Knight-Jones Theodore J D, Hang'ombe M Bernard, Songe Mwansa M, Sinkala Yona, Grace Delia
Food Safety & Zoonoses Program, International Livestock Research Institute (ILRI), Lusaka 10101, Zambia.
Department, School of Veterinary Science, University of Zambia, Lusaka 10101, Zambia.
Int J Environ Res Public Health. 2016 Jul 21;13(5):737. doi: 10.3390/ijerph13070737.
A field study was performed to assess safety of smallholder fresh cow's milk around Mongu, Western Province, Zambia. This involved observation and sampling of milk along the value chain from milking to point-of-sale and storage. Samples were collected from 86 cows, from 9 farmers, selling through two dairy cooperatives, with additional samples from informal markets. Production was very low; around one litre/day/cow and 10 L/day/herd. The milk was typically transported by bicycle in high ambient temperatures without refrigeration until reaching the point-of-sale (journey times of 30-120 min), where it was sold without pasteurisation despite milk-borne zoonoses being endemic (bovine tuberculosis (bTB) and Brucellosis). Although microbiological contamination was initially low, with geometric mean total bacterial count (TBC) of 425 cfu/mL (cfu = colony forming units) upon arrival at point-of-sale, poor hygiene led to high bacterial loads later on (geometric mean TBC > 600,000 cfu/mL after two days refrigeration), with almost all samples culture positive for Staphylococcus aureus and Escherichia coli. After milking, milk was kept for 100-223 min at temperatures favouring microbial growth (median 34 °C) and sold without a microbial kill step. In this situation limited variation in observed standards of milk hygiene had no significant effect on milk end-product bacterial counts. Options for refrigerated transport are limited. Pasteurisation at the cooperative should be investigated, as this would largely remove pathogenic microbes present in the milk whether resulting from cattle infection or poor hygiene during milking and transportation. As milk is also purchased directly from producers, on-farm milk heating options should also be assessed. Smallholders may benefit from access to national markets by providing milk to large dairies, which have systems for ensuring safety. However, this requires significant investment and an increased and more consistent supply of milk; and many consumers, unable to afford milk sold through formal sectors, would not benefit.
在赞比亚西部省蒙古周边地区开展了一项实地研究，以评估小农户新鲜牛奶的安全性。该研究包括对从挤奶到销售及储存的整个价值链中的牛奶进行观察和采样。样本取自9位农户的86头奶牛，这些牛奶通过两家乳制品合作社销售，另外还从非正式市场采集了样本。牛奶产量很低，每头奶牛每天约产1升，每群奶牛每天产10升左右。牛奶通常在高温环境下由自行车运输，且未冷藏，直到到达销售点（运输时间为30至120分钟），在销售点牛奶未经巴氏杀菌就出售，尽管通过牛奶传播的人畜共患病（牛结核病（bTB）和布鲁氏菌病）在当地很常见。尽管最初微生物污染程度较低，到达销售点时几何平均总细菌数（TBC）为425 cfu/mL（cfu = 菌落形成单位），但卫生条件差导致随后细菌数量大幅增加（冷藏两天后几何平均TBC > 600,000 cfu/mL），几乎所有样本的金黄色葡萄球菌和大肠杆菌培养均呈阳性。挤奶后，牛奶在有利于微生物生长的温度下（中位数为34°C）保存100至223分钟，且未经过杀菌步骤就出售。在这种情况下，观察到的牛奶卫生标准的有限差异对牛奶最终产品的细菌数量没有显著影响。冷藏运输的选择有限。应研究在合作社进行巴氏杀菌，因为这将在很大程度上消除牛奶中存在的致病微生物，无论这些微生物是由牛感染还是挤奶及运输过程中的卫生条件差导致的。由于牛奶也直接从生产商处采购，还应评估农场内的牛奶加热选项。小农户通过向大型乳制品厂供应牛奶进入全国市场可能会受益，大型乳制品厂有确保安全的系统。然而，这需要大量投资以及增加且更稳定的牛奶供应；而且许多买不起正规渠道销售的牛奶的消费者将无法受益。
