Pigs Can Detect Multiple Amino Acid Deficiencies in a Choice Feeding Setting

Abstract

Background

It is unknown whether pigs can detect deficiencies in multiple amino acids (AA) and consequently change their feed choice.

Objectives

We investigated whether pigs compensate for a diet deficient in three AA (Thr, Trp, and Val) by selecting multiple diets and whether this compensation is affected by the supplemented AA concentration.

Methods

Pair-housed 5-wk-old pigs (n = 96) were exposed to one of four treatments: 1) AA-adequate: offered a low-protein (LP) diet adequate in AA for growth (LP⁺); 2) AA-deficient: offered LP diet deficient in Thr, Trp, and Val by 20% (LP^–); 3) Two-choice between LP⁺ and LP^–; and 4) Four-choice between LP^– and three diets supplemented with Thr, Trp, Val at +40% (n = 12 pens/treatment) from d0 to d21 (phase 1). From d21 to d28, AA concentration of supplemented diets increased to +60% (phase 2). Average daily feed intake (ADFI) and gain (ADG) were recorded.

Results

Dietary treatment did not affect ADFI and ADG in phase 1 (P > 0.05). In phase 2, ADFI and ADG were higher in AA-adequate and two-choice treatments than in AA-deficient treatment with four-choice in between (P < 0.05). In both phases, Thr, Trp, and Val intake was lower in AA-deficient treatment than in other treatments. For the two-choice treatment, consumption of LP^– was higher than LP⁺ in both phases (P < 0.05 and P < 0.001). Four-choice treatment consumed more LP^– and Trp-supplemented than Thr- and Val-supplemented diets in phase 1 (P < 0.001); in phase 2, consumption of the Trp-supplemented diet was the highest (P < 0.01).

Conclusions

Pigs can detect multiple AA deficiencies and compensate by consuming AA-supplemented diets. In a two-choice setting, pigs proportionally decrease consumption of a supplemented diet with increased dietary AA concentration. However, when given the choice between individual AA-supplemented diets, pigs proportionally decrease consumption of a highly concentrated Val diet and increase preference for a highly concentrated Trp diet.