Trial Location: Fairview Research Farm
Research Coordinator: Dr. Akim Omokanye
Winter feed is very costly for cow-calf operations. To reduce feed costs and the overall yearly cost of production, producers are exploring various options in lengthening the grazing season. For years, options such as swath grazing of annual crops, stockpiling of perennial forages, bale grazing and bale processing have been common practises for extending grazing season. However, in recent years in parts of the Peace, there is a gradual increase in the number of producers wanting to explore the potential and suitability of warm season crops (particularly corn) in extending the grazing season.
Warm season plants require higher soil temperatures for germination in spring. The optimum growing temperature is 18 - 24°C for cool season plants and 32 - 35°C for warm season plants. Temperatures below 10°C at night will slow the growth of warm season plants. The objective of this project was to evaluate warm season cereal crops (corn, millet and forage sorghum) for forage yield and feed value.
Methods
Seeding and Management:
For this project, 9 corn varieties, 2 millet varieties (Proso & German millet), 1 sorghum variety (CFS30) and 2 forage oat varieties (CDC Baler & CDC SO-I) as checks were seeded. Both Proso and German millets are two of the most commonly grown millet varieties in western Canada. CDC SO-I (CDC Super Oats, variety number one) is a new forage/feed oat variety. The corn heat units (CHUs) for corn varieties varied from 2000 to 2400. The seeded corn varieties were: P7213R (2050 CHU), 39F44 (2000 CHU), P8107HR (2350 CHU),
X70B140R (2000 CHU), P7443R (2100 CHU), X70B144R1 (2000 CHU), 39M26 (2100 CHU), 39F60 (2250 CHU) and 39V05 (2350 CHU). The CHUs rating is an indicator of how many heat units is required for the grain to reach maturity. Less CHUs are required for corn grazing or silage. The crops were seeded into small plots measuring 2.5m x 10m and replicated twice. Seeding was done on May 18, 2011 at the rate of 32,000 kernels/acre for corn; 20 pounds/ acre for Proso & German millet, and CFS30 (Sorghum). Oats were seeded at 2.5 bushels/acre. A plot seed drill was used for seeding. Fertilizer was broadcast at 50lb N + 20 lb P/acre prior to seeding. Roundup at 400ml/acre was used to control weeds in the corn plots one month after seeding. For millet, sorghum and oats, Basagran forte was used.
Results & Discussion
Forage Dry Matter (DM) Yield
Generally, forage DM yields were far higher for corn varieties than for millet, sorghum or oat varieties (Figure 1). The order of forage DM yield was corn > oats > sorghum > millets. Forage DM yield varied from 2.8 t/acre for German millet to 15 t/acre for corn variety 39M26. Four corn varieties had up to 11.70 t/acre and above. Both oat varieties out yielded the two millet varieties. Forage DM yield of forage sorghum wasn’t far off those of CDC Baler or CDC SO-I oats. We observed that German millet was slow to establish and remained green longer into the season. Although, Proso millet yielded low, it has the advantage that, if an earlier seeded crop such as oat or barley for greenfeed or swath grazing has failed, its rapid maturity will make it an excellent emergency forage crop.
Forage Quality
In most cases, the crude protein (CP) content of the corn varieties were below 10%. German millet and forage sorghum had protein levels that were well above all corn and oat varieties, as well as that of proso millet (Figure 2). The protein requirements for beef cows, on a dry matter basis, are 7% in the second trimester, 8-9% percent in the third trimester and 10 to 11% post calving. Except for forage sorghum, German and Proso millets, corn and oats tended to be marginal for protein content. As a result, pregnant beef cows may need to be supplemented as they approach calving, particularly for corn varieties 39F44 and X70B140R.
Looking at total digestible nutrients (TDN), the two millet varieties (Proso & German), forage sorghum and corn variety P8107HR all had less than 60% TDN. All other corn and oat varieties had above 60% TDN (Figure 3) and will result into some savings if a hard winter comes our way.
Of all the corn, millet and oat varieties examined, SO-I oat had the least ADF (30.88%) and NDF (50.96%) contents (Table 1). Both millet varieties (Proso & German) had higher ADF contents than other crop varieties. For the NDF content, this was higher for Proso millet and forage sorghum DF (about 65%) than other crop varieties tested.
Out of the 14 crop varieties tested, only 4 crop varieties (corn P7213R, Proso millet, forage sorghum and CDC Baler oat) did not have sufficient forage Ca content that is required by beef cattle for optimum production. With the exception of German millet and forage sorghum, forage P content was low for all the crop varieties tested and not sufficient for what is required by dry pregnant cows through to post calving.
Observations/notes:
As expected, warm season crops (corn, millet and sorghum) were affected to some extent by a soft frost in early June compared to those of the cool season crops (oats). No stand loss was recorded after a few weeks and they later started to show new leaves. The crops eventually survived and recovered very well. It is important to note that yield loss to early season frost damage in corn is related primarily to the degree of stand loss, not to the degree of leaf damage.
No lodging was observed with any of the corn, German millet, forage sorghum and SO-I oats. Both Proso millet and CDC Baler oats had some lodged stands, but it was very minimal. German millet did not head out throughout the growing season and that probably explains why it had the highest CP content, as it was very green at harvest and still in the active vegetative growth stage when it was harvested in September.