| ||An Alberta Agriculture and Forestry (AF) specialist warns that spring-threshed cereal crops may contain ergot, fusarium, moulds, dirt and fecal contamination.
“Any problem that was present in the crop last fall will still be there in the spring,” says Barry Yaremcio, beef and forage specialist, AF. “Freezing temperatures during the winter only stopped further microbial development.”
In the warmer fall temperatures of 2016, there was a risk that mycotoxins were produced by various moulds and fungi, which could be harmful to all classes of livestock. “Before feeding a salvaged spring-threshed cereal grain or greenfeed have the feed tested for nutrient content and also screened for mycotoxins.”
Salvaging overwintered feed by ensiling is not recommended, says Yaremcio. “Ensiling is the process of controlled fermentation to preserve wet forage material to a stable feed source. There are two stages of fermentation during the fermentation process and understanding the process helps explain why ensiling an overwintered crop is not an option.”
Under normal conditions:
“Overwintered cereal crops should not be chopped or baled to make pit, pile or bale silage because they may not ensile properly,” says Yaremcio. “The overwintered plant material would have been wetted and dried repeatedly, resulting in the leaching of soluble sugars and proteins out of the plant material. Without adequate amounts of sugars, microbe populations die off, and normal fermentation doesn’t occur.”
- The first stage involves aerobic respiration because oxygen is present. When plant material is first chopped and put in a pit, pile, bag or bale, oxygen is present. Bacteria use up available oxygen and plant sugars. Carbon dioxide and heat are produced. A shorter aerobic stage produces less heat and uses less soluble sugars resulting in higher quality silage.
- The second stage follows in an anaerobic environment when all the oxygen is used up within the sealed pit, pile, bag or bale. Anerobic bacteria use plant sugars to increase their populations to produce lactic acid, which lowers the pH of the silage allowing the preservation or “pickling” to occur. The entire process typically takes 3 to 4 weeks to complete and requires a minimum of 6 to 12 per cent plant sugars in the material to ensile effectively.
It is very unlikely that overwintered corps will have adequate moisture to create a good environment for proper fermentation. For proper fermentation with chopped silage, the recommended moisture content is 60 to 65 per cent and for bale silage, 45 to 50 per cent.
“If moisture levels are lower than those for chopped or baled silage, it’s very difficult to pack the material in a pit or pile, resulting in higher oxygen content, longer fermentation and possibly, lower quality silage,” says Yaremcio. “In bale silage, the drier material will not pack in the bale, and the desired fermentation may not occur.
“There is no point in going to the expense of making silage only to find a marginal to poor quality product that may not be suitable for use.”
For more information, see AF’s new Risks of Using Overwintered Crops as Livestock Feed factsheet.
Alberta Ag-Info Centre