Optimization of Milk Substitutes for the Artificial Rearing of Chinese Tree Shrews (Tupaia belangeri chinensis)

SIMPLE SUMMARY: The Chinese tree shrew, a squirrel-like mammal, has been widely used as a laboratory animal in biological research. However, the low survival rate of the pups has seriously hindered the establishment of inbred lines of this species and further limited its wider use. We found a milk substitute appropriate for artificial rearing of Chinese tree shrew pups independent of any obvious adverse effects on their survival, health, and reproductive performance compared to those of the maternally reared pups. The successful optimization of a milk substitute for the artificial rearing of Chinese tree shrew pups may increase the availability of this experimental animal. ABSTRACT: The Chinese tree shrew (Tupaia belangeri chinensis) has the potential to replace the use of non-human primates in biomedical research. To increase the availability of this species, we have undertaken the ambitious task of establishing inbred lines of the Chinese tree shrew; however, we have been hindered by a low survival rate of inbred pups. Here, we report our artificial rearing (AR) of Chinese tree shrew pups using four different milk substitutes: the formula described by Tsang and Collins (milk TC) and three commercially available milk substitutes intended for possums (milk A and milk C) and for guinea pigs (milk B). We compared the effects of these milk substitutes and maternal milk on the daily milk consumption, growth performance, and survival of the pups. We also assessed the life span and reproductive performance of the F(1) individuals given the best milk substitute as compared to the maternally reared (MR) pups. Milk B was found to be appropriate for AR. Pups fed with milk B had a high survival rate at the weaning age compared to those fed with the other milk substitutes. The AR pups fed with milk B had a life span similar to that of MR pups. AR females fed with milk B had an earlier age of the first reproduction, a larger number of litters, and a higher rate of survival of the offspring at the weaning age compared with the MR females. The successful optimization of a milk substitute for AR of Chinese tree shrew pups will undoubtedly facilitate the wide usage of this experimental animal.