SOMICS: genetics, genomics and evolution of prolific breeds of domestic sheep (Ovis aries)

• Ovulation rate and litter size in sheep (Ovis aries) are complex traits affected by endocrinological, genetic and environmental conditions. We analyzed factors affecting fecundity of the prolific Finnsheep breed and searched for related structural (SNP genotyping) and functional (mRNAs and miRNAs) variations in its genome. A total of 31 ewes representing three breed groups (Finnsheep, Texel and their F1-crossbreds) and two diets (control and flushing) were included. Experiments were focused on two different time points during establishment of pregnancy: follicular growth phase (the first phase) and early pregnancy prior to implantation (the second phase). Blood parameters were used to monitor ovary function and energy status of the ewes. In the first phase, one ovary of each ewe was surgically removed determined by individual progesterone profiles. After estimation of follicular counts, a sample of each ovary was used for RNA extraction followed by mRNA and miRNA sequencing using HiSeq200 Illumina technology. This revealed a total of 13 537 ovine genes expressed in all 31 samples. The gene expression profiles were then compared within and between breed-diet pairs. In the second phase, the sheep were inseminated and slaughtered followed by collecting another set of tissue samples (pituitary gland, CL, oviductal and uterine epithelial cells, preimplantation embryos) for RNA extractions and sequencing. In the final phase, SNP genotyping data will be correlated to transcriptome and phenotypic data. Preliminary results from the first phase show no significant effects of the diet (control vs flushing) on follicular counts within pure breeds (p>0.05). However, 503 genes showed significantly different expression levels between Finnsheep and Texel having flushing diets compared to one gene significantly differentially expressed between Finnsheep and Texel having control diets. This study provides new information on effects of flushing diet on fertility in the high-prolific Finnsheep breed, a valuable genetic resource for global sheep farming.

Ämnesord

LANTBRUKSVETENSKAPER  -- Bioteknologi med applikationer på växter och djur -- Genetik och förädling inom lantbruksvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agricultural Biotechnology -- Genetics and Breeding in Agricultural Sciences (hsv//eng)

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