Effect of an Escherichia coli-derived phytase and a carbohydrase-protease cocktail derived from Bacillus spp. on performance, digestibility, bone mineralization and gut morphology in broilers fed different nutrient density diets.

BACKGROUND: Enzyme combinations, particularly phytase (PHY) with various carbohydrases and proteases, are utilized in commercial broiler production to enhance nutrient and energy bioavailability. OBJECTIVE: A feeding study was undertaken to determine whether the efficiency of an Escherichia coli-derived PHY and a feed enzyme complex (FEC) derived from Bacillus spp. containing carbohydrase and protease as main activities in broiler chickens is dependent on diet quality. A total of 900 male one-day-old broiler chickens (Ross 308) were assigned to a 2 × 3 factorial arrangement of the treatments with 2 different nutrient density diets, standard nutrient diet (SN diet) and a low-nutrient diet (LN diet; -100 kcal/kg for AMEn and -5% for crude protein [CP] and limiting amino acids), and 3 enzyme treatments (control [no enzymes], PHY and PHY + FEC). Each treatment group was composed of 6 replicates of 25 birds each. RESULTS: The LN diet caused a decrease in performance index, tibia length and diameter, tibia calcium content and jejunal villus surface area (VSA). The interaction effects between diet and enzyme supplementation were observed (p < 0.05) on overall average daily gain (ADG), performance index, tibia ash content and jejunal villus height (VH) and VSA, with the favourable benefits of PHY + FEC treatment being more pronounced in the LN diets. Regardless of dietary nutrient density, supplementation with PHY alone or combined with FEC enhanced (p < 0.05) final body weight, overall ADG and jejunal villus height (VH)/crypt depth, with the highest values observed in the PHY + FEC group. The PHY + FEC treatment also improved (p < 0.05) overall feed conversion ratio, apparent ileal digestibility of dry matter, organic matter, CP, and energy, and tibia phosphorus content compared to the control treatment. CONCLUSIONS: The results indicate that the simultaneous addition of PHY and FEC to the LN diets improved the growth rate, bone mineralization and gut morphology.

The effect of bone and analytical methods on the assessment of bone mineralization response to dietary phosphorus, phytase, and vitamin D in nursery pigs.

A total of 360 pigs (DNA 600 × 241, DNA; initially 11.9 ±â€…0.56 kg) were used in a 28-d trial to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to dietary P, vitamin D, and phytase in nursery pigs. Pens of pigs (six pigs per pen) were randomized to six dietary treatments in a randomized complete block design with 10 pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: (1) 0.19% standardized total tract digestibility (STTD) P (deficient), (2) 0.33% STTD P (NRC [2012] requirement) using monocalcium phosphate, (3) 0.33% STTD P including 0.14% release from phytase (Ronozyme HiPhos 2700, DSM Nutritional Products, Parsippany, NJ), (4) 0.44% STTD P using monocalcium phosphate, phytase, and no vitamin D, (5) diet 4 with vitamin D (1,653 IU/kg), and (6) diet 5 with an additional 50 µg/kg of 25(OH)D3 (HyD, DSM Nutritional Products, Parsippany, NJ) estimated to provide an additional 2,000 IU/kg of vitamin D3. After 28 d on feed, eight pigs per treatment were euthanized for bone (metacarpal, 2nd rib, 10th rib, and fibula), blood, and urine analysis. The response to treatment for bone density and ash was dependent upon the bone analyzed (treatment × bone interaction for bone density, P = 0.044; non-defatted bone ash, P = 0.060; defatted bone ash, P = 0.068). Thus, the response related to dietary treatment differed depending on which bone (metacarpal, fibula, 2nd rib, or 10th rib) was measured. Pigs fed 0.19% STTD P had decreased (P < 0.05) bone density and ash (non-defatted and defatted) for all bones compared to 0.44% STTD P, with 0.33% STTD P generally intermediate or similar to 0.44% STTD P. Pigs fed 0.44% STTD P with no vitamin D had greater (P < 0.05) non-defatted fibula ash compared to all treatments other than 0.44% STTD P with added 25(OH)D3. Pigs fed diets with 0.44% STTD P had greater (P < 0.05) defatted second rib ash compared to pigs fed 0.19% STTD P or 0.33% STTD P with no phytase. In summary, bone density and ash responses varied depending on bone analyzed. Differences in bone density and ash in response to P and vitamin D were most apparent with fibulas and second ribs. There were apparent differences in the bone ash percentage between defatted and non-defatted bone. However, differences between the treatments remain consistent regardless of the analytic procedure. For histopathology, 10th ribs were more sensitive than 2nd ribs or fibulas for the detection of lesions.

Lameness is defined as impaired movement or deviation from normal gait. There are many factors that can contribute to lameness, including but not limited to: infectious disease, genetic and conformational anomaly, and toxicity that affects the bone, muscle, and nervous systems. Metabolic bone disease is another cause of lameness in swine production and can be caused by inappropriate levels of essential vitamins or minerals. To understand and evaluate bone mineralization, it is important to understand the differences in diagnostic results between different bones and analytical techniques. Historically, percentage bone ash has been used as one of the procedures to assess metabolic bone disease as it measures the level of bone mineralization; however, procedures and results vary depending on the methodology and type of bone measured. Differences in bone density and ash in response to dietary P and vitamin D were most apparent in the fibulas and second ribs. There were apparent differences in the percentage of bone ash between defatted and non-defatted bone; however, the differences between the treatments remain consistent regardless of the analytic procedure. For histopathology, 10th ribs were more sensitive than 2nd ribs or fibulas for detection of lesions associated with metabolic bone disease.

Evaluation of a novel phytase derived from Citrobacter braakii and expressed in Aspergillis oryzae on growth performance and bone mineralization indicators in nursery pigs.

