Physicochemical Characteristics of Dual-Purpose Cow's Milk During the Dry and Rainy Seasons in a Tropical Environment

Using an Ekomilk Bond Total Ultrasonic Milk Analyzer, the physicochemical characteristics of milk from 10 herds and 237 samples were analyzed during the rainy season (July and August; 109 samples) and dry season (January and February; 128 samples), providing the following measures: fat (%), non-fat solids (NFSs; %), density (g/mL), freezing point (°C), acidity (%), temperature (°C), lactose (%), conductivity (mS/cm), pH and water (%). In this study, there was a higher percentage of fat (2.975 vs. 5.001%) and a higher density (1033.692 vs. 1035.45 g/mL) in milk during the dry season compared to during the rainy season (p < 0.05). The rest of the milk characteristics were not significantly different relative to the study season (p > 0.05). The variables of fat and temperature of milk presented higher values in the dry season than in the rainy season, whereas the variables of density, freezing point and conductivity presented higher values in the rainy season than in the dry season (p < 0.001). Regarding the variables of NFSs, protein, acidity, lactose, pH and water percentage, the results were similar in the two study seasons (p > 0.05). Finally, density maintained significant positive correlations with the variables of protein, freezing point and lactose (p < 0.05). However, fat showed significant negative correlations with density, freezing point, acidity and conductivity (p < 0.05). In conclusion, the physicochemical characteristics of raw milk from dual-purpose cows per herd are better during the rainy season.