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August 12, 2004
Manitoba-grown corn: getting to know its nutritive value
by Florence Opapeju, Martin Nyachoti and James House,
Department of Animal Science
Corn is an excellent feed ingredient for swine and other livestock species, including poultry. In western Canada, barley and wheat have traditionally been used as the main sources of energy in swine diets. However, corn production in western Canada and Manitoba, in particular, has increased considerably and therefore availability should no longer limit its use in swine production. It is therefore important to better characterize the nutritional value of locally grown corn to facilitate its use as a feedstuff for swine.
A current research project in the Department of Animal Science, University of Manitoba in conjunction with the Manitoba Corn Growers Association, is investigating the nutritional value of corn hybrids grown in the province. Corn, which is originally from the tropics, has been successfully adapted to areas with short growing season such as Manitobas. In regions with low temperatures, cumulative temperatures such as corn heat units (CHU) are used instead of calendar days as a measure of the useful heat required for growth and development of corn. Based on CHU, Manitoba can be divided into 10 regions with CHU ranging from 1800 2800. The annual minimum requirement to produce grain corn is 2200 CHU and six regions in Manitoba would support this production. These six regions make up 95.3% of the total arable land in Manitoba.
Factors, such as temperature, soil types, soil fertility, management practices and hybrids, are known to affect the nutritional composition of feed ingredients which can vary over different regions. For this basic reason, it is important that ingredients grown within a region are well characterized in terms of their nutritive value so as to optimize their use in livestock feeding. An important question that is yet to be addressed with respect to corn is how differences in CHU might influence its nutritive value. A current University of Manitoba research project is aimed at providing some information on this very question.
We have assessed the chemical and nutrient profile of 36 corn hybrids grown in the St. Pierre and Reinland areas, chosen to represent regions with low and high CHU, respectively. The parameters for which the samples were analyzed included contents of dry matter, protein, fat, fiber, and minerals. Also, agronomic data including yield, moisture content at harvest and bushel weight were collected.
The results (Figure 1) show that more than 60% and 90% of hybrids in Reinland and St. Pierre had higher protein compare with protein content reported in feed tables from the 1998 National Research Council. As would be expected, field location had an effect on the contents of dry matter, protein, total and phytate phosphorus, bushel weight and yield of the hybrids. Corn heat unit rating of the hybrids affected the protein content, bushel weight and the yield. Samples with low CHU rating tend to have higher nutritive content compared to samples with high CHU rating.
The results obtained thus far show that Manitoba-grown hybrids have significant nutritive potential. Also, the field location and total CHU over the growing season have significant effects on the nutritional composition and agronomic parameters of corn hybrids. Generally, the results from this study are expected to provide useful information for formulating nutritionally adequate swine diets containing Manitoba-grown corn hybrids. Such data will be of great benefit to the grain growers and pork producers as it will promote the use of locally grown corn in swine diets.