Abstract

Knowledge on reproductive success is vital for successful management of large ungulates and is often measured by means of observing surviving offspring. In harvested ungulates, postmortem investigations of reproductive organs are used to estimate reproductive potential by obtaining ovulation rates and fetus numbers. However, there are differences in numbers of offspring observed, fetal/embryo counts, and ovulation rates. We hypothesize that the discrepancy between estimated reproductive potential and reproductive outcome in large ungulates is not only due to ova loss but also due to embryonic mortality. We investigated reproductive status in early pregnancy by sampling hunter-harvested moose (Alces alces) in southern Sweden from 2007 to 2011. In all, 213 reproductive organs were examined postmortem, and in confirmed pregnant moose (n = 53), 25 % (19 of 76) embryos were nonviable and 6 % of ova was unfertilized. The discrepancy between the ovulation rate of all pregnant moose (1.49) and the number of expected offspring per pregnant female, when embryonic mortality and unfertilized oocytes were accounted for (1.08), was 27.5 %. An association between inflammation of the inner mucous membrane (endometritis) of the moose's uterus and embryonic mortality was observed. This is the first comprehensive report of embryonic mortality and endometritis in moose. The observed discrepancy between ovulation rates and early embryonic development/survival shows that ovulation rates are indicative but not accurate estimates of moose reproductive rate. The use of ovulation rates as a sole estimator of future offspring rates may lead to an overharvest of a managed moose population.

Keywords

Conception rate; Embryonic mortality; Moose; Ovulation; Pregnancy failure; Reproduction

Published in

Acta Theriologica
2014, Volume: 59, number: 3, pages: 449-455
Publisher: SPRINGER HEIDELBERG

SLU Authors

• Malmsten, Jonas

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    
  • National Veterinary Institute (SVA)

• Dalin, Anne-Marie

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Zoology
Fish and Wildlife Management


Publication identifier

DOI: https://doi.org/10.1007/s13364-013-0173-6

Permanent link to this page (URI)

https://res.slu.se/id/publ/67635