ETH Library Benzoic acid as feed additive in pig nutrition Effects of diet composition on performance, digestion and ecological aspects Doctoral Thesis Author(s): Bühler, Kathrin Publication date: 2009 Permanent link: https://doi.org/10.3929/ethz-a-005834561 Rights / license: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use. Diss. ETH No 18298 Benzoic acid as feed additive in pig nutrition: Effects of diet composition on performance, digestion and ecological aspects A dissertation submitted to ETH ZURICH for the degree of Doctor of Sciences presented by KATHRIN BÜHLER Dipl. Sc. Nat. ETH born May 2, 1979 citizen of Winterthur ZH accepted on the recommendation of Prof. Dr. C. Wenk, examiner Dr. B. Bucher, co-examiner Dr. J. Broz, co-examiner 2009 Abbreviations ADF Acid detergent fibre AGP Antimicrobial growth promoter(s) AP Total alkaline phosphatase BMC Bone mineral content BMD Bone mineral density BW Body weight BW 0.75 Metabolic body weight CA Crude ash CP Crude protein (N * 6.25) d(xy) Apparent digestibility of nutrient xy DE Digestible energy DM Dry matter DWG Daily weight gain FCR Feed conversion ratio GE Gross energy MT Metatarsus NDF Neutral detergent fibre NH Ammonia 3 OC Osteocalcin SCL Serum crosslaps SD Standard deviation SEM Maximal standard error of the means SI Small intestine VFA Volatile fatty acid(s) - I - Abbreviations Experimental diets: LPr- Low protein diet without benzoic acid LPr+ Low protein diet with 1 % benzoic acid HPr- High protein diet without benzoic acid HPr+ High protein diet with 1 % benzoic acid CC Low-P diet without phytase, without benzoic acid CB Low-P diet without phytase, with 0.5 % benzoic acid PhyC Low-P diet with 750 U/kg phytase, without benzoic acid PhyB Low-P diet with 750 U/kg phytase, with 0.5 % benzoic acid LF- Low fibre diet without benzoic acid LF+ Low fibre diet with 0.5 % benzoic acid HF- High fibre diet without benzoic acid HF+ High fibre diet with 0.5 % benzoic acid - II - Tables Benzoic acid and nitrogen Table 1.1. Composition of the experimental diets (g/kg).........................................................25 Table 1.2. Analysed nutrient content of the experimental diets per kg diet.............................27 Table 1.3. Daily weight gain (DWG), feed intake and feed conversion ratio (FCR)..............28 Table 1.4. N metabolism (g /kg BW0.75/d) and N digestibility (d(N)).....................................29 Table 1.5. Urinary pH and excretion of hippuric acid.............................................................30 Benzoic acid and phytase I Table 2.1. Composition of the experimental diets (g/kg).........................................................36 Table 2.2. Analysed nutrient composition of experimental diets fed in experiments A and B.......................................................................................................................39 Table 2.3. Daily weight gain (DWG) and feed conversion ratio (FCR) in experiment B.......40 Table 2.4. Apparent total tract digestibility of crude protein (d(CP)), energy (d(E)), phosphorus (d(P)) and calcium (d(Ca)) in experiments A and B...........................42 Benzoic acid and phytase II Table 3.1. Composition of the experimental diets (g/kg).........................................................50 Table 3.2. Ash (g/kg DM) and mineral content (g/kg DM) in metatarsal bones at 66 kg (experiment A) and at 108 kg (experiment B) BW................................................57 Table 3.3. Bone mineral density (BMD, mg/cm3) and bone mineral content (BMC, mg/cm) in the midshaft of the tibia at 66 kg (experiment A) and at 108 kg (experiment B) BW................................................................................................58 Table 3.4. Bone mineral density (BMD, mg/cm3) and bone mineral content (BMC, mg/cm) in the distal metaphyse of the tibia at 66 kg (experiment A) and at 108 kg (experiment B) BW....................................................................................59 Table 3.5. Breaking strength (kN) of tibia and metatarsal bones II + III at 66 kg (experiment A) and at 108 kg (experiment B) BW................................................60 Benzoic acid and dietary fibre Table 4.1. Composition of the experimental diets (g/kg).........................................................67 Table 4.2. Analysed nutrient content of the experimental diet................................................68 - III - Tables Table 4.3. Apparent total tract digestibility of crude protein (d(CP)), energy (d(E)) and neutral and acid detergent fibre (d(NDF), d(ADF))...............................................71 Table 4.4. Apparent digestibility of nitrogen (d(CP)), energy (d(E)) and neutral detergent fibre (d(NDF)) in different parts of the gastrointestinal tract at 56 kg BW.....................................................................................................................72 Table 4.5. Total volatile fatty acid (VFA) and concentration of acetic, propionic and butyric acid at 56 kg BW........................................................................................74 - IV - Figures Introduction Figure 1.1. Nitrogen flow in poultry and swine.........................................................................6 Figure 1.2. Structure of phytic acid............................................................................................8 Figure 1.3. Analytical fractionations used in relation to dietary fibre analysis.......................10 Figure 1.4. Predicted cytoplasmic weak-acid/anion equilibrium.............................................19 Benzoic acid and phytase II Figure 2.1. Mean (± SE) serum calcium and phosphor concentrations (mmol/l) of the four groups in experiment A..................................................................................53 Figure 2.2. Mean (± SE) serum alkaline phospatase (AP) activities (U/l) and serum crosslaps (SCL) and osteocalcin (OC) concentrations (ng/ml) of the four groups in experiment A..........................................................................................55 - V - Table of contents Summary...................................................................................................................................1 Zusammenfassung....................................................................................................................3 General Introduction...............................................................................................................5 Nutrient composition..............................................................................................................6 Nitrogen..............................................................................................................................6 Phosphorus.........................................................................................................................8 Dietary fibre.......................................................................................................................9 Organic acids as feed additives............................................................................................12 Benzoic acid.....................................................................................................................13 Citric acid.........................................................................................................................14 Formic acid......................................................................................................................15 Fumaric acid....................................................................................................................15 Lactic acid........................................................................................................................16 Propionic acid..................................................................................................................16 Sorbic acid........................................................................................................................16 Other acids and acid blends.............................................................................................17 Mode of action..................................................................................................................18 Aim of the study...................................................................................................................20 