genes in broiler chicken were studied. One-day-old male Ross308 broilers (n = 432) were allocated into 6 treatment groups with each group consisting of 6 cage pens. Each treatment group received diet containing different amounts of VD3 (80, 200, 500, 1,250, 3,125, or 7,813 IU per kg of diet) from a day-old to 31 D of age. Dietary available phosphorus and calcium were kept the same across all treatments in each phase. At 14 D, influence of VD3 on BW gain was found in the birds that received VD3 of 3,125 IU/kg and 200 IU/kg (P < 0.05). Toe ash and tibia ash linearly increased (P < 0.05) at 14 D with increase in dietary VD3. There was no significant influence of dietary VD3 on tibia breaking strength. In both phases, relative expression of duodenal NaPi-IIb linearly increased (P < 0.01) with increase in dietary VD3. At 14 D, highest expression of 3.2 folds was observed in birds treated with VD3 at 7,813 IU/kg of feed. At 31 D, birds that received VD3 levels of 3,125 and 7,813 IU/kg of feed showed 2.9 folds higher in NaPi-IIb expression compared with those fed lowest level of VD3 at 80 IU/kg of feed. When dietary calcium and phosphorus were maintained at the standard requirement, increase in dietary VD3 did not improve growth performance. For optimum growth and bone characteristics, dietary inclusion of VD3 at 500 IU/kg was adequate for both starter and grower broiler diets. Vitamin D3 enhanced the expression of NaPi-IIb at higher doses and thus improving the tibia ash content in high VD3 treatment groups. This study reported for the first time an increased in the expression of duodenal NaPi-IIb in 31-day-old broilers in response to high dietary VD3 levels.

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 Graded Levels of an Enhanced E.coli Phytase with Step-Wise Reduction of Supplemental Inorganic Phosphate on Growth Performance of Broilers Fed Corn-Soy Diet

ABSTRACT This study evaluated the potential of incremental doses of an enhanced Escherichia coli-derived phytase to support step-wise reduction of supplemental inorganic phosphate in an all-vegetable broiler diet. Corn-soybean meal-based diets containing 0.40/0.80%, 0.35/0.70%, and 0.30/0.60% avP and Ca, respectively from 0-10, 10-25, and 26-42 days posthatch served as experimental control (PC). Three test diets were formulated with 500, 1000, and 1500 FTU/kg of phytase assigned respectively an avP matrix of 0.15, 0.19, and 0.23% and a fixed Ca matrix of 0.15%. An additional diet (PC++) containing extra avP and Ca (+0.05% avP/+0.1% Ca) to that of PC was included to test if avP and Ca were not limiting in PC. Each diet was offered to 16 replicates of straight-run broilers kept in floor pens (30 birds per pen). PC++ had lower (p<0.05; 10 and 25 d) or similar (42 d) BW and toe ash compared with PC confirming the avP and Ca set in PC were sufficient to support optimal growth and bone mineralization. Compared to the PC, diets containing 1000 and 1500 FTU phytase had higher BW (p<0.05) at 10 and 25 d. For the overall period of 0-42 d, FI, BW and FCR did not differ across treatments. Percentage-, but not the absolute-, toe ash at phytase treated groups was significantly (p<0.05) low compared with the PC. The experiment demonstrated that 1500 FTU/kg of enhance E. coli phytase supports optimal BW and FCR of broilers fed corn-soy diet largely void of supplemental inorganic phosphate.

