Lérias Joana R, Hernández-Castellano Lorenzo E, Suárez-Trujillo Aridany, Castro Noemí, Pourlis Aris, Almeida André M
Instituto de Investigação Científica Tropical,Lisboa,Portugal.
Vetsuisse Faculty,Veterinary Physiology, University of Bern,Bern,Switzerland.
J Dairy Res. 2014 Aug;81(3):304-18. doi: 10.1017/S0022029914000235. Epub 2014 Jun 5.
The importance of small ruminants to the dairy industry has increased in recent years, especially in developing countries, where it has a high economic and social impact. Interestingly and despite the fact that the mammary gland is the specialised milk production organ, very few authors studied the modifications occurring in the mammary gland through the lactation period in production animals, particularly in the small ruminants, sheep (Ovis aries) and goat (Capra hircus). Nevertheless, understanding the different mammary gland patterns throughout lactation is essential to improve dairy production. In addition, associating these patterns with different milking frequencies, lactation number or different diets is also of high importance, directly affecting the dairy industry. The mammary gland is commonly composed of parenchyma and stroma, which includes the ductal system, with individual proportions of each changing during the different periods and yields in a lactation cycle. Indeed, during late gestation, as well as during early to mid-lactation, mammary gland expansion occurs, with an increase in the number of epithelial cells and lumen area, which leads to increment of the parenchyma tissue, as well as a reduction of stroma, corresponding macroscopically to the increase in mammary gland volume. Throughout late lactation, the mammary gland volume decreases owing to the regression of the secretory structure. In general, common mammary gland patterns have been shown for both goats and sheep throughout the several lactation stages, although the number of studies is limited. The main objective of this manuscript is to review the colostrogenesis and lactogenesis processes as well as to highlight the mammary gland morphological patterns underlying milk production during the lactation cycle for small ruminants, and to describe potential differences between goats and sheep, hence contributing to a better description of mammary gland development during lactation for these two poorly studied species.
近年来，小型反刍动物对乳制品行业的重要性日益增加，尤其是在发展中国家，其具有很高的经济和社会影响。有趣的是，尽管乳腺是专门的产奶器官，但很少有作者研究生产动物在泌乳期乳腺发生的变化，特别是在小型反刍动物绵羊（Ovis aries）和山羊（Capra hircus）中。然而，了解整个泌乳期不同的乳腺模式对于提高乳制品产量至关重要。此外，将这些模式与不同的挤奶频率、泌乳次数或不同的饮食联系起来也非常重要，直接影响乳制品行业。乳腺通常由实质和间质组成，其中包括导管系统，在泌乳周期的不同阶段和产量中，各自的比例会发生变化。事实上，在妊娠后期以及泌乳早期到中期，乳腺会扩张，上皮细胞数量和管腔面积增加，这导致实质组织增加，间质减少，宏观上对应于乳腺体积的增加。在整个泌乳后期，由于分泌结构的退化，乳腺体积会减小。总体而言，尽管研究数量有限，但在山羊和绵羊的几个泌乳阶段都显示出了常见的乳腺模式。本手稿的主要目的是回顾初乳生成和泌乳生成过程，以及突出小型反刍动物在泌乳周期中乳汁分泌背后的乳腺形态模式，并描述山羊和绵羊之间的潜在差异，从而有助于更好地描述这两个研究较少的物种在泌乳期间的乳腺发育情况。
