The effect of feeding phytase alone or in combination with nonstarch polysaccharides-degrading enzymes on broiler performance, bone mineralization, and carcass traits

Abstract

A broiler study was conducted to compare the effectiveness of nonstarch polysaccharides-degrading enzyme (NSPase) in the presence of high dose of phytase, by comparing the effect of phytase alone or in combination, on growth performance, bone mineralization, and carcass traits. In total, 4,536 day-old male broiler birds were randomly allocated into 9 dietary treatments with 14 replicates and 36 birds in each/per replicate. A standard diet was used as a benchmark (positive control [PC]), containing corn, soybean meal, and corn distillers dried grains with solubles to meet the requirement for normal growth, followed by a 2 × 4 factorial design, namely 2 levels of nutrition (negative control [NC] 1, reduced AME 75 kcal/kg, digestible amino acids (DAA) 3%, calcium and available phosphorus [Ca and avP] 0.15 percental units; NC2, reduced AME 150 kcal/kg, DAA 6% and Ca and avP 0.20 percental units), and 4 enzyme programs: 1) no added enzymes; 2) phytase alone (1,000 FTU/kg, Buttiauxella sp.); 3) phytase (1,000 FTU/kg, Buttiauxella sp.) + NSPase (1,250 VU/kg of Talaromyces versatilis, Rovabio Advance T) as 2 separate enzyme preparations; and 4) 2 enzymes of the same origin and activity level but premerged as 1 enzyme preduct (2 in 1 Combo, Rovabio Advance Phy T), to gain logistic and cost advantages over 3). The diets were fed in 3 phases as starter (day 0–10), grower (day 11–21), and finisher (day 22–35). The results showed that birds responded proportionally to the tiered reduction of nutrients on weight gain (2,375, 2,313, and 2,222 g, P < 0.05), feed efficiency (mortality-corrected feed conversion ratio [mFCR] 1.533, 1.596, and 1.677, P < 0.05), and performance index (PI) (437, 409, and 375, P < 0.05) for PC, NC1, and NC2, respectively. The birds also responded to the enzyme program accordingly: the addition of phytase alone improved both mFCR and bone mineralization (P < 0.05), further supplementing with NSPase significantly (P < 0.05) improved overall performance including growth rate, mFCR, and PI. Interactions were observed between the levels of nutrients and enzyme programs. Supplementing both phytase and NSPase showed more strength to help birds to recover mFCR than using phytase alone. For NC1, while using phytase alone recovered 8 PI points, inclusion of both phytase and NSPase restored PI to the PC level; For NC2, despite the addition of both enzymes recovered 20 PI points (P < 0.05), none of enzyme programs was able to restore PI to the PC level. The results suggest the phytase and NSPase function synergistically in the gastrointestinal tract, resulting in improved digestion and absorption of nutrients.