Apparent and standardised ileal amino acid digestibilities in heat‐stressed pigs fed wheat‐soybean meal diets supplemented with l‐arginine and dl‐methionine

Heat stress (HS) exposure may damage the small intestine epithelia of pigs affecting the digestibility and absorption of amino acids (AA). Arg and Met can enhance antioxidant and intestinal cell proliferation activity, thus supplementing them in diets might alleviate epithelial damage and correct the reduced AA digestibility. The effect of adding extra l‐Arg and dl‐Met to diets on the apparent (AID) and standardised ileal digestibility (SID) of AA was analysed in a 10‐day experiment conducted with 10 ileal‐cannulated HS pigs (25.3 ± 2.4 kg body weight). The pigs were divided into two treatments: Control, wheat‐soybean meal diet supplemented with l‐Lys, l‐Thr, dl‐Met and l‐Trp; and control diet plus 0.20% l‐Arg and 0.20% dl‐Met (Arg + Met). Following an 8‐day diet adaptation period, ileal digesta was continuously collected for 12 h, starting at 0700, on Days 9 and 10. All pigs were daily exposed to 29.6–36.1°C; ileal temperature was continuously monitored at 15‐min intervals. Feed was provided twice a day. The ileal temperature ranged from 40.3 to 41.5°C. Daily ileal outflow of His, Ile, Leu, Phe, Thr, Ser and Tyr decreased (p