Voluntary Intake, Chemical Composition, and Nutrient Digestibility of Pangolagrass and Stargrass Hays

Abstract

Pangolagrass (Digitaria decumbens) and stargrass (Cynodon nlemfuensis) harvested at 30, 45, and 60 days and made in to hay, were fed to four castrated male ruminants (goats and steers) in individual digestion stalls. The grasses were fertilized at the rate of 4,480 kg/ha/yr with 15-5-10, harvested, sun-dried for 2 days and cut in 3- to 6-cm pieces. Each experimental period lasted 21 days, divided into a 14-day preliminary feed ing period and a 7-day collection period. Each hay was offered at a level of 90% intake, as determined in the preliminary period. Hays, offered and refused, and feces were weighed and sampled daily. Representative samples were analyzed for dry matter, crude protein, neutral-detergent fiber, acid-detergent fiber, cellulose, lignin, and silica. Hemicellulose was determined as the difference between neutral-detergent fiber and acid-detergent fiber. Apparent digestion coefficients for each fraction were calculated on all hays and all ruminants. Pangolagrass dry-matter intake was significantly (P < .01) greater than that of stargrass hay by both goats and steers. No significant differences in dry-matter intake were obtained between hay ages of 30, 45, and 60 days. Goats had a higher dry-matter intake (P < .01) than steers. Significant differences were obtained between hays in neutral-detergent fiber (P < .01), hemicellulose (P < .01), and cellulose (P < .05) contents and between hay ages in crude protein (P < .05), cellulose (P < .01), lignin (P < .05), and silica (P < .01) contents. For digestibilities, significant differences were obtained between hays in dry matter (P < .05), neutral-detergent fiber (P < 05), and cellulose (P < .01); between hay ages in lignin (P < .01) and silica (P < .01); and between ruminants in dry matter (P < .01), neutral-detergent fiber (P < .01), acid-detergent fiber (P < .01), hemicellulose (P < .01), and cellulose (P < .01). Goats may not necessarily substitute for steers in digestion trials; and lignin, but not silica, tends to be a valid marker for determining digestibility.