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Extending the Grazing with Corn: Corn Hybrids, Forage Yield and Feed Value

Updated: May 12, 2023

Collaborating Producer: Pat & Jay Eaton, Valleyview

Research Coordinator: Dr. Akim Omokanye

There are many different ways to extend the grazing season. Benefits from extending the grazing season include reducing winter feed costs, improving manure distribution, decreasing fertilizer costs, reducing labour and time spent feeding, increasing soil organic matter content, yardage cost savings and improving animal performance and health. Some producers have experimented in recent years with grazing corn as a means of extending the grazing season in parts of the Peace. Results from these producers and the availability of corn hybrids with lower corn heat units (CHUs) have shown that grazing corn varieties might have potential in parts of the Peace region where this crop has not traditionally been grown. The results of corn hybrids tested for forage yield and feed value in Valleyview in 2012 are presented and discussed here.


The trial took place at the Eaton family ranch, on Alder Ridge Road, near Valleyview. There were 2 sites, one was on Alder Ridge road by RGE road 204 (50 acres) and the other one was on RGE road 205 (40 acres). The soil test for the Alder Ridge road by RGE RD 204 site showed a pH of 7.9, 9.6% organic matter, 100% base saturation, optimum K and S, while both N and P were low. So, we applied only a total of 250 lb/acre of N and P for the Alder Ridge road by RGE RD 204 site. For the RGE road 205 site, the soil test showed a pH of 7.4, 6.1% organic matter, optimum level of N, P, and S and excess K, so a total of 135 lb/acre of N (100 lb/ac) and P (35 lb/ac) was applied. In this report, the Alder Ridge road by RGE RD 204 site will be referred to as “Jones”, while the RGE road 205 site will be referred to as “Home”.

The Jones site had a canola crop last year, which was used to feed cows during the winter. The land was worked before seeding. For the Jones site, 4 corn hybrids (Pioneer 39V05, BrettYoung Fusion RR, Pickseed 2501RR, Pickseed 2219RR) and for the Home site, BrettYoung Fusion RR were used. The corn hybrids had CHUs varying from 2200 to 2350. The CHUs rating is an indicator of how many heat units are required for the grain to reach maturity. On average, 200 fewer CHUs are required for grazing or silage corn to reach 65 per cent whole plant moisture (35 per cent dry matter) as compared to grain corn. This moisture level is normal when silage corn is ready to harvest. To increase the chances of a high yielding and high quality corn crop for grazing, it is advisable to select a variety that will match the CHUs rating for your area. Silage varieties of corn are more palatable and better suited to grazing than grain corn. Seeding was done at a row spacing of 12 inches and at about 31,000 kernels/acre. Weeds were controlled once with Roundup at 0.67 L/acre. On September 24, 2012, each corn hybrid forage yield was determined. Some corn plants were chopped with a corn chopper (small wood chopper) for determination of moisture content and feed value in a laboratory. On the sampling day, the number of cobs per plant, moisture content and cob maturity were determined.

Results and Discussion

Number of Cobs and Forage Dry Matter (DM) Yield (Table 1) At Jones, number of cobs per corn stand was in the order of 2501RR (1.93 cobs/ plant) > Fusion RR (1.83 cobs/plant) > 2219RR (1.58 cobs/plant) > 39V05 (1.18 cobs/plant). At Home, where only Fusion RR was seeded, there was 1.66 cobs/plant.

At Jones, DM yield was highest for Fusion RR with 9.60 t/acre, closely followed by 2501RR with 9.13 t/acre, then 39V05 with 7.35 t/acre and then 2219RR with 6.71 t/acre. The higher DM obtained for both Fusion RR and 2501RR compared to the other 2 corn hybrids was partially due to the number of cobs and largely due to cob development. On the corn sampling date for DM yield determination on September 24 (about 10 days after the first killing frost), the cobs particularly those of Fusion RR and 2501RR were almost fully mature and nearing full corn grain maturity. Had it not been for the frost a few days before, most of the corn cobs would have reached full grain maturity by the end of September. The DM yield of individual corn plant parts was not determined here, but several studies have shown that at least 60 per cent of the dry matter yield of corn comes from the cob, grain and husk while the leaf, stalk and tassel provide less than 40 per cent of the dry matter yield. At Home, the DM yield from Fusion RR was lower than any of the corn hybrids planted at Jones.

Corn Forage Feed Value

The corn forage protein varied from 7.95% for 39V05 to 9.76% for 2219RR (Table 1). For both Fusion RR and 2219RR, the protein is adequate for cows in the mid and late pregnancy stages. But for 2501RR and 39V05, and the Fusion RR plated at the Home site, some legume hay with high protein or protein blocks may be necessary particularly if grazed by cows in the late pregnancy stage.

The corn hybrids forage Ca contents varied from 0.22% for the Fusion RR to 0.38% for 2219RR at the Jones site. The Fusion RR at the Home site had similar Ca content to that of the Jones site. 39V05 had the highest P content (0.20%), followed by 2219RR with 0.19% and then by both Fusion RR and 2501RR with 0.17% P. Generally, both Ca and P contents obtained for all the hybrids regardless of the sites, were met and in some cases even exceeded the Ca and P requirements of dry pregnant cows. For growing and finishing cattle, which require 0.31% Ca and 0.21% P, some minerals would be needed to address the short fall in Ca and P contents.

All the corn hybrids forage Mg and K contents far exceeded the requirements of both Mg and K by growing and finishing cattle as well as dry gestating cows.

At the Jones site, Fusion RR significantly had the least ADF content, an indication of high DM digestibility from Fusion RR compared to other corn hybrids. At the Home site, Fusion RR had 35% ADF and this also lower than the ADF contents obtained for other corn hybrids at the Jones.

At the Jones site, Fusion RR also had the highest energy (TDN) content with 62.48% TDN. Other corn hybrids had <60.00% TDN. This shows that Fusion RR had enough energy content to meet the energy requirements of cows which are in the mid and late pregnancy stages that respectively require 55 and 60% TDN. This also applies to the Fusion RR at Home, which had 60.30% TDN. Other corn hybrids had high energy (58.77-59.28% TDN) and they were more than adequate for the energy requirements of cows in mid pregnancy stage.


Looking at the number of cobs per corn stand, DM yields and feed nutritive value (particularly CP, ADF, TDN, ME, DE, NEL , NEM, NEG) to determine how the corn hybrids rank at the Jones site, Fusion RR out performed the other corn hybrids and therefore ranks first.

Notes on cows grazing the Home site planted to Fusion RR

The collaborating producer grazed the Home site first using 280 cows and he got 310 cow days/acre from the site. Grazing at the Jones site, which is 50 acres in size will commence later. The Jones site is presently being grazed with 240 cows. The producer is very happy with his success in using corn to extend the grazing season.

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