Ingestive behaviour of beef cattle offered different forms of lucerne (Medicago sativa L.)†

A change‐over design was used to establish the ingestive behaviour of twelve adult Angus cows (Bos taurus), live weight (LW) of 475 ± 18 kg, while grazing luceme (Medicago sativa L.) (T1), eating from a swath of freshly cut lucerne (T2), or eating wilted lucerne from a swath (T3). In the first experiment, the herbage dry matter (DM) allowance was 4‐7 kg h−1 and in T1 the available herbage DM mass (>5 cm) was 2892 kg ha−1. Herbage DM intake was 2.5, 1.6 and 2.0 kg h−1 (0.53,0.35 and 0.41 kg (100 kg LW)−1h−1) for T1, T2 and T3, respectively. Cattle grazed at 29 bites min−1 and ate the swathed lucerne at 6 bites min−1. Herbage DM intake per bite was 1‐2, 4‐9 and 6‐7 (2‐5,104 and 14‐4 mg(kg LW)−1)for T1, T2 and T3, respectively. The DM content of the luceme was 227, 263 and 309 g kg−1 for the same sequence. In a second experiment with luceme of available herbage DM mass of 5321 kg ha−1 and an allowance of 7‐ 3 kg h−1 cows grazed lucerne at 2‐9 kg h−1, ate freshly cut material at 21 kg h−1 and wilted herbage at 25 kg h−1 (0.61, 0.45 and 0.52 kg (100 kg LW)−1h−1), respectively. Leaf accounted for 80%, 68% and 54% of intake for T1, T2 and T3, respectively. Swathing lucerne reduced the diet selectivity by forcing cattle to take large bites that required many jaw movements to form a bolus that could be swallowed. It appeared that the mechanics of bolus formation determined ingestive behaviour of cattle eating swathed herbage.