Abstract
Voluntary intake and apparent digestibility of an artificially dried tropical grass, Cynodon nlemfuensis variety nlemfuensis. was evaluated utilizing Holstein bull calves. Two regrowth ages of grass hays, 30 and 45 days, were fed to two groups of four calves each: 16 and 24 weeks old. The grass hays were analyzed for dry matter and crude protein and for fiber fractions according to Goering and Van Soest. There were no significant differences between means for voluntary intake (g/kg body weight (BW)/day) of the chemical constituents for the four calf-hay groups. However, the trend was for higher intake by the 24-week old calves fed the 30-day hay than by the other three groups. Among the 16- week old calves, there was a higher voluntary intake by those consuming the 45-day hay despite the slightly higher nutritive value of the 30-day hay. When the data were pooled across calf ages, voluntary intake of 30-day hays was greater than for the 45-day ones, although only differences in crude protein intake were significant (P < .05). Pooled across hay ages, voluntary intake by the 24-week old calves was significantly greater (P < .05) than by the 16-week old calves for dry matter and neutral-detergent fiber only, indicating that hay intake was related to reticulo-ruminal capacity. Differences in apparent digestibility were significant (P < .05) only for crude protein with the 24-week old calves fed the 30-day hay, having a greater coefficient of digestibility than the 16- and 24-week old calves fed the 45-day hay. Crude protein digestibility of the 30-day hays (pooled across calf ages) was significantly greater (P < .05) than that of the 45-day hays. Although not significant for all constituents, the values were higher for the 30-day hay than for the 45-day hay (pooled across calf ages) and for the 24- week old calves than for the 16-week old calves (pooled across hay ages).