I want to study on mouses after birth, but unfortunately litters are eaten after birth by their mother.How can I prevent mothers from cannibalizing their litters?
This is a behavioral pathology that can sometimes be genetic; however, it usually occurs as a consequence of stress, which is most commonly caused by animal husbandry issues. You may want to look into environmental enrichment strategies for lab rodents. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4176978/ and http://www.ncbi.nlm.nih.gov/pubmed/19112447 are a good start.
Make sure you feed pregnant mothers a high calorie chow for breeding. Also, try mating the females again, often they do much better on the second litter. Make sure you have bedding material so the females can build a nest, we usually use cotton gauze pads or Nestlets. Also, make sure your animal room is on a 12 hour light/dark cycle. This happens occasionally even under the best of circumstances.
I find noise to be a major factor, so I would recommend keeping that to a minimum. Also, avoid handling pups because foreign smells can trigger mums to cannibalise the pups. You can try distracting the mother with enrichment such as treats (sunflower seeds is a popular one) and lots of nesting materials. Also, if it is the first litter for a new mum, she is more likely to cannabilise but most of the time females improve in their second litter.
Best wishes!