Document Type

Thesis - University Access Only

Award Date

2004

Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Hans H. Stein

Abstract

A series of studies was conducted with the objective of formulating, implementing, and verifying a new method for measuring phosphorus (P) digestibility in feed ingredients. The first study was designed to measure amino acid digestibility in a newly developed diet. Apparent (AID) and standardized (SID) ilea] digestibility were measured in soybean meal (SBM) and in two P-free diets based on pork-gelatin or beef-gelatin. Results showed that the two gelatin sources were similar to SBM in the digestibility of all amino acids except for His and Thr in the beef gelatin diet. With the supplementation of crystalline His, Ile, Met, and Trp, both gelatin sources were found to be well suited as amino acid sources in a P-free diet. In the second study, the P-free diet based on pork[1]gelatin was used to measure apparent (A TTD) and true (TTTD) total tract digestibility of P in five different sources of inorganic P. The five feed phosphates were dicalcium phosphate (DCP), monocalcium phosphate with 70% purity (MCP70), monocalcium phosphate with 85% purity (MCP85), monocalcium phosphate with 100% purity (MCP I 00), and monosodium phosphate (MSP). The A TTD of P for MSP was higher (P < 0.05) than for DCP, MCP70, and MCP85 (91.9 vs. 81.5, 82.6, and 81.7%, respectively), but the ATTD for MCPI00 (88%) was not different from any of the other P-sources. The endogenous loss of P was measured in pigs fed the P-free basal diet and was estimated at 0.139 g per kg DMI. For MSP, the TTTD was 98.2%. This value was higher (P < 0.05) than the TTTD for DCP, MCP70, and MCP 85 (88.2, 89.5, and 88.4%, respectively). For MCP 100, a TTTD of 94.9% was calculated - this number was not different from the TTTD for any of the other P-sources. In the final study, the same P-sources as used in exp. 2 were used in a slope-ratio assay to measure the relative bioavailability of P in each source, and these values were compared to the values for bone density. It was found that MSP, MCPIO0, MCP85, and MCP70 had a higher (P < 0.05) bone ash contents than DCP. Likewise, pigs fed MSP had a higher bone breaking strength than pigs fed DCP. Global bone mineral content and global bone mineral density were measured on Dual-energy X-ray Absorptiometry (DXA). The cortical area and total mineral content of bone at the 50% slice was measured on Peripheral Quantitative Computed Tomography (pQCT) and had a high correlation with bone breaking strength. It was concluded that P in MSP has the highest digestibility and availability of the inorganic feed phosphates, followed by MCP 100. Numerically, the lowest digestibility and availability of P is in DCP, while there are no differences between the different sources of MCP.

Library of Congress Subject Headings

Swine -- Feeding and feeds.
Phosphorus in animal nutrition.
Digestion.

Publisher

South Dakota State University

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Rights Statement

In Copyright