Effects of Dietary Fiber and Acid-Detergent Lignin on Body Fill of Ruminating Calves

Abstract

Twenty male Holstein calves, 8 weeks of age, were used to define quantitatively the relationship between dietary fiber and stomach-fill. Calves were randomly allotted equally to five rations containing 0, 22.5, 45, 67.5 and 90% hay and fed for a 12-week experimental period. Feeding was ad libitum throughout the experiment, and intake and body weights were recorded. Fecal grab samples, taken during the last three weeks of the experiment, were used to determine digestibility of dry matter, crude protein, and fiber constituents by ratio techniques. All animals were slaughtered at 20 weeks of age to obtain stomach-fill measurements and corrected body weights. Feed intake was maximum for the 67.5% hay ration. Hay substitution for concentrute resulted in a linear increase in stomach fill. Corrected body weight gain did not begin to decline measurably until the amount of hay substitution exceeded 45% (acid-detergent fiber : 18.0%). Stomach-fill, as a per cent of live weight, declined 2.5 percentage units for each percentage unit increase in ration acid-detergent lignin. This value was similar to earlier values derived from calves consuming varying ]ignin from straw rations.