M. Nasi et E. Helander, EFFECTS OF MICROBIAL PHYTASE SUPPLEMENTATION AND SOAKING OF BARLEY SOYBEAN-MEAL ON AVAILABILITY OF PLANT PHOSPHORUS FOR GROWING PIGS, Acta agriculturae Scandinavica. Section A, Animal science, 44(2), 1994, pp. 79-86
The efficacy of phytase supplement, 1200 U/kg, produced by Aspergillus
niger on phytin phosphorus (P) availability was assayed in a 6 x 6 La
tin square designed digestibility and balance trial with growing pigs
at live weight 35-88 kg. The pigs were fed on barley-soybean meal diet
s without inorganic P either soaked for 3 h or without soaking. The P
content of the control diet with added inorganic P was 6.5 g and that
of unsupplemented diets 3.7 g/kg. The calcium content was 8.0 g/kg in
all diets, and in the composition of other nutrients, the diets were e
qual. Soaking of the meal had no effect on digestibility of any nutrie
nt. The digestibility of ash in a diet supplemented with phytase was i
mproved (P<0.001). There were no differences in any organic constituen
t digestibility between the treatments. No effect on nitrogen utilizat
ion was found as a result of phytase addition or soaking. The addition
of microbial phytase improved (P<0.001) the apparent absorption of P
to 0.64 as compared to the unsupplemented 0.45. The retained P, on ave
rage 4.9 g/d in diets with supplementary phytase, was significantly hi
gher (P<0.001) than that without, 3.7 g/d. In pigs fed a diet with add
itional inorganic P, the retention of P was 5.5 g/d. P retention in te
rms of daily amount of intake was greater (P<0.001) in diets with adde
d phytase than without (0.58 vs. 0.44). From the diet with inorganic P
supplementation a significantly lower value, 0.38 (P<0.001) was achie
ved than from the unsupplemented diets. Calcium digestibility and rete
ntion tended to be higher in phytase-treated diets. Owing to its effec
t on phytate P availability in a barley-soybean meal diet, phytase tre
atment of feedstuffs allows a greater proportion of the pig's P requir
ement to be met by P of plant origin and results in reduced losses of
dietary P in faeces and urine.