Efficacy of phytase in improving the bioavailability of phosphorus in soybean meal and corn-soybean meal diets for pigs

Abstract

Four experiments involving 225 pigs were conducted to assess the efficacy of a microbial phytase (FINASE, Alko Ltd. Biotechnology, Rajamäki, Finland) produced by Aspergillus niger in corn-soybean meal or dextrose-cornstarch-soybean meal-based diets. In two experiments with growing-finishing pigs, fortified corn-soybean meal diets were formulated to be adequate (.50%) or inadequate (.40 or .30%) in P during the growing phase followed by adequate (.40%) or inadequate (.30%) P in the finishing phase. Mono-dicalcium phosphate was the source of supplemental P. Half the diets were supplemented with phytase (500 phytase units/g). Rate and efficiency of gain and bone breaking strength were decreased when P-deficient diets were fed. Phytase supplementation of the low-P diets restored growth rate and feed:gain to levels that approached those of pigs fed the adequate-P control diet. Bone strength was partially restored to that of the controls. In two additional experiments, pigs were fed low-P basal diets in which all the dietary P came from soybean meal or a corn-soybean meal blend. Both diets contained .05% available P. Graded levels of monosodium phosphate were added to these diets, up to .15% added P, to establish a standard curve. Phytase was added to the basal diet at 250, 500, or 1,000 units/g. Growth rate and bone strength improved linearly (P < .01) with added monosodium phosphate and with increasing levels of supplemental phytase. Based on estimates of total and available P intakes, the highest level of phytase (1,000 units/g) increased the bioavailability of the P from 25% in the soybean meal diet to 57% in the phytase-supplemented diet, and from 15% in the corn-soybean diet to 43% in the phytase-supplemented diet. Expressed on the basis of the improvement in phytate P availability, this level of phytase converted approximately one-third of the unavailable P to an available form. The results indicate that the phytase was efficacious in improving the bioavailability of phytate P for pigs.

Desempenho, características de carcaça e composição óssea de suínos alimentados com diferentes níveis de ractopamina e fitase

“…A capacidade de suínos alimentados com dietas contendo fitase exógena em manter o mesmo desempenho em relação a dietas com fonte inorgânica de fósforo também foi apontada por trabalhos anteriores (Ludke et al, 2002(Ludke et al, , 2000Han et al, 1997;O'Quinn et al, 1997;Cromwell et al, 1995Cromwell et al, , 1993. De forma semelhante, Shelton et al (2004) averiguaram que a adição de fitase reverteu os efeitos negativos das dietas com reduzidos níveis de cálcio e fósforo disponível.…”

II. Quantitative aspects of phosphorus absorptionin ruminants

“…The question of the efficiency of phytase is important since phytate phosphorus, under the IP6 form, escaping the rumen without degradation might not be hydrolysed further in the digestive tract. In fact, the only phytase activity observed in the lower digestive tract is very low phytase activity of enterocytes in pigs [46] or in chyme in the distal ileum [1], probably unable to completely hydrolyse phytate under IP6 form [47]. Undegraded phytate phosphorus, still under IP6 form, is though to be unabsorbed [1,48] and phytate decreases the digestibility of other nutrients by inhibiting digestive enzymes [49] or binding with proteins [44] or with dietary minerals [50].…”

The effect of microbial phytase in diets for pigs on apparent ileal and faecal digestibility, pH and flow of digesta measurements in growing pigs fed a high-fibre diet

“…Normally, mucosal-phytase levels in pigs are,oo to* ,r, to affect the digestion of phytate (Pointillart 1988). As such, a substantial amount ofundigested dietary P is excreted in the manure (Cromwell et al 1993 (Lolas et al 19'16;pointillart, 1993).…”