Effects of dietary lysine levels on jejunal expression of amino acids transporters and hindgut microflora in weaned pigs.

The objective of the study was to evaluate the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) level on the expression of jejunal amino acids (AAs) transporters and the microflora in the hindgut of weaned pigs. One hundred and twenty weanling pigs weighing 8.10 ± 0.48 kg were randomly assigned according to body weight and sex to 5 treatments with 6 replicates per treatment and 4 pigs per replicate. Pigs were fed diets with 0.98, 1.11, 1.23, 1.35 or 1.48% of SID Lys for 28 days. The mRNA expression of cationic amino acids transporter 1 (CAT1) in jejunum was higher in groups fed with 1.23, 1.35 and 1.48% SID Lys addition (P < 0.05). There was stated a linear increase in the mRNA expressions of CAT1, excitatory amino acids carrier 1 (EAAC1) and peptide transporter T1 (PEPT1) (linear, P < 0.05). In the caecum, the populations of bacteria and the content of butyric acid were significantly influenced (P < 0.05) by dietary SID Lys. In animals fed diet with 1.35% SID Lys a content of butyric acid was the highest (P < 0.05). Moreover, the populations of Lactobacillus and Bifidobacterium in caecum and colon increased (linear, P < 0.05; quadratic, P < 0.05) as dietary SID Lys level increased. The obtained results showed that dietary SID Lys level may influence AAs absorption and promote the hindgut health. The suggested supplementation of SID Lys to the weaned pigs' diet is 1.35%. [ABSTRACT FROM AUTHOR]