Spatial Arrangement of Forages Affects Grazing Behavior of Beef Heifers Continuously Stocked at Low Stocking Rate

Abstract

ABSTRACTSpatially separated pastures may reduce foraging costs and provide a better balance of nutrients. The objective was to evaluate the grazing behavior of stocker heifers grazing different spatially arranged pastures. Treatments (three replicates) were: (i) annual ryegrass (Lolium multiflorum Lam.; RG); (ii) mixed (MIX) sward of annual ryegrass and clover mix (berseem [Trifolium alexandrinum L.], white [T. repens L.], and red clover [T. pratense L.]); (iii) clover mix (CL) alone; and (iv) adjacent areas (ADJ) of annual ryegrass and clover mix. Crossbred beef heifers (n = 48; 224 ± 14 kg) were continuously stocked at 2.5 heifers ha−1. Visual and video recording observations and pedometers were used to study grazing behavior. Forage mass and nutritive value and body weight of heifers were determined every 15 d. Crude protein content of CL and ADJ was greater (P = 0.02) than RG. Concentration of water‐soluble carbohydrate (WSC) was greater in RG than on CL. Heifers spent more time (P < 0.05) walking on RG and MIX when compared to those on ADJ. Grazing time was greater for heifers on RG compared to CL. Annual ryegrass had a greater concentration of WSC in the afternoon (221 g kg−1 DM) than in the morning hours (129 g kg−1 DM) and was greater than the concentration in the CL (99 and 61 g kg−1 DM, respectively). The concentration of WSC may explain the increase in grazing preference of RG during the afternoon; however, the reduction in the proportion of berseem clover during the last 30 d may have affected heifers’ grazing behavior.