Interaction of calcium and phytate in broiler diets. 1. Effects on apparent prececal digestibility and retention of phosphorus.
Phytate P utilization from soybean meal (SBM) included in broiler diets has been shown to be poor and highly dependent on dietary Ca intake. However, the effect of Ca on P utilization and on the optimal ratio of Ca to nonphytate P (Ca:NPP) when diets contained varying levels of phytate has not been clearly shown and was the objective of this research. A factorial treatment structure was used with 4 dietary Ca levels from 0.47 to 1.16% and 3 levels of phytate P (0.28, 0.24, and 0.10%). Varying dietary phytate P levels were obtained by utilizing SBM produced from 3 varieties of soybeans with different phytate P concentrations. Ross 508 broiler chicks were fed 1 of 12 diets from 16 to 21 d of age. Excreta were collected from 16 to 17 d and from 19 to 20 d of age and ileal digesta was collected at 21 d of age. Apparent prececal P digestibility decreased when dietary Ca concentration increased and was higher when diets contained low-phytate SBM. The apparent digestibility of Ca and percentage of phytate P hydrolysis at the distal ileum were not reduced when dietary phytate P concentration increased. Including low-phytate SBM in diets reduced total P output in the excreta by 49% compared with conventional SBM. The optimum ratio of Ca:NPP that resulted in the highest P retention and lowest P excretion was 2.53:1, 2.40:1, and 2.34:1 for diets with 0.28, 0.24, and 0.10% phytate P. These data suggested that increased dietary Ca reduced the extent of phytate P hydrolysis and P digestibility and that the optimum Ca:NPP ratio at which P retention was maximized was reduced when diets contained less phytate P.
Plumstead
P W
PW
Department of Poultry Science, North Carolina State University, Raleigh 27695-7608, USA.
Leytem
A B
AB
Maguire
R O
RO
Spears
J W
JW
Kwanyuen
P
P
Brake
J
J
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000494:pharmacology*; D002645:Chickens / Q000254:growth & development / Q000378:metabolism*; D004063:Digestion / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007082:Ileum / Q000378:metabolism; D007408:Intestinal Absorption / Q000187:drug effects; D008297:Male; D009753:Nutritive Value; D016226:Phosphorus, Dietary / Q000493:pharmacokinetics*; D010833:Phytic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D011897:Random Allocation; D013025:Glycine max
D002136:Calcium, Dietary; D016226:Phosphorus, Dietary; D010833:Phytic Acid