Supplementing a low-protein diet with synthetic amino acids can provide a cost-effective way to avoid adding excess crude protein (CP).

Two experiments with grow-finish pigs confirmed that performance could be maintained when either high- or low-crude protein diets are fed as long as amino acids are balanced and the diets are formulated to provide similar net energy.

The introduction of crystalline amino acids has allowed a reduction in the crude protein (CP) in swine diets. Low-CP diets supplemented with essential amino acids can decrease nitrogen excretion in the manure and may reduce diet costs.

This study compared the performance of grow-finish pigs fed either high- or low-CP diets supplemented with crystalline amino acids.

High-CP diets were formulated to meet the lysine and other amino acid requirements of the pig (Table 1). Low-CP diets were formulated to provide the same amount of lysine, but the CP was reduced from 20% to 16% in the grower and from 16% to 12% in the finisher diet.

Diets were formulated to provide equal net energy. Sodium bicarbonate was added to the low-CP diets to maintain the electrolyte balance of the diet.

Average daily feed intake was lower when the pigs consumed the high-CP diet, while average daily gain was similar between treatments, resulting in an improved feed:gain ratio with the high-CP diet (Table 2).

The low- and high-CP diets resulted in similar pig performance during the finishing phase (Table 2).

In summary, CP levels can be decreased by 4% in grower and finisher diets without impacting pig performance, provided that diets are formulated to be equivalent in available amino acid, net energy and dietary electrolyte balance.

Researchers: J.F. Patience, A.D. Beaulieu and I.U. Haq, all of the Prairie Swine Centre (PSC). Contact PSC's Ken Engele by phone (306) 373-9922, fax (306) 955-2501 or e-mail