Ahmad (1993a) evaluated cereal and cereal by-products for their total and phytate phosphorus contents. The concentration of percent total P, percent available P, percent total phytate, and percent available phytate was found to be 0.24, 0.13, 0.17, 0.06 in maize, 0.17, 0.10, 0.07, 0.03 in rice, 0.16, 0.11, 0.04, 0.02 in polished rice, 0.28, 0.18, 0.18, 0.08 in wheat, 0.25, 0.15, 0.15, 0.15 in barley, 0.28, 0.12, 0.24, 0.07 in sorghum white, 0.29, 0.13, 0.18, and 0.03 in sorghum red, 0.84, 0.31, 0.66, and 0.14 in wheat bran, and 1.31, 0.20, 1.16, 0.10 in rice polishing, respectively.

Ahmad (1993b) determined the bioavailability of total and phytate phosphorus in vegetable and animal protein sources commonly used in poultry rations. The percentages of total P, available P, total phytate, and available phytate was found to be 0.36, 0.19, 0.17, 0.04 in corn gluten meal (30% CP), 0.39, 0.21, 0.21, 0.04 in corn gluten meal (60% CP), 0.91, 0.47, 0.58, 0.14 in cotton seed meal (decorticated), 0.71, 0.34, 0.42, 0.05 in rape seed meal, 0.54, 0.27, 0.16, 0.02 in guar meal, 0.93, 0.50, 0.54, 0.11 in sunflower meal, 0.47, 0.30, 0.24, and 0.07 in soybean meal, 2.40, 1.37, 0.00, 0.00 in fish meal, and 0.19, 0.12,. 0.00  and 0.00 in blood meal, respectively.

Scheuermann et al. (1988) found that phytases from wheat and maize showed their greatest activities at pH 5.0. Maize Phytase activity was only about 6% that of wheat. Wheat phytase hydrolyzed maize phytate to the same extent as wheat phytate. Zinc (0.06-0.612 mmol/litre), calcium (29 mmol/litre), and pepsin (3.5-35 000¦mol tyrosine/min) inhibited the activity of wheat phytase. He concluded that in vivo, especially in diets high in Ca, phytase of plant origin are not solely responsible for gastrointestinal phytase hydrolysis.

Ghareib (1990) produced phytase enzyme from Aspergillus carneus. Maximum enzyme yield was obtained after 8 day incubation statically in a medium containing sucrose and K2HPO4 in a carbon:phosphorus ratio of 591.8:1 with 0.1% corn steep liquor as the sole source of nitrogen. The enzyme was purified approx. 43 fold from the culture filtrate by precipitation with acetone, gel filtration through Sephadex G-75 and ion exchange chromatography on DEAE-cellulose. Maximum activity of crude enzyme occurred at 35°C and pH 5.6, where as that of the purified preparation at 40°C and pH 5.6. The pure enzyme was found stable between pH 5.6-6.2. Approx. 68% of enzyme activity was lost by heating at 45°C for 60 min. The pure phyatse retained its activity over a long period when stored at 4°C.

Simons et al (1990) developed techniques to produce microbial phytase (MP) from Aspergillus ficuum (NRRL 3135), for addition to diets for simple stomached animals. The activity of the crude MP showed pH optima at pH 5.5 and 2.5. The enzyme was able degrade phytate in vitro in soybean meal, maize and a liquid compound feed. When MP was added to low-P diets for broilers the availability of P increased to over 60% and the amount of P in the droppings decreased by 50%. The growth rate and feed conversion ratio on the low-P diets containing MP were comparable or even better than those obtained on control diets.

Schoner et al. (1991a) concluded that technology production of phyatse using Aspergillus niger makes utilization of phytate phosphorus in broilers feasible. He reported that average utilization of total P was 47 and 65% with inorganic P and phytase supplements, respectively. Using a model equation, reduction of P excretion by phyatse amounted to 50%. Under present production conditions, annual P excretion as P₂O₅ of 55 kg/dung unit coressponds with 350 broilers per dung unit; with phyatse supplements, this value is reached with 525 broilers per dung unit.

Schoner et al. (1991b) fed corn-soybean meal based diet (phytate P 2.3, total P 4.5, and Ca 6 g/kg)) to male broiler chickens (from 0-14 days), supplemented with microbial phytase (0-800 U/kg), inorganic P and Ca 0-1.2 g/kg, or Ca+P together. Results revealed that live weight gain was improved  by phyatse, P and P+Ca (P<0.05), but not by Ca. Phosphorus retention was linearly related to supplemental phytase (r2=0.75) and P (r2=0.82), respectively. From the regression equation phytase 700 U/kg was calculated to be equivalent to P 1.0 g/kg. Toe ash weight was linearly related to P retention (r2=0.76). This indicate that toe ash, which has been used as an indicator of P retension in turkey poults, is also useful in 2-week-old broilers.

Vogt (1992) conducted a 6 wk trial, in which groups of caged male broilers were given mash diets based on maize/soybean meal containing total phosphorus 7.1, 5.8 and 4.5 g and phytase 0, 500, 750 or 1000 units/g feed. He observed that decreasing dietary phosphorus decreased growth and bone mineralization and increased mortality, while phytase improved all examined variables. Regression equation showed that dietary P can be decreased by 0.1% when phytase 650-900 units/g feed is given, without influencing performance.

Kiiskinen et al.  (1994) conducted a trial on 5100 broiler chicks and found that microbial (Aspergillus niger) phytase addition (250-1000 phyatse units PU/g) increases body weight by 4-7% and feed intake by 3-9%. With 0.05 and 0.1% mineral P (as DCP), phytase addition had a non significant effect on bone mineralization. Utilisation of P increased from 50.9-60% when phytase (1000 PU/g) was added to diets without mineral P supplementation.