Increased growth performance in weaned pigs fed a diet supplemented with graded amounts of two phytases

Phytase addition to swine diets generally causes a marked increase in mineral utilisation and bone strength with inconsistent effects on performance (Selle and Ravindran 2008). The aim of this study was to evaluate the effects on performance of a C. braakii-(Ronozyme HiPhos) and an E. coli-(Quantum Blue) derived 6-phytase at one, two and three times their commercial recommended feed inclusion levels in weaned pigs. The study tested the hypothesis that dosages of high phytase content in diets will give additional benefit in pigs by improving growth performance.

An experiment with 96, 28-day-old weaned pigs (Large-White x Redon) having an initial body weight of 7.9 ± 0.73 kg (mean ± SE) was performed. Pigs were randomly allotted into eight groups of 12 animals each. They were fed ad libitum for 42 days with diets based on corn, soybean meal and rapeseed meal. Diets were a positive control diet (PC) formulated to meet the animal requirements according to NRC (2012) [total P: 0.66%; total Ca: 0.80%; crude protein: 192 g/kg; metabolisable energy (ME): 14.2 MJ], or a matrix control diet (MC) with reduced nutrient content [total P: 0.55%; total Ca: 0.63%; crude protein: 188 g/kg; ME: 14.0 MJ]. The MC diets were supplemented with Ronozyme HiPhos at 1000 (H1000), 2000 (H2000) and 3000 U/kg (H3000), and with Quantum Blue at 500 (Q500), 1000 (Q1000) and 1500 U/kg (Q1500). Growth performance parameters were recorded throughout the study and average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) were calculated. Data were examined by ANOVA and differences between groups were determined by Fisher’s least significant difference multiple-range test (significant at P < 0.05).

For the first period (d 0 to 14), the ADG was improved (P < 0.05) in the H2000 group in comparison to the PC and MC groups but also to the H3000, Q500 and Q1000-fed pigs (Table 1). In the second period (d 15 to 42), all phytase-fed pigs except those in group Q500 performed better (P < 0.05) in ADG than the MC-fed pigs. Overall, ADG was improved (P < 0.05) and ADFI increased (P < 0.05) in H1000, H2000, H3000 and Q1500 treatments in comparison to MC-fed pigs.

Similar effects on performance with graded amounts of phytase have been previously reported (Kies et al. 2006; Guggenbuhl et al. 2012a, 2012b). In the present experiment, both phytases tested improved ADG similarly compared to the MC treatment group. These effects were not dose dependent. In conclusion, high dosages of phytase had beneficial effects on performance compensating for reduced nutrient levels.

Table 1.  Growth performance in weaned pigs fed graded amounts of two different phytases