Estimation of True Phosphorus Digestibility and Endogenous Phosphorus Loss in Growing Chicks Fed Conventional and Low-Phytate Soybean Meals

Abstract

This study evaluated regression of total P output against dietary P intake to simultaneously estimate endogenous P loss and true P utilization in broiler chicks. Soybean meal (SBM) served as the model ingredient, and a comparison was made between conventional and low-phytate SBM varieties. These feedstuffs were chosen to minimize nutritive differences to dietary phytate content. Low-phytate SBM contained 57% less phytate than conventional SBM. Four isocaloric diets were formulated to contain graded levels of each soybean meal (8 diets total); therefore, the diets also contained graded levels of dietary P. Chromium sesquioxide was included in diets as an indigestible marker, and free access to experimental diets was provided to 288 male broiler chicks from 15 to 22 d posthatch. The experiment was arranged as a randomized complete block design with 6 blocks of 8 cages (6 birds per cage) and similar initial BW across dietary treatments. As P intake ranged from 0.9 to 3.9 g/ kg of DM, apparent prececal P digestibilities increased (linear and quadratic, P < 0.01) for conventional SBM and low-phytate SBM. Increasing linear relationships (P < 0.01) were observed for total P output (mg/kg of DM intake) with graded P intake, regardless of SBM variety. True P retention was greater (P < 0.01) for low-phytate SBM (76.9%) than for conventional SBM (59.8%). Endogenous P estimates were not different between soybean meals (P > 0.10), and an overall estimate of 235 mg of P/ kg of DM intake was observed. This study concluded 1) the regression approach may be applicable in the estimation of endogenous P loss in broiler chicks and 2) the difference in P utilization between conventional and low-phytate soybean meals is influenced by dietary phytate content when broiler chicks are fed P-deficient diets.

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

“…There is little published data reporting CIAD of cereal grains included in diets with low P and Ca levels. Dilger and Adeola (2006) reported ileal P digestibility coefficients of 0.83-0.85 when broiler chicks were fed low-phytate or conventional soybean meal diets without Ca additions, which was similar to the apparent ileal P digestibilities obtained for all of the cereal grains evaluated in the present study. Tamim and Angel (2003) reported an apparent P absorption of 0.65 when broilers were fed a maize-soybean meal diet.…”

Coefficient of standardized total tract digestibility of phosphorus in oilseed meals and distillers dried grains in growing-finishing pigs

“…The CTTAD and CTTSD of P in SBM from the current study are greater than those reported in other studies (Bohlke et al, 2005;Dilger & Adeola, 2006;Akinmusire & Adeola, 2009;Almeida & Stein, 2010;NRC, 2012). The digestibility of P among sources of SBM used in this study showed no differences.…”

Endogenous losses and true digestibility of phosphorus in rice bran with or without phytase determined with piglets

“…Another possibility to lack of phytase effect could be the phosphorus intake above the requirements of piglets since a condition to observe when using the regression method is that the test nutrient intake must be below requirements (DILGER & ADEOLA, 2006). However, assuming that the total apparent digestibility of total P in the diet is 53.8%, the total consumption of digestible P was approximately 1.45gd -1 , a value that represents about 70% of requirements for piglets within the weight range used in this paper (NRC, 2012).…”