90 Efficacy of Different Phytases on Growth Performance, Energy and Nutrient Digestibility and Bone Quality of Weaned Piglets Fed a Wheat-Corn Soybean Meal Based Complex Diet

The study determined efficacy of different phytases in diets without inorganic phosphorus (P) in piglets. Piglets (initial body weight 9.7 ± 1.2 kg) were randomly assigned (2 piglets/pen), based on sex and body weight over 6 diets. Positive control (PC) corn-wheat based diet was formulated to meet NRC specification. Negative control (NC) diet was formulated without inorganic P (-0.16% STTD P), with reduced calcium (Ca; -0.15%), net energy (-33 kcal/kg), and standardized ileal digestible amino acids (average -0.02% unit). The NC diets were supplemented with 4 different phytases at 1,500 FTU/kg feed including a novel consensus bacterial 6-phytase variant expressed in Trichoderma reesei (PhyG), a Citrobacter braakii phytase expressed in Aspergillus oryzae (PhyC), a hybrid phytase (Hafnia sp., Yersinia sp. and Buttiauxella sp.) expressed in Aspergillus niger (PhyH) and an Escherichia coli phytase expressed in Pichia pastoris (PhyE). Piglets were fed ad libitum for 42 d. Fecal samples were collected during last 3 d. On d 42, 1 piglet per pen was euthanized and metacarpi collected for bone strength and ash analysis. Data were analysed by one-way ANOVA and treatment mean comparison by Tukey test using JMP 14. Pigs fed NC diets showed reduced (P < 0.05) growth, P digestibility, bone ash and bone strength vs PC and all phytases treatments. Overall feed conversion ratio (FCR) was less (P < 0.05) with PhyG (-22 points) and PhyE (-8 points) vs NC, while PhyC and PhyH showed intermediate FCR between PhyG and PhyE. PhyG improved (P < 0.05) bone strength and P digestibility vs PhyC, PhyE and PC. Based on FCR and bone strength, ranking of the phytases are: PhyG >PhyC >PhyH >PhyE. In conclusion, all phytases improved growth, nutrient digestibility and bone strength vs NC; however, only PhyG fully compensated nutrients and energy reduction, fully recovered performance to the level of PC and resulted in improved bone strength compared with PC.

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PSVI-3 Effect of Live Yeast Supplementation on Redox Potential, Gastrointestinal Microbiota, and Short-Chain Fatty Acids in Piglets

The post-weaning period is a stressful process for piglets with compromised gut health, increasing susceptibility to diarrhea and infection. Oxygen concentration in the gut affects microbiome and fermentation profile. Live yeasts have been used to promote gut health and performance of young animals. An experiment was carried out to determine the influence of live yeast on gut conditions including redox potential, microbial composition, and short chain fatty acid (SCFA) production of piglets. Sixteen Pietrain *(Landrace*Large White) piglets were distributed into blocks by live weight and allocated at 4 per pen for a 28-d trial. Each block was composed by a combination of the 2 dietary treatments corresponding to a control diet and a diet supplemented with live yeast (1 kg/tonne Vistacell, AB Vista). At the end of trial, piglets were euthanized to measure kinetics of redox potential (Eh) and pH from caecum until 35 min post-mortem. Then, digesta samples from stomach, duodenum, jejunum, ileum, caecum, and rectum were collected for microbial composition and SCFA production. Data were analyzed using GLM procedure of SAS 9.4 and means compared with a Student-Newman-Keuls test. Redox potential decreased with time (P < 0.001) until stabilizing after 20 min, and a clear difference was observed between treatments (P < 0.001). Supplemented live yeast survives throughout gastrointestinal tract and modifies microbial populations enhancing lactic acid bacteria (P < 0.001) while reducing enterobacteria (P < 0.001) or eliminating fungi (P < 0.001). The production of SCFA from caecum digesta was 3-fold higher than in ileum with significantly different molar proportion of individual SCFA. Lactic, formic, and acetic acids predominate on ileum (> 93%) whereas acetic, propionic, and butyric dominate on caecum digesta (> 90%). Nevertheless, no differences were observed due to dietary treatments. In conclusion, live yeast supplementation of diets modifies redox conditions prevailing in the gut modifying microbial populations and helping piglets to overcome post-weaning growth check.