A total of 297 pigs (DNA 241 × 600; initially 8.64 ±â€…0.181 kg) were used in a 21-d trial to determine the efficacy of a novel phytase derived from Citrobacter braakii and expressed in Aspergillis oryzae (HiPhorius; DSM Nutritional Products, Animal Nutrition & Health, Parsippany, NJ) on pig growth and bone mineralization indicators. Pens of pigs were assigned to 1 of 5 dietary treatments in a randomized complete block design with 5 pigs per pen and 12 pens per treatment. The trial was initiated 14-d after weaning. The first three treatments were formulated to contain 0.09% aP; without added phytase (control), or the control diet with 600 or 1,000 FYT/kg of added phytase (considering a release of 0.15% or 0.18% aP, respectively). The remaining two treatments were formulated to contain 0.27% aP, one without added phytase and the other with 1,000 FYT/kg. From days 0 to 21, pigs fed increasing phytase in diets containing 0.09% aP had increased (linear, P ≤ 0.002) ADG, ADFI, and G:F, but added phytase in the 0.27% aP diet did not impact growth performance. Increasing phytase in diets containing 0.09% aP increased percentage bone ash in metacarpals and 10th ribs (linear, P < 0.001; quadratic, P = 0.004, respectively), and increased grams of Ca and P in metacarpals, 10th ribs, and fibulas (linear, P ≤ 0.027). Adding 1,000 FYT/kg phytase in diets with 0.27% aP increased (P ≤ 0.05) percentage bone ash and grams of Ca and P in fibulas and 10th ribs compared with pigs fed 0.27% aP without added phytase. Increasing aP from 0.09% to 0.27% in diets without added phytase increased (P < 0.001) ADG, ADFI, and G:F. Increasing aP from 0.09% to 0.27% in diets without added phytase increased bone density (P ≤ 0.002) in fibulas and metacarpals, percentage bone ash in all bones (P ≤ 0.074), and increased (P < 0.05) grams of Ca and P in fibulas and 10th ribs. Pigs fed diets containing 0.09 or 0.27% aP, both with 1,000 FYT added phytase, had increased (P < 0.05) bone density in fibulas and metacarpals, percentage bone ash in all bones, and increased grams of Ca and P in fibulas and 10th ribs. For growth performance (average of ADG and G:F), aP release was calculated to be 0.170% for 600 FYT/kg and 0.206% for 1,000 FYT/kg. For the average of all bone measurements (average of 3 bones for both bone density and percentage bone ash), aP release was calculated to be 0.120% and 0.125% for 600 and 1,000 FYT/kg, respectively.

Approximately 60% to 80% of phosphorus (P) in feedstuffs of plant origin is stored in the form of phytic acid. Phytase is an enzyme used in swine diets to improve the digestibility of phytate-bound P. As phytase sources continue to advance, their efficacy must be evaluated. In this study, nursery pigs (9 kg) were used to determine the efficacy of a novel phytase derived from Citrobacter braakii and expressed in Aspergillis oryzae in releasing phytate-bound P. Increasing phytase added to diets deficient in aP improved growth performance and bone mineralization. Adding phytase to a diet already adequate in aP did not affect growth performance, but improved bone mineralization indicators. Available P release attributed to phytase was estimated using growth performance and found to be 0.170% for 600 FYT/kg and 0.206% for 1,000 FYT/kg. For the average of all bone measures, the estimated aP release was 0.120% for 600 FYT/kg and 0.125% for 1,000 FYT/kg. Results of this study indicate an increasing release of phytate-bound P with increasing additions of the novel phytase tested in nursery diets and confirm that additional P is needed for bone development compared to growth.

Effects of Dietary Supplementation of Arginine-Silicate- Inositol and Phytase Complex on Performance and Blood Biochemical Traits of Laying Hens.

Arginine silicate inositol complex (ASI; Arg = 49.47%, silicone = 8.2%, inositol = 25%) is a novel, bioavailable source of Si and Arg and may offer potential benefits for laying hens' performance. The aim of this study was to evaluate the effect of Arginine-Silicate and inositol/phytase on the performance of laying hens. A total of 90 laying hens, 25 weeks old, were randomly assigned to 6 treatments with 3 replicates (5 birds per replicate). The treatments were as follows: 1ST treatment PC: positive Control group (basal diet without additives (, 2nd treatment: basal diet +1000 mg/kg arginine-silicate complex (49.5±8.2 % respectively), 3d treatment: basal diet +1000 mg/kg arginine-silicate- inositol (ASI) complex (49.5, 8.2 , 25 % respectively) , 4th treatment: T 2 +500 FTU/kg , 5th treatment: T2 +1000 FTU/kg and 6th treatment: T2+2000 FTU/kg . Results indicate a significant increase (P<0.05) in hen house production (H.H. pro.%) of T5 (95.06 %)compared with T1(91.67%) and no significant differences between T2, T3, T4, T6 (91.84, 93.21, 93.46, 92.98%) and compared with T1 and T5. were no significant difference observed in average egg weight and egg mass between the experimental treatments all over the period. Daily feed intake (DFI) significantly decreased (P<0.05) with supplementing diets with deferent levels of phytase with arginine-silicate mixture T4, T5, andT6 (113.56،113.06، 112.10 g) compared with T1 (114.34 g ) which has no significant differences compared with T2 and T3 (113.96, 113.92 g). Phytase supplementation significantly (P<0.05) improved FCR g feed/egg in T5 (119.02) compared with T1 and T2 (124.89, 124.32), while no significant differences between T3.T4.T6 treatments (122.39, 121.80, 120.69) respectively and compared with other treatments. The experimental treatments observed no significant difference in g feed/ g egg.

Effects of Dietary Supplementation of arginine-silicate- Inositol and Phytase Complex on Egg Quality, Egg Shell Strength, and Blood Biochemical Characteristics of Laying Hens.

This study aimed to determine the effects of Arginine silicate inositol complex (ASI; Arg=49.47 %, silicone=8.2 %, inositol=25%) supplementation on egg quality, shell strength, and blood biochemical traits of laying hens, as well as the effects of substituting inositol with varying concentrations of phytase on the traits as mentioned above. 90 Lohmann Brown laying hens, 26 weeks old, were randomly distributed in 6 treatments with 3 replicates (cage) and 5 birds per replicate. The isocaloric and isonitrogenic diets are used according to the age period requirements of the Lohmann Brown Classic management guideline. The treatments were as follows: 1ST treatment T1: received basal diet without additives, T2 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2 % respectively), T3 received basal diet +1000 mg/kg arginine-silicate- inositol (ASI) mixture (49.5, 8.2 , 25 % respectively), T4 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2% respectively) +500 FTU/kg, T5 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2% respectively) +1000 FTU/kg and T6 received basal diet +1000 mg/kg arginine-silicate mixture (49.5±8.2% respectively) +1000 FTU/kg +2000 FTU/kg. Results indicate a significant increase (P<0.05) in the relative yolk weight in T4, T5, and T6 (26.93, 26.83, 26.77%) compared to T1 (25.84%) and a significant increase (P≤ 0.05) in T4, T5 compared to T3 (26.02%), while no differences observed between T2 (26.17%) compared to other experimental treatments. The relative albumin weight significantly decreased (P≤0.05) in phytase supplementation treatments T4, T5, and T6 (63.21, 63.05, 63.22%) compared to T1, T2, T3 (64.99, 64.30, 64.08%), while a significant decrease (P≤0.05) observed in T3 compared to T1. The relative shell weight significantly increased (P≤0.05) in T3, T4, T5, and T6 (9.90, 9.86, 10.12, 10.02%), respectively, compared to T1, T2 (9.17, 9.53%) with a significant increase (P≤0.05) in relative shell weight in T2 compared to T1. The eggshell thickness significantly increased (P≤0.05) in T3, T4, T5, T6 treatments (0.409, 0.408, 0.411, 0.413 mm), respectively compared to T1, T2 (0.384, 0.391 mm). A significant increased (P≤0.05) was observed in eggshell thickness in T2 compared to T1. A significant increase (P≤0.05) was observed in the egg shell breaking strength in T3 and T5 treatments (59.40, 58.83) compared to T1 and T2 (46.20, 48.23). No significant differences were observed between T4 and T6 (53.90, 53.57) compared to other experimental treatments. Non HDL, calcium, and phosphorus levels in blood serum significantly increased (P≤0.05) in T3, T4, T5, and T6 treatments compared to T1 and T2 treatments.

