Growth and development of Rattus lutreolus (Rodentia : Muridae) in the laboratory

Abstract

A laboratory breeding colony of R. l. lutreolus was used to obtain data on the growth in the length of head, hind foot, tail, head and body, and body weight during the first 130 days of life. The development of external body features was compared to that known for other Australian Rattus. The young are blind and naked at birth and are not fully furred until 13 days. Incisors are visible at day 8 (5-11) and erupt about day 12 (8-15) with the eyes opening at 17 days (15-18). Independence was achieved at about 25 days (23-30) with the first signs of reproductive maturity at about 60-70 days. Five stages of growth can be related to developmental features from teeth eruption to puberty and reproductive maturity. The onset of hearing (14-15) days appear to be as important in development as does the opening of the eyes. Body measurements show sigmoid relationships to a linear equivalence of weight (W*0.33), except for head and body length which is linear. R. l. lutreolus belongs to the fast-growing group in Australian murids. Measurements from laboratory-bred animals are in agreement with those for field animals, with head and body length the best single parameter for obtaining approximate ages.