Date of Graduation

5-2024

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Samuel J. Rochell

Committee Member

Michael T. Kidd

Second Committee Member

Casey M. Owens

Keywords

standardized ileal digestibility; apparent ileal digestibility; dietary P values

Abstract

Concerns around the economic and environmental consequences of suboptimal or excess dietary P levels in broiler diets has led to increased interest in determining ileal P digestibility values for feed ingredients. Therefore, two experiments (EXP) were conducted to determine the apparent (AID) and standardized ileal digestibility (SID) of P in various inorganic phosphates and meat and bone meals (MBM) using the direct method. In both EXP 1 and 2, ileal samples were collected at 22 d post-hatch from birds fed semi-purified diets based on dextrose and corn starch containing test ingredients and one N and P free (NPF) diet for determination of ileal endogenous P losses (IEL). In EXP 1, diets containing monocalcium phosphate (MCP), dicalcium phosphate (DCP), monodicalcium phosphate (MDCP), defluorinated phosphate (DFP), bovine meat and bone meal (B-MBM), and porcine meat and bone meal (P-MBM) were formulated to 0.31% total P and balanced to 0.65% total Ca with limestone. Monosodium phosphate (MSP) was included at 3 levels to provide 0.13, 0.23, and 0.33% total P. Apparent ileal digestibility of P values were separated on two levels of statistical significance (P<0.01) with all dietary concentrations of MSP (92.57, 91.44, and 88.53%), MCP (89.55%), DCP (90.04%), and B-MBM (92.24%) having similar and higher values than DFP (73.59%), MDCP (76.58%), and P-MBM (77.31%). Endogenous P flow was determined to be 0.075 g/kg DMI. Experiment 2 determined AID and SID of P for MSP and 5 MBM of varying physical characteristics. The MSP diets were formulated to contain 0.31% total P and 0.67% total Ca with limestone and the MBM diets were formulated to 0.31% total P and contained no added limestone. The AID of P was highest (P<0.05) for MSP (87.49%), B-MBM 2 (86.34%), B-MBM 3 (86.88%), intermediate for B-MBM 1 (83.65%) and P-MBM (83.22%), and lowest for B-MBM 4 (75.60%). Endogenous P losses were determined to be 0.042 g/kg DMI. Although all sources were highly digestible (all >73%), no P source, including MSP, was totally available. Additional work is needed to establish the factors that influence ileal P digestibility among inorganic and animal protein sources.

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