Supplementing corn-soybean meal diets with microbial phytase linearly improves phytate phosphorus utilization by weanling pigs

Production of cleavage-resistant phytase transgenic pigs by handmade cloning

With the rapid development of intensive animal husbandry in the livestock industry, large quantities of manure waste containing phytate phosphorus are being generated. Phytase can effectively solve the problem of high phosphorus pollution in the feces of monogastric animals. Enviropig, which produces phytase in the salivary glands and secretes the enzyme in the saliva, were first generated in 1999. However, phytase is easily inactivated during digestion. To address this problem, cleavage-resistant phytase transgenic pigs were generated using handmade cloning in this study. Transgene construction was improved and three cell lines carrying Cafp were obtained. In total, 810 blastocysts were generated and 712 good-quality were transferred into six recipients. Fourteen piglets were born, of which six survived after weaning. Polymerase chain reaction and sequencing results showed that seven (three live and four dead) of the fourteen piglets carried Cafp. Phytase activity in the saliva of the six live cloned pigs was tested at four months of age, and only one pig had 0.155 FTU/mL enzyme activity. The other five pigs may not have been activated in the transgenic parotid gland. Among all the transgenic pigs, the highest phosphorus digestion rate was 59.2% of intake, representing a 25.4% decrease in fecal emission compared to the average of controls. Immunohistochemical results on the three Cafp-positive pigs that died after six months of age showed that the transgene was only expressed in parotid glands, confirming tissue-specific gene expression. In conclusion, cleavage-resistant phytase transgenic pigs were successfully produced through handmade cloning. The cloned pigs offer a unique biological approach to managing phosphorus nutrition and environmental pollution in animal husbandry.

Effect of Microbial Phytase on Ileal Digestibility of Minerals, Plasma and Urine Metabolites, and Bone Mineral Concentrations in Growing-Finishing Pigs

The study was conducted to evaluate the effects of added phytase in the diet of pigs on utilization of minerals and to determine the essential levels of this supplement in compound feed. An additional aim of the study was a critical assessment of current recommendations regarding the level of phosphorus in the diet of pigs, taking into account the use of phytase. A total of 432 pigs were allotted to six dietary treatments, with nine replicate pens per treatment according to body weight (BW) and sex. The treatments included a negative control (NC) with reduced content of digestible phosphorus; the NC diet supplemented with 6-phytase produced by a genetically modified strain of Aspergillus oryzae in the amount of 250 (NC + 250), 500 (NC + 500), 1000 (NC + 1000), or 1500 (NC + 1500) FTU/kg of feed; and a positive control (PC) diet formulated to meet NCR nutrient requirements for pigs. The results showed that, the higher the phytase activity in the diet (NC+), the lower the concentration of P, Ca, and Mg in the chyme (p < 0.05). Pigs fed the PC and NC+ diets had higher plasma levels of P and Ca than group NC in both fattening periods (p < 0.05). The content of phosphorus in the femur of pigs increased with the level of phytase added to the diet (p < 0.05). The content of Cu and Zn in the femur of pigs in the growing period was higher in groups NC + 500 and NC + 1000 than in the remaining experimental groups (p < 0.001). The content of P and Ca in the feces was higher in pigs fed the PC diet in comparison to the remaining experimental groups in both fattening periods (p < 0.001). There was a decrease in the content of P, Ca, and Mg in the excreta of pigs fed NC+ diets in both fattening periods (p < 0.05). A linear decrease in excretion of zinc in the feces was noted in the case of high levels of phytase, i.e., 1000 and 1500 FTU (p < 0.001). Increasing the level of phytase decreased the Cu (p < 0.001) content in the urine of growing−finishing pigs. In conclusion, the analysis of the effects of the use of phytase in a range of 0−1500 FTU/kg in low-phosphorus diets for fattening pigs indicates that 1000 FTU is the most effective level of phytase for increasing utilization of minerals and reducing excretion of elements into the environment.

Growth Performance, Bone Development and Phosphorus Metabolism in Chicks Fed Diets Supplemented with Phytase Are Associated with Alterations in Gut Microbiota

Simple Summary

Phosphorus is a crucial component of nucleic acids, phospholipids, several coenzymes and bone, and plays numerous roles in nutrient metabolism in animals. We investigated the growth performance, bone development, phosphorus metabolism and gut microbiota changes elicited by different phosphorus levels with/without phytase in chicks during the brooding period. Low-phosphorus diets inhibited growth performance and bone development, decreased utilization of phosphorus and altered gut microbial structure and function in the brooding stage of chicks. Inclusion of phytase improved growth performance and bone development and decreased phosphorus emission. The potential mechanisms may be associated with gut microbiota reprogramming.

Abstract

Phosphorus pollution caused by animal husbandry is becoming increasingly problematic, especially where decreasing and non-renewable phosphorus resources are concerned. We investigated the growth performance, bone development, phosphorus metabolism and gut microbiota changes elicited by different phosphorus levels with/without phytase in chicks during the brooding period (1–42 d). Five-hundred-and-forty (540) egg-laying chickens were assigned to six groups (0.13% NPP, 0.29% NPP, 0.45% NPP, 0.13% NPP + P, 0.29% NPP + P and 0.45% NPP + P) according to a factorial design with three non-phytate phosphorus (NPP) levels (0.13, 0.29 and 0.45%) and two phytase (P) dosages (0 and 200 FTU/kg). Chicks fed with the diet with 0.13% NPP had the lowest body weight, average daily gain, shank length, average daily feed intake and highest ratio of feed to gain, while phytase supplementation was able to mitigate the adverse effects of low-phosphorus diets on growth performance. Moreover, phosphorus metabolism was affected by different dietary NPP and phytase levels. Thus, 0.13% NPP significantly reduced serum phosphorus, while phytase supplementation significantly increased serum phosphorus. Notably, phosphorus utilization in the 0.13% NPP group was significantly decreased and the phosphorus excretion ratio was increased. Phytase supplementation significantly improved phosphorus utilization by 43.79% and decreased phosphorus emission in the 0.13% NPP group but not in the 0.29% NPP or the 0.45% NPP group. Remarkably, the alpha diversity of gut microbiota was significantly decreased in the low-phosphorus group, while phytase supplementation increased alpha diversity and improved gut microbial community and function. The LEfSe analysis revealed that several differential genera (e.g., Bacteroides, norank_f__Clostridiales_vadinBB60_group and Eggerthella) were enriched in the different dietary NPP and phytase levels. Furthermore, correlations between differential genera and several crucial phenotypes suggested that the enrichment of beneficial bacteria with different levels of phosphorus and phytase promoted phosphorus utilization in the foregut and hindgut. In summary, low-phosphorus diets inhibited growth performance and bone development, decreased utilization of phosphorus and altered gut microbial structure and function in the brooding stage of chicks. Finally, phytase supplementation improves growth performance and bone development and decreases phosphorus emission, and the potential mechanisms may be associated with the reprogramming of gut microbiota.

Effects of phytase and 25-hydroxyvitamin D3 supplementation on growth performance and bone development in weaned piglets in Ca- and P-deficient dietary

BACKGROUND

The beneficial function of phytase and 25-hydroxyvitamin D3 (HyD) on the feed utilization rate has been widely investigated. However, studies concerning its influence on weaned piglets largely lag behind. The aim of this study was to investigate the effects of phytase and HyD supplementation on the growth performance and bone development in weaned piglets under dietary Ca and P deficiency.

RESULTS

The results showed that dietary Ca and P deficiency decreased (P < 0.05) the content of serum P in 6-10 kg piglets, as well as reducing (P < 0.05) the contents of serum Ca and P, average daily gain (ADG), bone mineral density (BMD), breaking force (BF), bone ash and femur Ca in 10-20 kg piglets. Compared with the control group, the feed-to-gain ratio (F/G) of 6-10 kg piglets in the Phy group was decreased (P < 0.05), whereas the ADG, blood Ca and P, BMD, BF, bone ash, P apparent digestibility, Ca and P retention rate of 10-20 kg piglets were increased (P < 0.05). The contents of serum osteocalcin and HyD in 6-10 kg piglets and ADG were higher than in the control group (P < 0.05), as well as the contents of serum Ca and HyD in 10-20 kg piglets in the HyD treatment group. Supplementation with both Phy and HyD decreased the F/D (P < 0.05) and increased the contents of serum Ca, P and HyD in 6-10 kg piglets as well as enhancing the ADG, BMD, BF, bone ash, femur Ca and P, serum Ca and P, HyD, and the apparent digestibility and retention of Ca and P (P < 0.05) in 10-20 kg piglets. Supplementation with Phy and HyD in Ca- and P-deficient dietary decreased bone resorption, and improved tight arrangement of collagen fibers and oblique fibers in weaned piglets.

