Department of Animal Science, Federal University of Paraiba, Areia-PB, 58397-000, Brazil.
J Dairy Sci. 2011 Jun;94(6):3166-75. doi: 10.3168/jds.2010-3471.
The aim of this study was to gain information on quality traits, mainly bacterial and somatic cell counts of bulk milk, produced by small- and medium-scale producers in a semiarid northeastern region of Brazil and to identify and characterize possible risk factors associated with those quality traits. A cross-sectional study was performed on 50 farms. Bulk milk samples were collected for bacterial and somatic cell counts. Additionally, information about farm demographics, general management practices, hygiene, and milking procedures was also obtained. Multivariable analysis using logistic regression was performed with predictors previously identified by univariate analysis using a Fisher's Exact test. Aerobic mesophilic bacteria counts varied from 3.59 log to 6.95 log cfu/mL, with geometric mean of 5.27 log cfu/mL. Mean total coliform count was 3.27 log (1.52 log to 5.89 log) most probable number (MPN)/mL, whereas mean thermotolerant coliforms was 2.38 log (1.48 log to 4.75 log) MPN/mL. A high positive correlation was observed between aerobic mesophilic bacteria and coliform counts. Although most farms met the standard for the current regulations for total bacteria (88%) and somatic cell counts (94%), nearly half of the producers (46%) would have problems in achieving the 2012 threshold limit for total bacteria count if no improvement in milk quality occurs. Mean value for staphylococci was 3.99 log (2.31 log to 6.24 log) cfu/mL, and Staphylococcus aureus was detected in 33 (66%) farms. Premilking teat-end wash procedure (odds ratio=0.191) and postmilking teat dip (odds ratio=0.67) were associated with lower aerobic mesophilic bacteria and Staphylococcus aureus counts in bulk milk, respectively. Considering that the farm characteristics in this study are representative of the semiarid northeastern region, these findings encourage further investigations for supporting intervention measures intended to improve the quality of milk produced by smallholders.
本研究旨在获取巴西东北部半干旱地区小规模和中等规模生产者所生产的散装奶的质量特性信息，主要是细菌和体细胞计数，并确定和描述与这些质量特性相关的可能风险因素。对 50 个农场进行了横断面研究。采集散装奶样本进行细菌和体细胞计数。此外，还获得了有关农场人口统计学、一般管理实践、卫生和挤奶程序的信息。使用逻辑回归进行多变量分析，使用 Fisher 精确检验进行单变量分析之前确定的预测因子。好氧嗜温细菌计数范围为 3.59 log 至 6.95 log cfu/mL，几何平均值为 5.27 log cfu/mL。总大肠菌群计数的平均值为 3.27 log（1.52 log 至 5.89 log）最可能数（MPN）/mL，而耐热大肠菌群的平均值为 2.38 log（1.48 log 至 4.75 log）MPN/mL。好氧嗜温细菌和大肠菌群计数之间存在高度正相关。尽管大多数农场符合当前总细菌（88%）和体细胞计数（94%）标准，但如果散装奶质量没有改善，近一半的生产者（46%）将难以达到 2012 年总细菌计数的阈值限制。葡萄球菌的平均值为 3.99 log（2.31 log 至 6.24 log）cfu/mL，33 个（66%）农场检测到金黄色葡萄球菌。预挤奶乳头末端清洗程序（比值比=0.191）和挤奶后乳头浸浴（比值比=0.67）与散装奶中好氧嗜温细菌和金黄色葡萄球菌计数较低相关。考虑到本研究中的农场特征代表了半干旱东北部地区，这些发现鼓励进一步调查，以支持旨在提高小农户生产的奶质量的干预措施。
