INFLUENCE OF SUPPLEMENTATION ON BEHAVIOR OF GRAZING CATTLE

Dormant grasses are usually deficient in nutrients needed to meet catt le requirements. Research results indicate that grazing activities are sensitive to some environmental variables and vegetative (sward) char acteristics; however, minimal information is available on the influenc e of supplementation regimens on cattle grazing activities. Supplement ation studies reviewed had forage N levels that ranged from .9 to 1.2% and forage intakes that ranged from 12.3 to 31.0 g of OM/kg of BW. Pr otein supplementation affected (P < .05) time spent grazing: unsupplem ented (NS) cattle grazed approximately 1.5 h/d more than did supplemen ted (S) cattle. Type of supplemental protein and time of daily feeding did not affect (P > .10) this response. Different types and timing of starch-based supplements produced variable results; however increasin g the level of supplemental starch decreased (P < .05) daily grazing t ime. Protein supplementation increased (P < .05) harvesting efficiency (HE; grams of forage intake.kilogram of BW-1.minute spent grazing-1); however, high-starch supplements either did not alter (P > .10) or de creased (P < .05) HE compared with NS. Progressive defoliation can inf luence grazing behavior in both sheep and cattle grazing actively grow ing forage; however, evaluation of vegetative characteristics of dorma nt forage and the corresponding effect on grazing behavior are not kno wn. The effects of various grazing management strategies on cattle beh avior are inconclusive and deserve additional attention. Methods and(o r) management practices that modify behaviors to control feed intake, improve efficiency, or reduce stress could be major contributions to t he livestock industry.