Research Coordinator: Dr. Akim Omokanye
Collaborating producer: John Prinse (MD of Big Lakes)
From: Peace Country Beef & Forage Association 2014 Annual Report
Over the past few years there has been much interest in growing corn for grazing in the Peace, especially for use as late fall and winter grazing. Corn is a warn season annual cereal crop. Corn is rated according to the number of accumulated heat units required to reach grain maturity. Ideal grazing or silage stage may be reached at 180-200 corn heat units (CHUs) less than the grain maturity. Studies at Lacombe Research Centre have shown that swath grazing triticale can save a producer time, money and machinery costs. Research indicates that swath grazing can reduce total daily feeding costs per cow by 41 to 48%. This is based on a 78% reduction in yardage costs and a 25% reduction in feed costs. In 2014, tested corn hybrids with low CHUs compared with triticale for forage yield and quality, and for use in extending the grazing season.
Methods
The study took place at John Prinse’s farm at Enilda, near High Prairie. The site had been used for swath grazing for a few years prior to the present study. Spring soil sample (0-6 inches) analyzed by Exova laboratory in Edmonton showed 13.9% OM and a pH of 6.6. The soil had marginal N, optimum P & S, and excess K required for crop growth. The soil was not tilled before seeding.
3 Pioneer corn hybrids: P732AM-R (2200 CHU), 39M26 (2100 CHU), and P7213R (2050 CHU)) were seeded on May 24 for a targeted 30,000 kernels/acre (or 1 corn bag/2.5 acres). Seeding was done with a John Deere 752 no till disk drill @ 22” row spacing. Fertility was a blend of 46-0-0 (206 lbs/acre) + 11-52-0 (48 lbs/acre). No K and S were applied as the soil had sufficient amounts for corn for the year. Weeds in the corn stands were controlled with roundup.
Bunker triticale, a forage variety was seeded at 120 lbs/acre on May 25 with a John Deere 752 no till disk drill @ 7.5” row spacing. About 20 acres was used for the triticale. Bunker is an awnletted (reduced awn expression) standard height spring triticale line that can be use as a feed grain and conserved forage. Fertility was 174 lbs/acre blend (116 lbs of 46-0-0 + 57 lbs of 11-52-0).
Swathing was done on September 16 at the mid-dough stage for triticale. The swathed triticale was grazed for about 30 days with 100 cows (80 cow/calf pairs + 20 bred heifers). The plan is to have the field grazed again in the spring. The corn hybrids were also grazed with the same set of cows. The cows were allowed to graze about a day and a half per acre.
Results
Corn Cob Development
The average number of cobs per plant was 1.7 for P7632AM-R and 1.0 cob/plant for 39M26 and P7213R. P7213R had better developed cobs (mostly ½-3/4 milk line stage) than 39M26 and P7632AM-R.
Forage Dry Matter (DM) Yield
Generally, the 3 corn hybrids had higher forage DM than Bunker triticale. The corn yield advantage over triticale was in the range of 0.36 to 1.35 ton DM/acre. Of the 3 corn hybrids, P7213R had the highest DM yield (5.31 tons/acre), followed by 39M26 (5.06 tons/acre) and then P7632AM-R (4.32 tons/acre) (Table 1). The pattern of forage DM obtained for the corn hybrids appeared to be a reflection of the CHUs. The lower the CHUs requirements the higher the DM.
Forage Quality
The forage protein (crude protein, CP) for P7213R, 39M26, P7632AM-R and bunker triticale was respectively 7.64, 7.97, 8.33 and 6.96% CP (Table 1). All corn hybrids and triticale had sufficient protein for a cow in mid pregnancy (7% CP). But all the crops fell short of meeting the 9% CP requirement of a mature cow in late pregnancy.
Forage Ca for corn hybrids 39M26 and P7632AM-R exceeded the 0.18% needed by a cow in mid pregnancy, while P7213R and triticale slightly fell short of the Ca requirement for this category of cow. The forage P was highest for triticale (0.18% P), followed by P7632AM-R (0.16% P), P7213R (0.12% P) and then 39M26 (0.11% P). Of the 3 corn hybrids, only P7632AM-R corn hybrid and triticale had adequate P for a mature cow in mid pregnancy. For forage Mg, with the exception of triticale, which significantly had a low Mg (0.07% Mg), all corn hybrids exceeded the suggested Mg requirement of a cow in mid pregnancy. All corn hybrids and triticale had enough K for a mature beef cow as well as for growing and finishing calves.
Using total digestible nutrients (TDN) as a measure of energy, the rule of thumb is 55-60-65. This rule says that for a mature beef cow to maintain her body condition score (BCS) through the winter, the ration must have a TDN energy reading of 55% in mid pregnancy, 60% in late pregnancy and 65% after calving. The energy (65.9-70.7% TDN) of the 3 corn tested far exceeded the energy requirements of a mature beef cow. But triticale was only able to meet the 55% TDN that is needed by a dry gestating cow in the mid-pregnancy stage.
Grazing
The 3 corn hybrids in the entire field lasted for 30 days. There were 22 heifer, 3 bulls and 84 cows and calves at the site.
Conclusion
In general, Pioneer corn P7213R with 2050 heat units appeared to have slightly higher DM yield and energy than other corn hybrids and triticale. With the exception of P7632AM-R, none of the corn hybrids and triticale had adequate Ca, P and Mg values that are needed by a dry gestating cow. Mineral/salt package would therefore be needed to address any mineral short falls during grazing. Because cows selectively graze cobs first and then the stalks, it is important to control access to the corn to ensure proper utilization and avoid wastage, and to provide a good water source.