Phosphorus equivalency value of microbial phytase in weanling pigs fed a maize-soyabean meal based diet

Abstract

Ninety-six crossbred pigs with an average initial weight of 10.3 kg were used in a 4-wk experiment to investigate the P equivalency value of microbial phytase in weanling pigs using performance, rib mineralization and faecal digestibility measurements. A 19% CP, maize-soyabean meal basal diet low in P (0.35 %) and Ca (0.50 %) was fed. Diets 1, 2, 3, and 4 contained 0, 167, 333, and 500 units (U) of added Natuphos® phytase per kg of diet, respectively. Diets 5, 6, and 7 contained no added phytase, and 0.40, 0.45, and 0.50 % P, respectively. Body weight and pen feed consumption were measured weekly. During wk 4, pen faecal samples were collected twice daily for 5 d for determination of P, Ca and DM digestibilities. At the end of wk 4, the barrow from each pen (n = 48) was killed for collection of tenth ribs for determination of rib shear force, and ash content. Adding phytase to low P diets linearly increased (P < 0.02 to 0.001) ADG, rib shear force, rib ash weight and ash percent. Added P linearly increased (P < 0.02 to 0.001) ADG, rib shear force, rib ash weight, and ash percent, Ca and P digestibility and digestible Ca and P. Based on phytase and P linear or nonlinear response equations for ADG, P digestibility, rib ash weight and rib shear force, 500 U/kg of microbial phytase was equivalent to 1.03, 0.78, 0.89, and 0.69 g of inorganic P, respectively. The average equivalency of 500 U/kg of phytase was 0.84 g of P per kg of diet.

Effects of dietary Ca/P ratio, P level and microbial phytase supplementation on nutrient digestibilities in growing pigs: precaecal, post‐ileal and total tract disappearances of OM,

“…(1996) , Yi et al . (1996) , Kemme (1998) and Radcliffe & Kornegay (1998) also observed an improvement of total tract P and Ca disappearances by adding mineral phosphate.…”

“…M roz et al . (1995) and Radcliffe & Kornegay (1998) also, observed no effect on precaecal and (or) total tract disappearances of OM, whereas Eeckhout et al . (1995) , Yi et al .…”

“…(1992) , Ketaren (1993), Kemme & Jongbloed (1994), Näsi (1994), Bruce & Sundsto‐L (1995), Yi (1996), Harper (1997), O'Quinn et al . (1997) and Radcliffe (1998) found no effect of phytase supplementation on precaecal and (or) total tract OM disappearance. Mroz (1994) observed enhanced precaecal and total tract disappearances of OM by adding 800 FTU/kg to a corn–tapioca–soybean meal‐based diet, whereas Kemme (1997a) found that dietary addition of phytase significantly reduced the total tract disappearance of OM in piglets (30–38 kg), but not in growing‐finishing pigs and sows.…”

“…(1995) , Qian (1996), Yi et al . (1996) , Kemme (1997b), Kemme (1998) and Radcliffe & Kornegay (1998) also reported improvements in total tract P disappearance from supplementing phytase to growing pig diets. However, from these studies it remains unknown whether this increased absorption of P took place precaecally or post‐ileally.…”

Phytase, a New Life for an “Old” Enzyme

“…Thus, inorganic phosphorus equivalences of phytases and their determinants in different diets for various species have been studied and reviewed intensively (8-10, 15-17, 19). Briefly, an estimated 300-600 phytase activity units/kg of diets releases approximately 0.8 g of digestible phosphorus and may replace either 1.0 or 1.3 g/kg of phosphorus from mono-and dicalcium phosphate, respectively (60)(61)(62). Meanwhile, supplemental phytase improves calcium, zinc, and iron utilization by animals (63-66).…”