Impact of dietary analyzed calcium to phosphorus ratios and standardized total tract digestible phosphorus to net energy ratios on growth performance, bone, and carcass characteristics of pigs.

A total of 2,184 pigs (337 × 1,050, PIC; initially 12.4 ± 0.17 kg) were used in a 143-d study to evaluate the effects of feeding varying analyzed calcium to phosphorus ratios (Ca:P) at two standardized total tract digestible (STTD) phosphorus to net energy ratios (STTD P:NE). Pens of pigs (26 pigs per pen) were assigned to 1 of the 6 dietary treatments in a 2 × 3 factorial with main effects of STTD P:NE and Ca:P ratio. Diets consisted of two levels of STTD P:NE; High (1.80, 1.62, 1.43, 1.25, 1.10, and 0.99 g STTD P/Mcal NE from 11 to 22, 22 to 40, 40 to 58, 58 to 81, 81 to 104, and 104 to 129 kg, respectively); or Low (75% of the High levels), and three analyzed Ca:P ratios (0.90:1, 1.30:1, and 1.75:1). There were 14 pens per treatment. Diets were corn-soybean meal-based and contained a constant phytase concentration within each dietary phase with levels decreasing throughout the trial (phases 1 through 3, 500 FTU/kg, assumed release of 0.13% STTD P; phase 4, 400 FTU/kg, assumed release of 0.11% STTD P; phase 5, 290 FTU/kg, assumed release of 0.09% STTD P; and phase 6, 210 FTU/kg, assumed release of 0.07% STTD P). Overall, there was a Ca:P × STTD P:NE interaction (P < 0.05) observed for average daily gain (ADG), feed efficiency (G:F), final body weight (BW), hot carcass weight (HCW), bone mineral density, bone mineral content, and bone-breaking strength. When feeding Low STTD P:NE levels, increasing the analyzed Ca:P ratio decreased (linear, P < 0.001) ADG final BW, HCW, and tended to worsen G:F, bone mineral density, and bone mineral content (linear, P < 0.10). However, when feeding High STTD P:NE levels, increasing the analyzed Ca:P ratio significantly improved bone mineral content and bone mineral density (linear, P < 0.05), and tended to improve ADG and final BW (linear, P < 0.10) and G:F (quadratic P < 0.10). Additionally, increasing the analyzed Ca:P ratio worsened ADG, G:F, and bone mineralization with Low STTD P:NE but had marginal impacts when adequate STTD P:NE was fed.

Calcium (Ca) and phosphorus (P) are the most abundant minerals in the pig and are involved in lean tissue deposition and synthesis and maintenance of the skeletal structure. Swine diets are typically formulated with low margins of safety for P and excess P in the diet can lead to increased P excretion, which can result in negative environmental effects. To have an adequate utilization of both Ca and P, it is important to consider the Ca:P ratio when formulating pig diets. Research has shown that a wide Ca:P is detrimental to pig growth performance and bone mineralization when diets are low in STTD P. Therefore, the objective of this study was to evaluate the impact of varying Ca:P ratios fed at two levels of STTD P:NE on growth performance, bone, and carcass characteristics of pigs from 12 to 129 kg. When P levels were below requirement estimates, widening the Ca:P ratio from 0.90:1 to 1.75:1 reduced growth performance and bone mineralization; however, widening the Ca:P ratio improved performance and bone mineralization when P levels of the diet were above requirement estimates.

Efficacy of a bacterial 6-phytase supplemented beyond traditional dose levels on jejunal mucosa-associated microbiota, ileal nutrient digestibility, bone parameters, and intestinal health, and growth performance of nursery pigs.

This study aimed to determine the efficacy of a bacterial 6-phytase (Buttiauxella spp.) supplemented beyond traditional dose levels based on jejunal mucosa-associated microbiota, apparent ileal digestibility (AID), intestinal health and bone parameters, and growth performance of nursery pigs. Seventy-two weaned pigs (36 barrows and 36 gilts at 21 d of age with 5.8 ± 0.5 kg BW) were allotted to six treatments based on randomized complete block design with sex and initial BW as blocks and fed in three dietary phases (phase 1 for 14 d, phase 2 for 10 d, and phase 3 for 14 d). The treatments included a negative control (NC) diet without phytase formulated meeting nutrient requirements by NRC and the other five treatments were deficient in calcium (Ca) and phosphorus (P) by 0.12% with increasing levels of a bacterial 6-phytase (0, 500, 1,000, 2,000, and 5,000 FTU/kg feed). Titanium dioxide (0.4%) was added to phase 3 diets as an indigestible marker to measure AID of nutrients. On day 45, all pigs were euthanized to collect ileal digesta to measure AID, the third metacarpus to measure bone parameters, and jejunal mucosa to evaluate intestinal health and microbiota. Data were analyzed using the MIXED procedure for polynomial contrasts and the NLMIXED procedure for broken line analysis using the SAS 9.4. Broken line analysis demonstrated that 948 FTU/kg feed increased (P < 0.05) the ADG and the bone P content. Increasing phytase supplementation increased (linear, P < 0.05) AID of CP, bone P, and ash content. Increasing phytase supplementation reduced (P < 0.05) the fecal score during phases 2 and 3. Broken line analysis demonstrated that 1,889 FTU/kg feed increased (P < 0.05) bone breaking strength. Increasing phytase supplementation (PC vs. Phy) increased (P < 0.05) AID of ether extract (EE) and P. The supplementation of phytase at 2,000 FTU/kg feed tended (P = 0.087) to reduce the relative abundance of Prevotellaceae. In conclusion, the supplementation of a bacterial 6-phytase beyond traditional dose levels improved bone breaking strength, bone ash, and P content, AID of CP, EE, and P, and growth performance of nursery pigs with reduced relative abundance of Bacteroidetes specifically Prevotellaceae in the jejunal mucosa. Supplementation of a bacterial 6-phytase between 1,000 and 2,000 FTU/kg feed provided benefits associated with growth performance and bone parameters of nursery pigs.