CONCLUSION

These data indicated that supplementation with both 1500 U kg^-1 Phy and 50 μg kg^-1 HyD could enhance dietary Ca and P utilization and promote bone development in low Ca and P dietary, and supplementation with both Phy and HyD had a significant synergy effect compared to single supplement. © 2021 Society of Chemical Industry.

Phosphorus Restriction in Brooding Stage Has Continuous Effects on Growth Performance and Early Laying Performance of Layers

Simple Summary

Phosphorus plays a critical role in bone and eggshell formation. Dietary phosphorus oversupply depletes non-renewable natural resources and causes environmental concerns in animal husbandry. This study evaluated the effects of phosphorus restriction in the brooding stage and subsequent recovery on growth performance, tibia development and early laying performance of layers. Phosphorus restriction decreases growth performance and bone characters in the brooding stage, and the adverse effects on body weight and early laying performance do not disappear after phosphorus supplementation. These findings give a foundation and new perspective on low phosphorus feeding strategies in the production of layers.

Abstract

This study evaluated the effects of phosphorus restriction in the brooding stage and subsequent recovery on growth performance, tibia development and early laying performance of layers. 360 one-day-old hens were randomly divided into 4 groups with 6 replicates and 15 chicks per replicate. Chicks were fed diets containing 0.13% (L), 0.29% (M), 0.45% (N), 0.59% (H) non-phytate phosphorus (nPP) from 1 to 8 weeks of age. From 9 to 20 weeks of age, the L and N group were divided into two groups fed normal level phosphorus (n, 0.39% nPP) and high-level phosphorus (h, 0.45% nPP) separately, then all the birds were fed a normal diet (0.39% nPP) from 21 to 26 weeks of age. Four treatments were tested: Ln, Lh, Nn, and Nh. The lower body weight, average daily feed intake, tibia length and daily tibial increment were observed in the L group (p < 0.05) and the ratio of feed to gain was significantly increased in the L group at 8 weeks of age (p < 0.05). In addition, the fresh and degreased tibia weight, bone ash, Ca content in the tibia and P content in the ash and tibia were significantly decreased in the L group at 8 weeks of age (p < 0.05). After compensatory processes, there was no significant difference in tibia characters; however, body weight in the Ln group was significantly lower than in the Nn group (p < 0.05) and was significantly lower in the Lh group than the Nn group (p < 0.01) and Nh group (p < 0.05). In addition, the laying rate and average daily egg mass in the Lh group were lower than Nn and Nh (p < 0.05). In conclusion, severe dietary phosphorus restriction impaired growth performance and bone mineralization in the brooding stage. Subsequent phosphorus supplementation could not alleviate this adverse effect on body weight, which continued to affect egg production. These findings give a foundation and new perspective on a low phosphorus feeding strategy in layer production.

How do pigs deal with dietary phosphorus deficiency?

Feeding strategies for growing monogastric livestock (particularly pigs) must focus on maximising animal performance, while attempting to reduce environmental P load. Achieving these goals requires a comprehensive understanding of how different P feeding strategies affect animal responses and an ability to predict P retention. Although along with Ca, P is the most researched macromineral in pig nutrition, knowledge gaps still exist in relation to: (1) the effects of P feed content on feed intake (FI); (2) the impact of P intake on body composition; (3) the distribution of absorbed P to pools within the body. Here, we address these knowledge gaps by gathering empirical evidence on the effects of P-deficient feeds and by developing a predictive, mechanistic model of P utilisation and retention incorporating this evidence. Based on our statistical analyses of published literature data, we found: (1) no change in FI response in pigs given lower P feed contents; (2) the body ash–protein relationship to be dependent upon feed composition, with the isometric relationship only holding for pigs given balanced feeds and (3) the priority to be given towards P retention in soft tissue over P retention in bones. Subsequent results of the mechanistic model of P retention indicated that a potential reduction in P feeding recommendations could be possible without compromising average daily gain; however, such a reduction would impact P deposition in bones. Our study enhances our current knowledge of P utilisation and by extension excretion and could contribute towards developing more accurate P feeding guidelines.

Effects of a novel corn-expressed E. coli phytase on digestibility of calcium and phosphorous, growth performance, and bone ash in young growing pigs1

Two experiments were conducted to test the hypothesis that a corn-expressed phytase increases growth performance, bone measurements, and nutrient digestibility by young growing pigs, if added to diets that are deficient in Ca and P. In Exp. 1, 60 pigs (initial BW: 10.78 ± 0.67 kg) were randomly allotted to 6 dietary treatments that included a positive control diet (PC; 0.70% total Ca and 0.60% total P) and a negative control diet (NC; 0.50% total Ca and 0.42% total P). Four additional diets were formulated by supplementing the NC diet with 250, 500, 1,000, or 1,500 phytase units (FTU)/kg. Diets were fed for 28 d and the individual BW of pigs on days 1 and 28 were recorded. Fecal samples were collected from days 25 to 27 to calculate apparent total tract digestibility (ATTD) of Ca and P. On the last day of the experiment, all pigs were euthanized, and the left femur was removed and analyzed for ash, Ca, and P. Results indicated that growth performance, ATTD of Ca and P, and bone ash measurements were reduced (P < 0.05) in NC fed pigs compared with PC fed pigs. However, growth performance, ATTD of Ca and P, and bone ash measurements were improved (linear and quadratic, P < 0.05) by including increasing concentrations of phytase to the NC diet. In Exp. 2, experimental procedures were similar to those used in Exp. 1. Forty-eight pigs (initial BW: 11.15 ± 0.85 kg) were randomly allotted to 6 dietary treatments in a 28-d experiment. Treatments included a PC diet, an NC diet, and 4 diets in which 500 or 1,000 FTU/kg of either the corn-expressed phytase or a commercial microbial phytase were added to the NC diet. Pigs fed the NC diet had reduced (P < 0.01) final BW, ADG, G:F, and bone ash concentrations compared with pigs fed the PC diet. When 500 FTU/kg phytase was fed, no differences were observed in growth performance or bone ash measurements between phytase sources, and there were no differences in growth performance among pigs fed 1,000 FTU/kg of either phytase source or the PC diet. However, regardless of concentration or source of phytase, pigs fed the PC diet had greater (P < 0.001) amount of bone ash, bone Ca, and bone P compared with pigs fed phytase diets. In conclusion, the corn-expressed phytase is effective in improving growth performance, Ca and P digestibility, and bone measurements in pigs fed diets that are deficient in Ca and P.

Effect of phytase on phosphorous balance in 20-kg barrows fed low or adequate phosphorous diets

The effects of phytase on phosphorus (P) digestibility are well established. However, there are few studies that report P balance, particularly when phytase is used in diets that have adequate or deficient P. The main objective of the study was to determine the effect of dietary P levels and exogenous phytase on P balance in growing pigs. The first part of the experiment was a 14-d metabolism study conducted with 80 barrows (initial body weight 18.5 ± 0.5 kg) with a 2 × 5 factorial arrangement of treatments and main effects of available P (0.13% available P, low P [Low-P] diet; 0.35% available P, adequate P [Adeq-P] diet) and phytase (0, 250, 500, 2,500, and 12,500 U/kg). A portion of the pigs (n = 24) fed the Low-P diet, with 0, 500, 2,500, 12,500 U/kg phytase, and those fed the Adeq-P diet, with 0 and 12,500 U/kg phytase, remained on test diets for another 4 d, and tissues were collected for determination of bone characteristics and tissue P concentration. There was a P × phytase interaction for P retention that was accounted for by a lack of response to phytase in pigs fed the Adeq-P diet. Retention of P was greater with incremental levels of phytase in pigs fed Low-P diets as compared to those fed Adeq-P diets (P level × phytase, P < 0.01), but calcium (Ca) retention was greater in pigs fed Adeq-P diets (P level × phytase P < 0.01). Apparent total tract digestibility (ATTD) of P was improved by phytase (P < 0.001) and was greater in pigs fed Adeq-P diets as compared to those fed Low-P diets (P = 0.006). Metatarsal bone ash (quadratic, P = 0.01) and strength (linear, P = 0.03) was increased by phytase addition to the Low-P diets. There were no phytase or dietary P effects on P concentrations of the heart, kidney, liver, muscle, and spleen. These results suggest that as compared to the effects in an Adeq-P diet, adding phytase to a Low-P diet was more effective at reducing the P and Ca excretion and restoring average daily gain (ADG). The P released by phytase is absorbed and contributes to improved bone growth, greater rates of tissue accretion, and increased body weight, but does not change tissue P concentrations. There is, however, a threshold for P retention, beyond which it is excreted in the urine.

