Age Versus Weight

Customers should be aware that there are many reasons for variations in body weight, including:

  • Age is based on one week (7 days) of births. For inbred mice this can often result in a 5-6g weight range. For outbred mice this can easily be 12-15g. Rat weight ranges are obviously much bigger.
  •  We always sell the biggest stock first.
  •  We always try and size match stock, but in periods of high sales this may mean that we only have small stock to work with.
  •  We also have the problem that sorting through stock regularly can slow down or stop them growing. This can result in small animals of a particular age range being lighter than animals in a younger age range.
  •  Travel stress is always a factor and often affects body weight on arrival. Animals generally regain the weight within 48 hours, but this can vary depending on the strain and age of the animals as well as the conditions on the day the animals travel.

If size is important we suggest customers order by weight. We can then make a judgement about adding additional weight at the time of despatch to compensate for travel stress.