After weaning, pigs start to receive solid diets throughout nursery phase with high amounts of plant-based feedstuffs containing various antinutritional and allergenic compounds. Feed enzymes have been used in nursery diets to reduce or remove the negative impacts associated with these compounds. This study used the phytase at normal and beyond traditional doses, which specifically catalyze the hydrolysis of phytic acid and can provide benefits on bone and intestinal health, intestinal microbiota, nutrient digestibility, and growth performance of pigs. The aim of this study was to investigate the efficacy of a bacterial 6-phytase beyond traditional dose levels on intestinal microbiota, nutrient digestibility, bone parameters and intestinal health, and growth performance of nursery pigs. Phytase supplementation improved bone breaking strength and mineralization, apparent ileal digestibility of crude protein, ether extract, and phosphorus, average daily gain, feed intake, and reduced relative abundance of Bacteroidetes specifically Prevotellaceae in the jejunal mucosa.

Effect of phytase and xylanase enzymes on growth performance and Mucin2 gene expression in broiler chickens.

BACKGROUND: Development of exogenous enzymes is one of the most important discoveries in animal nutrition. The supplementation of exogenous enzymes in broiler diets allows for supplying nutrient deficiencies and to decrease endogenous losses. OBJECTIVES: The effects of phytase (Hostazym and Phyzyme) and xylanase (Ronozyme) enzymes were investigated on growth performance and Mucin2 gene expression in broilers. METHODS: A completely randomized design was applied, including 7 treatments, 4 replicates and 25 birds per replicates. A total of 700 male Ross (308) broiler chickens were fed with similar diets supplemented by Hostazym and Phyzyme (500 and 1000 FTU/kg) and Ronozyme (100 and 200 EXU/kg). Weight gain (WG), feed intake (FI) and feed conversion ratio (FCR) were determined for three phases and entire rearing period. On 42 days of age, four birds per replicate were slaughtered. Total RNA was extracted from jejunum samples, and Mucin2 gene expression was measured by real-time PCR. RESULTS: Phytase and xylanase enzymes had a significant effect (p < 0.05) on traits (WG and FCR) in grower and finisher phases and whole rearing period, but FI was not affected by enzymes (p > 0.05). Carcass (74.13 g) and breast (27.76 g) weights by Hostazym (1000 FTU/kg) were higher than other treatments (p < 0.05). Weight of liver, bursa and spleen were significantly influenced by enzymes (p < 0.05). Likewise, bursa and spleen weights in Hostazym (1000 FTU/kg feed) and Ronozyme (200 EXU/kg feed) were significantly higher than other treatments (p < 0.05). Mucin2 gene expression was affected by enzymes in whole treatments. The lowest amount of Mucin2 gene expression belonged to Ronozyme (200 and 100 EXU/kg), and the highest was belonging to Hostazym (1000 FTU/kg). CONCLUSIONS: Phytase enzymes have higher effect on broiler performance and Mucin2 gene expression compared to xylanase. High doses of Hostazym (1000 FTU/kg feed) could be supplemented in broiler chicken diets to improve optimum growth and feed efficiency.

Effect of a biosynthetic bacterial 6-phytase on the digestibility of phosphorus and phytate in midlactating dairy cows.

The effect of a biosynthetic bacterial 6-phytase (PhyG) on the digestibility and excretion of crude protein (CP), phosphorus (P), and phytate-P (PP) in midlactating dairy cows was investigated. Thirty Holstein-Friesians were assigned to three treatments with 10 cows per treatment in a randomized block design. Cows were fed forage (grass and corn silage) provided ad libitum, and a concentrate (without added inorganic phosphate) administered separately in amounts individualized per cow according to milk production, supplemented with phytase according to treatment. The formulated forage-to-concentrate-ratio was ~65%:35%. Dietary treatments comprised the control diet (CON) and CON supplemented with 2,000 (PhyG2,000) or 5,000 (PhyG5,000) phytase units (FTU)/kg DM in the total diet. The experiment comprised an 18-d preperiod for the collection of data to facilitate the allocation of cows to the treatments, followed by a 19-d experimental period comprising a 14-d diet adaptation period and 5 d of twice daily feces collection. Fecal samples were analyzed for the determination of apparent total tract digestibility (ATTD) of chemical constituents in the diet. The ATTD of PP was 92.6% in CON suggesting a high but incomplete degradation of phytate by ruminal microbial phytases. Cows fed PhyG2,000 exhibited increased ATTD of CP and PP [68.4% (2.7% points above CON) and 95.1% (2.5% points above CON), respectively] whilst PhyG5,000 further increased ATTD PP and also increased ATTD P [54.1% (7.8% points above CON)]; ATTD of Ca tended to be increased in PhyG5,000 vs. CON. Linear dose-response relationships were observed for ATTD of DM, CP, P, Ca, and PP. In addition, fecal excretion of P, and PP linearly reduced and that of Ca and CP tended to linearly reduce with increasing PhyG dose level. No difference was observed for DM intake and milk composition was unaffected except for milk protein which tended to be higher in cows fed PhyG5,000 than CON. In summary, the addition of exogenous phytase at 2,000 FTU/kg or higher to diets of lactating dairy cows improved P, PP, Ca, and CP digestibility and reduced fecal excretion of P, PP, and CP in a dose-dependent manner.

Traditionally, it has been believed that dairy cows are able to fully utilize the phosphorus (P) in feed, including that from plant-derived phytate, because of phytase activity of bacteria in the rumen. However, recent data have shown otherwise. This study investigated the effect of a biosynthetic bacterial 6-phytase supplemented to the diets of midlactating dairy cows on the digestibility and excretion of phosphorus and other key nutrients, over a 19-d experimental period. The experimental diets were commercially relevant in composition and low in phosphorus. At either or both of two tested dose levels (2,000 and 5,000 phytase units (FTU) per kilogram DM in the total diet), the exogenous phytase increased the digestibility and reduced fecal excretion of crude protein (CP), total P, and phytate-P compared with a comparable unsupplemented diet. The increases in CP, PP, and P digestibility were phytase-dose dependent. In addition, at the highest dose level, the phytase tended to increase the protein content of milk. The findings indicate that the use of exogenous phytase can improve P and protein utilization in dairy cows and offers an important approach to optimizing nutrient balance and reducing environmental P and nitrogen (N) pollution from dairy farms.