Effects of exogenous phytase supplementation on phosphorus metabolism and digestibility of beef cattle

Objectives were to determine interactions between phytase inclusion and dietary P concentration on P utilization by beef cattle fed a starch-based diet. Six ruminally-fistulated steers (BW = 750 ± 61 kg) were allotted to a 6 × 6 Latin square design with a 3 × 2 factorial arrangement of treatments. Factors included phytase inclusion, at 0, 500, or 2,000 phytase units (FTU)/kg of diet DM, and dietary P concentrations, at 0.10% and 0.30% of total diet DM. Feed ingredients, fecal samples, and orts were composited within period, lyophilized and ground. Samples were analyzed for NDF, ADF, CP, fat, ash, total P, and other minerals. Data were analyzed using the MIXED procedure of SAS with animal as the experimental unit. The CORR procedure was used to compare blood and urinary P concentrations. There were no treatment interactions (P ≥ 0.30) for any parameter measured. There were no main effects (P ≥ 0.45) of phytase inclusion on DMI, total fecal output, apparent DM digestibility, water intake, or urinary output. Steers fed 0.10% P had decreased (P < 0.01) DMI and total fecal output, but increased (P < 0.01) apparent DM digestibility compared with steers fed 0.30% P. Although N intake and retention were not affected by treatment, steers fed the 0.10% P diet tended (P = 0.10) to absorb more N compared with steers fed 0.30% P; and, steers fed the 0.10% P diets excreted more N in the urine (P = 0.02) and less N in the feces (P < 0.01) compared with steers fed the 0.30% P diets. Steers fed the 0.10% P diets also consumed 70.1% less (P < 0.01) total P each day, and excreted 51.9% less (P < 0.01) P in feces and 94.6% less P in the urine (P < 0.01) compared with steers fed 0.30% P. Excretion of water-soluble P in the feces was greater (P < 0.01) on a g/d basis for steers fed 0.30% P when compared with steers fed 0.10% P. However, the proportion of total fecal P excreted as water-soluble P increased (P < 0.05) by 23.0% in steers fed 0.10% P compared with steers fed 0.30% P, regardless of phytase inclusion level. There was no effect of dietary phytase concentration on blood or urinary (P ≥ 0.27) P concentrations. Blood P concentration was positively correlated (r = 0.60; P < 0.01) to urinary P concentration when steers were fed 0.10% P; however, when steers were fed 0.30% P, there was no correlation (r = 0.36; P = 0.16) between blood and urine P. Regardless of dietary P concentration, phytase supplementation did not increase calculated P absorption or retention.

Standardized total tract digestibility of phosphorus in copra meal, palm kernel expellers, palm kernel meal, and soybean meal fed to growing pigs

Sixty-six barrows (initial BW: 27.4 ± 2.8 kg) were used to determine the standardized total tract digestibility (STTD) of P in copra meal (CM), palm kernel expellers from Indonesia (PKE-IN), palm kernel expellers from Costa Rica (PKE-CR), palm kernel meal from Costa Rica (PKM), and soybean meal (SBM) without or with exogenous phytase. Pigs were housed individually in metabolism cages and allotted to 11 diets with 6 replicate pigs per diet in a generalized randomized block design. Five diets were formulated by mixing cornstarch and sugar with CM, PKE-IN, PKE-CR, PKM, or SBM. Five additional diets, which were identical to the initial 5 diets but supplemented with 800 units of phytase, were also formulated. A P-free diet was used to measure basal endogenous losses of P by the pigs. Feces were collected for 5 d using the marker to marker approach after a 5-d adaptation period. Analyzed total P in CM, PKE-IN, PKE-CR, PKM, and SBM was 0.52, 0.51, 0.53, 0.54, and 0.67%, respectively. Phytate P was 0.22, 0.35, 0.38, 0.32, and 0.44% in CM, PKE-IN, PKE-CR, PKM, and SBM, respectively. Addition of phytase increased (P < 0.05) the apparent total tract digestibility (ATTD) of P from 60.6 to 80.8, 27.3 to 56.5, 32.6 to 59.9, 48.9 to 64.1, and 41.1 to 72.2% in CM, PKE-IN, PKE-CR, PKM, and SBM, respectively. The ATTD of P in CM was greater (P < 0.05) than in any of the other ingredients. The ATTD of P in SBM and PKM was greater (P < 0.05) than in PKE-IN, with PKE-CR being intermediate. The STTD of P increased (P < 0.05) from 70.6 to 90.3, 37.6 to 66.4, 43.2 to 69.9, 57.9 to 73.5, and 49.6 to 81.1% in CM, PKE-IN, PKE-CR, PKM, and SBM, respectively, when microbial phytase was added to the diets. When expressed as a percentage of total P, phytate P concentration in the ingredient negatively affected (P < 0.05) the ATTD of P (107.09 - 1.0564 × % phytate P; R(2) = 87.1) and the STTD of P (116.3 - 1.0487 × % phytate P; R(2) = 89.4). In conclusion, microbial phytase increased P digestibility of CM, PKM, PKE-CR, PKE-IN, and SBM when fed to growing pigs, and the concentration of phytate P affects the response to microbial phytase.

Effects of a novel bacterial phytase expressed in Aspergillus Oryzae on digestibility of calcium and phosphorus in diets fed to weanling or growing pigs

In 2 experiments, 48 weanling (initial BW: 13.5 ± 2.4 kg, Exp. 1) and 24 growing pigs (initial BW: 36.2 ± 4.0 kg, Exp. 2) were used to determine effects of a novel bacterial 6-phytase expressed in Aspergillus oryzae on the apparent total tract digestibility (ATTD) of phosphorus and calcium in corn-soybean meal diets fed to weanling and growing pigs. In Exp. 1 and 2, pigs were randomly allotted to 6 dietary treatments using a randomized complete block design and a balanced 2 period changeover design, respectively. In both experiments, 6 diets were formulated. The positive control diet was a corn-soybean meal diet with added inorganic phosphorus (Exp. 1: 0.42 and 0.86% standardized total tract digestible phosphorus and total calcium, respectively; Exp. 2: 0.32 and 0.79% standardized total tract digestible phosphorus and total calcium, respectively). A negative control diet and 4 diets with the novel phytase (Ronozyme HiPhos, DSM Nutritional Products Inc., Parsippany, NJ) added to the negative control diet at levels of 500, 1,000, 2,000, and 4,000 phytase units (FYT)/kg were also formulated. In Exp. 1, the ATTD of phosphorus was greater (P < 0.01) for the positive control diet (60.5%) than for the negative control diet (40.5%), but increased (linear and quadratic, P < 0.01) as phytase was added to the negative control diet (40.5% vs. 61.6%, 65.1%, 68.7%, and 68.0%). The breakpoint for the ATTD of phosphorus (68.4%) was reached at a phytase inclusion level of 1,016 FYT/kg. In Exp. 2, the ATTD of phosphorus was greater (P < 0.01) for the positive control diet (59.4%) than for the negative control diet (39.8%) and increased (linear and quadratic, P < 0.01) as phytase was added to the negative control diet (39.8% vs. 58.1%, 65.4%, 69.1%, and 72.8%). The breakpoint for the ATTD of phosphorus (69.1%) was reached at a phytase inclusion level of 801 FYT/kg. In conclusion, the novel bacterial 6-phytase improved the ATTD of phosphorus and calcium in both weanling and growing pigs. The optimum level of inclusion for this phytase is 800 to 1,000 FYT/kg of complete feed to maximize ATTD of phosphorus and calcium in weanling and growing pigs.

