A high level of activity in the low pH conditions prevailing in the pig's upper digestive tract is another phytase feature that has been shown to impact the effectiveness of phytase application. The latest bioefficacious phytases have been developed with a view to quickly achieving maximum phytate degradation thereby improving animal performance and producer profitability. Figure 2 highlights the difference between E. coli and other phytases and the latest Buttiauxella phytase in terms of activity at low pH, where the Buttiauxella phytase shows a clear advantage over other phytases. Use of a highly bio-efficacious phytase during the post-weaning phase can help producers get around challenges caused by change of diet and environment that not only impact digestibility but also increase the maintenance energy requirements of the animal, leaving less 'spare' metabolic energy available for productive processes e.g. growth and lean gain. Table 1 shows the results of a digestibility trial in weaner pigs with diets reduced in available phosphorus by 0.20%, calcium by 0.14% and a dietary phytate P level of 0.21%. A Buttiauxella phytase used in this particular trial was as effective as the E. coli