Effects of protease enzyme supplementation and varying levels of amino acid inclusion on productive performance, egg quality, and amino acid digestibility in laying hens from 30 to 50 weeks of age.

An experiment was conducted to evaluate the effects of protease supplementation and reduced digestible amino acid (dAA)/ crude protein (CP) level on productive performance, AA digestibility, and egg quality parameters in Hy-Line W-36 laying hen from 30 to 50 wk of age. A total of 768 hens (12 replicates of 8 hens per treatment) were equally and randomly allocated into 8 experimental diets in a 4 × 2 factorial arrangement of dAA/CP level (100, 95, 90, and 85% of breeder recommendation) and protease (exclusion or inclusion). Protease was added at 60 g/metric ton of feed in the inclusion group. Hens were housed in raised-wire cages with a stocking density of 870 cm2/bird. The adequate (100%) diet was based on corn and soybean meal and formulated based on the digestible (d) Lys and dAAs (dMet, dThr, dTrp, dTSAA, dIle, and dVal) to meet 100% of the current management guide recommendation. Variations in dAA/CP (95, 90, and 85% diets) were accomplished by reducing the 100% dAA by 5, 10, and 15%, respectively. All diets were supplemented with phytase at 500 phytase units (FTU)/kg. Data were analyzed using PROC GLM of SAS 9.4. There was a main effect of dAA/CP level on 85% diet where it had a lower mean hen-day egg production (HDEP, P < 0.01), egg mass (EM, P < 0.01), and higher feed conversion ratio (FCR, P < 0.001). Higher egg weight (P < 0.01) was observed in 95 and 100% dAA/CP level diets. However, Haugh unit (P < 0.01) and albumen height (P < 0.01) were higher in 85 and 90% diets. The inclusion of protease reduced the feed consumption (P = 0.0247), FCR for dozens of eggs (P = 0.0049) from 30 to 49 wk of age without affecting the HDEP or EM. Protease supplementation and dAA/CP level had an effect on the apparent ileal digestibility (AID) of CP (P = 0.019), Lys (P < 0.01), Thr (P < 0.01), Trp (P = 0.017), and Val (P < 0.01). Addition of protease significantly increased egg income (P = 0.033) and return on investment (P = 0.00223) from 30 to 37 wk of age. At 38 to 50 wk of age, dAA/CP level had a significant effect on egg income (P < 0.001), feed cost (P < 0.001), and return on investment (P < 0.001). This experiment indicates that the inclusion of protease in 90 and 95% lower dAA/CP diets could help improve the digestibility of CP, and key amino acids and maintain productive performance of corn and soybean meal-based diets in Hy-Line W-36 laying hen from 30 to 50 wk of age.

Effects of dietary calcium and phosphorus restrictions on growth performance, intestinal morphology, nutrient retention, and tibia characteristics in broiler chickens.

1. This study evaluated the effects of dietary calcium (Ca) and available phosphorus (aP) restrictions on growth performance, intestinal morphology, nutrient apparent total tract retention (ATTR), and tibia characteristics.2. A total of 1296, one-day-old male Ross-308 broilers were reared for 42 d. During the starter phase (1-10 d), all birds were fed a nutrient-adequate diet (C). Diets fed during the grower phase (11-24 d) included: 1. C; 2. 15% of the Ca and aP in C; 3. 30% of the Ca and aP in C. At the beginning of the finisher phase (25 d), chickens fed the C diet were divided into two subgroups including C, and C+ phytase (500 FTU/kg). Restricted treatments were divided into eight subgroups as 1. C; 2. 10% of the Ca and aP in C; 3. 20% of the Ca and aP in C; 4. 30% of the Ca and aP in C; 5. C+ phytase; 6. 10% of the Ca and aP in C+ phytase; 7. 20% of the Ca and aP in C+ phytase and 8. 30% of the Ca and aP in C+ phytase. 3. On d 24 and 42, ATTR of Ca and phytate phosphorus (pP) were linearly increased by decreasing Ca and aP levels (P < 0.05). Birds receiving phytase showed higher nutrient ATTR compared to those fed non-phytase supplemented diets (P < 0.05). Tibia Ca and P were linearly decreased at 24 d (P < 0.05) and tibial ash was linearly decreased (P < 0.05) at 42 d by decreasing levels of Ca and aP in finisher diets (without phytase) . By decreasing the levels of Ca and aP in the finisher diets (with phytase) with a 30% reduction of Ca and aP in the grower phase, tibia ash linearly decreased (P < 0.05). Using 500 FTU/kg phytase improved tibia traits compared to non-phytase supplemented treatments (P < 0.05).4. In general, decreasing dietary Ca and aP (up to 30%) during grower and finisher phases increased ATTR of minerals and decreased Ca, P and breaking strength (BS) of tibia without any negative effect on growth performance or intestinal morphology. Reduced dietary Ca and aP decreased tibial ash content, although 500 FTU/kg phytase improved ATTR of minerals and tibia attributes.

Effects of dietary supplementation with microbial phytase on the growth, bone minerals, antioxidant status, innate immunity and disease resistance of African catfish fed on high soybean meal-based diets.

The microbial phytase, derived from Buttiauxella gaviniae, Yersinia mollarettiv and Hafnia spp., is proven to be safe for avian and porcine feeding and promotes their overall growth performance. Here, we have evaluated microbial phytase's effects on the growth, bone mineral content, antioxidant status, immune responses and the resistance of African catfish (Clarias gariepinus) fed with high soybean meal-based diets against Aeromonas hydrophila infection. Five isonitrogenous diets (40% protein) were supplemented with different levels of microbial phytase ranging from 0 as a control to 250, 500, 750 and 1000 FTU/kg diet. African catfish (n = 300; 8.5 ± 0.3 g) were allocated in 15 50-L tanks (in triplicates) and were fed on the prepared tested diets for 12 weeks. After the end of the feeding period of 12 weeks, 10 fish from each replicate was intraperitoneally infected with A. hydrophila (0.5 × 105 CFU/ml) and monitored for 14 days. Dietary phytase levels linearly and quadratically improved the growth performance of African catfish and stimulated feed intake. Bone levels of calcium, phosphorus, magnesium and zinc were also positively modulated in phytase-fed fish, especially at 750-1000 FTU/kg diet. Similarly, counts of red and white blood cells as well as haemoglobin, packed cells volume, platelets, lymphocytes and heterocytes were significantly modulated in all fish fed with phytase-supplemented diets. Higher levels of serum total protein, albumin and globulin were also observed in fish fed with a 750-1000 FTU/kg diet of phytase. Conversely, aspartate and alanine aminotransferase activities were lower in fish fed with a 750-1000 FTU/kg diet of phytase, compared to those fed the control diet. Moreover, antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), reduced glutathione levels and immune responses (lysozyme, respiratory burst, protease and alkaline phosphatase activities) biomarkers were linearly and quadratically elevated, while malondialdehyde values were linearly and quadratically decreased in fish groups fed with phytase-based diets. After administering A. hydrophila, 60.0% of the fish fed the control diet perished, while no mortalities were observed in fish fed with 750-1000 FTU/kg diets. Taken together, the current study reveals that dietary phytase could improve the growth performance, blood profile, bone mineralization, antioxidant activities, immunity and overall protection of African catfish against A. hydrophila infection. Dietary phytase may be efficiently used in the feeding of African catfish to enhance their overall performance and mitigate health conditions with optimum level of 900 FTU/kg diet.

