Evaluation of immune system function in neonatal pigs born vaginally or by Cesarean section

Full term crossbred sows were selected to study the interaction of the immune system, hypothalamus-pituitary-adrenal axis, and growth in pigs born by Cesarean section (c-section; n = 4 sows) or vaginal birth (n = 4 sows). Gestation length and birth weight did not differ between vaginal birth and c-section pigs (P = 0.34 and 0.62, respectively). Blood and tissue samples were collected from 44 pigs at birth. Forty-five pigs were weaned at 13 d. On d 14, pigs received an i.p. injection of lipopolysaccaride (LPS; 150 μg/kg) or saline at min 0, and blood samples were collected at −20, −10, 0, 5, 10, 20, 40, 60, 90, and 120 min. Vaginal birth pigs had 21% greater average daily gain than c-section pigs on d 14 (P < 0.01). Basal serum concentrations of adrenocorticotrophin (ACTH) and cortisol were greater in c-section than vaginal birth pigs at birth (P < 0.01) but were not different at 14 d (P = 0.99 and 0.80, respectively). LPS increased serum concentrations of ACTH, cortisol, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α; P < 0.01) but the response was not different between c-section and vaginal birth (P > 0.22). Basal serum concentrations of TNF-α tended to be greater in c-section vs vaginal birth pigs at 14 d (P = 0.0967); however, basal serum concentrations of IFN-γ tended to be lower in c-section pigs vs vaginal birth pigs at 14 d (P = 0.0787). Expression of interleukin (IL)-6, IL-6 receptor, IL-1β, and TNF-α mRNA did not differ between vaginal birth and c-section pigs but changed in an age and tissue dependent manner. Thus, reduced growth rate of c-section pigs is associated with altered immune system function.