Meta-analysis of phosphorus utilization by growing pigs: effect of dietary phosphorus, calcium and exogenous phytase

Optimizing phosphorus (P) utilization in pigs requires improving our capacity to predict the amount of P absorbed and retained, with the main modulating factors taken into account, as well as precisely determining the P requirements of the animals. Given the large amount of published data on P utilization in pigs, a meta-analysis was performed to quantify the impact of the different dietary P forms, calcium (Ca) and exogenous phytases on the digestive and metabolic utilization criteria for dietary P in growing pigs. Accordingly, the amount of phytate P (PP) leading to digestible P (g/kg) was estimated to be 21%, compared with 73% for non-phytate P (NPP) from plant ingredients and 80% for NPP from mineral and animal ingredients (P < 0.001). The increase in total digestible dietary P following the addition of microbial phytase (PhytM) from Aspergillus niger (P < 0.001) was curvilinear and about two times higher than the increase following the addition of plant phytase, which leads to a linear response (P < 0.001). The response of digestible P to PhytM also depends on the amount of substrate, PP (PhytM(2) × PP, P < 0.001). The digestibility of dietary P decreased with dietary Ca concentration (P < 0.01) independently of phytase but increased with body weight (BW, P < 0.05). Although total digestible dietary P increased linearly with total NPP concentration (P < 0.001), retained P (g/kg), average daily gain (ADG, g/day) and average daily feed intake (ADFI, g/day) increased curvilinearly (P < 0.001). Interestingly, whereas dietary Ca negatively affected P digestibility, the effect of dietary Ca on retained P, ADG and ADFI depended on total dietary NPP (NPP × Ca, P < 0.01, P < 0.05 and P < 0.01, respectively). Increasing dietary Ca reduced retained P, ADG and ADFI at low NPP levels, but at higher NPP concentrations it had no effect on ADG and ADFI despite a positive effect on retained P. Although the curvilinear effect of PhytM on digestible P increased with PP (P < 0.001), this effect was lessened by total NPP for ADG and ADFI (PhytM × NPP and PhytM(2) × NPP, P < 0.05) and depended on both total NPP and Ca for retained P (PhytM(2) × NPP × Ca, P < 0.01). This meta-analysis improves our understanding of P utilization, with major modulating factors taken into account. The information generated will be useful for the development of robust models to formulate environmentally friendly diets for growing pigs.

Growth performance, diet nutrient digestibility, and bone mineralization in weaned pigs fed pelleted diets containing thermostable phytase

Traditional supplemental dietary phytase loses activity during steam pelleting. The thermal tolerance and bioefficacy of a phytase product with a thermoprotective coating [coated phytase (C-phytase)] was compared in mash and pelleted diets to a traditional, uncoated phytase (U-phytase) added to a negative control (NC) diet, formulated with reduced dietary Ca and P, and compared with a corn-soybean meal based positive control (POC) diet. Growth performance, nutrient digestibility, and third metacarpal bone characteristics were response variables. Weaned pigs (n = 56; 8.20 ± 0.5 kg initial BW; 28 d of age) were individually housed and randomly allotted to 1 of 7 diets for 21 d. The diets were 1) POC mash, 2) NC mash, 3) NC pelleted at 90°C, 4) NC mash + 500 U/kg U-phytase, 5) NC mash + 500 U/kg C-phytase, 6) NC + 500 U/kg C-phytase pelleted at 80°C, and 7) NC + 500 U/kg C-phytase pelleted at 90°C. The POC and NC diets were formulated to be isoenergetic and isolysinic. The content of Ca and available P was 1.01 and 0.40% and 0.83 and 0.22% in the POC and NC diets, respectively. Pig BW and feed intake were measured on d 7, 14, and 21, and feces were collected for 2 d. On d 21, pigs were killed and ileal digesta and the third metacarpal bone collected. Pigs fed POC had greater (P < 0.05) ADG, G:F, P digestibility, and bone mineralization but lower (P < 0.01) energy digestibility than pigs fed NC. Pelleting the NC diet did not improve performance, nutrient digestibility, or P use. Adding the U-phytase to NC mash diet increased (P < 0.05) ADG, G:F, apparent ileal digestibility (AID) of CP and Ile, Leu, Phe, Thr, Val, and Ser, and apparent total tract digestibility (ATTD) of P compared with pigs fed NC. Pigs fed C-phytase in NC mash diets had increased (P < 0.05) G:F and an AID of CP and AA and ATTD of P compared with pigs fed NC but not different than pigs fed U-phytase NC mash diets. Pigs fed pelleted NC diet with C-phytase had a greater (P < 0.05) ATTD of P and energy than pigs fed mash NC diet with C-phytase but had similar growth performance, AID of CP and AA, and bone mineralization to pigs fed U-phytase. In conclusion, release and bioefficacy of phytase after pelleting was not affected by the thermal protective coating.

Effect of dietary inulin and phytase on mineral digestibility and tissue retention in weanling and growing swine

The effect of dietary phytase and the prebiotic inulin on apparent mineral digestibility, bone mineralization, and tissue mineral contents was evaluated in weanling and growing pigs. In Exp. 1, inulin and phytase were incorporated in a 2 × 3 factorial arrangement of treatments with 8 replicate pens per treatment in a randomized complete block design. There were 2 levels of phytase [0 and 1000 phytase units (FTU)/kg] and 3 levels of chicory inulin (0, 3, and 6%). Weanling pigs (17 d of age; 5 or 4 pigs per pen) with an initial BW of 6.0 ± 0.6 kg were evaluated for 35 d postweaning. Macromineral digestibility was calculated using chromic oxide as an index in fecal samples collected during the final week of the experiment in replicates 1 through 4. On d 36, 1 pig per pen was killed and the heart, liver, kidney, and left tibia were excised and weighed. Inulin did not have any effect on growth performance measurements. Phytase increased (P < 0.05) BW on d 35 and ADG and ADFI during the 21-to-35-d and 0-to-35-d periods. Inulin did not result in increased tissue mineral concentrations on a per unit (mg/kg) or total tissue basis. Phytase increased (P < 0.05) the concentration of Zn in the liver, Mn and Zn in the heart, and Mg and Mn in the kidney. Phytase also increased (P < 0.05) total P, Mg, S, Mn, Se, and Zn in the liver as well as tibia ash. Phytase increased the digestibility of Ca (P < 0.01) and P (P < 0.05). Experiment 2 was conducted with growing pigs (initial BW, 41 ± 5 kg) to evaluate 2 levels of inulin (0 or 6%) and 2 levels of phytase (0 or 1000 FTU/kg) in a 2 × 2 factorial with 6 replicates in a randomized complete block design. Total urine and feces were collected for 10 d from each of 24 barrows after a 21-d acclimation period. Inulin inclusion resulted in reduced Ca digestibility (P < 0.05). Phytase increased (P < 0.05) the digestibility of both Ca and P. These results indicate that dietary inulin does not affect the overall mineral status or growth performance of pigs, whereas phytase increases the utilization of Ca and several microminerals, in addition to P, and also increases growth performance. Inulin and phytase do not appear to interact to affect pig growth or mineral status.

Effect of phytase and xylanase supplementation or particle size on nutrient digestibility of diets containing distillers dried grains with solubles cofermented from wheat and corn in ileal-cannulated grower pigs

Nutrient digestibility in distillers dried grains with solubles (DDGS) is limited by physical constraints such as particle size and by biochemical limitations such as phytate and fiber or nonstarch polysaccharides (NSP). To determine the separate effects of these limitations on nutrient digestibility, ground DDGS (383 µm) supplemented with phytase (0 or 250 units/kg of feed) and xylanase (0 or 4,000 units/kg of feed) was evaluated in a 2 × 2 factorial arrangement of treatments together with unground DDGS (517 µm) and an N-free diet in a 6 × 6 Latin square. Cofermented wheat and corn DDGS contained 8.6% moisture, 31.0% CP, 1.04% Lys, 8.0% ether extract, 2.0% starch, 40% NDF, and 0.85% P (as-is basis). Diets contained 43.7% DDGS as the sole source of AA; the digesta from pigs fed the N-free diet served to subtract basal endogenous AA losses and as control for energy digestibility. Six ileal-cannulated barrows (37.1 ± 0.8 kg of BW) were fed 6 diets at 2.8 × maintenance for DE in six 9-d periods. Feces and ileal digesta were collected for 2 d each. The apparent ileal digestibility (AID) of GE and apparent total tract digestibility (ATTD) of GE and NDF were 2.3, 0.5, and 5.1%-units greater (P < 0.05) for the ground than unground DDGS diet, respectively. Consequently, the ATTD of GE was 1.3%-units greater (P < 0.05) and the DE content was 0.06 Mcal/kg greater (P < 0.05) for ground than unground DDGS, respectively. Grinding of DDGS did not affect (P > 0.05) the ATTD of crude fiber, ADF, P, and Ca in diets. Grinding of DDGS increased (P < 0.05) the AID of most AA in diets including Lys, Met, and Thr by 6.9, 1.1, and 1.7%-units, respectively. Grinding of DDGS increased (P < 0.05) the SID of Lys by 6.2%-units and SID content of Lys and Thr by 0.06 and 0.02%-units, respectively. Phytase and xylanase did not interact (P > 0.05) to affect nutrient digestibility. Phytase increased (P < 0.001) the ATTD of P by 10.5%-units, but did not affect (P > 0.05) AA digestibility. Xylanase did not affect nutrient digestibility. In conclusion, particle size is an important physical characteristic affecting digestibility of energy and AA, but not P in DDGS. Phytate in DDGS limits digestibility of P, but not energy and AA. The substrate for xylanase in DDGS did not hinder energy and AA digestibility.