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

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

In broilers, an excess of dietary calcium (Ca) or imbalance with phosphorus (P) can impair mineral digestion and utilization. As a result, diets are being formulated with less Ca, but the quality of the added Ca (that is mainly from limestone) is also important. This study investigated effects of limestone solubility (high [HSL] vs. low [LSL]) on the capacity of a novel consensus bacterial 6-phytase variant, PhyG, to improve P and Ca digestion and utilization in low-Ca diets containing no added inorganic phosphate. Increasing the phytase dose increased ileal P and phytate digestibility and the digestible P content of the diet at 21 d of age regardless of limestone solubility and reduced the negative effects of HSL (relative to LSL). Total tract digestibility of P and Ca, retainable P and Ca, and tibia ash were also increased by phytase, but responses were reduced with LSL relative to HSL. The findings highlight that phytase dose-responses differ in diets containing different limestones and it is therefore recommended to formulate diets based on the content of digestible rather than total Ca to ensure that Ca requirements are met but not exceeded, with optimal phytase efficacy. In diets containing HSL, a higher PhyG dose level is needed to meet the requirement for P.

Effects of microbial phytase on standardized total tract digestibility of phosphorus in feed phosphates fed to growing pigs.

An experiment was conducted to test the hypothesis that the apparent total tract digestibility (ATTD) and the standardized total tract digestibility (STTD) of P in feed phosphates are increased by microbial phytase when fed to growing pigs. Monocalcium phosphate (MCP), monosodium phosphate (MSP), and magnesium phosphate (MgP) from volcanic deposits were used in the experiment. Three corn-soybean meal based diets that contained 0, 500, or 4,000 units of microbial phytase (FTU), but no feed phosphates, were formulated. Nine additional diets were formulated by adding each of the three feed phosphates to the three basal diets. A P-free diet was also formulated to estimate the basal endogenous loss of P, and therefore, 13 diets were used in the experiment. A total of 117 growing barrows (initial body weight: 15.56 ±â€…1.68 kg) were allotted to the 13 diets with 9 pigs per diet. Pigs were housed individually in metabolism crates equipped with a feeder and a nipple drinker. Installation of a screen floor under the slatted floor allowed for collection of feces. Diets were fed for 10 d, with the initial 5 d being a period of adaptation to the diet followed by a collection period of 4 d. During the experiment, pigs were fed equal amounts of feed twice daily at 0800 and 1600 h. Results indicated that the ATTD and STTD of P in all diets increased with the inclusion of 500 or 4,000 FTU, but the ATTD and STTD of P in the feed phosphates were not affected by the inclusion of phytase. This indicates that the increases in ATTD and STTD of P that were observed in the mixed diets when phytase was used were due to the release of P from phytate in corn and soybean meal and not from an increase in digestibility of P in feed phosphates. However, MgP had a lower (P < 0.05) ATTD and STTD of P than MCP and MSP. In conclusion, microbial phytase does not increase the digestibility of P in MCP, MSP, or MGP, but the digestibility of P in MgP is less than in MCP and MSP.

Microbial phytase increases the digestibility by pigs of phytate-bound P in feed ingredients of plant origin, but digestible P can also be increased in diets by the addition of feed phosphates due to their high digestibility of P and lack of phytate. However, it is possible that the phytate from plant ingredients complexes with P from feed phosphates, resulting in a lower digestibility of P, but research to address this possibility has not been reported. Therefore, the hypothesis was that phytase can increase the digestibility of P in feed phosphates fed to pigs. Monocalcium phosphate (MCP), monosodium phosphate (MSP), and magnesium phosphate (MgP) were the three feed phosphates used in the experiment and the three ingredients were included in corn-soybean meal based diets. Results indicated that the inclusion of phytase increased the digestibility of P in the diets, but there was no indication that phytase affected the digestibility of P from any of the three feed phosphates, which indicates that the increase in digestibility of P likely was due to the release of P from plant ingredients in the diets. However, the digestibility of P was lower in MgP compared with MCP and MSP.

Exogenous enzymes, meal size, and meal frequency: effect on ileal and total tract digestibility of carbohydrates, and energy and fiber degradation in growing pigs fed a wheat-barley grain-based high-fiber diet.

When conducting a digestibility trial, pigs are usually fed only twice a day with a restricted feed intake which is not representative of the feeding conditions in a commercial farm. This study aimed to determine the effects of meal size and frequency, and exogenous enzymes (xylanase and phytase) on the digestibility of a high-fiber diet using porcine in vivo and in vitro approaches. Pigs (n = 6) were fitted with a T cannula, and each received all treatments using a 6 × 6 Latin square experimental design. The diets were supplemented (Enz) or not with a combination of xylanase and phytase and distributed into three feeding programs: one received two meals per day that met three times the maintenance energy requirement (2M), one received the same quantity of feed in eight meals (8M), and another received an amount that met five times the maintenance energy requirements in eight meals (8M+). For in vitro experiment, the degradability of fiber with or without xylanase supplementation only was determined. Enzyme supplementation increased apparent ileal digestibility (AID) of dry matter, starch, and degradation of insoluble non-starch polysaccharides (I-NSP) in all in vivo treatments (P < 0.05). The 2M compared with 8M increased the AID of starch and total tract digestibility of organic matter and I-NSP (P < 0.05). Enzyme supplementation decreased the content of insoluble arabinoxylan (P < 0.05) and increased arabinoxylan oligosaccharides (P < 0.05) in the in vivo ileal digesta and in vitro incubation. The results of this study confirm degradation by xylanase of the fiber fraction at the ileal level, which resulted in less fermentation of fiber in the large intestine. However, number and size of meals had little influence on feed digestibility. The consequences of shifting fiber fermentation more towards the upper part of the gastrointestinal tract need further investigation. The in vitro model provided a confirmation of the action of xylanase on the degradation of non-starch polysaccharides.

