ABSTRACT
In vivo and in vitro experiments were conducted to test for beneficial effects of dietary clays on broiler chicks challenged with Salmonella enterica serovar Typhimurium and to explore potential mechanisms. First, two hundred forty 1-d-old male broilers (initial BW: 41.6 ± 0.4 g) were allotted in a 2 × 4 factorial arrangement in a randomized complete block design. There were 2 infection treatments (with or without Salmonella) and 4 diets: basal (BAS), 0.3% smectite A (SMA), 0.3% smectite B, and 0.3% zeolite. The Salmonella reduced (P < 0.05) the growth rate of chicks fed the BAS, and feeding clay largely restored it (challenge × diet interaction, P < 0.05). Goblet cell number and size were increased (P < 0.05) by Salmonella in chicks fed the BAS and were reduced (P < 0.05) in Salmonella-challenged chicks by feeding SMA. Villus height was reduced by the Salmonella challenge in the chicks fed dietary clays (P < 0.01) but not in chicks fed the BAS (interaction P < 0.05). A human adenocarcinoma cell line (LS174T) was cultured in vitro in 3 separate experiments in the absence or presence of 3 concentrations (0.05, 0.10, and 0.50%) of SMA. Expression of mucin 2 (MUC2), resistin-like molecule ß (RELMß), and trefoil factor 3 (TFF3) were determined by real-time reverse-transcription PCR. The expression of RELMß was increased and expression of MUC2 was reduced (P < 0.05) by 0.10% SMA. Also, LS174T cells were cultured without or with SMA (0.05 and 0.10%) and the medium and cell lysate were analyzed for RELMß using an immunoblot assay. Protein expression of RELMß in the cell lysate was reduced (P < 0.05) by SMA addition but increased in the medium, indicating that SMA increased secretion of RELMß, thus depleting the cell and concentrating this protein in the medium. In conclusion, the dietary clays restored the growth depression caused by Salmonella, and changes in goblet cell function may contribute to the benefits of one of the clays, specifically SMA.