Cloning and characterization of a novel phytase from wastewater treatment yeast Hansenula fabianii J640 and expression in Pichia pastoris

Phosphohydrolysis of organic phosphorus compounds by acid phosphatases (EC 3.1.3.1 and EC 3.1.3.2) is an important method for efficient removal of phosphorus from high concentration organic wastewater. Another important method is supplementation of animal feed with phytase (EC 3.1.3.8 and EC 3.1.3.26), which improves the availability of phytate-phosphates (phosphate that are hydrolyzed by phytases), making it possible to add less phosphate to animal feed and resulting in the excretion of less phosphorus by the animals. In the present study, we purified a novel phytase from the wastewater treatment yeast Hansenula fabianii J640 (Hfphytase), cloned the 1456 bp open reading frame (ORF) encoding Hfphytase, and characterized Hfphytase. The molecular weight of Hfphytase after deglycosylation by PNGaseF was 49 kDa. The optimal pH and temperature for enzyme activity were 4.5 and 50 degrees C, respectively. Hfphytase exhibits 40% identity with Debaryomyces castellii phytase, 37% identity with Aspergillus niger PhyB, and 34% identity with Saccharomyces cerevisiae Pho5p. Recombinant Hfphytase was transformed and expressed in Pichia pastoris. The yield was 23 g/l by jar fermenter cultivation. The marked phosphohydrolysis activity exhibited by Hfphytase on six substrates (pNP-P, sodium phytate, glucose-1 phosphate, glucose-6 phosphate, alpha-glycerophosphate and beta-glycerophosphate) indicated that it is a non-specific acid phosphatase.

Effect of phytase on apparent total tract digestibility of phosphorus in corn-soybean meal diets fed to finishing pigs

Five experiments were conducted to investigate the ability of different phytase products to improve P digestibility in finishing pigs. A corn-soybean meal basal diet containing 0.50% Ca, 0.32% P, and 0.40% Cr(2)O(3) was used to calculate apparent P and GE digestibility. Pigs were individually penned and fed their respective diet for ad libitum intake for 12 d before fecal sampling on d 13 and 14 and blood collection on d 14 for plasma P determination. Experiments 1 through 4 used gilts with across-trial average initial and final BW of 84 and 97 kg, respectively. Pigs were fed Natuphos (Exp. 1), OptiPhos (Exp. 2), Phyzyme (Exp. 3), or RonozymeP (Exp. 4) at 0, 200, 400, 600, 800, or 1,000 phytase units (FTU)/kg (where 1 FTU is defined as the quantity of enzyme required to liberate 1 micromol of inorganic P per min, at pH 5.5, from an excess of 15 micromol/L of sodium phytate at 37 degrees C). Experiment 5 used barrows with initial and final BW of 98 and 111 kg, respectively, and were fed diets containing 0, 500, or 1,000 FTU/kg of Natuphos, OptiPhos, Phyzyme, or RonozymeP. Pigs fed Natuphos (Exp. 1) and OptiPhos (Exp. 2) exhibited a linear and quadratic (P < 0.01) improvement in P digestibility with increasing levels of dietary phytase, whereas pigs fed Phyzyme (Exp. 3) and RonozymeP (Exp. 4) exhibited a linear (P < 0.01) improvement in apparent P digestibility with increasing levels of dietary phytase. In Exp. 5, the improvement in apparent P digestibility with increasing levels of dietary phytase was linear (P < 0.01) for Natuphos, Phyzyme, and RonozymeP, but was linear and quadratic (P < 0.01) for OptiPhos. Based on regression analysis, inorganic P release at 500 FTU/kg was predicted to be 0.070, 0.099, 0.038, and 0.030% for Natuphos, OptiPhos, Phyzyme, and RonozymeP, respectively. These estimates are comparable with those of pigs in Exp. 5, for which the estimated inorganic P release at 500 FTU/kg was 0.102, 0.039, and 0.028% for OptiPhos, Phyzyme, and RonozymeP, respectively, but not for the 0.034% value determined for Natuphos. The effect of dietary phytase on GE digestibility was inconsistent with a linear (P < 0.01) improvement in GE digestibility noted for OptiPhos (Exp. 2 and 5) and RonozymeP (Exp. 4), but the quadratic (P < 0.01) improvement for Natuphos. There was no effect of dietary phytase on plasma inorganic P. The data presented show clear improvements in P digestibility, with the estimated level of inorganic P release being dependent on phytase source and level.

Brewer's yeast efficiently degrades phytate phosphorus in a corn-soybean meal diet during soaking treatment

Microbes such as yeast and Aspergillus are known to produce phytase, and Aspergillus phytase has been used as a feed additive for improving phytate-phosphorus bioavailability in monogastric animals. We measured phytase activity in some by-products from fermented food and beverage productions by yeast and Aspergillus. The phytase activity was as high as 3577 and 2225 PU/kg DM in raw and dried brewer's yeasts, respectively. On the other hand, the phytase activity was approximately 400 PU/kg DM in white-wine yeast and red-wine yeast. The phytase activity was further low in natto (fermented soybean) residue, soy sauce cake, rice brewer's grain and the activity was not detected in dried corn-barley distiller's grain with soluble and sweet-potato distiller's residue. The stability of phytase against pepsin was much lower in the brewer's yeast than in an Aspergillus phytase preparation. On the other hand, the addition of raw brewer's yeast effectively degraded phytate phosphorus in a corn-soybean meal diet during soaking. These results suggest that phytase in the examined by-products is not suitable for the phytase source of conventional diets, but that the soaking treatment with a raw brewer's yeast is an alternative method for improving phytate-phosphorus bioavailability in corn-soybean meal diets for pigs.

Nutrient utilization and manure P excretion in growing pigs fed corn-barley-soybean based diets supplemented with microbial phytase

The effect of high levels of microbial phytase supplementation in diets for growing pigs was studied in a 2-week performance and nutrient digestibility trial involving 28 growing pigs weighing 16.4 +/- 1.06 (mean +/- SD) kg. Seven corn-barley-soybean meal-based diets consisting of a positive control (PC) formulated to meet or exceed NRC nutrient requirements; a negative control (NC) with non-phytate P reduced by 0.1% unit from NRC requirement and fed without or with 500 or 1000 U/kg; a doubled negative control (DNC) with no added inorganic P and fed without or with 2000 or 4000 U/kg. Chromic oxide was added as an indigestible marker and all diets were fed as mash. Pigs fed the PC diet had a higher P digestibility compared with those fed the NC (P < 0.02) and the DNC (P < 0.001) diets. Supplementing the NC diet with pyhtase tended to improve P digestibility (P < 0.10). However, addition of phytase to the DNC diet resulted in linear (P < 0.001) and quadratic (P < 0.03) increases in P digestibility with an overall improvement of 8% and 121% at 4000 phytase U/kg of diet, respectively, compared with the PC and DNC diets. Apparent total tract digestibility of N, OM and DM were higher (P < 0.05) in the PC diet compared with the DNC diet, but not the NC diet (P < 0.10). No effect of phytase addition to NC was observed on Ca, N, DM and OM digestibility. Phytase addition to the DNC diet resulted in a linear increase (P < 0.05) in N, DM and OM digestibility but not Ca. Increasing the levels of phytase supplementation in the NC and the DNC diets linearly decreased fecal P (P < 0.05) content by 45 and 42%, respectively. Adding phytase at 1000 or 4000 U/kg increased P retention (P < 0.05) by 14.3 or 15.6% units, respectively, compared with the PC diet. Urinary P excretion was higher in the group fed the PC diet compared with those fed the NC and DNC diets (P < 0.05). The results of this study show that complete removal of inorganic P from growing pig diets coupled with phytase supplementation improves digestibility and retention of P and N, thus reducing manure P excretion without any negative effect on pig performance.