The influence of exogenous phytase on the post-enteral availability of amino acids in broiler chickens offered wheat-based diets

To investigate the influence of exogenous phytase inclusions in poultry diets on the post-enteral availability of amino acids, wheat-soybean meal diets containing 0, 500, 1000 and 2000 phytase units (FTU)/kg were offered to eight replicate cages (six birds per cage) or a total of 192 male Ross 308 chicks from 7 to 28 days post-hatch. The parameters determined included growth performance, nutrient utilisation, bone mineralization, parameters of gizzard functionality, apparent ileal digestibility coefficients and disappearance rates (g/bird/day) of amino acids, plus concentrations of amino acids, glucose and ammonia in plasma from the portal circulation (anterior mesenteric vein). The inclusion of 500 FTU/kg significantly improved weight gain by 8.39% (1485 versus 1370 g/bird) and feed conversion ratio (FCR) by 5.10% (1.397 versus 1.472 g/g) in comparison to the control. Phytase inclusions significantly increased gizzard pH but not toe ash. The 2000 FTU/kg phytase inclusion significantly increased digestibility of 15 from 16 amino acids by an average of 5.29% (0.716 versus 0.680) and significantly increased apparent metabolisable energy (AME) by 0.45 MJ (12.43 versus 12.88 MJ) and N-corrected AME (AMEn) by 0.45 MJ (11.43 versus 11.88 MJ) relative to the control. The 500 FTU/kg phytase inclusion significantly increased free concentrations of seven amino acids (isoleucine, leucine, lysine, phenylalanine, tryptophan, valine and serine) in plasma from the anterior mesenteric vein based on pairwise comparisons and numerically increased concentrations of a further six amino acids. Phytase inclusions linearly reduced concentrations of glutamic acid and glutamine in the portal circulation, and there was a logarithmic relationship between phytase inclusions and increased plasma glucose concentrations. Reductions in the ratio of glutamate plus glutamine to glucose concentrations in portal plasma were significantly related to improvements in FCR. The outcomes of this study indicate that phytase can positively influence the post-enteral availability of amino acids. The inference is that phytase is manipulating the metabolic fates of amino acids and glucose in the gut mucosa and consideration is given to the possible responsible mechanisms for the observed outcomes.

Restriction of dietary non-phytate phosphorus on growth performance and expression of intestinal phosphate cotransporter genes in broilers

Effects of dietary non-phytate phosphorus (nPP) restriction on growth and duodenal type IIb sodium-dependent phosphate cotransporter (NaPi-IIb) genes were observed. A total of 432 one-day old Cobb500 male broiler chickens in 36 cage pens were divided into 6 groups with each group containing 6 pens. Each group was treated with one of the diets containing 0.33, 0.37, 0.41, 0.45, 0.49, and 0.53% of nPP up to 14 D. During 15 to 31 D, birds were treated with one of the diets containing 0.23, 0.27, 0.31, 0.35, 0.39, and 0.43% of nPP. Level of Ca was kept the same across all treatments. Dietary nPP level influenced (P < 0.001) weight gain and feed intake in both growth phases, whereas effect on feed per gain ratio was seen only in the second phase. Toe ash, tibia ash, and tibia breaking strength responded to treatments (P < 0.01) at 14 D. Only tibia ash content was significantly improved (P < 0.001) at 31 D. Growth and bone parameters linearly improved with an increase in dietary nPP content (P < 0.05). Above dietary nPP 0.41% and 0.31% for first phase and second phase, respectively, no significant improvement was seen. Duodenal NaPi-IIb mRNA overexpressed with a decrease in dietary nPP in both phases (P < 0.05). Relative expression of NaPi-IIb in lowest nPP group were 2.2 folds higher in the first phase and 3.6 folds higher in the second phase compared to respective highest nPP groups of each phase. No significant change in NaPi-IIb expression was seen above 0.37% of dietary nPP for 14 D and 0.31% of dietary nPP for 31 D. Dietary requirements of nPP 0.41% for 0 to 14 D and 0.31% for 15 to 31 D were adequate for optimal growth and bone parameters. This study fills the gap in understanding of intestinal NaPi-IIb expression in response to dietary nPP restriction in broilers older than 21 D of age.

