Grazing Behavior of Steers On Different Forage Systems Comprising Annual Ryegrass and White Clover.

Studying grazing behavior of ruminants may help in understanding utilization of forage systems of varying types and composition.  This study was conducted during 2008 at Raymond, MS to evaluate grazing time by ruminants on various forage systems in order to examine any relationship with pasture composition and stocking rate.  Annual ryegrass (Lolium multiflorum Lam. cv. Marshall) and white clover (Trifolium repens L. cv. Durana)  were used to create forage systems treatments of either a grass (MG) or legume monocultures (ML), a binary mixture of grass and legume (MIX), or a spatial system (SS) of adjacent grass and legume monocultures in 50:50 land area ratio within the same paddock.  Two levels of stocking rate (SR; 3 or 6 steers ha^-1) were imposed on each of the four forage systems to give a 4 × 2 factorial arrangement of treatments with two replicate paddocks of each treatment combination in a completely randomized design experiment.  Two Angus crossbred yearling beef steers (initial body weight [BW] of 236 ± 24 kg), were randomly assigned to each of the 16 paddocks.  Time spent grazing per animal on continuously stocked pastures was recorded for 10 d selected randomly during the months of April and May, with each day of observation lasting for 14 h (0615 h to 2015 h).  Forage system had an effect (P < 0.0001) on time spent grazing daily.  Animals grazing MG and MIX spent similar time grazing (mean = 442 min animal^-1), which was greater than daily grazing time on SS (380 min animal^-1).  Grazing time was least on ML (341 min animal^-1).  Also, SR had an effect (P < 0.0001) on daily grazing time.  Animals on high SR (431 min animal^-1) spent greater time grazing than those on low SR (371 min animal^-1).   There was no difference in time spent grazing on each component of the adjacent monocultures of grass (SSG) and legume (SSL) within the SS system [P = 0.23; 197 (SSL) vs. 182 min animal^-1 (SSG)].  Grazing time on SS was less than MG and MIX pastures and this may have implications for performance of animals grazing such a system.