Nutrition

Field Peas Trim Diet Costs, Phosphorus Excretion

Swine diets containing field peas can cut ration costs and reduce phosphorus excretion in manure, based on research at South Dakota State University.

The study provides the first evidence that phosphorus in field peas provides a high level of digestibility (55%). Adding microbial phytase to the diet increases the level of phosphorus digestibility to 70%.

With field peas, diets can be formulated with less expensive, inorganic phosphorus that will reduce overall ration costs. The level of dicalcium phosphate can be reduced by about 1 lb./ton of feed if field peas are added at a rate of 30-40% of the diet. That will reduce diet costs by about $1/ton.

And because less phosphorus is being excreted in the manure, the cost of manure application on fields is reduced if manure is being applied according to the phosphorus concentration.

Three experimental diets were fed to 40-lb. pigs (Table 1). Diet 1 was based on 75% field peas, corn, starch, dextrose, and vitamins and minerals. Field peas were the only ingredient in the diet that contained phosphorus.

Diet 2 was the same as Diet 1 except that microbial phytase was added at the rate of 0.02%, providing 500 phytase units/kg. (2.2 lb.).

Diet 3 was a phosphorus-free diet used to estimate losses of phosphorus.

Results revealed a high level of digestibility of phosphorus in field peas.

Table 2 shows results of diets containing field peas with or without phytase. For the diet without phytase, true total digestibility was 60.8%, and increased to 75.6% when phytase was added.

Researcher: Hans H. Stein, South Dakota State University. Contact Stein by phone (605) 688-5431; fax (605) 688-6170 or e-mail hans.stein@sdstate.edu.

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