Reproduction, Growth and Body Composition of Rivière George Caribou in Captivity

Abstract

Twenty females from the Rivière George caribou herd were captured in April 1987 in northern Quebec and were held in a zoo in Quebec City. Until November 1989, they were kept in an enclosure with a male from the same herd and they were fed ad libitum with pelleted concentrates and hay, supplemented with fresh deciduous leaves in summer. Daily food consumption exhibited an annual cycle, peaking at over 100 g·kg**-0.75 in summer and decreasing to ca. 70 g·kg**-0.75 by late winter. Food consumption decreased at the end of the last summer, due perhaps to lower hay quality. Mean body mass of adult females increased from 90 kg upon arrival at the zoo to ~115 kg in the autumn of 1987, ~125 kg in September 1988, and then decreased to 113 kg in November 1989. Pregnancy rate increased from 65% in 1987 to 82% in 1989 for animals captured in the wild. Two females born in captivity in 1987 became pregnant as yearlings, while 1 of 3 yearling females ovulated in 1989. Mass of calves at birth was higher in 1988 and 1989 than in 1987, while the calving period advanced by two weeks in the last two years. Growth of calves in summer was unrelated to birth mass and was higher in 1987 and 1988 (450-490 g/d) than in 1989 (365 g/d). Male calves grew at a faster rate than females. Carcass composition, in terms of lipids, protein and water, did not differ much between calves and yearlings born in captivity and free-ranging animals collected in 1983-84. However, the mass of each component was much lower in free-ranging lactating females than in captive ones. All captive females that had ovulated before necropsy, including one yearling, had at least 7.2 kg of stored fat.

Key words: captivity, caribou, fat, growth, George River, nutrition, protein, Québec, Rangifer tarandus, reproduction