Investigation of acute stress impact on nursery pig gastrointestinal function and ability of bioactive components of garlic to mitigate stress-induced physiological changes
Experiments were conducted to determine the effect of post-weaning feed and water deprivation on nursery pig growth performance, gastrointestinal function, and ability of garlic-derived diallyl disulfide (DADS) and diallyl trisulfide (DATS) to mitigate deprivation-induced effects. For the first experiment, the effects of a 24-h post-weaning feed, water, or feed + water deprivation event on nursery pig growth and intestinal characteristics were determined. Water deprivation more severely impacted nursery pig growth and intestinal measurements compared to feed deprivation. The water deprivation event resulted in an increase in serum stress markers and altered intestinal morphology and tight junction gene expression during the first week post-weaning. Furthermore, the acute post-weaning deprivation event impacted growth performance throughout the nursery period and resulted in pigs 0.57 kg lighter at 28 d post-weaning. A second experiment examined the interaction between a 24-h post-weaning feed + water deprivation event and a subsequent cyclic heat stress event. The results showed that the feed + water deprivation event reduced growth performance, increased serum stress markers, decreased ileal morphology, and altered intestinal tight junction gene expression similar to the first experiment. Growth performance and intestinal tight junction gene expression were decreased during the heat stress period. Growth performance results showed a stress event interaction in which nursery pig performance was poorest in pigs exposed to both stress events. Next, an in-vitro experiment was conducted to determine if garlic-derived DADS + DATS could mitigate hydrogen peroxide- and LPS-induced oxidant and endotoxin stress, respectively, in porcine epithelial (IPEC-J2) cells. Results showed that the garlic-derived compounds could mitigate oxidative stress by increasing superoxide dismutase and catalase activity. Furthermore, DADS + DATS were immune modulatory and augmented the LPS-induced increase in interleukin 8 (IL-8) secretion. Following the in-vitro evaluation, two in-vivo pilot trials were conducted to identify the optimal dosage of DADS + DATS and to evaluate the effect of graded doses of DADS + DATS on nursery pig and broiler chicken performance and gastrointestinal function. Garlic-derived DADS + DATS were supplemented to pigs and chickens by daily oral gavage for a period of 6 d. The oral gavage of DATS + DATS did not impact nursery pig growth performance, although ileal villus height was increased. Furthermore, there was a linear increase in IL-8 and a decrease in zonula occludens 1 (ZO-1) ileal gene expression due to oral DADS + DATS administration. The optimal dosage of DATS + DATS to maximize ileal villus height was determined to be 1.7 mg per kg BW. For the broiler chicken trial, DADS + DATS supplementation by oral gavage improved BW gain, ileal morphology, and digestibility of DM, N, and E. The average optimal oral dose of DADS + DATS to optimize BW gain and villus height in broiler chickens was 2.5 mg DADS + DATS per kg BW. In the final experiment, the ability of a daily oral gavage of DADS + DATS to mitigate effects of a post-weaning feed + water deprivation event in nursery pigs was investigated. The post-weaning feed + water deprivation event reduced growth performance, reduced ileal villus height, decreased activity of mucosal superoxide dismutase, and decreased expression of occludin and ZO-1 tight junction genes in the ileum. Oral supplementation of DADS + DATS partially mitigated the effects of the feed + water deprivation event on ileal villus height and superoxide dismutase activity. In conclusion, the overall results from these studies showed that post-weaning stress events have short- and long-term implications on nursery pig growth performance and intestinal characteristics. Additionally, garlic-derived DADS + DATS impact epithelial cell oxidative and immune status, improve pig and chicken ileal morphology, and can partially mitigate effects of an acute post-weaning feed + water deprivation event.
Adeola, Purdue University.
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