Document Type

Thesis - University Access Only

Award Date

2007

Degree Name

Master of Science (MS)

Department / School

Animal Science

Abstract

Five experiments were conducted to determine the effects of adding an E. coli-derived phytase (Quantum) to com soybean meal-based diets fed to growing pigs. Experiments 1 and 2 were designed to determine the optimal inclusion level of Quantum when added to weanling and growing pig diets. Quantum was added at different inclusion levels from 500 to 1500 phytase units/kg (U) for weanling and 250 to 650 U for growing pigs. Growing pig performance and bone composition were compared with a fungal derived phytase (Natuphos). Weanling pig ADG increased (linear, P < 0.10) as the level of Quantum in the diet increased. The ADG for growing pigs increased (linear, P < 0.05) when pigs were fed diets containing increasing concentrations of phytase. Bone ash and mineral concentration was greater for pigs fed Quantum than pigs fed Natuphos. Experiment 3 was designed to determine the site of phytase activity in growing pigs fed Quantum or Natuphos. The apparent duodenal (ADD), ileal (AID), and total tract (ATTD) digestibility of P were calculated for a low-P diet, Quantum diet (500 U), and. Natuphos diet (500 U). The concentrations of myainositol hexaphosphate, myainositol pentaphosphate, myainositol tetraphosphate, myainositol triphosphate, and myainositol biphosphate (IP6, IP5, IP4, IP3, and IP2, respectively) in the diet, duodenal digesta, ileal digesta, and fecal samples were determined. The A TTD of P was similar for Quantum and Natuphos (42.2 and 45.3%, respectively), but both were greater (P < 0.05) than for the low-P diet (14.2%). The diets containing phytase had lower (P < 0.05) concentrations of IP6 and IP5 in the duodenal digesta compared with the low-P diet. Experiments 4 and 5 used ATTD values obtained from Exp. 3 and 3 diets (adequate-P, low-P, and Quantum) were formulated to determine the effects of feeding Quantum to growing pigs. Pig growth, P absorption, and P retention were calculated. Pigs fed the adequate P diet and the Quantum diet grew faster (P < 0.05) than pigs fed the low-P diet. Pigs fed the Quantum diet had a lower (P < 0.001) fecal P excretion (7.63 g/5d) and a greater (P < 0.01) ATTD of P (62.46%) than pigs fed the adequate P diet (11.57 g/5 d and 56.35%) or low-P diet (11.73 g/5d and 41.85%). The results from these studies show that Quantum can be fed to weanling and growing pigs without reducing pig growth or bone tissue synthesis. Quantum can replace some inorganic P that is added to pig diets and reduce fecal P excretion.

Library of Congress Subject Headings

Swine -- Feeding and feeds

Phytases

Phosphorus in animal nutrition

Format

application/pdf

Number of Pages

131

Publisher

South Dakota State University

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