Assessment of Total Bacterial Count in Milk Collection Chain in Different Climatic Zones of Sri Lanka

Cow milk is initially contaminated on the inner surface of the teat canal. Microbes from teat surfaces, milkers’ hands, equipment, poor hygiene and unhygienic environments contribute to raw milk contamination on farms and along the milk collection chain, leading to high bacterial counts that compromise milk quality. Total Bacterial Count (TBC) is a key indicator of raw milk quality, relevant to processors, consumers, and public health decision making. This study aimed to assess TBC along the milk collection chain, including farms, milk collecting points (MCP), milk chilling centres (MCC), and a milk processing plant (MPP) across different climatic zones in Sri Lanka from January to December 2024. A total of 353 raw milk samples were collected from farm cans, 40 L cans, chilling tanks, bowsers, and storage tanks, and tested by Total Plate Count (TPC). Samples included 93 (farm), 150 (MCP), 46 (MCC), and 64 (MPP). Median TBC values were 4.40×10⁶, 4.80×10⁷, 9.35×10⁷, and 6.00×10⁸ cfu/ml, respectively, while mean values were 2.11×10⁸, 3.79×10⁸, 6.11×10⁸, and 1.27×10⁹ cfu/ml. TBC differed significantly among collection points (p<0.05), with Tukey’s HSD test identifying milk at the MPP as most contaminated. A substantial increase was observed from MCP to MPP. No statistically significant relationship was found between TBC and milk temperature, likely due to fluctuations during transport. Titratable acidity showed a weak, non-significant positive correlation with TBC. This study demonstrates progressive bacterial contamination along the collection chain, with the highest levels at the processing plant. Adoption of good hygienic practices at farm and collection levels is essential to ensure milk safety, improve product quality, and protect public health.