Harper L A, DiLeo C, Basran P S, Wieland M
College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
JDS Commun. 2024 Mar 2;5(4):338-343. doi: 10.3168/jdsc.2023-0542. eCollection 2024 Jul.
Mastitis is among the costliest diseases affecting dairy cows, partly due to the resulting permanent reduction in the quantity and quality of milk produced. Most mastitis cases involve pathogenic organisms entering the cow's mammary gland through the teat canal. The teat has natural defenses against these pathogens that can be disrupted during milk harvesting. These disruptions of the teat's circulatory system and tissue integrity can predispose them to mastitis. Traditionally, machine milking-induced changes in teat blood circulation and tissue integrity have been assessed by means of manual evaluation and ultrasonography. Infrared thermography has previously been shown to produce precise and consistent measurements of skin surface temperatures (SST) on cows' hind teats. Our objective was to describe the variability in the teat SST following machine milking. Describing the variability in teat SST before and after milking could be useful to guide further studies to elucidate the physiology of the effects of milking on teat defense mechanisms. In this observational study, thermographic images of both hind teats from 140 cows immediately pre- and postmachine milking were analyzed. The average SST were subsequently determined at the proximal, middle, and distal aspects of each hind teat using image analysis software. The LSM (95% CI) from general linear mixed models of the pre- and postmilking SST, respectively, were 33.6 (33.5-33.8)°C and 35.4 (35.3-35.5)°C at the proximal aspect, 33.2 (33.1-33.4)°C and 35.2 (35.1-35.3)°C at the middle aspect, and 32.3 (32.1-32.5)°C and 34.0 (33.9-34.1)°C at the distal aspect. The observed increase in SST from pre- to postmilking SST at all 3 aspects of the teat suggest that some of the variability in the SST can be attributed to the milking event. Future research is warranted to investigate the biological relevance of SST changes during machine milking and any potential change in teat defense mechanisms, risk of mastitis, or other pathologies.
乳腺炎是影响奶牛的成本最高的疾病之一，部分原因是由此导致的牛奶产量和质量的永久性下降。大多数乳腺炎病例涉及致病生物体通过乳头管进入奶牛的乳腺。乳头对这些病原体具有天然防御能力，但在挤奶过程中可能会受到破坏。乳头循环系统和组织完整性的这些破坏会使它们易患乳腺炎。传统上，机器挤奶引起的乳头血液循环和组织完整性变化是通过手动评估和超声检查来评估的。先前的研究表明，红外热成像能够精确且一致地测量奶牛后乳头的皮肤表面温度（SST）。我们的目标是描述机器挤奶后乳头SST的变异性。描述挤奶前后乳头SST的变异性可能有助于指导进一步的研究，以阐明挤奶对乳头防御机制影响的生理学原理。在这项观察性研究中，分析了140头奶牛在机器挤奶前后立即采集的两个后乳头的热成像图像。随后使用图像分析软件在每个后乳头的近端、中部和远端确定平均SST。挤奶前和挤奶后SST的一般线性混合模型的最小二乘均值（LSM，95%置信区间）在近端分别为33.6（33.5 - 33.8）℃和35.4（35.3 - 35.5）℃，在中部为33.2（33.1 - 33.4）℃和35.2（35.1 - 35.3）℃，在远端为32.3（32.1 - 32.5）℃和34.0（33.9 - 34.1）℃。在乳头的所有三个部位观察到的挤奶前到挤奶后SST的升高表明，SST的一些变异性可归因于挤奶事件。有必要进行未来的研究，以调查机器挤奶期间SST变化的生物学相关性以及乳头防御机制、乳腺炎风险或其他病理状况的任何潜在变化。
