Preparation of swine feed
On-farm mixing allows hog producers to increase control over feed costs by producing consistent quality product from home or locally grown commodities.
Hog feed prepared on-farm is usually ground using a hammer or roller mill. Most mills are portable proportioner grinder-mixers.
The objective when grinding is to reduce the particle size of the grains in order to increase the surface area of the feed. Increased surface area improves nutrient digestibility by giving digestive enzymes access to the nutrients. Reducing particle size also improves mixing with finer particle premix or supplement ingredients, increases the nutrient density of the feed and improves handling while reducing separation of ingredients.
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How fine a ration should be depends on the age of the pig and type of grains being processed. Young pigs tend to chew feed more than grower-finisher pigs, so the effect of particle size on feed conversion efficiency is likely to be greater for grower-finisher pigs than for younger stock.
Aim for a particle size of 700 microns for barley and 800 for wheat. If the average size drops below 500 microns, there might be more cases of esophagal ulcers or bridging in the feed bin, as well as increased dustiness.
A survey of particle size analysis of feed samples conducted by Kansas State University showed a majority of producers lose three to eight percent of their feed efficiency by not grinding their feed fine enough. Better grinding could save $2 to $6 per hog in feed costs alone.
In more than 2,500 samples tested, only 21 percent fell in the 700 to 800 micron range, so there is an enormous potential to improve feed use efficiency.
Savings from improved feed conversions will outweigh increased processing costs associated with switching to a smaller screen size.
To determine if a grinder is working properly, pass a sample of feed through a series of screens with decreasing screen sizes. Weigh the feed left on each screen. This process gives a good indication of how fine the feed is being ground and how the equipment can be better set up to be more economical.
– Sue Charlton, M.Sc.
nutritionist, Calmar Feed Mill Ltd.