The effects of calcium source and concentration on performance, bone mineralisation and serum traits in male broiler chickens from 1 to 21 days of age

In total, 840 1-day-old male broiler chickens (Ross 308) were used to evaluate the effects of seven dietary calcium (Ca) concentrations (4.0, 5.5, 7.0, 8.5, 10.0, 11.5 and 13.0 g/kg, at a fixed concentration of 4.0 g/kg of non-phytate phosphorus) and two calcium sources (oyster shell and limestone) on broiler chicken Ca requirements for optimal growth rate and bone mineralisation from 1 to 21 days of age. All chickens were randomly distributed into 14 treatment groups (seven treatments of each Ca source), each being replicated four times, with 15 birds per each replicate. Results indicated that Ca source and Ca source × Ca concentration interaction had no significant (P &amp;gt; 0.05) effects on birds average feed intake, but increasing Ca concentration to &amp;gt;8.5 g/kg significantly deteriorated average feed intake. Average weight gain and feed conversion ratio were significantly influenced by Ca source × Ca concentration interaction, whereby high concentrations of Ca from oyster shell resulted in a poorer performance for both criteria than did those from limestone. Serum Ca, P and total protein were not affected by Ca source. However, increasing Ca concentrations had adverse effects on serum P concentration (P &amp;lt; 0.05). Toe ash, tibia ash and phosphorus concentrations at 21 days were not influenced by Ca source, but were depressed as dietary Ca concentration increased (P &amp;lt; 0.05). A broken-line regression analysis indicated that the Ca requirements to optimise average weight gain and tibia ash when limestone was used as a Ca source were 5.54 and 6.58 g/kg of diet respectively, and 5.80 and 6.43 g/kg of diet respectively, when oyster shell was used. In conclusion, the results indicated that Ca concentration, more than Ca source, has a significant influence on broiler chicken performance and bone mineralisation, all of which deteriorate when the dietary Ca concentration exceeds 8.5 g/kg at the constant available-phosphorus concentration of 4.0 g/kg.

Effects of dietary calcium and phosphorus deficiency and subsequent recovery on broiler chicken growth performance and bone characteristics

The ability of birds to modify dietary phosphorus utilisation when fed with low-phosphorus and calcium (Ca) diets was studied using different sequences of dietary phosphorus and Ca restriction (depletion) and recovery (repletion) during the grower and the finisher phases. A total of 3600 Ross 708 broilers were randomly divided into 10 replicate pens per treatment (60 per pen, six pens per block). Chicks were fed a common starter diet from days 0 to 10, then a grower control diet (C: 0.90% Ca, 0.39% non-phytate phosphorus, nPP), mid-level diet (M: 0.71% Ca, 0.35% nPP) or low Ca and nPP diet (L: 0.60% Ca, 0.30% nPP) from days 11 to 21, followed by a finisher diet C, M or L containing, respectively, 0.85%, 0.57% or 0.48% Ca and 0.35%, 0.29% or 0.24% nPP from days 22 to 37. Six treatment sequences were tested: CC, MM, LL, ML, LC and LM. Bone mineral content by dual-energy X-ray, tibia ash, toe ash weight and tibia breaking strength were measured on days 21 and 37. No significant effect was observed on growth performance throughout the experiment. Diet L reduced bone mineral content, breaking strength, tibia and toe ash by 9%, 13%, 11% and 10%, respectively, on day 21 (compared with diet C, for linear effect, P<0.05). On day 37, bone mineral content, breaking strength, tibia and toe ash remained lower compared with control values (CC v. MM v. LL, P<0.05 for linear and quadratic effects). Mineral depletion duration (ML v. LL) did not affect bone mineral status. Replenishing with the C diet during the finisher phase (LC) restored bone mineral content, tibia ash and toe ash weight better than the M diet did, but not to control levels (CC v. LC v. LM, for linear effect, P<0.05). These results confirm that dietary Ca and nPP may be reduced in the grower phase without affecting final growth performance or breaking strength as long as the finisher diet contains sufficient Ca and nPP. The practical applications of this strategy require further study in order to optimise the depletion and repletion steps.