Effects of various methods of milking, container types, and chilling durations on bacterial load of milk

This study was carried out to evaluate the quality of raw milk measured by Standard Plate Count (SPC). Individual raw milk for the Colony Forming Units (CFU) study was carried out in the National Cattle Research Program Rampur Chitwan, Nepal. Milk from Jersey and Holstein cows with two types of milking (hand and machine milking) in collecting three types of containers (Plastic, aluminum, and steel). Milk had different chilling durations (0, 4, 8, 12, 24, 48, and 72 hours). Altogether, 252 milk samples for SPC were examined at farm levels. Results showed significant variability in SPC throughout the study period. The lowest CFU was observed in Holstein cows (80.49±4.83 × 104), while the highest was found in the Jersey breed (122.88±4.69 × 104). Similarly, the lowest CFU count was recorded in milk from machine milking (92.42±4.69 × 104), whereas the highest CFU count was observed in milk from hand milking (110.95±4.83 × 104). For three milk collecting and transporting containers, the CFU count was lowest in the steel container (90.09±5.82×104) compared to the aluminum container (102.42±5.82×104) and plastic container (112.55±5.82×104). The results of mean CFU for the chilling duration effects at farm 0, 4, 8,12,24,48 and 72 hours were (114.33±8.11×104, 108.21±10.28×104, 107.71±10.28×104, 106.75±10.28 ×104, 104.07±6.36 ×104, 94.79±8.11×104, and 75.94±8.11×104). CFU count in hand and machine milking milk differed significantly (p<0.01) from each record of the same date at the farm level. The CFU in milk from different containers was significant (p<0.05) for the overall experimental period. Steel containers showed a low CFU count compared to Aluminum and plastic containers. The highest number of CFU (114.33×104) was observed in the 0-hour chilling, which was significantly (p <0.05) different from the rest of the chilling duration.  The results obtained from the study indicated that the current situation is critical and needs real improvement from farm to chilling centers. The findings could guide dairy producers in adopting effective strategies to enhance milk quality, minimize bacterial contamination, and ensure safer dairy products for consumers by using these results.