Effect of low-phytate barley or phytase supplementation to a barley-soybean meal diet on phosphorus retention and excretion by grower pigs

Two studies were conducted to determine the effect of diets containing low-phytate barley or supplemented with phytase on P balance and excretion in grower pigs. In Exp. 1, eight 32-kg barrows were assigned to a repeated, 4 x 4 Latin square design and fed 4 diets that contained 96% barley: normal-phytate hulled barley (HB), low-phytate hulled barley (LPHB), normal-phytate hull-less barley (HLB), and low-phytate hull-less barley (LPHLB). The barley cultivars contained 0.16, 0.05, 0.24, and 0.03% phytate, respectively. Inorganic P (iP) was added to the HB and HLB diets to meet the 1998 National Research Council recommendation of available P (aP, 0.23%), whereas LPHB and LPHLB contained sufficient aP. The diets were fed at 2.5 times the maintenance requirement for ME. The apparent total tract digestibilities (ATTD) of P did not differ between the hulled and hull-less barley diets, but P retention (%) and excretion were greater in pigs fed the hull-less barley diets (P < 0.05). The ATTD of P was greater and P excretion was 35% lower in pigs fed the low-phytate compared with the normal-phytate diets (P < 0.001). The amount of P retained (g/d) was greater (P < 0.001) in pigs fed low-phytate barley, reflecting an ATTD of P of 65 and 49% for low-phytate and normal-phytate barley, respectively (P < 0.001). In Exp. 2, eight 21-kg barrows were assigned to a repeated, 4 x 4 Latin square design and fed 4 diets based on barley and soybean meal (SBM): HB-SBM, HB-SBM + iP, HB-SBM + phytase, and LPHB-SBM. The HB-SBM and HB-SBM + phytase diets were deficient in aP, whereas the HB-SBM + iP and LPHB-SBM diets had adequate aP. The feeding regimen was similar to that of Exp. 1. Adding iP to the HB-SBM diet did not affect the ATTD but increased the amount of P retained (g/d) and excreted (P < 0.001). The ATTD and amount of P retained (g/d) did not differ among pigs fed the HB-SBM + iP, HB-SBM + phytase, and LPHB-SBM diets. However, pigs fed the HB-SBM + phytase and LPHB-SBM diets excreted 32 and 29% less P, respectively, than pigs fed the HB-SBM + iP diet (P < 0.05), confirming that low-phytate barley is as effective as supplemental phytase in improving P digestibility and utilization and decreasing P excretion in grower pigs.

Virginiamycin improves phosphorus digestibility and utilization by growing-finishing pigs fed a phosphorus-deficient, corn-soybean meal diet1,2

Evaluations of the nutritional effect of antibiotics have largely centered on effects related to the digestibility and utilization of protein and energy. The current study evaluated the potential effect of virginiamycin (VIR) on P digestibility in swine. A total of 70 barrows (mean initial BW = 51 to 64 kg) were used in 4 nutrient-balance experiments. A basal, corn-soybean meal diet that was not supplemented with any inorganic source of P was used in each experiment. In Exp. 1, two diets were tested: basal vs. basal plus 11 mg/kg of VIR. In Exp. 2, four diets were used with a 2 x 2 factorial arrangement of 0 and 11 mg/kg of VIR and 0 and 750 phytase (PHY) units/kg of diet (PU/kg). Experiments 3 and 4 were the same as Exp. 2, except PHY was reduced to 300 PU/kg. For all experiments, VIR improved P digestibility (32.71 to 37.72%, P < 0.001) and Ca digestibility (54.99 to 58.30%, P = 0.002). The addition of PHY improved both P and Ca digestibility (P < 0.001); 750 PU/kg increased P digestibility 27.3% (from 34.6 to 61.9%, P < 0.001), whereas 300 PU increased it 13.8% (from 33.4 to 47.2%, P < 0.001). In an experiment conducted to evaluate the long-term effects of VIR on gut microbial profile, pigs (24 gilts and 8 barrows; mean BW = 29.1 +/- 0.50 kg) were fed a simple corn-soybean meal diet for 16 wk with a 2 x 2 factorial arrangement of VIR (0 and 11 mg/kg) addition and 0.15% dicalcium phosphate deletion. The long-term feeding of VIR in both the control diet and the diet with a marginally reduced P level resulted in a change in ileal microbial profile. A positive numerical increment in the number of phytate-utilizing bacteria was observed in both the normal and P-deleted diets (log unit increments of 12.4 and 17.2% over the respective controls, P = 0.13) when VIR was added. The addition of VIR also tended to affect lactobacilli populations (main effect, P = 0.11; interaction, P = 0.02); VIR decreased lactobacilli in the normal-P diet but did not affect this bacterial population in the P-deleted diet. In conclusion, the antibiotic VIR improves both Ca and P digestibility in pigs. The increase in digestibility is not as great as that provided by PHY, but because the potential mechanism of action (altered microbial populations) differs from that of PHY (direct addition of an enzyme), there can be a degree of additivity in P digestibility improvement when both products are used.

Corn expressing an Escherichia coli-derived phytase gene: a proof-of-concept nutritional study in pigs

Two experiments were conducted to investigate the concept that the addition of corn expressing an Escherichia coli-derived gene (corn-based phytase; CBP) to a P-deficient diet would improve growth performance and P utilization in pigs. An E. coli-derived microbial phytase (expressed in Pichia pastoris) sprayed onto a wheat carrier (Quantum) was included for comparison. In Exp. 1, forty-eight 10-kg pigs were blocked by BW into 6 blocks and allotted to 8 dietary treatments such that the BW among dietary treatments was similar and given free access to feed for 28 d. The dietary treatments were a negative control (NC) with no inorganic P supplementation; NC + 2, 4, or 6 g of monosodium phosphate/kg; NC + 16,500, 33,000, or 49,500 phytase units (FTU) of CBP/kg; and NC + 16,500 FTU of Quantum/kg. In Exp. 2, twenty-four 13-kg barrows were assigned to the NC, NC + 16,500 or 33,000 FTU of CBP/kg, or NC + 16,500 FTU of Quantum/kg, in a nutrient- and energy-balance study consisting of 5 d of adjustment and 5-d collection periods. The total collection method was used to determine nutrient and energy balance. Addition of CBP to the low-P NC diet linearly increased (P < 0.01) ADG, G:F, and plasma P concentration of pigs during the 28-d study. There was no difference in ADG, G:F, or plasma P concentration between pigs fed the CBP or Quantum phytase at 16,500 FTU/kg. Weight gain, G:F, and plasma P concentration of pigs increased (P < 0.01) with monosodium phosphate supplementation, confirming P deficiency of the NC diet. Linear improvements (P < 0.05) in DM digestibility and energy retention were observed with CBP supplementation of the NC diet. Although there were linear (P < 0.01) and quadratic (P < 0.05) increases in N digestibility, N retention was unaffected by CBP supplementation of the NC diet in growing pigs. Phosphorus and Ca digestibilities and retentions improved linearly and quadratically (P < 0.01) with the addition of CBP to the NC diet. There was no difference in digestive utilization of P or Ca between pigs fed CBP and Quantum phytase at 16,500 FTU/kg. The data showed that the addition of a corn expressing an E. coli-derived gene to a P-deficient diet improved growth performance and indices of P utilization in pigs, and corn expressing phytase was as efficacious as Quantum phytase when supplemented in P-deficient diets for weanling pigs.

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

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

Shifting the pH profile of Aspergillus niger PhyA phytase to match the stomach pH enhances its effectiveness as an animal feed additive

Environmental pollution by phosphorus from animal waste is a major problem in agriculture because simple-stomached animals, such as swine, poultry, and fish, cannot digest phosphorus (as phytate) present in plant feeds. To alleviate this problem, a phytase from Aspergillus niger PhyA is widely used as a feed additive to hydrolyze phytate-phosphorus. However, it has the lowest relative activity at the pH of the stomach (3.5), where the hydrolysis occurs. Our objective was to shift the pH optima of PhyA to match the stomach condition by substituting amino acids in the substrate-binding site with different charges and polarities. Based on the crystal structure of PhyA, we prepared 21 single or multiple mutants at Q50, K91, K94, E228, D262, K300, and K301 and expressed them in Pichia pastoris yeast. The wild-type (WT) PhyA showed the unique bihump, two-pH-optima profile, whereas 17 mutants lost one pH optimum or shifted the pH optimum from pH 5.5 to the more acidic side. The mutant E228K exhibited the best overall changes, with a shift of pH optimum to 3.8 and 266% greater (P < 0.05) hydrolysis of soy phytate at pH 3.5 than the WT enzyme. The improved efficacy of the enzyme was confirmed in an animal feed trial and was characterized by biochemical analysis of the purified mutant enzymes. In conclusion, it is feasible to improve the function of PhyA phytase under stomach pH conditions by rational protein engineering.

