CHEMICAL COMPOSITION OF BOVINE MILK DURING THE FIRST WEEK POSTPARTUM AND ITS INFLUENCE BY SOME HEAT TREATMENTS

Bovine colostrum is the early milk produced by cows during the first several days postpartum. This early milk has a nutrient profile and immunological composition substantially different from mature milk. In the present study the chemical composition and immunoglobulin G (IgG) of bovine milk during the first week of postpartum were determined and the effect of heat treatments on bovine milk IgG contents was evaluated. Individual milk samples were collected from five cows at 0- 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 increased. The concentrations of IgG were significantly higher during 0-0.5 and 1^st 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 1^st days postpartum, respectively. However, IgG concentrations were dropped markedly with time progress of lactation at the end of the first week (7^th day), the mean±SD of IgG concentration was 55.16±17.30 g/L that dropped to 55.01% when compared with its concentrations at 0-0.5 day. IgG of bovine milk was influenced by heat treatments, where the concentrations of IgG in thermal treated milk were decrease to 28.24, 30.27 and 30.18% at 63°C/30 min and 57.33, 73.54 and 95.1% at 72°C/15 sec during 1, 2 and 3 days postpartum, respectively. On the other hand, the most thermal influence on IgG in milk was during thermal heated at 100°C/10 min, where the percentages of losses were 95.72% at 1^st and 100% at 2 and 3 days postpartum.