Effect of feeding broilers diets differing in susceptible phytate content

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Morgan, Natalie K. ; Walk, Carrie L. ; Bedford, Michael R. ; Scholey, Dawn V. ; Burton, Emily J. (2016)
  • Publisher: KeAi Publishing
  • Journal: Animal Nutrition, volume 2, issue 1, pages 33-39 (issn: 2405-6545, eissn: 2405-6383)
  • Related identifiers: pmc: PMC5941011, doi: 10.1016/j.aninu.2016.01.002
  • Subject: Phytase | Broiler | Poultry Nutrition | Digestibility | Phytate | Phosphorus

Measurements of total phytate phosphorus content of diets may be deceptive as they do not indicate substrate availability for phytase; it may be that measurements of phytate susceptible to phytase effects are a more accurate measure of phosphorus (P) availability to the bird. To verify this hypothesis, an experiment was conducted to compare diets formulated to contain either high or low susceptible phytate, supplemented with either 0 or 500 FTU/kg phytase. Susceptible phytate was determined by exposing the feed samples to conditions that mimicked the average pH of the proximal gastrointestinal tract (pH 4.5) and the optimum temperature for phytase activity (37 °C) and then measuring phytate dissolved. Ross 308 birds (n = 240) were fed one of 4 dietary treatments in a 2 × 2 factorial design; 2 diets with high (8.54 g/kg, 57.90% of total phytate) or low (5.77 g/kg, 46.33% of total phytate) susceptible phytate, containing 0 or 500 FTU/kg phytase. Diets were fed to broilers (12 replicate pens of 5 birds per pen) from d 0 to 28 post hatch. Birds fed diets high in susceptible phytate had greater phytate hydrolysis in the gizzard (P < 0.001), jejunum (P < 0.001) and ileum (P < 0.001) and resulting greater body weight gain (BWG) (P = 0.015) and lower FCR (P = 0.003) than birds fed the low susceptible phytate diets, irrespective of phytase presence. Birds fed the high susceptible diets also had greater P solubility in the gizzard and Ca and P solubility in the jejunum and ileum (P < 0.05) and resulting greater tibia and femur Ca and P (P < 0.05) content than those fed the low susceptible diets. All the susceptible phytate was fully degraded in the tract in the absence of added phytase, suggesting the assay used in this study was able to successfully estimate the amount of total dietary phytate that was susceptible to the effects of phytase when used at standard levels. No interactions were observed between susceptible phytate and phytase on phytate hydrolysis. Hydrolysis of phytate was greater (P < 0.05) in the gizzard of birds fed the diets supplemented with phytase, regardless of the concentration of susceptible phytate in the diet. Phytase supplementation resulted in improved BWG (P < 0.001) and FCR (P = 0.001), increased P solubility (P < 0.001) in the gizzard, Ca and P solubility (P < 0.001) in the jejunum and ileum and Ca and P concentration (P < 0.001) and strength (P < 0.001) in the tibia and femur. Pepsin activity was higher in birds fed the diets supplemented with phytase (P < 0.001) and was greater (P = 0.031) in birds fed the high susceptible phytate diets compared with the low susceptible phytate diets. Findings from this study suggest that there may be a measure more meaningful to animal nutritionists than measurements of total phytate.
  • References (15)
    15 references, page 1 of 2

    Angel R, Saylor WW, Mitchell AD, Powers W, Applegate TJ. Effect of dietary phosphorus, phytase, and 25-hydroxycholecalciferol on broiler chicken bone mineralisation, litter phosphorus, and processing yields. Poult Sci 2006;85: 1200e11.

    Applegate TJ, Webel DM, Lei XG. Efficacy of a phytase derived from Escherichia coli and expressed in yeast on phosphorus utilisation and bone mineralisation in turkey poults. Poult Sci 2003;82:1726e32.

    Bohn L, Meyer AS, Rasmussen SK. Phytate: impact on environment and human nutrition. A challenge for molecular breeding. J Zhejiang Univ Sci B 2008;9(3): 165e91.

    Cohen J. Statistical power analysis for the behavioural sciences. 2nd ed. Hilssdale, NJ: Erlbaum; 1988.

    Engelen AJ, Van der Heeft FC, Randsdorp PH, Somers WA, Schaefer J, Van der Vat BJ. Determination of phytase activity in feed by colorimetric enzymatic method: collaborative interlaboratory study. J AOAC Int 2001;84:629e33.

    Hall LE, Shirley RB, Bakalli RI, Aggrey SE, Pesti GM, Edwards Jr HM. Power of two methods for the estimation of bone ash of broilers. Poult Sci 2003;82:414e8.

    Kocabaúli N. The Effect of dietary phytase supplementation at different levels on tibial bone characteristics and strength in broilers. Turk J Vet Anim Sci 2001;25: 797e802.

    Leytem AB, Plumstead PW, Maguire RO, Kwanyuen P, Burton JW, Brake J. Interaction of calcium and phytate in broiler diets. 2. Effects on total and soluble phosphorus excretion. Poult Sci 2008;87:459e67.

    Liu N, Cowieson AJ. Effect of phytic acid and pH value on the activation of chicken pepsinogen in vitro. In: Proceedings of the 22nd annual Australian poultry science symposium; 14e16th February 2011. p. 84e7. Sydney, New South Wales, Australia.

    Maenz DD, Engele-Schaan CM, Newkirk RW, Classen HL. The effect of minerals and mineral chelators on the formation of phytase-resistant and phytasesusceptible forms of phytic acid in solution and in a slurry of canola meal. Anim Feed Sci Tech 1999;81:177e92.

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