The University of Arizona

Cattle diet quality under short duration grazing on tallgrass prairie.

F.T. Mccollum, R.L. Gillen, J.E. Brummer

Abstract


Paddocks of tallgrass prairie were grazed at intervals similar to 8-paddock short duration grazing. Two replicates of a 2 X 3 factorial treatment design were evaluated to determine the influence of stocking rate and grazing schedule on crude protein and digestible organic matter content of cattle diets. Stocking rates were 1.3 or 1.8 multiples of the rates recommended by the Soil Conservation Service for the study site. Grazing schedules were 2, 3, or 4 complete cycles during a 152-day grazing season. Grazing and rest periods were lengthened as the season progressed and forage accumulation rate slowed. Masticate samples were collected from the experimental paddocks on alternate days during the grazing periods in 2 consecutive years. No stocking rate by grazing schedule interactions were observed (P > 0.10). Diet crude protein was depressed (P < 0.05) slightly at the higher stocking rate. Diets collected from the 4-cycle paddocks contained more (P < 0.05) protein than diets from the 2- and 3-cycle paddocks. Diets from the 2- and 3-cycle paddocks were not different (P > 0.20). In vitro digestibility was not influenced by stocking rate but tended (P < 0.13) to be higher for the 3- and 4-cycle grazing schedules. The balance of crude protein and digestible organic matter was most favorable (P < 0.05) for the 3-cycle diets. Based on diet composition, more frequent grazing periods appeared to maintain a higher, more stable plane of nutrition than the slower rotation schedules.

Keywords


dietary protein;grazing experiments;stocking rate;rotational grazing;Oklahoma;crude protein;cattle;in vitro digestibility;prairies;grasses;forage

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