Colostrum and milk samples from 20 goats were analysed for concentrations of immunoglobulin G (IgG), β-lactoglobulin (β-lg), α-lactalbumin (α-la) and serum albumin (CSA) throughout the first 14 milkings post partum (7 d of lactation) using single radial immunodiffusion assay. Concentrations (mg/ml, means± SD ) at first milking were IgG 47·9±25·5, β-lg 30·7±10·4, α-la 2·77±0·82 and CSA 2·97±2·46 mg/ml. Large variations were recorded for IgG concentrations (19·9–94·5 mg/ml) and β-lg (9·3–49·8 mg/ml). Concentrations of IgG, β-lg and CSA dropped abruptly in the subsequent milkings and α-la concentration decreased slowly. Mean IgG concentration was <2 mg/ml after 7 milkings and <1 mg/ml after 11 milkings. However, IgG concentration does not differ significantly, at the 1% level, from milkings 7–14. The contribution of β-lg to the increase in whey proteins in early milks was greater than that of IgG from milkings 5 to 14. The results were tabulated to make it possible to calculate the excess of whey proteins that would be obtained if early milks were illegally added to milk supply.
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LEVIEUX et al. (2002) studied this question.