Phytate utilization and phosphorus excretion by broiler chickens fed diets containing cereal grains varying in phytate and phytase content

Abstract

Eighty, 12-day-old, male broiler chicks, were fed one of four diets to determine the effects of feeding grains varying in phytate phosphorus (P) and intrinsic phytase activity on ileal and excreta P digestibility and composition. The diets contained approximately 970.7 g grain kg −1 (maize, high fat-low lignin oat, normal barley or low-phytate barley) with the cereal supplying the sole source of dietary P. The diets were fed for a 7-day acclimation period followed by a 2 day excreta collection while ileal digesta was collected at slaughter on day 21. The coefficients of ileal apparent digestibility (CIAD) for P and phytate P ranged from 0.79 (normal barley) to 0.86 (maize and low-phytate barley) and 0.76 (low-phytate barley) to 0.89 (maize), respectively. The CIAD for phytate P was significantly greater in the maize and high fat-low lignin oat diets, while the low-phytate barley diet had the lowest coefficient (P>0.002). The coefficients of total tract apparent digestibility (CTTAD) for P and phytate P ranged from 0.25 (maize) to 0.35 (low-phytate barley) and 0.90 (maize and low-phytate barley) to 0.96 (high fat-low lignin oat), respectively, with no significant differences between diets. There was Abbreviations: AOAC, Association of Official Analytical Chemists; Ca, calcium; CIAD, coefficient of ileal apparent digestibility; Cr, chromium; CTTAD, coefficient of total tract apparent digestibility; P, phosphorus; 31 P NMR, 31-phosphorus nuclear magnetic resonance spectroscopy. Author's personal copy A.B. Leytem et al. / Animal Feed Science and Technology 146 (2008) 160-168 161 very little phytate P in excreta regardless of the type of grain fed (<0.13 of total P) with no significant differences between diets. Phytate P degradation was not related to the level of intrinsic phytase in the diet. In summary, current results indicate that, regardless of the type of grain fed, dietary phytate P is highly digestible when large amounts of calcium and P are not added into poultry diets and little phytate P is excreted.

Intestinal and total tract phytate digestibility and phytase activity in the digestive tract of hens fed a wheat-maize-soyabean diet

“…The authors concluded that the absorbed P was re-directed into the excreta, likewise via the urine. A similar finding has been reported in broiler chickens by Leytem et al (2008b).…”

“…It has been shown in the excreta of laying hens on a maize-soyabean diet (Marounek et al, 2008a), broiler chickens (Leytem et al, 2008b), and in other animal species (for references see Marounek et al, 2008b). As for the total P concentration in the excreta, similar values were reported in laying hens on a wheat-maize-soyabean diet by Zobac et al (1998).…”

“…Kerr et al (2000) pointed out the role of microorganisms in the crop and hindgut in phytate hydrolysis, and results of Leytem et al (2008b) demonstrated that the majority of phytate P hydrolysis occurred prior to the terminal ileum, with only a 1-18% increase in the phytate P hydrolysis in the hindgut. Phytate-degrading lactic acid bacteria from the chicken intestine have been reported by Raghavendra and Halami (2009).…”

Effect of Low- And High Phytase Barley on Phosphorus Retention and Bone Mineral Composition in Broilers

“…Destruction of endogenous phytase had only a little negative influence (P > 0.05) on the total P retention coefficient and bone mineral density. Similar results with different intrinstic phytase activity of cereal grains (16-99 U/kg) were reported by Leytem et al (2008). In contrast, the effect of endogenous phytase was significant (P < 0.05) in the present study.…”

The quality of different mono- and dicalcium phosphates estimated on the basis of their crystalline phases, chemical composition, solubility, and biological parameters of broiler chickens

“…The low availability of native phosphorus from the phytates present in natural feeds, especially in grains (the main components of poultry diets), makes it necessary to add microbial phytases to diets (Leytem et al, 2008). Nonetheless, the supplementation of phosphates, inorganic phosphorus sources, in broiler diets is still indispensable.…”