Características do leite de búfala em diferentes fases da lactação e análise da transferência de imunidade passiva

Abstract

In this study, the physicochemical composition of milk from Murrah buffaloes at different lactation stages was evaluated, as well as the efficiency of passive immunity transfer (PIT) to their calves. The experiment was conducted at Castanha Grande Farm, located in the municipality of São Luís do Quitunde, Alagoas, Brazil, using buffaloes maintained under a semi-intensive management system. Milk samples were collected from three lactation stages: colostrum (1 to 3 days postpartum), transitional milk (4 to 9 days), and mature milk (35 to 86 days). The contents of fat, protein, lactose, total solids, and non-fat solids were determined using a Dairy Spec FT analyzer. The immunological quality of colostrum and PIT was assessed by measuring the Brix percentage of both colostrum and calf serum using a portable refractometer. The average values of fat were 7.03%, 5.50%, and 5.14%; protein 7.29%, 6.23%, and 3.89%; lactose 3.15%, 3.30%, and 4.69%; total solids 18.89%, 16.35%, and 14.15%; and non-fat solids 11.85%, 10.87%, and 9.03%, respectively for colostrum, transitional milk, and mature milk. A gradual decrease in the main milk constituents was observed as lactation progressed, except for lactose, which increased over time. Colostrum %Brix values ranged from 14.2% to 25.0%, demonstrating considerable variability in the immunological quality of the colostrum produced by the buffaloes. Serum %Brix values in the calves ranged from 9.0% to 13.0%, indicating that all animals showed adequate serum levels of proteins and immunoglobulins. Although some colostrum samples showed values below the 23% Brix threshold recommended for cattle, PIT was satisfactory in all cases, supporting the literature that suggests lower cut-off values (around 18%) are more appropriate for buffaloes. This finding reinforces the importance of adopting species-specific thresholds to avoid misinterpretations based on bovine parameters. In this study, the correlation between colostrum and serum Brix values in buffalo calves was weak and negative, showing no clear evidence of the expected direct relationship between colostrum quality and the efficiency of passive immunity transfer.