The effects of different thawing methods on equine colostral IgG integrity and perseverance

Abstract

The equine placenta being epitheliochorial, is a barrier to immunoglobulins, which means that the foal is unable to receive passive immunity (Davies Morel, 2003) other than a small quantity of IgM which is synthesised in utero. McClure (as cited in McKinnon and Voss, 1993) suggests that the most significant component of passive immunity passed to foals, is that obtained from colostral immunoglobulins. When the foal ingests the colostrum and absorbs the antibodies therein, a temporary protection is provided until autogenous production of immunoglobulins reaches protective levels (McClure as cited in McKinnon and Voss, 1993). It is highly important that the foal receives colostrum within the first 24 hours and preferably within the first 12 hours of life (Davies Morel, 2003). This enables immunoglobulins to be absorbed by enterocyte cells lining the small intestine which are controlled by cortisol, and over time are replaced by ones which are unable to absorb proteins. For foals where colostrum is not readily available (for example, if the foal is orphaned at birth), then stored colostrum could be used. However, it is postulated that IgG integrity could be compromised by freezing, and consequently, thawing of the colostrum. The aim of this experiment is to evaluate five thawing methods for their ability to preserve IgG content of stored colostrum.