Utilizing Solanum glaucophyllum alone or with phytase to improve phosphorus utilization in broilers

Iowa State University, Ames, Iowa 50010, USA.

Experiments were conducted to determine if Solanum glaucophyllum (SG), a plant containing a glycoside of 1,25-dihydroxyvitamin D, could be used as a feed additive to improve P utilization of broilers. SG leaves (1, 2.5, or 5 g/kg), 1,25-dihydroxyvitamin D (15 microg/kg), or Ca and P (to achieve a 0.92% Ca:0.65% P:0.41% nonphytate P control diet) were added to a 0.56% Ca/0.45% P/0.28% nonphytate P basal diet and fed to broilers from 7 to 28 d of age. Birds fed basal ration alone exhibited reduced weight gain, bone density, and bone mineral content when compared with birds fed the 0.92% Ca:0.65% P diet. Adding 5 g SG leaves or 15 microg of 1,25-dihydroxyvitamin D/kg to the basal diet increased body weight gain, plasma Ca and P, bone ash, and bone density above basal diet levels. Plasma P and weight gain of birds fed 5 g SG or 15 microg of 1,25-dihydroxyvitamin D/kg basal diet were equivalent to those observed in birds fed the 0.92% Ca:0.65% P diet. In experiment 2, the effect of higher doses of SG, as well as the additive effect of SG with 1,200 phytase units/kg diet, were examined in chicks fed a 0.59% Ca and 0.42% P basal diet. Two levels of SG leaves (7.5 g and 10 g), phytase, or both SG (7.5 g) and phytase were added per kilogram of basal diet. Adding SG or phytase to the basal diet increased weight gain, plasma Ca, plasma P, and bone mineral content over that observed in birds fed basal diet alone. Combining SG with phytase provided no significant gains in growth or bone parameters over treatment with phytase alone.