Knight C H, Wilde C J
Hannah Research Institute, Ayr, Scotland.
J Dairy Sci. 1987 Sep;70(9):1991-2000. doi: 10.3168/jds.s0022-0302(87)80241-2.
Milk yield is greatly influenced by the size of the mammary secretory cell population. In rats, proliferation of cells during early lactation may account for as much as three-quarters of the increase in daily milk yield between parturition and peak lactation; the remainder is due to increased activity of existing cells. Conversely, in goats, all the initial decline in milk yield after peak lactation can be attributed to loss of secretory cells. Increased frequency of milking enhances milk yield and reduces secretory cell loss, whereas goats hemimastectomized at peak lactation undergo compensatory changes in the remaining gland, which include a complete maintenance of cell number for at least 18 wk. Cell proliferation is increased in both cases, showing that mammary growth can occur during established lactation. The significance of this observation is discussed in relation to ways in which the milk yield of dairy animals might be increased.
产奶量受乳腺分泌细胞群体大小的影响很大。在大鼠中，泌乳早期细胞的增殖可能占分娩至泌乳高峰期每日产奶量增加量的多达四分之三；其余部分则归因于现有细胞活性的增加。相反，在山羊中，泌乳高峰期后产奶量最初的所有下降都可归因于分泌细胞的损失。增加挤奶频率可提高产奶量并减少分泌细胞损失，而在泌乳高峰期进行半乳切除的山羊，其剩余乳腺会发生代偿性变化，包括至少18周内细胞数量完全维持不变。在这两种情况下细胞增殖都会增加，表明乳腺生长可在既定泌乳期发生。结合提高奶牛产奶量的方法对这一观察结果的意义进行了讨论。