Effect of phytase supplementation to a low- and a high-phytate diet for growing pigs on the digestibilities of crude protein, amino acids, and energy1,2,3

Supplementation of microbial phytase usually improves the digestibility and utilization of phosphorus in feedstuffs of plant origin. The effect of phytase supplementation on the digestibilities of AA also has been examined, but the results have been inconsistent. This study was carried out to determine the effect of phytase (Natuphos) supplementation, at a rate of 2,000 phytase units/kg, to two basal diets on the apparent ileal digestibilities (AID) of GE, CP, and AA, and on the apparent total-tract digestibilities (ATTD) of CP and GE. The basal diets contained 18% CP and were formulated (as-fed basis) to contain either a low (0.22%) or high content (0.48%) of phytate P. The high-phytate diet contained 20% rice bran, which is a rich source of phytate and has low intrinsic phytase activity. Eight barrows (average initial BW = 40.6 kg), fitted with a simple T-cannula at the distal ileum, were fed the four diets according to a replicated 4 x 4 Latin square design. The pigs were fed twice daily at 0800 and 2000, equal amounts each meal, at a rate of 2.4 times the daily maintenance requirement for ME. Each experimental period comprised 14 d. Ileal digesta were collected from 0800 to 2000 on d 12, 13, and 14. Feces were collected from 0800 on d 8 until 0800 on d 12. Chromic oxide was used as the digestibility marker. The AID of GE, CP, and AA and the ATTD of CP and GE were less in the high- than in the low-phytate diet (P < 0.01). With the exception of glutamic acid, phytase supplementation did not affect (P > 0.10) the AID of CP and AA. There was no effect (P > 0.05) of phytase on the ATTD of CP and GE. These results show that if a response occurs to phytase supplementation, it is independent of the dietary phytate content.

Escherichia coli phytase improves growth performance of starter, grower, and finisher pigs fed phosphorus-deficient diets1

Corn-soybean meal-based diets, consisting of a high-P control (HPC) containing supplemental dicalcium phosphate (DCP), a basal diet containing no DCP, and the basal diet plus Escherichia coli phytase at 500 or 1,000 phytase units per kilogram (FTU/kg; as-fed basis) were fed to evaluate growth performance in starter, grower, and finisher pigs. Pigs were blocked by weight and gender, such that average weight across treatments was similar, with equal numbers of barrows and gilts receiving each treatment in each block. In Exp. 1, 48 pigs with an average initial BW of 11 kg, housed individually, with 12 pens per diet, were used to evaluate growth performance over 3 wk. Overall ADG and G:F were increased linearly (P < 0.05) by dietary phytase addition. Final BW and plasma P concentrations at 3 wk also increased linearly (P < 0.05). In Exp. 2, 128 pigs with an average initial BW of 23 kg, housed four pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase in response to phytase was noted for ADG and G:F in all three 2-wk periods, as well as overall (P < 0.05). Percentage of bone ash also showed a linear increase (P < 0.01). In Exp. 3, 160 pigs (53 kg), housed five pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase was detected for final BW, as well as ADG and G:F in the first and second 2-wk periods, and overall (P < 0.01). Twenty-four 15-kg individually housed pigs were used to evaluate total-tract nutrient digestibility in Exp. 4. Daily absorption of P linearly increased (P < 0.05) with phytase supplementation. Results of this research indicate that E. coli phytase is effective in liberating phytate P for uptake and utilization by starter, grower, and finisher pigs.

Influence of phytase added to a vegetarian diet on bone metabolism in pregnant and lactating sows

The purpose of the study was to find out if the supplementation of phytase to a diet of gestating and lactating sows has any effects on performance and bone parameters of the animals. Forty primiparous gilts were assigned into four groups: group A with phytase [4.2 g total phosphorus (P)/kg (gestation) and 4.5 g total P/kg (lactation)], group B without phytase (with phytase supplementation in diet for rearing) and same P content as group A, group C without phytase and higher P contents [5.0 g total P/kg (gestation) and 5.5 g total P/kg (lactation)] and group D with the same diet as group B (no phytase during the rearing). A 6-phytase was used in this trial (750 FTU/kg diet). The four diets were fed during gestation and lactation. Faeces were collected to determine apparent digestibility of minerals. Blood samples were taken to analyse minerals and bone markers. After weaning the sows were slaughtered and the bones of one hind leg were prepared to measure bone mineral density (BMD) and bone mineral content (BMC) of the tibia. Bone ash and mineral content of the phalanx III were determined. Mean P concentrations in serum decreased during gestation and lactation. But there were no significant differences between the groups. Bone formation marker bone-specific alkaline phosphatase decreased at the beginning of lactation whereas bone resorption marker serum crosslaps increased. The BMD and BMC of the tibia were slightly higher in the groups fed higher concentrations of P and phytase. The ash and mineral contents of the phalanx were the highest for the group fed the highest concentration of P. The apparent digestibility of P increased during gestation mostly in group A (57%--> 69%). In conclusion, high P content and addition of phytase to the diet induced a slightly higher ash content of the bones. It is of high importance, that sows during gestation absorb enough P, to avoid lamenesses and sudden fractures. As not many studies with phytase have been performed during gestation and lactation in sows yet, we can recommend, that phytase as supplement can be used to keep P in the diet at a lower level without negative consequences for bone health.

Effect of phytase supplementation to diets for weanling pigs on the digestibilities of crude protein, amino acids, and energy1,2,3

Four experiments were conducted with weanling pigs fitted with a simple T-cannula at the distal ileum, to determine the effect of phytase supplementation to four diets on the apparent ileal digestibilities (AID) of CP and AA, and the apparent total-tract digestibilities (ATTD) of CP and DE. Phytase (Natuphos, DSM Food Specialties, Delft, The Netherlands) was supplemented at rates of 0, 500 or 1,000 FTU/kg to the four diets. A 20% CP (as-fed basis) corn-soybean meal diet was used in Exp. 1; a 20% CP wheat-soybean meal diet in Exp. 2; a 20% CP wheat-soybean meal-canola meal diet in Exp. 3; and a 19% CP barley-peas-canola meal diet in Exp. 4. In each experiment, six barrows, fitted with a simple T-cannula at the distal ileum, were fed the basal plus phytase-supplemented diets according to a repeated 3 x 3 Latin square design. Each experimental period comprised 14 d. The piglets were at fed 0800 and 2000 daily, equal amounts for each meal, at a daily rate of at least 2.4 times the maintenance requirement for ME. Feces were collected from 0800 on d 8 until 0800 on d 12 of each experimental period. Ileal digesta were collected from 0800 to 2000 on d 12, 13, and 14. Chromic oxide was used as the digestibility marker. The average initial and final BW (average of all experiments) were 7.9 and 16.5 kg, respectively. Phytase supplementation did not improve the AID of CP and AA in Exp. 1, 2, and 4; however, there were improvements (P < 0.05) or tendencies (P < 0.10) toward improvements in the AID of CP and AA or the ATTD of CP and the content of DE with phytase supplementation in Exp. 3. These results suggest that the AA response factor to microbial phytase supplementation depends on diet composition.

Dietary supplementation with multienzyme preparations improves nutrient utilization and growth performance in weaned pigs

Two experiments with young pigs (25 d of age) were conducted to investigate the effect of multienzyme preparations on nutrient digestibility, growth performance, and P utilization and excretion. In Exp. 1, 24 pigs (six pigs per treatment) were used in a 28-d performance and digestibility trial using four diets: control (no enzyme) and control supplemented with enzyme preparation A, B, or C. The control diet was formulated to meet 95% of NRC (1998) nutrient specifications (except for available P, which was at 44% NRC) and composed of corn, wheat, wheat by-products, barley, soybean meal, canola meal, and peas. All three enzyme preparations contained xylanase, glucanase, amylase, protease, invertase, and phytase activities and differed in the type of plant cell wall-degrading activities; Enzyme A contained cellulase, galactanase, and mannanase; Enzyme B contained cellulase and pectinase; and Enzyme C contained cellulase, galactanase, mannanase, and pectinase. Pigs fed enzyme-supplemented diets had higher ADG (P = 0.02) and G:F (P = 0.01) than those fed the control diet. On average, and when compared with control diet, enzyme supplementation improved (P = 0.001 to 0.04) ileal digestibility of DM (60 vs. 66%), GE (62.8 vs. 70.4%), CP (62 vs. 72%), starch (86.7 vs. 94.2%), nonstarch polysaccharides (NSP; 10.1 vs. 17.6%), and phytate (59 vs. 70%). Compared with the control, total-tract digestibility of nutrients was increased (P = 0.001 to 0.01) owing to enzyme supplementation, with Enzyme C showing the highest improvement in DM, GE, CP, starch, NSP, phytate, and P utilization. Pigs fed enzyme-supplemented diets had decreased (P = 0.04) fecal P excretion. The benefit from improved nutrient utilization with enzyme supplementation was further substantiated in a 38-d growth performance study with 48 pigs. The control and Enzyme C-supplemented diets (same as Exp. 1) were assigned to six replicate pens (four pigs per pen). The study was conducted in three phases (Phase 1 = d 0 to 7; Phase 2 = d 7 to 21; Phase 3 = d 21 to 38). Individual BW and pen feed disappearance were monitored. Average daily gain and G:F were 231 and 257 g (P = 0.01), and 0.56 and 0.63 (P = 0.001) for the control and enzyme-supplemented diets, respectively. It is evident from this study that the use of enzyme preparations may allow for cost-effective and environmentally friendly formulation of young pig diets.

