Abstract
In November 1971, Italian ryegrass (Lolium multiflorum Lamarck) was infected with crown rust (Puccinia coronata Corda) at field in National Institute of Animal Industry. It was considerable that there was a deterioration of its crop quality besides loss in yield. Therefore to determine the influence of disease on forage quality was indispensable for production of good feedstuff. This investigation was undertaken to evaluate the influence of crown rust infection on the chmical composition and nutritive value of Italian ryegrass.
Dry matter percentage of 0-IV were about 18% and V 36%. Thus, fresh weight of Italian ryegrass did not much decrease up to IV severity of crown rust infection. In color of samples, 0 showed bright green, then with increasing disease severity the color faded away into yellowish brown, and showed brown. The optical density at 432nm and 664nm chromogen decreased in more than disease severity III. The percentage of cell content, water soluble carbohydrates, crude protein and true protein also gradually decreased, while crude fiber, lignin, crude ash and crude silica were almost proportional to the area covered by rust lesions. Especially non-digestible fiber fraction increased remarkably and crude silica content in V was four times as much as in the quantity in 0. These may explain a decrease in digestibility, resulting in lower forage quality. Of other minerals, Sodium was abundant in mild infected plant and little in severe infection, while Calcium was in reverse tendency. Contents of Phosphoric acid, Potassium and Magnesium were constant through all disease severity.
