Effect of Phytase Addition on Growth and Carcass Traits of Pigs Fed Diets Deficient in Lysine, Calcium, and Phosphoruss

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© 2009 American Registry of Professional Animal Scientists. One hundred fifty gilts (initial and final BW 20 and 107 kg, respectively) were used in a 106-d experiment to determine the effects on growth performance and carcass traits of phytase addition to diets deficient in Lys, Ca, and P. The treatments were 1) positive control [NRC adequate in amino acids (AA), ME, Ca, and P]; 2) a diet with 85% of the Lys of diet 1, but adequate in Ca and P (85L+CaP); 3) 85L+CaP with 500 phytase units/kg phytase, expected to supply Lys, ME, Ca, and available P (aP; 85L-CaP+Phy); 4) 85L-CaP+Phy but with no added phytase (85L-CaP-Phy); and 5) 85L-CaP-Phy but adequate in Ca and P (85L+CaPE- AA). The nutrient matrix values used for the phytase addition were as follows: Ca 144%, aP 144%, ME 15,246 kcal/ kg, Lys 12%, Met 5%, Thr 5%, and Trp 2%. The phytase was provided at 0.083% of the diet and therefore was expected to provide the following nutrients: Ca 0.12%, aP 0.12%, ME 12.7 kcal/kg, Lys 0.01%, Met 0.004%, Thr 0.004%, and Trp 0.002%. Treatment diets were fed in a 4-phase feeding program. The standardized ileal digestible Lys levels in the control were 0.91, 0.79, 0.69, and 0.57% for diet changes at 20, 44, 68, and 87 kg, respectively. Each treatment was replicated 5 times with 6 gilts each. Pigs fed diets with reduced Lys concentrations had lower daily gain (P < 0.01) than pigs fed the control diet. Pigs fed 85L-CaP+Phy had G:F equal to, or slightly greater, than pigs fed the control or 85L+CaP, but pigs fed 85L-CaP+Phy had greater G:F than pigs fed 85L-CaPPhy (P < 0.05). Pigs fed a phytase-added diet with reduced levels of Lys, Ca, aP, and ME had G:F not different from, and slightly greater than, pigs fed the control or 85L+CaP. However, G:F was reduced in pigs fed 85L-CaP-Phy. Pigs fed 85LCaP+ Phy had greater lean and backfat than pigs fed 85L+CaP. Phytase addition increased bone-breaking strength, but not to the level of pigs fed the diets with added Ca and aP. In conclusion, phytase addition improved utilization of Ca and P and some data (but not all) suggest that phytase addition improved utilization of Lys and ME.

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Professional Animal Scientist

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