ORCID Profile
0000-0003-2784-6922
Current Organisation
Nottingham Trent University
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Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 02-2014
Abstract: There is little consensus as to the most appropriate methodology for the measurement of gastrointestinal pH in chickens. An experiment was conducted to establish the optimum s ling method for the determination of broiler digesta pH in birds fed differing levels of dietary calcium. Ross 308 broilers (n = 60) were fed 1 of 2 experimental diets, one containing 0.8% monocalcium phosphate and 2% limestone and one containing 0.4% monocalcium phosphate and 1% limestone. Four factors were investigated to determine the most appropriate method of measuring broiler gastrointestinal digesta pH: removal from the tract, prolonged air exposure, altering the temperature of the assay, and controlling the water content of the digesta. The conditions were assessed at bird ages from 7 to 42 d posthatch. Dietary Ca content had no significant effect on in situ pH, but it contributed toward variance in ex situ pH of both gizzard and duodenum digesta. Digesta pH read higher when the digesta was removed from the tract, but the amount of time the digesta was exposed to air did not affect the reading. Digesta pH read higher when measured at room temperature than when measured at 41°C temperature made the strongest unique contribution to explaining variance in duodenum pH, and the second strongest contribution to explaining variance in gizzard pH, after diet. When water was added to the digesta, before pH determination, the pH of the digesta read higher (P < 0.001) than when measured in situ. The method that resulted in pH readings that were most representative of bird gastrointestinal environment was insertion of a pH probe directly into the gut lumen posteuthanasia, because measurement ex situ likely encourages dissociation of carbonic acid, the major buffer in the gastrointestinal tract, which causes pH to read to be higher than when measured in situ. This study shows that the method of pH measurement needs careful consideration to ensure the validity of the result.
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.3382/PS/PEW394
Abstract: Zinc (Zn) is the most vulnerable cation to complexation with phytate. An experiment was conducted to evaluate the potential of measurements of Zn concentration in the gastrointestinal tract as a marker to assess the anti-nutritional impact of phytate and susceptibility of phytate to phytase in broilers. Ross 308 broilers (n = 180) were fed one of 5 experimental diets with differing phytase activity levels, analyzed at 605, 1150, 1804, 3954, and 5925 U/kg. Broiler performance and Zn concentration, pH, and amount of phytate hydrolyzed in the gizzard, duodenum, and ileum were analyzed at d 21 post hatch. Phytate susceptibility to phytase degradation was determined in vivo and in vitro by measuring total phytate-P hydrolyzed in the tract or in conditions that mimicked the tract, respectively. Phytase activity level had a significant (P < 0.05) impact on Zn concentration and phytate hydrolyzed in the gizzard and ileum, but not in the duodenum. Strong relationships were observed between the amount of phytate hydrolyzed and Zn concentration in the gizzard in birds fed the diets with 1804 U/kg or higher levels of phytase. Phytate and phytase effects could therefore potentially be evaluated by measuring Zn concentration in the gizzard. Susceptible phytate levels measured in vivo and in vitro were almost identical in the diet with phytase activity of 5925 U/kg, but in the diets with lower phytase activity levels the in vitro assay overestimated the amount of P released. There were strong relationships between in vivo susceptible phytate level and pH and amount of phytate hydrolyzed in the gizzard, duodenum, and ileum and Zn concentration in the gizzard and ileum. This illustrates that phytate susceptibility directly effects mineral availability in the gastrointestinal tract. Measurements of Zn concentration in the gastrointestinal tract, particularly in the gizzard, can potentially be used as a marker to assess the anti-nutritional impact of phytate and susceptibility of phytate to phytase in broilers.
