Effects of inadequate maternal dietary protein: carbohydrate ratios during pregnancy on offspring immunity in pigs

Background: Inadequate nutrition in utero may retard foetal growth and alter physiological development of offspring. This study investigated the effects of low and high protein diets fed to primiparous German Landrace sows throughout pregnancy on the immune function of their offspring at different ages. Sows were fed diets with adequate (AP, 12.1%; n = 13), low (LP, 6.5%; n = 15), or high (HP, 30%; n = 14) protein content, made isoenergetic by varying carbohydrate levels. Cortisol, total protein and immunoglobulin (IgG, IgM, IgA) concentrations were measured in the blood of sows over the course of pregnancy. Cortisol, total protein, immunoglobulins, lymphocyte proliferation, immune cell counts, and cytokines were assessed in the blood of offspring at baseline and under challenging conditions (weaning; lipopolysaccharide (LPS) administration). Results: In sows, the LP diet increased cortisol (P < 0.05) and decreased protein levels (P < 0.01) at the end of pregnancy. Immunoglobulin concentrations were decreased in LP (IgA) and HP piglets (IgG, IgM and IgA) on the first day of life (P < 0.05), whereas the number of lymphocytes and mitogen-induced lymphocyte proliferation of the piglets were unaffected by the maternal diet. Mortality during the suckling period was higher in LP piglets compared with AP and HP offspring (P < 0.01). Furthermore, LP piglets showed an elevated cortisol response to weaning, and in HP piglets, the CD4(+) cell percentage and the CD4(+)/CD8(+) ratio increased after weaning (P < 0.05). The lipopolysaccharide-induced rise of IL-6 was higher in LP (P = 0.09) and HP (P < 0.01) compared with AP piglets, and LP piglets displayed higher IL-10 levels than AP piglets (P < 0.05). Conclusions: Our results indicate that both low and high protein: carbohydrate ratios in the diet of pregnant sows can induce short-term as well as long-lasting effects on immune competence in piglets that may have serious consequences for host defence against bacterial pathogens.