The influence of benzoic acid and dietary protein level on performance, nitrogen metabolism and urinary pH in growing-finishing pigs.......................................................21 Introduction..........................................................................................................................22 Materials and methods.........................................................................................................23 Animals and experimental design....................................................................................23 Diets.................................................................................................................................24 Analytical methods...........................................................................................................25 Statistical analysis............................................................................................................26 Results and discussion..........................................................................................................26 Diets.................................................................................................................................26 - VI - Table of contents Body weight and pig performance...................................................................................27 N metabolism....................................................................................................................28 Urinary pH and urinary hippuric acid.............................................................................30 Conclusion............................................................................................................................31 Effect of benzoic acid and phytase in low-phosphorus diets on performance and nutrient digestibility of growing-finishing pigs...................................................................32 Introduction..........................................................................................................................33 Material and methods...........................................................................................................34 Animals and housing........................................................................................................34 Diets and feeding..............................................................................................................34 Collection and analysis of samples..................................................................................36 Statistical analysis............................................................................................................37 Results and discussion..........................................................................................................37 Diets.................................................................................................................................37 Pig performance...............................................................................................................40 Apparent nutrient digestibility.........................................................................................41 Conclusion............................................................................................................................45 Influence of benzoic acid and phytase in low-phosphorus diets on bone parameters in growing-finishing pigs............................................................................................................46 Introduction..........................................................................................................................47 Material and methods...........................................................................................................48 Animals and housing........................................................................................................48 Diets and feeding..............................................................................................................49 Collection and analysis of samples..................................................................................51 Statistical analysis............................................................................................................52 Results..................................................................................................................................52 Blood parameters.............................................................................................................52 Bone composition.............................................................................................................56 Bone stability....................................................................................................................57 - VII - Table of contents Discussion............................................................................................................................60 Conclusion............................................................................................................................63 Influence of benzoic acid in high fibre diets on nutrient digestibility and VFA production in growing-finishing pigs....................................................................................64 Introduction..........................................................................................................................65 Material and methods...........................................................................................................66 Animals and housing........................................................................................................66 Diets and feeding..............................................................................................................66 Collection of samples.......................................................................................................68 Analytical methods...........................................................................................................69 Statistical analyses...........................................................................................................69 Results and discussion..........................................................................................................70 Pig performance...............................................................................................................70 Apparent nutrient and fibre digestibility..........................................................................70 Volatile fatty acids............................................................................................................73 Conclusion............................................................................................................................75 Concluding Discussion...........................................................................................................76 Performance and digestion...................................................................................................77 Animal health.......................................................................................................................79 Ecological aspects................................................................................................................80 Outlook.................................................................................................................................82 Appendix.................................................................................................................................83 Appendix I: Chemical properties of different organic acids................................................84 Appendix II: Organic acids in animal nutrition – A literature review.................................86 Benzoic acid.....................................................................................................................87 Citric acid.........................................................................................................................90 Formic acid......................................................................................................................95 Fumaric acid..................................................................................................................102 - VIII -