Bite size characteristics of Holstein and Japanese black steers grazing ryegrass-dominant pasture of different heights in boxes
1991
Betteridge, K. (National Grassland Research Inst., Nishinasuno, Tochigi (Japan)) | Shioya, S. | Ochiai, K. | Togamura, Y.
Bite size of 3 or 4 Holstein and 3 or 4 Japanese Black yearling steers were estimated on 4 occasions from spring (trial 1) through autumn (trial 4) on ryegrass-dominant turfs. Turfs in trays (460 x 600 x 100mm) were fed to cattle for a maximum of 20 bites or 3 minutes and reductions in weight and canopy height (bite depth) were measured. Two high (20cm) and two medium (13cm) length turfs were offered to 4 animals of each breed on each of 4 days in trial 1. In trials 2-4 one high, one medium and one low (8cm) turf were offered to 3 animals of each breed on each of 3 days. No differences in bite size (dry matter (DM) intake/bite), bite area or bite volume were found between the breeds in any season. Bite depth increased from between 1.7 to 4.3cm on low turfs to between 11.0 to 12.8cm on high turfs (P0.05). Mean bite area (43.6 square cm) tended to be smaller in the low turfs (P0.01, trial 2) than in the medium and high turfs. Bite volume was greatest on high turfs (565 cube cm) and smallest on low turfs (73 cube cm; P0.05). DM intake/bite and organic matter intake/bite/kg live weight in trials 2 and 4 were greater (P0.05) on high than on low turfs which contained a high proportion of dead material in the uppermost horizon. Highest DM intake occurred in late summer (August) when pasture DM content in the grazed horizon (28%) was greatest
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