337
Influence of a superdose of phytase on finishing pig performance and carcass characteristics
A total of 1,188 finishing pigs (PIC 337 × 1050; initially 36.4 kg) were used in a 92-d experiment to determine the influence of providing phytase above that needed to meet the P requirement for growth and carcass characteristics. At initiation of the study pens were randomly allotted to treatments based on initial BW. There were 27 pigs per pen and 11 replications per treatment. The 4 dietary treatments were formed by increasing phytase (Optiphos 2000, Enzyvia LLC) to provide 250, 500, 1,000, and 2,000 phytase units (FTU)/kg. Diets were corn-soybean meal–based and contained 15% bakery meal and decreasing levels of dried distillers grains with solubles in each phase. Diets were fed in 4 phases from approximately 36 to 59, 59 to 82, 82 to 109, and 109 to 131 kg BW and all phases contained the same phytase concentrations. The first 250 FTU/kg of phytase was considered to provide 0.10 % P release in meeting the dietary available P levels of 0.29, 0.28, 0.24, and 0.23% and STTD P levels of 0.32, 0.31, 0.27, and 0.27% in phase 1, 2, 3, and 4, respectively, with further additions exceeding the phosphorus requirement. All other nutrients were provided at or above requirement of the pigs as defined by NRC (2012). All data were analyzed as a completely randomized design with pen as the experimental unit. Overall (d 0 to 92) increasing dietary phytase did not influence (P > 0.05) ADG but reduced (cubic, P < 0.01) ADFI, resulting in increased G:F (cubic, P < 0.01). The cubic response occurred because ADFI was reduced and G:F increased with increased phytase inclusion from 250 to 500 FTU/kg with no response from 1,000 to 2,000 FTU/kg. Phytase addition to the diet did not influence (P> 0.05) carcass measurements. These results suggest that providing phytase up to 500 FTU/kg has the potential to improve feed efficiency.
Keywords: Finishing pigs, phosphorus, phytase
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Added phytase (FTU)/kg |
|
|
|
|
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Item |
250 |
500 |
1,000 |
2,000 |
SEM |
Linear |
Quadratic |
Cubic |
d 0 to 92 |
||||||||
ADG, kg |
1.04 |
1.03 |
1.04 |
1.02 |
0.008 |
0.25 |
0.27 |
0.54 |
ADFI, kg |
2.64 |
2.53 |
2.61 |
2.57 |
0.028 |
0.49 |
0.72 |
0.01 |
G:F |
0.393 |
0.409 |
0.400 |
0.398 |
0.004 |
0.88 |
0.20 |
0.01 |
BW, kg |
||||||||
d 0 |
36.4 |
36.3 |
36.4 |
36.3 |
0.54 |
0.94 |
1.00 |
0.94 |
d 92 |
130.9 |
130.1 |
130.9 |
129.5 |
1.05 |
0.42 |
0.68 |
0.52 |