Calving time and foetus growth among wild reindeer in Norway

  • Eigil Reimers The Norwegian School of Veterinary Science, P.O.Box 8146 Dep., N-0033 Oslo, Norway & Institute of Biology, Division of General Physiology, University of Oslo, P.O.Box 1051 Blindern, N-0316 Oslo, Norway
Keywords: birth weight, carcass weight, calving date, foetus development, gestation, Rangifer tarandus, calving time, wild reindeer, Norway

Abstract

Mean calving dates among 7 wild reindeer (Rangifer t. tarandus) herds in southern Norway varied between the 6th and the 27th of May. Ln transformed foetus weights relate linearly to ln age in days. Regression analyzes based upon 225 days pregnancy predicts birth wet weights between 4600 and 7500 g in the different areas and years. At 130 days, foetus weights varied between 547 and 746 g (mean=681, standard deviation s=63) in all areas and years, indicating that foetus growth up to this size is independent of mothers body weight or condition. During the remaining 95 days of pregnancy, very poor body condition, reflected in dressed weights, resulted in slower foetus growth and smaller regression estimated birth weights. The foetus weight variation recorded at similar dates within areas and sampling years indicates a dispersed breeding time mostly within two ovulations. A small sample of foetuses from pregnant yearlings and calves indicate that these cohorts conceive later than 2 yr + females. Assuming similar foetus growth pattern among all female age cohorts within areas, yearlings conceive around 1 week later and calves (in Ottadalen) more than 3 weeks later than 2 + yr olds.
Published
2002-06-01
How to Cite
ReimersE. (2002). Calving time and foetus growth among wild reindeer in Norway. Rangifer, 22(1), 61-66. https://doi.org/10.7557/2.22.1.689
Section
Articles