Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Department of Animal Sciences, University of Illinois-Urbana-Champaign, IL, 61801, Urbana, USA.
J Mammary Gland Biol Neoplasia. 2023 May 30;28(1):11. doi: 10.1007/s10911-023-09534-0.
Many studies on bovine mammary glands focus on one stage of development. Often missing in those studies are repeated measures of development from the same animals. As milk production is directly affected by amount of parenchymal tissue within the udder, understanding mammary gland growth along with visualization of its structures during development is essential. Therefore, analysis of ultrasound and histology data from the same animals would result in better understanding of mammary development over time. Thus, this research aimed to describe mammary gland development using non-invasive and invasive tools to delineate growth rate of glandular tissue responsible for potential future milk production. Mammary gland ultrasound images, biopsy samples, and blood samples were collected from 36 heifer dairy calves beginning at 10 weeks of age, and evaluated at 26, 39, and 52 weeks. Parenchyma was quantified at 10 weeks of age using ultrasound imaging and histological evaluation, and average echogenicity was utilized to quantify parenchyma at later stages of development. A significant negative correlation was detected between average echogenicity of parenchyma at 10 weeks and total adipose as a percent of histological whole tissue at 52 weeks. Additionally, a negative correlation between average daily gain at 10 and 26 weeks and maximum echogenicity at 52 weeks was present. These results suggest average daily gain and mammary gland development prior to 39 weeks of age is associated with development of the mammary gland after 39 weeks. These findings could be predictors of future milk production, however this must be further explored.
许多关于牛乳腺的研究都集中在发育的一个阶段。在这些研究中经常缺少对同一动物的多次发育测量。由于产奶量直接受到乳房内实质组织数量的影响，因此了解乳腺的生长以及在发育过程中对其结构的可视化是至关重要的。因此，对来自同一动物的超声和组织学数据进行分析，将有助于更好地了解乳腺随时间的发育情况。因此，本研究旨在使用非侵入性和侵入性工具来描述乳腺的发育，以描绘负责潜在未来产奶量的腺体组织的生长速度。从 10 周龄开始，从 36 头奶牛小牛中收集乳腺超声图像、活检样本和血液样本，并在 26、39 和 52 周进行评估。在 10 周龄时使用超声成像和组织学评估来量化实质组织，并利用平均回声强度来量化发育后期的实质组织。在 10 周龄时，实质组织的平均回声强度与 52 周时的总脂肪作为组织学全组织的百分比之间存在显著的负相关。此外，10 周和 26 周时的平均日增重与 52 周时的最大回声强度之间也存在负相关。这些结果表明，在 39 周龄之前的平均日增重和乳腺发育与 39 周龄后的乳腺发育有关。这些发现可能是未来产奶量的预测因素，但这还需要进一步探讨。
