Ileal and total tract digestibility of energy and nutrients in pig diets supplemented with a novel consensus bacterial 6-phytase

The effect of microbial phytase on Ca and P digestibility in diets for pigs and poultry is well established. In poultry, it also appears that the effect of phytase in increasing amino acid (AA) digestibility is consistent, but that is not the case when phytase is added to diets for pigs. However, in many experiments, relatively low levels of phytase was used and it is not known if greater concentrations of phytase will result in a different result. A novel phytase has been recently developed; however, it is also not known if this phytase source can increase digestibility of AA and other nutrients. Therefore, an experiment was conducted to test the hypothesis that inclusion of increasing levels of the novel phytase in diets for growing pigs increases the apparent ileal digestibility (AID) of crude protein (CP) and AA, and the apparent total tract digestibility (ATTD) of gross energy (GE) and minerals.


Experimental design

A negative control (NC) diet based on corn, soybean meal, and canola meal was formulated to be deficient in Ca, P, and standardized ileal digestible AA. Five additional diets were formulated similar to the NC diet with the exception that 250, 500, 1,000, 2,000, or 4,000 phytase units/kg of the novel phytase was added to these diets. Eighteen ileal-cannulated pigs (17.81 ± 1.71 kg) were allotted to a 6 × 3 incomplete Latin square design with six diets and three 11-day periods. There were three pigs per diet in each period; therefore, there were nine replicate pigs per diet. The initial 5 days of each period were considered an adaptation period to the diet. For each period, fecal samples were collected via anal stimulation on days 6, 7, 8, and 9, whereas ileal digesta were collected on days 10 and 11 using standard procedures.



The AID of crude protein, indispensable AA, and dispensable AA increased (linear, P < 0.01; quadratic P < 0.05) as concentration of phytase increased in the diets (Table 1). Linear (P < 0.01) and quadratic (P < 0.05) increases in the ATTD of Ca, P, K, and Cu were also observed as phytase increased in the diets (Table 2). The ATTD of GE and Mg linearly increased (P < 0.05) as phytase concentration increased in the diets.


Key points

  • Inclusion of a novel consensus phytase to corn-soybean meal-canola meal based diets increased the AID of CP and AA, as well as the ATTD of GE and minerals.
  • Further investigations are warranted if and how certain factors (e.g., diet composition, phytate and phytase concentrations, and pig maturity) influence phytase efficiency on AA digestibility.


Table 1. Apparent ileal digestibility of crude protein and amino acids in experimental diets1

1Data are least squares means of 9 observations per treatment.


Table 2. Apparent total tract digestibility of gross energy and minerals in experimental diets1

1Data are least squares means of 9 observations per treatment.


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