Browsing by Author "Sneddon N"
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- ItemA frameshift-deletion mutation in Reelin causes cerebellar hypoplasia in White Swiss Shepherd dogs(John Wiley & Sons Ltd on behalf of Stichting International Foundation for Animal Genetics, 2023-10) Littlejohn MD; Sneddon N; Dittmer K; Keehan M; Stephen M; Drögemüller M; Garrick DCerebellar hypoplasia is a heterogeneous neurological condition in which the cerebellum is smaller than usual or not completely developed. The condition can have genetic origins, with Mendelian-effect mutations described in several mammalian species. Here, we describe a genetic investigation of cerebellar hypoplasia in White Swiss Shepherd dogs, where two affected puppies were identified from a litter with a recent common ancestor on both sides of their pedigree. Whole genome sequencing was conducted for 10 dogs in this family, and filtering of these data based on a recessive transmission hypothesis highlighted five protein-altering candidate variants - including a frameshift-deletion of the Reelin (RELN) gene (p.Val947*). Given the status of RELN as a gene responsible for cerebellar hypoplasia in humans, sheep and mice, these data strongly suggest the loss-of-function variant as underlying these effects. This variant has not been found in other dog breeds nor in a cohort of European White Swiss Shepherds, suggesting a recent mutation event. This finding will support the genotyping of a more diverse sample of dogs, and should aid future management of the harmful allele through optimised mating schemes.
- ItemDry matter yield, nutritive value and tiller density of tall fescue and perennial ryegrass swards under grazing(New Zealand Grassland Association, 2016-12-31) Hendricks S; Donaghy D; Matthew C; Bretherton M; Sneddon N; Cosgrove G; Christensen C; Kaufononga S; Howes J; Osborne M; Taylor P; Hedley MAlternative pasture species with the potential to supply quality forage during summer feed shortages, such as tall fescue (TF), are of interest to dairy farmers. A paddock scale study was undertaken to compare performance of TF managed on a shorter rotation similar to perennial ryegrass (RG) (TF-RG) with TF managed on a longer rotation more consistent with its morphology of 4 live leaves/tiller (TF-TF), and with RG (RG-RG). Accumulated dry matter (DM) yields were similar for the three treatments. Patch grazing was observed during the first spring, with more long patches in TFTF than in either TF-RG or RG-RG. Sown-species leaf area index (LAI) was greater in TF-TF compared with TF-RG and RG-RG (2.25, 1.56 and 0.90, respectively; P<0.05). The proportions of grass weeds were higher in the TF-RG (P<0.05) compared with TF-TF and RG-RG treatments (302, 207 and 164 g/kg DM, respectively). A soil fertility gradient with distance along the paddock away from the farm race was recorded, with Olsen P declining at 0.130 mg/kg/m with distance from the farm race. Tiller density, LAI and yield of sown species and total yield sampled were all positively correlated with Olsen P. Overall, this study highlights the importance of managing TF pastures according to its specific growth habits. However, attaining longer grazing rotations under field conditions whilst trying to maintain cow intakes, is likely to continue to prove elusive.