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FORAGE UTILIZATION AND COW PERFORMANCE WHILE GRAZING CORN RESIDUE IN NEBRASKA

Animal Science

Mary Drewnoski
Beef Systems Specialist
UNL
Lincoln

Abstract

Winter grazing corn residue by spring calving cows can be an effective and economical strategy, yet cattle producers often report variable cow performance measured by body condition score.  The amount of corn residue available for grazing is assumed to be positively correlated with grain yield. The principal residue components available for grazing are the husks and leaves which are loosely spread on the ground following grain harvest. This means they can be susceptible to wind loss, in addition to consumption. On-farm data was collected from 8 herds across Nebraska during the winter of 2021-2022. Grain yield of fields used for residue grazing ranged from 153 to 200 bushels per acre across 24 grazed fields. Based on the reported yields and stocking rates, it was found that these producers were not as aggressive as the recommended 1.2 animal unit months (AUM) for each 100 bushels per acre of harvested grain. They stocked 10 to 87% of this suggested carrying capacity and on average used 50% of the carrying capacity. Cows grazed for an average of 30 days (range 14 to 120) per field at an average stocking rate of 1.3 animal units per acre (range 0.25 to 2.6) resulting in an average of 1.1 AUM/ac grazed. At the start of grazing, corn residue in these fields averaged 4.8 tons per acre (range from 2.4 to 7.1) with 82% ground cover. At the end of grazing, there was 2.8 tons of corn residue per acre (range of 1.4 to 4.2) and 59% ground cover. This corresponds to a mean disappearance (intake plus weather loss and trampling) of 2.1 tons of corn residue per acre or 43% of the total corn residue. Previous research has shown that cattle consume the higher energy residue parts first. Although husks are 3.5% crude protein (CP), they have the greatest energy of the corn residue components with 60% in vitro dry matter digestibility (IVDMD). When grazed, cattle first seek remaining grain followed by husks and leaves with minimal intake of cobs and stalks. Initial and ending husk amounts were used to calculate a mean husk disappearance of 69%. This indicates much greater husk disappearance as a portion of the total residue. Monitoring visual change of husk presence or absence could be a good measure of diet quality and a potential indicator of when to move herds to new fields. Across 8 cow herds grazing 24 corn residue fields, there was no change in cow body condition score. However, the mild winter likely had a major influence on cow response. Additional data will be collected and summarized to develop adaptive grazing management strategies that maintain cow body condition when grazing corn residue.

Authors: Kaylee Wheeler, Daren Redfearn , Brent Plugge, Randy Saner, Steve Neimeyer, Jay Parsons, Mary Drewnoski
  1. Kaylee Wheeler Graduate Student, University of Nebraksa, Nebraska, 68583
  2. Daren Redfearn Forage and Crop Residue Specialist, University of Nebraska, Nebraska, 68583
  3. Brent Plugge Extension Educator, Nebraska Extension , Nebraska, 68847
  4. Randy Saner Extension Educator, Nebraska Extension , Nebraska, 69101
  5. Steve Neimeyer Extension Educator, Nebraska Extension, Nebraska, 68823
  6. Jay Parsons Farm and Ranch Management Specialist, University of Nebraska, Nebraska, 68583
  7. Mary Drewnoski Beef Systems Specialist, University of Nebraska, Nebraska, 68583