To reduce cost and also utilize locally produced ingredients, pig diets nowadays can include a large proportion of fiber-rich ingredients. Exogenous enzymes can be added to diets to improve their digestibility and limit negative effects of fiber. Usually, when conducting a digestibility trial, pigs are fed only twice a day with a restricted feed intake which is not representative of feeding conditions in a commercial farm. This study aimed to determine the effect of meal size and frequency, and enzyme supplementation on digestibility of a diet rich in fiber in growing pigs and in vitro. The diets were supplemented (Enz) or not with xylanase and phytase, and according to different size and frequency: one treatment was pig receiving two meals per day with five times the maintenance energy requirement (2M), another received the same quantity of feed in eight meals (8M), and the last received an amount close to ad libitum feeding in eight meals (8M+). An in vitro experiment was also conducted to look at degradability of fiber with and without xylanase. The results showed that xylanase allows degradation of fiber and increases digestibility of dry matter, starch, and energy. The number and size of meals have little influence on digestibility.

Effects of 25-hydroxycholecalciferol (25-OH-D3) and 1-hydroxycholecalciferol (1-OH-D3) on serum bone biomarkers and calcium and phosphorus balance and concentrations of energy in diets without or with microbial phytase fed to sows in late gestation.

The objective was to test the hypothesis that supplementation of diets for gestating sows with 25-hydroxycholecalciferol (25-OH-D3) or 1-hydroxycholecalciferol (1-OH-D3) affects serum biomarkers for bone and increases Ca and P balance and the apparent total tract digestibility (ATTD) of gross energy (GE), and the concentrations of digestible energy (DE) and metabolizable energy (ME) in diets without or with microbial phytase. Sixty multiparous sows were allotted to 1 of 6 diets. Diets were formulated using a 3 × 2 factorial with 3 inclusions of supplemental vitamin D metabolite (no metabolite, 25-OH-D3, or 1-OH-D3) and 2 inclusion levels of microbial phytase (0 or 1,000 units). Sows were housed individually in metabolism crates and feces and urine were collected quantitatively. Results indicated that there was no difference in the ATTD of dry matter (DM) and GE and concentration of DE among the 3 diets containing microbial phytase, but the ATTD of DM and GE and concentration of DE was greater (P < 0.05) in diets containing 1-OH-D3 compared with the diet without a vitamin D metabolite if phytase was not used (interaction; P < 0.05). In diets without microbial phytase, ME was greater in diets containing either one of the 2 vitamin D metabolites than in the diet without a vitamin D metabolite, but among diets with microbial phytase, the ME of the 1-OH-D3 diet was less than of the 25-OH-D3 diet (interaction; P < 0.05). No effect of microbial phytase on concentrations of DE and ME was observed. There was no interaction between supplementation of microbial phytase and vitamin D metabolites for Ca and P balances, and regardless of metabolite supplementation, use of microbial phytase increased (P < 0.05) the ATTD and retention of Ca and P. Regardless of dietary phytase, the ATTD and retention of Ca and P increased (P < 0.05) for sows fed a diet containing one of the vitamin D metabolites compared with sows fed the diet without a vitamin D metabolite. Serum biomarkers for bone resorption or bone tissue synthesis were not affected by experimental diets. In conclusion, the ATTD of DM and GE, concentrations of DE and ME, and Ca and P balance in phytase-free diets fed to sows in late gestation were increased by supplementation with 1-OH-D3 or 25-OH-D3, but no differences between the 2 vitamin D metabolites were observed. Supplementation of diets with microbial phytase increased Ca and P balance, but did not affect DE and ME of diets.

The role of vitamin D is to increase absorption of calcium and phosphorus in the gastrointestinal tract and maintain serum concentrations of calcium, but dietary vitamin D needs to be converted to an active form by 2-hydroxylation steps that take place in the liver and the kidneys. The conversion efficiency to active vitamin D may be increased if pre-hydroxylated metabolites rather than vitamin D are provided, which also increases calcium and phosphorus utilization. In a previous experiment it was also demonstrated that a vitamin D metabolite increases energy absorption in gestating sows. It is possible that use of a vitamin D metabolite and phytase have additive effects and the hypothesis, therefore, was that supplementation of a vitamin D metabolite increases calcium and phosphorus balance and energy digestibility in diets fed to gestating sows without or with microbial phytase. Results indicated that in diets without phytase, the 2 vitamin D metabolites increased energy concentration in diets by increasing apparent energy digestibility. There was no interaction between supplementation of phytase and vitamin D metabolites for calcium and phosphorus balances. Use of phytase and vitamin D metabolites increased calcium and phosphorus digestibility and retention.

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

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

Effects of phytase supplementation of high-plant-protein diets on growth, phosphorus utilization, antioxidant, and digestion in red swamp crayfish (Procambarus clarkii).

Fish meal is increasingly being replaced by plant protein raw materials, meanwhile, it brings phytic acid, which combines with phosphorus to form phytate phosphorus and leads to a low utilization rate of phosphorus in shrimp. To solve this problem, this study investigated the effects of phytase supplementation on growth performance, phosphorus utilization, antioxidants, and digestion in red swamp crayfish (Procambarus clarkii). Crayfish (initial mean weight: 8.69 ± 0.15 g, N = 324) were randomly divided into six groups each with three replicates of 18 individuals each, and hand-fed for 8 weeks with one of six experimental diets (50 and 490 g kg-1 animal and plant protein raw material, respectively): negative control (NC; 11.0 g kg-1 phosphorus), positive control (PC; 15 g kg-1 NaH2PO4 added to NC; 14.7 g kg-1 phosphorus), and phytase supplementation diets (P1-P4: 0.1, 0.2, 0.4, and 0.6 g kg-1 phytase added to NC, respectively). The feeding trial was performed in a micro-flow water culture system. P2 showed a significantly higher weight gain rate (WGR), specific growth rate, protein efficiency ratio, and protein retention efficiency (PRE) but showed the lowest feed conversion ratio (FCR) than other groups. Broken-line regression analyses using WGR, FCR, and PRE as evaluation indices showed that the optimal dietary phytase supplementation level was 0.233, 0.244, and 0.303 g kg-1, respectively. P2 showed the highest crude protein content of whole crayfish and abdominal muscle, and phosphorus deposition rate, which was significantly higher than that in NC and PC. P3 showed the highest calcium and phosphorus contents in whole crayfish and phosphorus content in abdominal muscle, and calcium and inorganic phosphorus content in serum, which were significantly higher than those in NC. P3 showed significantly lowest serum alkaline phosphatase, alanine aminotransferase, aspartate transaminase activities, malondialdehyde content in hepatopancreas, and highest catalase activity, which were significantly lower and higher, respectively, than those in NC and PC. In summary, the addition of 0.2-0.4 g kg-1 phytase significantly improves the growth performance, feed utilization, digestive enzyme activity, and antioxidant of P. clarkii, which has a similar effect to the direct addition of NaH2PO4 at 15 g kg-1 to the feed.

