Trott Josephine F, Simpson Kaylene J, Moyle Richard L C, Hearn Cyrma M, Shaw Geoffrey, Nicholas Kevin R, Renfree Marilyn B
Division of Molecular Biology and Genetics, Victorian Institute of Animal Science, Attwood, Victoria 3049, Australia.
Biol Reprod. 2003 Mar;68(3):929-36. doi: 10.1095/biolreprod.102.005934.
Specific changes in milk composition during lactation in the tammar wallaby (Macropus eugenii) were correlated with the ages of the developing pouch young (PY). The present experiment was designed to test the hypothesis that the sucking pattern of the PY determines the course of mammary development in the tammar wallaby. To test this hypothesis, groups of 60-day-old PY were fostered repeatedly onto one group of host mothers so that a constant sucking stimulus on the mammary gland was maintained for 56 days to allow the lactational stage to progress 42 days ahead of the age of the young. Analysis of the milk in fostered and control groups showed the timing of changes in the concentration of protein and carbohydrate were essentially unaffected by altering the sucking regime. The only change in milk protein secretion was a small delay in the timing of down-regulation of the secretion of whey acidic protein and early lactation protein in the host tammars. In addition, the rates of growth and development of the foster PY were significantly increased relative to those of the control PY because of ingesting more milk with a higher energy content and different composition than normal for their age. The present study demonstrates that the lactating tammar wallaby regulates both milk composition and the rate of milk production and that these determine the rates of PY growth and development, irrespective of the age of the PY.
袋鼠（尤金袋鼠）哺乳期乳汁成分的特定变化与育儿袋中发育幼崽（PY）的年龄相关。本实验旨在验证一个假设，即PY的吮吸模式决定了袋鼠乳腺发育的进程。为了验证这一假设，将60日龄的PY组反复寄养到一组宿主母亲那里，以便对乳腺保持持续56天的吮吸刺激，使泌乳阶段比幼崽年龄提前42天进行。对寄养组和对照组乳汁的分析表明，改变吮吸方式基本上不会影响蛋白质和碳水化合物浓度变化的时间。乳汁蛋白质分泌的唯一变化是，宿主袋鼠中乳清酸性蛋白和早期泌乳蛋白分泌下调的时间略有延迟。此外，由于摄入了比其年龄正常情况能量更高、成分不同的更多乳汁，寄养PY的生长和发育速度相对于对照PY显著加快。本研究表明，泌乳期的袋鼠会调节乳汁成分和产奶速度，而这些决定了PY的生长和发育速度，与PY的年龄无关。
