PSIV-13 Basal endogenous loss, standardized total tract digestibility, and retention of Ca in sows change throughout gestation, but microbial phytase reduces basal endogenous loss of Ca by gestating sows

Abstract

Abstract The objective was to test the hypothesis that standardized total tract digestibility (STTD) of Ca and Ca and P retention and the response to microbial phytase in diets fed to sows are constant throughout gestation. Thirty-six sows (parity = 3.3) were allotted to 4 diets on d 7 post-breeding. Two corn-based diets in which calcium carbonate was the sole source of Ca and 2 Ca-free diets were formulated without or with phytase (500 units per kg). Sows were housed individually in metabolism crates during early-gestation, mid-gestation, and late-gestation, and feces and urine were quantitatively collected. Data were analyzed by repeated measures using a model that included phytase, period of gestation, and the interaction between phytase and period as fixed effects, and block and replicate as random effects. Interactions between period and phytase were not observed. The basal endogenous loss (BEL) of Ca was greater (P < 0.05) in early-gestation than in mid- and late-gestation, but phytase reduced (P = 0.002) BEL of Ca and tended (P = 0.099) to increase apparent total tract digestibility (ATTD) of P in the Ca-free diet. Phytase did not affect ATTD of DM, STTD of Ca, ATTD of P, or Ca and P retention in sows fed the diet containing calcium carbonate (Table 1). The ATTD of DM was not affected by period, but Ca retention and ATTD of Ca and P were least (P < 0.05) in mid-gestation, followed by early- and late-gestation, and the STTD of Ca in mid-gestation was also reduced (P < 0.05) compared with early- or late-gestation. Phosphorus retention was greater (P < 0.05) in late-gestation than in the earlier periods. In conclusion, BEL of Ca, STTD of Ca, ATTD of P, and Ca and P retention in sows change throughout gestation regardless of use of phytase. http://www.conferenceharvester.com/