Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Robert C. Thaler


This study was conducted to determine the effect of body weight and reproductive status on apparent ileal digestibility coefficients (AID) and apparent total tract digestibility coefficients (ATTD) of P, and the efficacy ofphytase in pigs. The study was divided into three phases. In phase 1, piglets from 10 to 40 kg BW were used; in phase 2, growing pigs from 40 to 130 kg BW were used; and in phase 3, multiparous sows (ave. parity= 5) were used. In each phase, six animals were surgically fitted with a T-cannula in the distal ileum. Two experimental diets were formulated. Diet 1 was a com-soybean meal-canola meal-based diet containing 0.45% total P without phytase supplementation and diet 2 was identical to diet 1, but supplemented with 500 FYT/kg of Peniophora lycii phytase (Ronozyme P®). The Ca to total P ratio was 1.1: 1 in both diets. Chromium oxide was included in the diets at 0.25% as an inert marker. In growing pigs, AID and ATTD were detennined at 10, 20, 40, 70, 100, and 130 kg BW. In sows, AID and ATTD were determined in each trimester of gestation and in lactation. In phase 1, BW had no effect (P > 0.05) on AID or on ATTD of P regardless of the diet being fed. As BW increased from 40 to 130 kg, AID and ATTD of P decreased linearly (P < 0.05) regardless of the diet fed. In phase 1 and phase 2, phytase supplementation improved (P < 0.05) both AID and ATTD of P. In phase 3, an increase (P < 0.01) in AID and ATTD of P was observed as sows proceeded through gestation and lactation regardless of the diet being fed. Phytase addition increased (P < 0.05) AID only during lactation. Phytase improved (P < 0.05) ATTD in the last trimester of gestation and in lactation. No differences between AID and ATTD of P were observed (P > 0.05). Efficacy of phytase was highest in lactating sows, followed by growing-finishing pigs, piglets and gestating sows. In conclusion, the physiological status of the pig affects apparent digestibility of P and the efficacy of phytase.

Library of Congress Subject Headings

Swine -- Feeding and feeds.
Sows -- Feeding and feeds.
Swine -- Weight.
Phosphorus in animal nutrition.


South Dakota State University



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