Publisher: Elsevier BV
Date: 07-2015
DOI: 10.3382/PS/PEV108
Abstract: There is little consensus as to the capability of poultry to utilize dietary phytate without supplemental phytase. Therefore, an experiment was conducted to examine the extent to which endogenous phytase of intestinal and cereal origin contributes to phytate degradation in birds aged 0 to 14 d posthatch. Ross 308 broilers (n = 720) were fed one of 4 experimental diets with differing dietary ingredient combinations and approximate total phytate levels of 10 g/kg, dietary phytase activity analyzed at 460 U/kg, dietary calcium (Ca) levels of 11 g/kg, and nonphytate-phosphorus (P) levels of 4 g/kg. Broiler performance, gizzard, duodenum, jejunum and ileum pH, Ca and P digestibility and solubility, amount of dietary phytate hydrolyzed in the gizzard, jejunum, and ileal digesta phytase activity were analyzed at d 4, 6, 8, 10, 12, and 14 posthatch. Intestinal endogenous phytase activity increased significantly (P < 0.001) between d 4 and 6, resulting in increased phytate hydrolysis in the gizzard (P = 0.003), jejunum (P < 0.001), and ileum (P < 0.001). Phytase activity and phytate hydrolysis continued to increase with age, with a greater phytase activity and associated increase in phytate hydrolysis and mineral utilization between d 10 and 12. Gizzard and jejunum Ca and P solubility and ileal Ca and P digestibility increased significantly (P < 0.001), and gastrointestinal pH decreased significantly (P < 0.001) between d 4 and 6. By d 14, phytase activity recovered in the ileum was approximately 45 U/kg. There were strong correlations between phytase activity measured in the ileum and phytate hydrolyzed in the gizzard (r = 0.905, P < 0.001), jejunum (r = 0.901, P = 0.023), and ileum (r = 0.938, P = 0.042). This study shows intestinal- and dietary-derived endogenous phytase activity is responsible for phytate-P hydrolysis in broilers.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.3382/PS/PEY088
Abstract: There has been discussion regarding microbial phytase replacing inorganic phosphorus (P) supplementation in broiler diets. Therefore, an experiment was conducted to examine the effect of phytase supplementation on diets low in inorganic P. Ross 308 broilers (n = 288) were fed one of 6 experimental diets in 4 phases. The control diet had 16.20, 10.90, 9.40, and 6.10 g/kg inorganic P in the Starter, Grower 1, Grower 2 and Finisher phase respectively. The remaining diets had 10.50 g/kg inorganic P in the Starter phase. Two of the diets had graded reductions in inorganic P of 5.10, 3.60, and 0.60 g/kg or 2.00, 0.50, and 0.60 g/kg for the Grower 1, Grower 2 and Finisher phase respectively, plus 500 FTU phytase. Three of the diets had inorganic P levels of 0.40, 0.50, and 0.60 g/kg for the Grower 1, Grower 2 and Finisher diets respectively and either 500, 750, or 1,000 FTU phytase. Broiler performance was analyzed at d 10, 20, 26, and 35. On d 35, ileal calcium (Ca) and P digestibility and tibia bone strength, mineralization, and mineral content were analyzed. There were no significant differences between the control diet and diet containing 1,000 FTU phytase and low inorganic P in the grower or finisher diets based on bird performance, tibia strength, and Ca and P digestibility. Birds fed the control diet had significantly higher BWG (P = 0.001), bone strength (P < 0.001) and ash content (P < 0.001) compared to birds fed the diets with 500 FTU or 750 FTU phytase and low inorganic P in the grower and finisher stages. This may be due to incomplete dephosphorylation of the inositol ring of phytate with these doses of phytase, but with 1,000 FTU phytase there was almost complete phosphate hydrolysis of each phytate. This study showed that relying on phytase alone to ensure full supply of P in broiler diets is viable in finisher diets but is not recommended in grower diets unless phytase is supplied at doses of 1,000 FTU or greater.
Publisher: Informa UK Limited
Date: 04-03-2014
DOI: 10.1080/00071668.2014.880876
Abstract: 1. In vitro assays provide a rapid and economical tool to evaluate dietary effects, but have limitations. In this study, the effect of phytase supplementation on solubility, and presumed availability, of calcium (Ca) and phosphorus (P) in soya bean meal (SBM) and rapeseed meal (RSM) based diets were evaluated both in situ and by a two-step in vitro digestion assay that simulated the gastric and small intestine (SI) phases of digestion. 2. Comparison of the in vitro findings to in situ findings was used to evaluate the in vitro assay. Ross 308 broilers (n = 192) were fed on one of 6 SBM or RSM diets supplemented with 0, 500 or 5000 FTU/kg phytase from 0 to 28 d post hatch. The 6 diets and raw SBM and RSM were exposed to a two-step in vitro assay. Ca and P solubility and pH in the gizzard and jejunal digesta and in the gastric and SI phase of in vitro digestion were measured. 3. Both in vitro and in situ analyses detected that Ca solubility was lowest when diets were supplemented with 500 FTU/kg phytase, compared to the control diets and diets supplemented with 5000 FTU/kg phytase. Phosphorus solubility increased with increasing phytase level. Both methods also identified that mineral solubility plateaus in the gastric phase. 4. Overall relationship of the two methods was strong for both determination of gastric phase Ca and P solubility (r = 0.96 and 0.92, respectively) and also SI phase Ca and P solubility (r = 0.71 and 0.82, respectively). However, mineral solubility and pH were higher when measured in vitro than in situ, and the in situ assay identified an interaction among the effects of phase, protein source and phytase inclusion level on Ca solubility that the in vitro assay did not detect. 5. This two-step in vitro assay successfully predicted phytase efficacy, but to determine detailed response effects in the animal, in situ data is still required.
Publisher: Elsevier BV
Date: 2017
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Emily Burton.