Standardized Ileal Digestibility of Calcium and Phosphorus in Feed Ingredients for 21-Day-Old Broilers

초록

Simple Summary Plant-based ingredients are the major constituents of poultry diets and supply a significant portion of dietary phosphorus (P). However, approximately two-thirds of the P of plant origin is bound to phytic acid, which is poorly available to monogastric animals. Broiler diets have been formulated based on non-phytate P (NPP), which might lead to the excessive use of inorganic P sources and reduced P availability for birds. Recent research has suggested using digestible P to assess availability, and due to nutritional interactions, there is also increasing interest in determining calcium (Ca) digestibility. The objectives of this study were to determine the standardized ileal digestibility (SID) of Ca and P in the feed ingredients for broilers. On day 18 post-hatch, 512 male and female broilers were individually weighed and randomly allocated to eight treatments with four replicates for each sex (eight birds/cage) in a randomized complete block design based on body weight and sex. No significant interaction between experimental diets and sex regarding the SID of Ca or P was found, and no effect of sex on the SID was observed. There were significant differences in the SID of the feed ingredients.Abstract This study aimed to determine the standardized ileal digestibility (SID) of calcium (Ca) and phosphorus (P) in various feed ingredients using the direct method. This study comprised eight experimental diets: a Ca-P-free diet and seven experimental diets, each containing monocalcium phosphate (MCP), dicalcium phosphate (DCP), monosodium phosphate (MSP) + limestone, corn, and soybean meal (SBM) as the sole sources of Ca and/or P. These diets provided 4.21 g/kg of non-phytate P from MCP, DCP, or MSP, and the MSP + limestone diet included 7.50 g/kg of Ca. The corn and SBM diets formulated to determine P digestibility maintained a dietary Ca/total P ratio of 1.4 through the addition of limestone. Chromic oxide was added to the diets as an indigestible index. On day 18, 256 male and 256 female broilers were individually weighed and randomly assigned to eight treatments, each with four replicates for each sex (eight birds per cage). This allocation followed a randomized complete block design based on body weight. On day 21, the birds were euthanized using carbon dioxide, and ileal digesta samples were collected from the distal two-thirds section of the ileum. No significant interactions between the experimental diets and sex regarding the SID of Ca or P were detected, and no effect of sex on the SID was observed. The standardized ileal Ca digestibility of MCP, DCP, limestone, corn, and SBM was found to be 84.7%, 70.1%, 52.6%, 88.6%, and 81.6%, respectively. The standardized ileal P digestibility of MCP, DCP, MSP, corn, and SBM was determined to be 91.8%, 76.8%, 94.4%, 73.1, and 88.4%, respectively. Given the variable digestibility of Ca and P across different feed ingredients, the consideration of the specific type of ingredients used in diet formulation is crucial.

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