Accessibility of herbage allowance and ingestive behavior of beef cattle

Abstract

Rate of intake may be accelerated when grazing cattle ( Bos taurus) are given access to fresh pasture. Two experiments using a balanced change-over design and tethered adult cows of 471±18 kg liveweight were used to measure the effect of accessibility of alfalfa ( Medicago sativa L.) on ingestive behavior. In the first experiment, herbage dry matter (DM) allowances of 10.5 kg were available for 90 min in one, two or three equal portions by area and time. These treatments had little effect on ingestive behavior and cattle ate DM at a mean rate of 2.25 kg h −1 by taking bites of 1.5 g DM at 25 bites min −1. In a second experiment, cows had access to 8.8 kg herbage DM allowances as a whole (T 1), in two equal portions (T 2) in time and area within the same plot, or in two separate plots (T 3). A mean rate of DM intake of 2.2 kg h −1 was attained by forming bites of 1.6 g at 23 bites min −1. Accessibility of allowance had no significant ( P<0.05) effect on ingestive behavior. Rates of biting immediately before and after the change-over were 26 and 20, 17 and 33, and 16 and 28 for T 1, T 2, and T 3, respectively. It was apparent that rates of biting accelerated when cows were exposed to fresh swards but the effects were transitory and contributed little to overall rates of DM intake.