Bacterial Quality Of Fresh Cow Milk Obtained From Three Production Management Systems

ABSTRACT

A total of 30 samples of fresh milk from cows managed intensively, semi intensively and extensively were evaluated and compared for quality. Milk quality was assessed by three methods: the methylene blue reduction test, the agar plate count and the direct microscopic count. Determination of the bacteria isolates was carried out by incubation in the nutrient agar medium and the three bacteria that featured prominently were Escherichia coli, Pseudomonas spp. and Lactobacillus spp. The results of the methylene blue reduction test revealed that only 90% and 70% of the milk samples from cows managed intensively and semi-intensively merited excellent rating respectively. 10% and 30% of the milk samples from cows managed intensively and semi-intensively respectively merited good while 70% of the milk samples from cows managed extensively merited fair. No sample was rated poor. The agar plate count showed a range of 1.333±0.88 for intensive management system to 2.167±0.128 for semi-intensive management system and 3.633±0.122 cells/ml for extensive management system. The direct microscopic count showed the highest mean bacteria load for milk from cows managed extensively. The high bacterial counts as observed were probably indicative of poor management system. The result indicated that management system had significant effect (P < 0. 05) on milk quality for the methylene blue reduction test, the agar plate count and the direct microscopic count methods. In conclusion, it is suggested that milk from such cows managed extensively should be properly pasteurized before consumption and marketed early at source to reduce the time for microbial multiplication.