Studies of the Effect of Phosphate Fertilization on the Composition and Nutritive Value of Certain Forages for Sheep

Phosphate fertilization of soybean hays grown on a Bladen silt loam soil deficient in phosphorus produced no significant change in composition as measured by standard feedingstuffs analysis, which included calcium and phosphorus. This was also true of the bull grass contaminant. Fattening trials and digestibility studies with lambs using soybean hay for roughage and raw soybeans for concentrate gave no significant differences either in weight gains or apparent digestibilities between feeds from phosphate-fertilized and those from non-phosphate-fertilized plots. When cerelose replaced soybeans as the concentrate, lambs which received soybean hay fertilized with phosphate gained an average of .282 pound daily per lamb as compared to .192 pound for the non-phosphate group. This difference was significant at the 5 percent level. Digestion studies using soybean hay alone as well as with cerelose as the concentrate on a second hay crop gave a significantly higher apparent digestibility for the protein of hay from the phosphate-fertilized plots. This was shown to be related to the quantity of protein rather than the quality of protein. Serum phosphate values and digestibility of ash by lambs fed hay from phosphate-fertilized plots plus cerelose were higher than those lambs receiving hay from non-phosphated plots plus sugar. Generalizations on the influence of fertilization on the nutritive value of plants for animal feed are not warranted at this stage of the investigation.