Dietary salbutamol and level of protein: Effects on the acute stress response in pigs

Abstract

Effect on the acute stress response of dietary inclusion of 3 ppm salbutamol (beta-2-adrenergic agonist) at two levels of protein were investigated in growing pigs (from 25 kg live weight). The trial comprised six litters (blocks) of four females allocated randomly to four treatment groups in accordance with a 2 × 2 factorial arragement. The response to an open-field test and to an intruder were measured at 50 kg live weight. Salbutamol increased immobility and looking, reduced total exploration, and increased plasma ACTH after test. At high dietary levels of protein, salbutamol also increased the latency to attack. High dietary levels of protein reduced standing still, latency to contact a novel object and an intruder, and level of plasma cortisol before test. Moreover, high protein without salbutamol seemed to reduce the latency to attack an intruder. In conclusion, chronic treatment with salbutamol shifted the acute stress response in pigs toward a passive response, whereas high dietary level of protein provoked an active response, which may have consequences in pig production.