Cattle grazing dynamics under continuous and rotational grazing on sandy rangeland

Cattle performance was evaluated for 161 consecutive days on a ranch in eastern New Mexico, in three cells managed under rotational grazing (RG) and in three pastures under continuous grazing (CG). Objectives were to examine animal performance, diet composition, diet quality, grazing behavior and plant selectivity from these CG and RG systems that were stocked at the same rates (east-26 ac/head, middle-19 ac/head, and west-23 ac/head). Average daily weight gains were greater (P<0.05) for CG cattle, 2.52 lb, than for RG cattle, 2.18 lb. No differences (P<0.05) in grazing time (CG-771 min, RG-794 min), loafing time (CG-627 min, RG-607 min) and rapid eye movement sleep time (CG-42 min, RG-40 min) were recorded between grazing systems. The RG cattle avidly selected certain plant species when first allowed into a new pasture; species selection changed by the second observation. Differences in plant species selection by CG cattle were not as pronounced as RG cattle. No differences (P<0.05) in diet composition occurred between the two grazing treatments, with 24 and 23 species of plants found in the diets of CG and RG cattle, respectively. Gummy lovegrass, fall witchgrass and sand dropseed were the main species occurring in the diets. Diet quality, evaluated using fecal crude protein was 7.0% and 7.1% for the CG and RG,respectively. Ko differences (?<0.05) were observed in forage samples hand-picked fror. RG and CG pastures when analyzed for crude protein (CG- 6.5%, RG-6.1%), phosphorus (CG-.13%, RG-.14%), in vitro dry matter digestibility (CG and RG-38%), neutral detergent fiber (CG-70%, RG-72%), and acid detergent fiber (CG and RG-38%). Selective grazing, which may reduce intake, by the RG cattle offers at least one possible explanation for lower daily gains by RG cattle than CG cattle.