Selection, Maternal Effects and Inbreeding in Reindeer Husbandry
In extensive grazing systems where several owners ’ flocks are allowed to mix, selection strategies will also interact, due to gene flow between flocks. The aim of the thesis was to analyse breeding schemes in terms of genetic gain and rate of inbreeding (∆F), given the complexity of ownership and i...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.137.6759 http://diss-epsilon.slu.se/archive/00000156/01/91-576-6400-5.fulltext.pdf |
| Summary: | In extensive grazing systems where several owners ’ flocks are allowed to mix, selection strategies will also interact, due to gene flow between flocks. The aim of the thesis was to analyse breeding schemes in terms of genetic gain and rate of inbreeding (∆F), given the complexity of ownership and interaction of selection strategies within a mixing reindeer population. The data, collected between 1986 and 1997 in the reindeer herding district of Ruvhten Sijte, Sweden, comprised 12,500 records of autumn calf weights. The mean phenotypic difference in calf weights between selected and non-selected flocks was 0.67 kg after 11 years of selection in Ruvhten Sijte. The genetic difference was 0.35 kg and the realized heritability was 0.2. Based on the realized heritablility, it was shown that if all owners had applied selection, the genetic response would have been 2 kg (corresponding to an annual genetic gain of 0.4 % of the phenotypic mean, including the initial lag due to age structure). The relationships between life-time patterns of female weight, calving incidence and offspring weight were examined. A female rearing a calf was shown to weigh 3.1 kg less in winter than one not rearing a calf. The regression coefficient of calf autumn weight on |
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