Waste milk feeding practices have been implicated as a potential source for disseminating antimicrobial resistant bacteria among animals and the environment. Two interventions that have shown potential for degrading antimicrobial drugs in milk are heat and pH treatment. The aim of this study was to evaluate the effect of heat and pH treatments on the degradation of ceftiofur and ceftiofur free acid equivalents in milk at concentrations previously found in waste milk on dairy farms by spiking saleable pasteurized whole milk with ceftiofur sodium. Three heat treatments of ceftiofur sodium spiked milk were evaluated for their ability to degrade ceftiofur: 63°C for 30 min (LTLT), 72°C for 15 s (HTST) and 92°C for 20 min (HTLT). Two pH treatments of ceftiofur sodium spiked milk were evaluated: pH 4.0 (LpH) and pH 10 (HpH). Control samples spiked with ceftiofur sodium were kept at room temperature and samples collected at corresponding times for heat and pH treatments. Four treatment replicates were performed for each treatment group. Ceftiofur was quantified in milk samples using liquid chromatography mass spectrometry (LC-MS/MS) and ceftiofur free acid equivalents (CFAE) were measured using high-performance liquid chromatography (HPLC). HTLT resulted in a degradation of 35.24% of the initial concentration of ceftiofur. Ceftiofur degradation did not differ between control and the remaining two heat treatment groups (LTLT and HTST). HpH resulted in degradation of the 95.72 and 96.28% of the initial concentration of ceftiofur and CFAE, respectively. No significant changes in degradation of ceftiofur or CFAE were observed for control or LpH treatments. In conclusion, our study results were that alkalinizing milk to pH 10 and heating milk to 92°C for 20 min degraded ceftiofur and CFAE in spiked simulated waste milk demonstrated promising potential as treatment options for degrading ceftiofur and CFAE in waste milk, and further research is needed to evaluate the viability for implementation of these treatments in dairy farms.

中文翻译：

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热处理和 pH 处理对全脂牛奶中头孢噻呋降解的评价。

废牛奶喂养方式被认为是在动物和环境中传播抗菌药物耐药细菌的潜在来源。热处理和 pH 处理是两种已显示出降解牛奶中抗菌药物潜力的干预措施。本研究的目的是通过在可销售的巴氏灭菌全脂牛奶中添加头孢噻呋钠，评估加热和 pH 处理对牛奶中头孢噻呋和头孢噻呋游离酸当量降解的影响（以前在奶牛场废奶中发现的浓度）。评估了头孢噻呋钠掺入牛奶的三种热处理降解头孢噻呋的能力：63°C 30 分钟（LTLT）、72°C 15 秒（HTST）和 92°C 20 分钟（HTLT）。对掺入头孢噻呋钠的牛奶的两种 pH 处理进行了评估：pH 4.0 (LpH) 和 pH 10 (HpH)。将掺有头孢噻呋钠的对照样品保存在室温下，并在相应时间收集样品进行加热和 pH 处理。每个治疗组进行四次治疗重复。使用液相色谱质谱法 (LC-MS/MS) 对牛奶样品中的头孢噻呋进行定量，并使用高效液相色谱法 (HPLC) 测量头孢噻呋游离酸当量 (CFAE)。HTLT 导致头孢噻呋初始浓度降解 35.24%。对照组和其余两个热处理组（LTLT 和 HTST）之间的头孢噻呋降解没有差异。HpH 导致头孢噻呋和 CFAE 的初始浓度分别降解 95.72% 和 96.28%。对于对照或 LpH 处理，没有观察到头孢噻呋或 CFAE 的降解发生显着变化。总之，我们的研究结果表明，将牛奶碱化至 pH 10，并将牛奶加热至 92°C，持续 20 分钟，可降解加标模拟废奶中的头孢噻呋和 CFAE，这表明作为降解废奶中头孢噻呋和 CFAE 的处理方案具有广阔的潜力，并且需要进一步研究需要评估在奶牛场实施这些处理的可行性。