Determinação da dinâmica da infecção intramamária e seu impacto no perfil físico-químico do leite de cabras da raça saanen em diferentes momentos da lactação

Abstract

The milk production of small ruminants stands out in the agricultural sector, establishing itself as a viable alternative for small producers. Goat milk is recognized for its high nutritional value, better digestibility, high protein content, and hypoallergenic characteristics. However, milk quality is not assessed solely by its composition but also by its microbiological safety. There is commonly observed a prevalence of subclinical mastitis in herds, which leads to increased production costs. The somatic cell count (SCC) is an indicator of intramammary infection, and studies show that it can be influenced by factors such as the number of parturitions, stage of lactation, season of the year or climate, and breed. Another relevant aspect that reflects the health of the mammary gland is the physicochemical composition of the milk, which includes fat, lactose, protein, total solids (TS), and non-fat solids (NFS) content. These parameters are susceptible to changes due to inflammatory processes caused by pathogens, toxins, or tissue damage. This study aimed to evaluate the dynamics of SCC and the physicochemical composition of Saanen goat milk throughout different stages of lactation while also monitoring the microbiological condition. The research was conducted at the Laboratory of Goat and Sheep Farming at the Federal University of Paraíba, where milk samples were collected from nine Saanen goats at seven distinct moments during lactation (day of parturition – D0, and after 3, 7, 30, 60, 90, and 120 days). The SCC, physicochemical composition, and microbiological growth were analyzed, identified by MALDI-TOF MS. The results evidenced a prevalence of Staphylococcus spp., with a focus on coagulase-negative staphylococci. A progressive reduction in fat, protein, lactose, TS, and NFS was observed in healthy glands throughout lactation. In contrast, in infected glands, fat, protein, TS, and NFS showed a decrease on D7 compared to non- infected glands, suggesting that the initial impact of the infection may persist throughout lactation. It is concluded that non-aureus staphylococci are predominant in subclinical mastitis in goats and that mastitis causes changes in the physicochemical compositions of the milk, highlighting the relationship between udder health and milk quality.