Immunoglobulin G (IgG), chemical composition contents of bovine milk during the first week of postpartum and the effect of heat treatments on bovine colostrum IgG contents were evaluated. Individual milk samples were collected from five cows at 0 to 0.5, 1, 2, 3, 4, 5, 6 and 7 days postpartum. The obtained results showed that the total solids, total protein, fat and ash contents decreased irregular with time after parturition, while the lactose content had an opposite trend. IgG concentrations were higher significantly during 0 to 0.5 and 1st days than those of other days postpartum, where the mean±SD of IgG concentrations were 122.60±5.24 and 118.44±5.90 g/L during 0-0.5 and 1st days postpartum, respectively. However, IgG concentrations dropped markedly with time progress of lactation at the end of the first week (7th day); it was 55.16±17.30 g/L that had dropped ratio of 55.01% when compared with its concentrations at 0 to 0.5 day. The IgG concentrations of thermally treated colostrum were decreased to 28.24, 30.27 and 30.18% at 63°C/30 min as well as 57.33, 73.54 and 95.1% at 72°C/15 s during 1, 2 and 3 days postpartum, respectively. On the other hand, the most thermal influence on IgG was at 100°C/10 min, where the percentage losses were 95.72% at 1st and 100% at 2 and 3 days postpartum. The total amino acids values of bovine milk immunoglobulins (IgS) were highest at 0 to 0.5 day and dropped markedly with time progress of lactation.
Key words: Bovine milk, colostrum, immunoglobulin G (IgG), heat treatments, amino acids.
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