Ingestion Control in Growing Ruminant Animals by the Components of Cell-wall Constituents

The ad libitum intake by growing Jersey steers of seventeen forages (16 orchardgrass, 1 alfalfa) harvested dtu-ing 1964 and 1965 involved 109 observations (67 individual, 42 preference). The daily mean dry matter intake by steers fed individually ranged from 254 to 366 g per W'~t First harvests were ingested at slower rates than aftermaths; alfalfa was found to give a greater intake than all grasses; and as date of harvest was delayed, consumption declined. Ingestion choices (preference studies) of the grasses were inversely related to harvest dates or regrowth interval for both first and aftermath forages. Alfalfa was consumed by steers in preference to all grasses. When dry matter intake (g)was expressed per W '~' for 109 observations, it was significantly (P < .01) correlated (--0.48) to per cent forage cell-wall constituents. To predict dry matter intake and digestible d1T matter intake from a functional power of W, the power of W became 0.60 when adjusted for the components of cell-wall constituents. By using stepwise regression, body weight, hemicellulose, cellulose and lignin accounted for 59, 6, 4 and 1% of the variation in dry matter intake, respectively. Similarly for digestible dry matter intake the values were 52, 12, 6 and 0%. Simple correlations showed relationships for cell-wall constituents and hemicellulose, acid-detergent fiber and cellulose, and other chemical components in relationship to dry matter intake and digestible dry matter intake.