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Comparison of genetically engineered Aspergillus and canola in weanling pig diets. In the swine studies, similar levels of the two sources
of phytase were included in the corn-soybean meal based diet that contained
0.35% total phosphorus, 0.09% available phosphorus, and 0.50% calcium.
Both sources of phytase were equally effective in increasing daily gain;
feed efficiencies; apparent digestibilities of dry matter, phosphorus
and calcium; and 10th rib bone strength measurements. Fecal phosphorus
excretion was reduced with phytase addition. General necropsy and histological
examinations of tissue indicated no toxic effects of the phytase. These
studies indicate that the efficiency of genetically engineering Asperillus
niger (Natuphos) or canola (Phytaseed) was similar for improving phytate
phosphorus utilization in practical corn-soybean meal diets for broilers
and swine. No toxic effects were observed feeding 2,500 U/kg of diet
in these experiments. The significance of these studies indicate that
plants may be genetically modified to contain a microbial phytase gene
and the activity of the phytase may be as effective in improving phytate
phosphorus as adding microbial phytase to the diet. |
