Abstract
New methodology was developed to investigate bite weight and bite force of sheep using simulated swards, hand-constructed from bunches of orchardgrass (Dactulis glomerata L.) leaves spaced 15cm apart. These leaves were attached to the 5 three-directional loadcells with 6mm iron bolts for a measurement of bite force. Three Suffolk wethers with a mean live weight of 35kg were used. Experimental variables in two studies were levels of applied nitrogen (nil, 100 and 200kg/ha) and leaf densitv (462 leaves/m^2 in Expt. 1 and 1026 leaves/m^2 in Expt. 2). Applied nitrogen increased width, thickness, DM weight per unit length and breaking force per leaf. Mean bite force per leaf was 9.8±0.80N in Expt. 1 and 6.8±0.53N in Expt. 2, compared with the higher mean of 15.4±0.75N of tensile strength of leaves. Bite number per min, and DM intake rate decreased with increasing nitrogen application, especially at high leaf density. DM intake per bite at high leaf density was approximately double that at low leaf density. DM intake per unit force was 2.5-4.1mg/N at high leaf density and 1.2-2.2mg/N at low leaf density.
