Forage removal and grazing time of cattle on small paddocks

Abstract

Animals used in grazing trials with small paddocks usually have not been exposed to the experimental site and related research procedures. Grazing trials conducted in May and August 1996 on smooth bromegrass (Bromus inermis Leyss.) quantified forage removal and grazing time of heifers adapted or not adapted to small paddocks. Treatments consisted of adapting heifers for 4 days to small paddocks (0.054 ha) and a control treatment of heifers continuously stocked in larger paddocks (>16 ha). On day 5, each group of heifers was moved to similar small paddocks and forage utilization and cattle grazing times were measured after 4 and 24 hours of grazing. In May, when sward structure was comparable in the large and small paddocks, tiller height reduction, leaf length reduction, herbage bio-mass reduction, and grazing time were similar (P > 0.10) for experienced and inexperienced heifers after 4 and 24 hours of exposure to day-5 paddocks. In August, when sward structure differed between the large and small paddocks, leaf length reduction after 4 hours was greater (P < 0.10) by experienced cattle than inexperienced cattle. Herbage reduction in August by experienced cattle was 435 kg ha-1 greater (P < 0.05) than by inexperienced cattle after 24 hours. Cumulative grazing time was 76 minutes (P < 0.10) greater at 4 hours for the experienced cattle than the inexperienced cattle. Grazing animals appear to adapt immediately to small paddocks but other unfamiliar grazing conditions, e.g., sward structure, may require short adaptation periods for experimental animals.