Jans J E, Woodside B
Dev Psychobiol. 1987 May;20(3):333-44. doi: 10.1002/dev.420200310.
Under a number of circumstances the duration of mother-young contact in the rat can be drastically reduced while pup growth is maintained. We investigated the possibility that under some of these conditions the timing of milk delivery is changed. We assessed the time of onset and pattern of milk delivery over a nest bout in litters of two different ages (Day 4 or Day 10) and three different sizes (4, 8, or 12 pups). Ambient temperature fluctuated over the course of the study and was found to correlate significantly with the latency to the first milk ejection (ME). Specifically, the warmer the ambient temperature, the quicker the first ME occurred. Durations between successive MEs correlated with ambient temperature in a similar fashion. Analysis of covariance revealed that the onset of the first ME occurred earlier in Day 10 litters than in Day 4 litters, but litter size had no effect. Durations between successive MEs were not affected by either litter age or litter size. These data indicate one possible mechanism by which adequate milk delivery can be maintained despite some reduction in mother-young contact.
在许多情况下，大鼠母婴接触的持续时间可以大幅缩短，同时幼崽的生长仍能维持。我们研究了在其中一些条件下乳汁分泌时间是否会改变的可能性。我们评估了两窝不同年龄（第4天或第10天）和三种不同大小（4只、8只或12只幼崽）的幼崽在一次哺乳期间乳汁分泌开始的时间和模式。在研究过程中，环境温度有所波动，并且发现其与首次乳汁喷射（ME）的潜伏期显著相关。具体而言，环境温度越高，首次ME出现得越快。连续两次ME之间的持续时间与环境温度的相关性类似。协方差分析表明，首次ME的开始时间在第10天的幼崽窝中比在第4天的幼崽窝中更早，但窝的大小没有影响。连续两次ME之间的持续时间不受幼崽年龄或窝大小的影响。这些数据表明了一种可能的机制，通过该机制，尽管母婴接触有所减少，但仍能维持充足的乳汁供应。
