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Pigs lack salivary or gastric phytase and endogenous phytase activity generated by the small intestinal mucosa is insufficient to hydrolyze phytate P. Thus, unused P will be excreted and may lead to environmental pollution if not managed properly. The objective of the present study was to study the efficacy of 500 FTU C. braakii microbial phytase/kg in lactating sows fed a pelleted wheat-based diet low in available P on apparent total tract digestibility coefficients (CATTD) of P, calcium (Ca), crude protein (CP), and gross energy, concentrations of plasma variables associated with nutrient uptake in comparison to a diet formulated to normal available P. Sow feed intake and body weight (BW) changes were monitored to ensure that sow performance was maintained. In total, 45 gestating sows (Large white × Landrace) were individually housed and fed 1 of 3 experimental diets: (1) positive control (PC; 5.2 g available P/kg), regular sow diet containing inorganic P; (2) negative control (NC; 2.0 g available P/kg) without inorganic P; and (3) NC + 500 FTU/kg diet (NC + PHY). Sows were fed from day 108 of gestation to day 15 of lactation. Blood samples were collected at day 1 and 15 of lactation to determine plasma minerals (P, Ca, magnesium, copper, iron, and zinc) and plasma urea, glucose, total protein, albumin, and globulin.
At day 15 of lactation, CATTD phytase supplementation to NC increased (P<0.05) CATTD of P from 0.34 to 0.46 compared to NC, but did not affect CATTD of CP, gross energy, and Ca. On day 1 of lactation, plasma P was 0.66 mmol/L lower (P<0.05) in sows fed NC than PC. Phytase supplementation to NC increased (P<0.05) plasma P by 0.40 mmol/L on day 1 but not on day 15 of lactation. Sow performance was measured as feed intake and body weight changes and did not differ between PC and NC or phytase supplementation to NC.
In conclusion, supplementing a wheat-based, low P diet for lactating sows with C. braakii-derived 6-phytase at 500 FTU/kg increased P digestibility and thus offers a means to reduce fecal P excretion by sows. Hence, it may reduce feed cost by reducing the amount of inorganic P added to sow diets and may reduce the environmental pollution.
Nasira, Z., Brozb, J. and Zijlstra, R.T. 2014. Supplementation of a wheat-based diet low in phosphorus with microbial 6-phytase expressed in Aspergillus oryzae increases digestibility and plasma phosphorus but not performance in lactating sows. Animal Feed Science and Technology, 198; 263-270. doi.org/10.1016/j.anifeedsci.2014.10.008