Effect of immunological stress to neuroendocrine and gene expression in different swine breeds.

Immunological stress is the status of animal in active immune when they are challenged by bacterial, virus and endocrine. It is associated with immunological, neurological, and endocrinological response. An immunological stress model was established in this study using Chinese indigenous breed (Laiwu), crossbred (Lulai), and exotic breed (Yorkshire), to explore the capacity of immunological stress resistance among different breeds. The study was also to reveal the effect of chromium yeast to immunological stress. 48 post-weaning piglets were taken from three breeds, 16 piglets of each breed from Laiwu, Lulai and Yorkshire. The experiment was designed as 2 × 2 factors, immunological stress (Saline, LPS) and Chromium (with Cr, without Cr). There were four treatments: control, LPS, Cr, and Cr+LPS. Blood parameters related to immunological stress, such as IL-1β, TNF-α, GH, and cortisol, were examined after blood sample were taken at 0, 2, 5, and 7 h of post-injection. The results showed that IL-1β, TNF-α, and cortisol increased in group of LPS treatment while GH declined at 2 h of post-injection in comparison to the control (p < 0.01). However, IL-1β, TNF-α, and cortisol in group of Cr+LPS were lower than that in group of LPS while GH were higher (p < 0.05). Total RNA was extractedfrom blood lymphocytes separation samples at 2 h of post-injection. Q-PCR was applied to determine the gene expression of IL-1β, IL-6 and TNF-α. The results showed that LPS injection increased the gene expression of IL-1β, IL-6 and TNF-α. Among three breeds, the expression of IL-1β, IL-6 and TNF-α in Yorkshire were significantly higher than in Laiwu and Lulai (p < 0.05), but there was no difference between Laiwu and Lulai. Among four treatments, the expression of three genes in group of LPS was the highest, compared to the group of Cr+LPS (p < 0.05) and control (p < 0.01). This study concluded that Laiwu had stronger capacity of immunological stress resistance and next was Lulai among three breeds. Chromium yeast helped piglets relieve immunological stress.