Date of Award
Doctor of Philosophy
Jesse P. Goff
Broilers excrete high P in feces because they do not have much intestinal phytase activity to effectively use phytate P in feeds. Adding synthetic 1,25(OH)2D3 in chicken feeds improves P utilization by increasing dietary P absorption. We demonstrated that the leaves of Solanum glaucophyllum (Sg) containing 1,25(OH)2D3 glycosides normalized growth rate and increased tibiae ash in broilers fed decreased Ca (0.6%) and P(0.5%) diet, which is similar to the effect by using synthetic 1.25(OH)2D3. In addition, when compared to Sg treatment alone, the combination of Sg and microbial phytase further improved weight gain and bone Ca concentration when broilers were fed 0.6% Ca and 0.45% P diet. In lactating cows, excessive dietary P decreases intestinal P absorption and increases fecal P excretion. We demonstrated that decreasing dietary P from 0.37% to 0.27% reduced 48% of fecal P and increased 60% of apparent P digestibility. When Sg was added in the 0.27% P diet and compared to the effect of 0.37% P diet, fecal P was decreased 60% whereas apparent P digestibility was increased 90%. In addition, the effect of Sg on increasing positive Ca and P balance may be a benefit to lactating cows requiring large amount of Ca and P in milk secretion. Therefore, Sg could also be used as a less expensive source of 1,25(OH)2D3 in broilers and dairy cattle to improve P utilization.;Dairy cattle suffer from hypocalcemia and hypophosphatemia during periparturition. The commercial treatment solution contains Ca and phosphite ions, which corrects hypocalcemia. However, the plasma P stays low and results in recumbency in some cows. Permanent damages on nerves and muscles are occurred after 24 hours recumbency. By intravenous administration of sodium phosphate and sodium phosphite solutions in hypophosphatemic cows, we demonstrated that plasma P concentration was increased by sodium phosphate rather than phosphite solution. Oral administration of sodium phosphate increased plasma P concentration in 30 minutes and the elevation was last for more than 12 hours. We concluded that sodium phosphate, either by oral or intravenous administration should be used for the treatment for hypophosphatmic cows.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
YaHsin Joan Cheng
Cheng, YaHsin Joan, "Phosphorus utilization in domestic animals " (2001). Retrospective Theses and Dissertations. 631.