Wilde C J, Blatchford D R, Knight C H, Peaker M
Hannah Research Institute, UK.
J Dairy Res. 1989 Feb;56(1):7-15. doi: 10.1017/s0022029900026169.
Lactating goats were milked incompletely in one gland and normally in the other gland twice daily for 24 weeks. Yields of the incompletely milked glands were adjusted so that a calculated 100 ml milk remained in the gland at the end of milking. On average this residual volume was greater by 7.6% of the total milk volume than that left after normal milking and was 25.9% greater than the capacity of the alveoli. After 24 weeks, the weekly milk yield of the incompletely milked gland was 23.8% lower than that of the other gland (P less than 0.001) when expressed in relation to cell number. The metabolic capacity of secretory cells in the two glands was measured in serial tissue biopsies. Two weeks of incomplete milking had no effect on enzyme activities or metabolic fluxes in the incompletely milked gland, but after 24 weeks the activities of several key enzymes were significantly lower in this gland. This was associated with a reduced rate of synthesis of total protein and casein in explants freshly prepared from the tissue. The rate of lactose synthesis also tended to be lower in explants from the incompletely milked gland. Secretory cell number in the two glands was similar at the end of incomplete milking. The data indicate that incomplete milking over a long period caused partial secretory cellular involution via a local chemical feedback mechanism in the gland.
对泌乳山羊的一个乳腺进行不完全挤奶，另一个乳腺正常挤奶，每天两次，持续24周。对不完全挤奶的乳腺的产奶量进行调整，以便在挤奶结束时，预计该乳腺中残留100毫升乳汁。平均而言，这个残留量比正常挤奶后残留的量多占总奶量的7.6%，比肺泡容量大25.9%。24周后，以细胞数量计，不完全挤奶的乳腺每周产奶量比另一个乳腺低23.8%（P<0.001）。通过连续组织活检测量两个乳腺中分泌细胞的代谢能力。不完全挤奶两周对不完全挤奶的乳腺中的酶活性或代谢通量没有影响，但24周后，该乳腺中几种关键酶的活性显著降低。这与从该组织新制备的外植体中总蛋白和酪蛋白合成速率降低有关。不完全挤奶的乳腺的外植体中乳糖合成速率也往往较低。在不完全挤奶结束时，两个乳腺中的分泌细胞数量相似。数据表明，长期不完全挤奶通过乳腺中的局部化学反馈机制导致部分分泌细胞退化。