Functionality of a next generation biosynthetic bacterial 6-phytase in enhancing phosphorus availability to weaned piglets fed a corn-soybean meal-based diet without added inorganic phosphate

The utility of a next generation biosynthetic bacterial 6-phytase (PhyG) in restoring bone ash, bone phosphorus (P) content and performance in piglets depleted in P was evaluated. A total of 9 treatments were tested as follows. Treatment 1, a negative control (NC) diet; treatments 2, 3, 4, NC supplemented with 250, 500 or 1,000 FTU/kg of PhyG; treatments 5, 6, NC supplemented with 500 or 1,000 FTU/kg of a commercial Buttiauxella sp phytase (PhyB); treatments 7, 8, 9, NC supplemented with monocalcium phosphate (MCP) to provide 0.7, 1.4 and 1.8 g/kg digestible P, equating to a digestible P content of 1.8, 2.5 and 2.9 g/kg. The latter constituting the positive control (PC) diet with adequate P and calcium (Ca). The NC was formulated without inorganic P (1.1 g digestible P/kg) and reduced in Ca (5.0 g/kg). Additional limestone was added to treatments 7 to 9 to maintain Ca-to-P ratio between 1.2 and 1.3. A total of 162 crossed Pietrain × (Large White × Landrace) 21-d-old piglets (50% males and 50% females) were fed adaptation diets until 42 d old and then assigned to pens with 2 pigs/pen and 9 pens/treatment in a completely randomized block design. Piglets were fed mash diets based on corn and soybean meal ad libitum for 28 d. At the end of the study, one piglet perpen was euthanized and the right feet collected for determination of bone strength, bone ash and mineral content. Compared with the PC, the NC group had reduced average daily gain (ADG) and increased feed conversion ratio (FCR) during all growth phases and overall, and at d 28 (70 d old) NC pigs had bones with reduced ash, Ca and P content (P < 0.05). The PhyG at 250 FTU/kg improved bone ash vs. NC. Increasing PhyG dose linearly or quadratically improved bone ash, ADG and FCR (P < 0.05). At ≥ 500 FTU/kg, both PhyG and PhyB maintained ADG and FCR equivalent to PC. Linear regression analysis was done to compare the measured response parameters to increasing digestible P from MCP. Based on this analysis it was shown that PhyG and PhyB at 1,000 FTU/kg could replace 1.83 and 1.66 g/kg digestible P from MCP in the diet, respectively, on average across metacarpi bone ash, ADG or FCR. These findings suggest that the biosynthetic phytase is highly effective in the tested dietary setting.

134 The efficacy of a Buttiauxella sp. phytase relative to diets with graded levels of inorganic phosphate in piglets

The effect of a Buttiauxella sp. phytase on performance and bone ash in piglets was evaluated. A negative control (NC) diet was formulated without inorganic phosphate [0.11% digestible phosphorus (P)] and lower in calcium (Ca, 0.5%). NC was supplemented with the phytase at 0, 500 and 1,000 FTU/kg diet or with mono-calcium phosphate (MCP) at 4 levels to add 0, 0.7, 0.14 and 0.18% digestible P and with additional limestone to maintain Ca to P ratio (1.2 to 1.3). The latter was the positive control (PC) and contained 0.7% Ca and 0.29% digestible P, meeting NRC requirement. A total of 108 Pietrain × (Landrace × Yorkshire) piglets were fed adaptation diets from 21 (weaned) to 42 d of age. Then, they were divided into 9 blocks according to body weight (BW) (9 replicates/treatment, mean initial BW 10.2 kg, mixed sex) and allocated at 2 piglets per pen. Piglets were fed mash test diets (based on corn, soybean meal with broken rice, rice bran and sugar beet pulp) ad lib for 28 d. At the end, 1 piglet per pen was euthanized and the right foot collected to determine metacarpal ash, Ca and P content. Data were analyzed using JMP 14.0. The NC reduced (P &lt; 0.05) average daily gain (ADG), average daily feed intake (ADFI), bone ash, Ca and P, and increased feed conversion ratio (FCR) vs PC (Table 1). Increasing phytase and MCP linearly increased (P &lt; 0.05) ADG, bone ash, Ca and P and reduced FCR. Linear regression analysis using increasing digestible P from MCP as reference indicated that phytase at 1,000 FTU/kg can replace 0.16, 0.18 or 0.16% digestible P from MCP, using bone ash, ADG or FCR as response parameter, respectively. In conclusion, Buttiauxella phytase improved performance and bone ash in piglets fed diet without added inorganic phosphate.

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