Breeding schemes in reindeer husbandry

The objective of the paper was to investigate annual genetic gain from selection (G), and the influence of
selection on the inbreeding effective population size (Ne), for different possible breeding schemes within a reindeer herding
district. The breeding schemes were analysed for different proportions of the population within a herding district
included in the selection programme. Two different breeding schemes were analysed: an open nucleus scheme where
males mix and mate between owner flocks, and a closed nucleus scheme where the males in non-selected owner flocks are
culled to maximise G in the whole population. The theory of expected long-term genetic contributions was used and
maternal effects were included in the analyses. Realistic parameter values were used for the population, modelled with
5000 reindeer in the population and a sex ratio of 14 adult females per male. The standard deviation of calf weights was
4.1 kg. Four different situations were explored and the results showed: 1. When the population was randomly culled, Ne
equalled 2400. 2. When the whole population was selected on calf weights, Ne equalled 1700 and the total annual genetic
gain (direct + maternal) in calf weight was 0.42 kg. 3. For the open nucleus scheme, G increased monotonically from
0 to 0.42 kg as the proportion of the population included in the selection programme increased from 0 to 1.0, and Ne
decreased correspondingly from 2400 to 1700. 4. In the closed nucleus scheme the lowest value of Ne was 1300. For a
given proportion of the population included in the selection programme, the difference in G between a closed nucleus
scheme and an open one was up to 0.13 kg. We conclude that for mass selection based on calf weights in herding districts
with 2000 animals or more, there are no risks of inbreeding effects caused by selection.