Collaborating Producer: Peter & Marilyn Dolen, Fourth Creek
Research Coordinator: Dr. Akim Omokanye
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. It also has the potential to produce more dry matter than tame hay or forage cereals. By replacing other forms of feed with standing corn particularly in late fall and during winter, labour time, machinery use and associated costs are reduced as no summer feed harvesting is required and winter supplemental feeding is limited. The objective of the study was to assess corn hybrids for forage yield and quality in Fourth Creek area.
The trial took place at Peter & Marilyn Dolen’s farm (NW 36-81-8-W6) in Fourth Creek (Saddle Hills County). The site was 50 acres in size and was worked before seeding. Seeding was done on May 10 and 11 at the rate of 30,000 kernels/acre with a 6-row corn planter at 30-inch row spacing and at a seeding depth of 1.5-2 inches. Four corn hybrids were seeded (BrettYoung Edge R, BrettYoung Fusion RR, Pioneer P7213R and BrettYoung 91B18 RR). Weeds were controlled once with Roundup at 0.67 L/ac.
On September 25, 2012, forage yield was determined from four 17.5ft long corn rows per corn hybrid. The corn forage samples were weighed, after which some corn plants were chopped with a corn chopper for determination of moisture content and feed value in a laboratory. Dry matter (DM) yield was later calculated for each corn hybrid. On the sampling day, the numbers of cobs per plant and cob maturity were also determined.
All corn hybrids had similar numbers of cobs/plant (Table 1). At sampling, 91B18 RR was wetter (>71% moisture) than other corn hybrids. Corn forage DM yield was in the order of: 91B18 RR (2.55 t/acre) > Fusion RR (2.45 t/acre) > P7213R (2.37 t/acre) > Edge R (1.86 t/acre). 91B18 RR, Fusion RR and P7213 R respectively had 37, 32 and 27% more DM than Edge R.
Both Edge R and 91B18 RR had 10.4% protein, which is more than adequate for cows in both mid and late pregnancy stages. But both Fusion RR and P7213 R respectively had 8.93 and 8.87% CP and these were only sufficient for cows in the mid pregnancy stage, which require 7% CP. None of corn hybrids have sufficient amount of protein (11% CP) that is needed by a cow that has just calved (a nursing cow).
The forage Ca content varied from 0.29% for Fusion RR to 0.34% for both Edge R and 91B18 RR. Only Fusion RR was not able to meet the Ca requirement of a dry pregnant cow, which requires 0.31% Ca. For a cow with an average milking ability, that requires 0.34% Ca, only Edge R and 91B18 RR were able to meet this requirement. For growing calves weighing between 400 and 600 lb, which require 0.38-0.51% Ca, none of the corn hybrids were able to meet these requirements. Generally, none of the corn hybrids had adequate amounts of P that are needed by dry gestating and lactating cows, but all corn hybrids far exceeded both Mg and K requirements by pregnant and lactating cows and even by growing and finishing beef cattle.
Using total digestible nutrients (TDN) per cent as the energy source, 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 per cent in mid pregnancy, 60 per cent in late pregnancy and 65 per cent after calving. In the present study, all corn hybrids had adequate energy needed by dry gestating cows, but they all fell short of what lactating cows need for energy. This further confirms that corn is a high energy feed that will normally match the nutritional needs of a dry cow in mid and late pregnancy.
Input Cost of Corn
Here, the total direct input cost of seeding corn was calculated to be $197.00 per acre (Table 2). The bulk of the cost comes from cost of seed ($86/acre) and fertility ($90.00/acre).
Grazing Aspect of the Trial
The site was grazed with 187 cows from November 11 to December 13, 2012 (32 days), giving about 120 cow days per acre.
The slightly lower DM obtained at this site than some other corn sites across the Peace was probably because of a combination of factors. Here, about 8 acres were drowned out at a point. The site was generally dry and it froze at the end of August. All these significantly affected general plant growth and cob development. The producer intends to try corn grazing for one more year.