Relationship between the values of density and immunoglobulin concentrations of buffalo's colostrum and their thermal stability

Abstract

Hydrometer is a simple, rapid tester and little cost method to evaluate the quality of colostrum. Colostral immunoglobulins (Igs) concentrations measured from one partial to third consecutive complete milking at 12 h intervals postpartum decreased at different rates over time or milking number. The colostrum is thicker, stickier and slightly yellow compared to normal milk, the specific gravity was higher than that of normal milk and the pH is lower. The thermal stability and some physico-chemical properties of individual buffalo's colostrum (5 animals) were followed during three days after postpartum. The heat stability of first postpartum milk can be visually defined in terms of the time required to induce coagulation at boiling temperature. Gradually marked variations of heat coagulation time were detected up to 60 h postpartum milking when heated at boiling temperature. The thermal stability of individual buffalo's colostrum was gradually increased with progressive postpartum milking, namely, at 1 h (0.55 min), 6h(3.53 min), 12h(7.10min), 24h(12.30min), 36 h(18.10min), 48 h (21.05 min) and 60 h (24.13 min). But at 72 h postpartum, it was observed no visual change (coagulation) during heating at boiling temperature for one hour. It can be seen that first postpartum milk was veiy unstable to heat treatment with coagulation at boiling temperature. The total solids, total protein, fat and ash contents were highest after parturition and then decreased rapidly to reach values of normal milk almost after three days of parturition, where the protein content was the most variable constituent. But, the changes in the lactose content followed an opposite trend.