| With the rapid development of the dairy industry as well as people’s pursuit to the healthy life, the safety of the dairy products has been paid much more attention. The effect of microorganism in raw milk on quality and safety of dairy products was focused. The microorganisms in cow breeding environment could influence the health of cattles, resulting the deterioration of the raw milk quality. Microbes in the air mainly exist in the form of microbial aerosols, which is a stable dispersion composed of suspended activity life particulates, such as microorganism, biological molecules, and so on. Staphylococcus, Streptococcus, Bacillus, Acinetobacter, yeasts, actinomycetes, fungi and viruses are the main microorganism in the air of cow breeding. And the main microorganism exist in the raw milk are pathogenic microorganisms, microbial bacteria, spoilage bacteria and fungi.Three barns of different breeding ways were selected and marked as barn A, barn B and barn C which are located at four different directions in Harbin. Microorganism in these there barns of four different seasons were collected by solid percussive type air microorganism sampler. Mean while the first three hands of milk and mixed samples in three barns were collected. The total bacterial counts were determined by plate count, and the flora composition were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS). The total number of colonies and flora composition of samples were compared, and the cluster of the dominant bacteria was also analysed. The influence of microorganisms in air on raw milk was discussed, providinge a theoretical basis for the control of quality of raw milk in pasture.There was a significant difference in total aerobic bacterial count among different milk samples. The total aerobic bacterial counts of the first three hands of milk was higher than that in the mixed milk. The microbial counts of milk samples collectedin spring and summer were higher than that in autumn. The microbial counts of Barn B is higher than that of barn A and barn C. Lactic acid bacteria, Escherichia coli and Staphylococcus in the milk in April and July accounted for 41.07%, 30.36% and 12.50%, respectively; the counts of Staphylococcus, Streptococcus agalactiae and Bacillus cereus in milk in January and November accounted for 64.86%, 10.81% and 6.76%, respectively. Cluster analysis showed that the sources of microorganisms in milk were extensive.The total aerobic bacterial counts in air of the three barns were compared and the results showed that the microbial counts in July was the lowest. There was a significant difference in microbial counts of the milk sample in Barn A among four months(P < 0.05). However, there wasn’t a significant differnce in microbial counts in both Barn B and Barn C between opend period and closed period. The counts of Staphylococcus, Bacillus genus of air in April and July accounted for 32.76% and 45.69% in opend period, respectively. The counts of Bacillus genus, Alternaria spp, Acinetobacter spp, Staphylococcus and Enterococcus of air in April and July accounted for 48.44%, 6.64%, 48.44% and 6.64% in closed period, respectively. Cluster analysis showed that the sources of microorganisms in milk were extensive.The results showed that the phylogenetic relationship of the same species of microganism between milk and cow barn was far, which indicated that the possibility of the same source is low. Therefore, health and hygiene of cows, environmental sanitation, cleans of milking and storage equipments play a significant role in the control of the counts an d species of milk. |
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