Effects of particle size and phytase supplementation on apparent and standardized total tract digestibility of phosphorus in hybrid rye fed to growing pigs.

An experiment was conducted to investigate the effects of particle size (PS) and levels of phytase supplementation on the apparent (ATTD) and standardized (STTD) total tract digestibility of P in hybrid rye fed to growing pigs. Thirty-six growing barrows (23.6 ± 1.5 kg initial BW) were individually housed in metabolism crates and randomly allotted to one of six dietary treatments to give six replicates per treatment. The six dietary treatments were arranged in a 2 × 3 factorial with main effects of PS and phytase supplementation levels (0, 500, or 2,500 FTU/kg). Hybrid rye was ground using a hammermill mounted with 4.0- and 3.2-mm screens to obtain material with coarse and fine PS, respectively. Pigs were fed experimental diets for 11 d, including 5 d for adaptation and 6 d for total collection of feces. All data were analyzed using the MIXED procedure of SAS with PS, phytase, and their interaction as fixed effects. Orthogonal polynomial contrasts were used to test linear and quadratic effects of phytase level in both coarse and fine hybrid rye diets. The ATTD and STTD of P were greater (P < 0.05) in diets with fine than in those with coarse hybrid rye. Increasing levels of phytase supplementation linearly (P < 0.01) and quadratically (P < 0.01) improved the ATTD and STTD of P in hybrid rye diets. There were no interaction effects between PS and phytase supplementation on the ATTD and STTD of P in hybrid rye diets. In conclusion, PS reduction improved the digestibility of P in hybrid rye, and supplementing increasing levels of phytase improved P digestibility in linear and quadratic manner in growing pigs fed hybrid rye diets.

Cereal grains such as corn, wheat, and barley are widely used as an energy source in swine diets. However, due to their recent soaring prices, it is necessary to use alternative feedstuffs for swine. New commercial hybrid rye with improved ergot resistance and higher yield has been developed. This hybrid rye contains similar energy content as barley and sorghum, making it a promising ingredient for pigs. Phosphorus is an essential nutrient in swine diets for bone growth and cellular functions. However, most phosphorus in hybrid rye is bound to phytic acid, which is not digested well by pigs. The excessive phosphorus in swine manure may runoff and cause environmental problems such as eutrophication. Increasing phosphorus digestibility can decrease its excretion in pigs. Therefore, in the current study, we formulated six diets including fine or coarse hybrid rye particle size supplemented with three levels of phytase to determine the effects of particle size and phytase supplementation on phosphorus digestibility in hybrid rye. Our results showed that fine particle size and supplementing increasing levels of phytase could improve the phosphorus digestibility in growing pigs fed hybrid rye diets.

Effect of limestone solubility on mineral digestibility and bone ash in nursery pigs fed diets containing graded level of inorganic phosphorus or increasing dose of a novel consensus bacterial 6-phytase variant.

The effect of a novel consensus bacterial 6-phytase variant (PhyG) on total tract digestibility (ATTD) of minerals and bone ash was evaluated in pigs fed diets containing medium- and high-solubility limestone (MSL and HSL, 69.6 and 91.7% solubility, respectively, at 5 min, pH 3.0) in a randomized complete block design. For each limestone, eight diets were formulated: an inorganic phosphate-free negative control (NC) based on wheat, corn, soybean-meal, canola-meal and rice-barn [0.18% standardized total tract digestible (STTD) P and 0.59% Ca]; the NC supplemented with 250, 500, 1,000, or 2,000 FTU/kg of PhyG, and; the NC with added monocalcium phosphate (MCP) and limestone to produce three positive controls (0.33, 0.27, and 0.21% STTD P, and 0.75, 0.70, and 0.64% Ca, respectively; PC1, PC2, PC3). In total, 128 pigs (12.8 ± 1.33 kg, 8 pigs/treatment, housed individually) were adapted for 16 d followed by 4 d of fecal collection. Femurs were collected from euthanized pigs on day 21. Data were analyzed by one-way ANOVA with means separation by Tukey's test, and by factorial analysis (2 x 4: 2 levels of limestone solubility, 4 STTD P levels, and 2 × 5: 2 levels of limestone solubility, 5 PhyG dose levels). Phytase dose-response was analyzed by curve fitting. A consistent negative effect of HSL on ATTD P and Ca was observed in control diets (P < 0.001). Across phytase-supplemented diets, HSL reduced (P < 0.05) ATTD Ca and P (% and g/kg) compared with MSL. Across limestones, increasing phytase dose level increased (P < 0.05) ATTD P exponentially. Limestone solubility had no effect on bone ash, but PhyG linearly increased (P < 0.05) bone ash; 500 FTU/kg or higher maintained bone ash (g/femur) equivalent to PC1. In conclusion, ATTD P and Ca were reduced by a high compared with a medium soluble limestone, but the novel phytase improved ATTD P and Ca independent of limestone solubility.

Microbial phytase is added to commercial pig diets to increase phosphorus (P) availability and reduce P excretion. It is known that an excess of calcium (Ca), mostly sourced from limestone, can affect phytase efficacy. However, less is known about the impact of limestone quality. This study investigated the effect of a medium- compared to a high-soluble limestone (MSL and HSL, respectively), in combination with increasing dose levels of a novel phytase (PhyG), on mineral digestibility and bone mineralization in young pigs. Without phytase, total tract digestibility of P was lower with HSL than MSL, indicating a negative effect of more soluble limestone on mineral digestibility. Increasing the phytase dose increased digestibility of P with either limestone, and reduced the negative effect of HSL at high dose. Bone mineralization was unaffected by limestone but markedly increased by phytase. At 1,000 FTU/kg, PhyG released an estimated 1.89 or 2.32 g/kg of digestible P from monocalcium phosphate in diets containing MSL and HSL, respectively based on bone ash content. The results demonstrate the efficacy of PhyG in young pig diets whilst indicating that limestone solubility can affect phytase efficacy.