The efficacy of an Escherichia coli-derived phytase preparation1

Five experiments were conducted to evaluate the effect of an Escherichia coli-derived phytase on phytate-P use and growth performance by young pigs. The first experiment involved time course, pH dependence, and phytase activity studies to investigate the in vitro release of P from corn, soybean meal, and an inorganic P-unsupplemented corn-soybean meal negative control diet. In Exp. 2, which was designed to determine the efficacy of the E. coli-derived vs. fungal phytase-added diets at 0, 250, 500, 750, 1,000, or 1,250 FTU/kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 micromol of inorganic P/min, at pH 5.5, from an excess of 15 microM sodium phytate at 37 approximately C) and a positive control diet, eight individually penned 10-kg pigs per diet (12 diets, 96 pigs) were used in a 28-d growth study. The third experiment was a 10-d nutrient balance study involving six 13-kg pigs per diet (four diets, 24 pigs) in individual metabolism crates. In Exp. 4, eight pens (four pigs per pen) of 19-kg pigs per treatment were used in a 42-d growth performance study to examine the effect of adding the E. coli-derived phytase to corn-soybean diets at 0, 500, or 1,000 FTU/kg (as-fed basis) and a positive control (four diets, 128 pigs). In Exp. 5, six 19-kg pigs per treatment were used in a 10-d nutrient balance study to investigate the effects of the E. coli-derived phytase added to diets at 0, 250, 500, 750, or 1,000 FTU/kg (as-fed basis) and a positive control diet (six diets, 36 pigs). The in vitro study showed that the E. coli-derived phytase has an optimal activity and pH range of 2 to 4.5. Inorganic phosphate release was greatest for soybean meal, least for corn, and intermediate for the negative control diet. Dietary supplementation with graded amounts of E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain, feed efficiency, and plasma Ca and P concentrations in 10-kg pigs in Exp. 2. Phytase also increased P digestibility and retention in the 13-kg pigs in Exp. 3. In Exp. 4, dietary supplementation with E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain and feed efficiency of 19-kg pigs. Supplementation of the diets of 19-kg pigs with the E. coli-derived phytase also improved Ca and P digestibility and retention in Exp. 5. In the current study, the new E. coli-derived phytase was efficacious in hydrolyzing phytate-P, both in vitro and in vivo, in young pigs.

Effect of phytase addition and dietary calcium and phosphorus levels on plasma metabolites and ileal and total-tract nutrient digestibility in pigs

Two experiments were conducted to determine the effect of phytase on plasma metabolites and AA and energy digestibility in swine. In Exp. 1, eight barrows (surgery BW = 52 kg) were fitted with steered ileocecal cannulas. The experiment was a Latin rectangle and the treatments were 1) corn-soybean meal diet adequate in Ca and P (0.5% Ca, 0.19% available P [aP]), 2) corn-soybean meal diet with reduced Ca and P (0.4% Ca, 0.09% aP), 3) Diet 1 with 500 phytase units/kg, or 4) Diet 2 with 500 phytase units/kg. Pigs were fed twice daily to a total daily energy intake of 2.6 x maintenance (106 kcal of ME/kg of BW(0.75)). For each ileal digesta sample, digesta samples were collected for two 24-h periods and combined for each pig. The combination of supplementing with phytase and decreasing the concentration of dietary Ca and P increased average ileal AA (P < 0.02), starch (P < 0.02), GE (P < 0.04), and DM (P < 0.03) digestibilities. In Exp. 2, a feeding challenge was conducted with barrows (eight per treatment; average BW of 53 kg). The treatments consisted of a corn-soybean meal diet or corn-soybean meal diet + 500 phytase units per kilogram of diet. In the diet with no phytase, Ca and aP were at 0.50% and 0.19%, respectively, and, in the diet with phytase, Ca and aP were each decreased by 0.12%. A catheter was surgically inserted into the anterior vena cava of each pig 6 d before the start of the feeding challenge. The barrows were penned individually, and the diets were fed for 3 d before the challenge. The pigs were held without feed for 16 h, and blood samples were obtained at -60, -30, and 0 min before the pigs were fed (2% of BW). Blood samples were then collected at 10, 20, 30, 40, 50, 60, 75, 90, 105, 120, 150, 180, 210, 240, 270, and 300 min after feeding. Glucose area under the response curve and plasma glucose, insulin, urea N, and total alpha-amino N concentrations were increased (P < 0.05) in pigs fed the diet with reduced Ca and P and the phytase addition. Area under the response curve for insulin, urea N, and total alpha-amino N; insulin:glucose; and plasma NEFA concentration, clearance, and half-life were not affected by diet. In conclusion, the combination of Ca and P reduction and phytase addition increased nutrient and energy digestibility in diets for pigs and increased plasma concentrations of glucose, insulin, urea N, and alpha-amino N.

Modeling of Parameters Affecting Phytate Phosphorus Bioavailability in Growing Birds

The current study was undertaken to establish a population from an unselected random-mating chicken population for the development of a model to predict factors that affect phytate P utilization in growing birds. A population was established from a mating of 40 male and 200 female chickens from the Athens Canadian randombred population. At 4 wk of age, birds were housed in individual metabolic cages and fed a diet containing 1.06% Ca, 0.35% total P, and 0.03% available P. After 3 d of acclimatization, feed consumption (FC) was measured and excreta produced in 3 consecutive d were collected. Individual 4-wk BW, BW gain (BWG), phytate P intake (PPI), inorganic P intake (IPI), Ca intake (CaI), N intake (NI), and energy intake (EI) during the 3 d excreta collection period were also measured. Feed conversion ratios (FCR) and relative growth rate were calculated. Phytate P bioavailability (PPB), Ca bioavailability (CaB), and N bioavailability (NB) were estimated from the disappearance of the nutrients during the passage of feed through the gastrointestinal tract. Energy bioavailability (EB) was measured by bomb calorimetry as the difference in the gross energy of the feed and the energy of the excreta. The major factors affecting PPB were CaB and EB for both sexes. In the males, BW contributed significantly to PPB. However, in the females, NB also contributed significantly to PPB. Faster growing birds tended to have a reduced retention time of feed compared with slow growing birds, and as a result utilized phytate P less. Birds that are able to utilize phytate P better are putatively able to release P for energy utilization. Therefore, the birds that were able to utilize phytate P better were also better energy utilizers.

the effect of the combination of microbial phytase and amino acid supplementation of diets for finishing pigs on p and n excretion and carcass quality

The objective of this study was to evaluate the effect of a combined low-protein, low-phosphorus diet supplemented with limiting amino acids and microbial phytase on performance, nutrient utilization and carcass characteristics of late-finishing barrows. 4 x 8 crossbreed barrows were continuously housed in metabolism cages from 70-110 kg BW and were fed diets, either conventional (A) or protein reduced (B) or protein and phosphorus reduced diets (C) based on barley, maize and soybean meal. Diet A (positive control) contained in air dry matter 13% and 10% CP as well as 0.49% and 0.42% P at growth phases I (70-100 kg BW) or 11 (100-110 kg BW), respectively. Diet B was low in CP (11.3%, 8.4%), diet C low in CP and low in P (CP: as B, P: 0.36%, 0.30%). To diet B the limiting amino acids lysine, methionine, threonine and trypthophan were added to meet the levels in diet A. To diet C the limiting amino acids and 800 FTU/kg Aspergillus-phytase were supplemented. At the end of the balance periods the barrows were slaughtered, the carcasses scored and loin chops, ham and Phalanx prima IV were analysed for nutrients and minerals. The CP or P reduction in diets B and C did not generally negatively affect growth, feed efficiency, absolute nitrogen retention or overall carcass performances of the pigs. With the low CP diets B and C, N excretion per unit BWG was decreased by about 23%. The addition of microbial phytase (diet C) increased apparent total tract digestibility of P by about 20%. In spite of 30% reduction of P intake (diet C), the absolute P retention related to 1 kg BW did not differ between treatments. Thus, phytase supplementation in diet C reduced P excretion per unit BWG by about 33%. Phytase raised apparent digestibility of Zn by about 20% but not Ca digestibility. Generally the carcass traits and meat characteristics were not affected by any of the diet strategies. Mineralization of the Phalanx prima IV was also similar in all treatment groups. However, phytase supplementation led to significantly increased zinc concentration in bones (25%). In contrast, Fe incorporation into the Phalanx prima IV was not affected. In general, the feeding regimen introduced in this experiment offers substantial benefits in maintaining a sustainable environmental-friendly pork production even at the stage of late-finishing barrows.