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

## TL;DR

This study shows how components in a ewe's first milk affect lamb immunity, antibody levels, and growth over four months.

## Contribution

The study reveals new interactions between colostrum immune factors and lamb growth, beyond just IgG.

## Key findings

- Higher colostrum IgG leads to higher lamb serum IgG and better weight gain.
- Higher colostrum SAA is linked to lower lamb serum IgG and slower growth.
- Serum IL-6 is negatively associated with colostrum IgG and SAA concentrations.

## Abstract

Colostrum, the first milk produced after parturition, is an important source of nutrition and antibodies for the newborn, affecting overall development and that of the immune system. Our study investigated associations between levels of important immunological factors in ewe colostrum and the serum of neonatal lambs. Higher antibody levels in colostrum led to higher levels in lambs’ blood. Higher concentrations of serum amyloid A in colostrum were related to lower antibody levels in the lambs’ blood. Higher antibody levels were associated with higher average daily weight gain, while higher levels of inflammatory markers were related to lower daily weight gain over four months. Our findings emphasize that multiple immune factors interact to shape both immediate protection and long-term performance.

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.