Nutrients in stored feeds can serve not only as a source of nutrition for cattle, but also as source of fertility for crops. Cattle retain only a small portion of the nutrients found in stored feeds, while the vast majority of the feed nutrients are excreted in the urine or dung.
Stored feeds such as alfalfa hay, grass hay or cereal silage contain significant concentrations of nutrients such as nitrogen, phosphorus and potassium.
Estimated Nutrient Content By Feed Type (lbs/tonne)
Feed Type Nitrogen Phosphorus Potassium
Alfalfa Hay 20% C.P. 70.0 5.0 38.0
Grass Hay 10% C.P. 35.0 4.0 29.0
Cereal Silage 12% C.P. 42.0 6.0 35.0
“In more traditional corral feeding systems, nutrients accumulate in the bedding pack,” says Gordon Hutton, provincial forage industry specialist with Alberta Agriculture and Rural Development, Airdrie. “With in-field feeding, excreted nutrients and feed waste accumulate in the field. Research by the University of Saskatchewan has shown that in-field feeding promotes better recycling of feed nutrients than spreading manure collected from corral feeding system. “This is especially true for nitrogen. A winter feeding project resulted in 30 to 40 per cent of the feed nitrogen being recovered after in-field feeding on a grass pasture versus only one per cent after corral manure was applied to the pasture. The higher nitrogen capture with in-field feeding is due in part to the reduction in nitrogen losses from gassing-off that occurs within corral feeding systems.” Bale grazing, bale processing or portable bunk feeders are examples of commonly use in-field feeding systems. The distribution of nutrients from urine, dung or feed waste in the field will vary with the size of the feeding area, quantity of feed delivered, length of feeding period and feed type. Legume based feeds generally provide the highest nutrient concentrations. “Winter feeding on old grass pastures may be one of the most promising options,” says Hutton. “Most older pastures are low in soil fertility and as result, low in forage productivity. With winter in-field feeding, high amounts of plant available nutrients can be introduced to the pasture and recycled through new forage growth over the next few growing seasons. However, there are limitations to in-field feeding. One of the challenges is managing nutrient placement. Regular rotation of feeding sites, bedding areas and water sources will improve nutrient distribution.” During this year’s winter feeding period, it may be worthwhile to reassess how nutrients in stored feed supplies are handled. With the rising costs of commercial fertilizers, stored feed nutrients may have increasing value for use as not only a livestock nutrient but also as source of crop fertility.