Effect of Colostrum Components on Early Inflammatory Response, IgG Concentration and Weight Gain in Lambs

Newborn sheep rely on passive transfer of immunity via colostrum as well as innate immunity for survival and adaptation to the extrauterine environment. This study examined associations between immunomodulatory constituents of colostrum, namely, immunoglobulin G (IgG), acute-phase proteins (APPs; serum amyloid A (SAA), and haptoglobin) and interleukin-6 (IL-6), and their corresponding concentrations in serum of 2-3-day-old offspring in a cohort of 296 Dorper lambs across three consecutive years. It also assessed the effects of these immunological markers on average daily weight gain (ADWG) during the first four months of life. IgG, APP, and IL-6 concentrations were measured, and mixed linear regression models were used for all analyses. Colostrum and serum concentrations of IgG and IL-6 were positively associated, whereas SAA levels in colostrum were negatively associated with IgG concentrations in serum. Serum IL-6 concentration was negatively associated with colostrum concentrations of IgG and SAA. Serum IgG concentration was positively associated with ADWG, while SAA and IL-6 concentrations were negatively associated with ADWG. These results show the importance of immunomodulating factors in colostrum other than IgG and emphasize the long-term effect of the serum concentrations of these factors on growth performance.