top of page

Testing of Corn Hybrids with Lower Heat Unit Requirements for Forage Yield & Quality

Updated: May 9

Research Program Manager: Dr. Akim Omokanye

From: Peace Country Beef & Forage Association 2018 Annual Report

Corn is a high energy feed with protein levels that will normally match the nutritional needs of a dry cow in mid and late pregnancy. Corn has an advantage as a winter grazing crop because it stands above the snow, and it stands up in windy conditions (with minimal leaf loss), as well as providing a windbreak for cattle grazing it. Matching a particular area’s available corn heat units (CHU) to the CHU requirements of corn hybrids or varieties in the market will go a long way in maximizing the potential of using corn to extend the grazing season. Grazing corn should be at 30-50% milk line at first killing frost. Several new corn hybrids that require lower heat units are now available in the market. The objective of this trial was to test some the corn hybrids that require less heat units, for forage quality and suitability for grazing and silage.


The study site was at the Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview. Soil tests from 0-6” depth showed an organic matter of 6.4%, a pH of 6.8, and an electrical conductivity of 0.39 dS/m. The site was lightly harrowed before seeding.

The following 6 DuPont Pioneer corn hybrids were tested:

1. P7202AM™ (2050 heat units)

2. P7005AM™ (2000 heat units)

3. P6909R (1950 heat units)

4. P7213R (2050 heat units)

5. 39F44 (2000 heat units)

6. P7211HR (2050 heat units)

Randomized complete block design was used, with 4 replications.

Seeding rate was 32,000 kernels/acre. Seeding was done on May 28 with a plot drill at 27” row spacing. Fertilizer was applied during seeding, at the rate of 111 lbs N/acre + 37 lbs P/acre + 49 lbs K/acre + 21 lbs S/acre. Roundup at 0.67 L/acre was used for pre-emergent and in-crop weed control.

Harvesting for forage dry matter (DM) yield determination and quality analysis was done on September 24. Two composite forage samples were sent to A & L laboratory in Ontario for quality determination.

The data for forage yield and quality were analyzed with ARM statistical software.