Browsing by Author "Miles, Asha M."

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Direct Phenotyping and Principal Component Analysis of Type Traits Implicate Novel QTL in Bovine Mastitis through Genome-Wide Association
(MDPI AG, 2021-04) Miles, Asha M.; Posbergh, Christian J.; Huson, Heather J.
Our objectives were to robustly characterize a cohort of Holstein cows for udder and teat type traits and perform high-density genome-wide association studies for those traits within the same group of animals, thereby improving the accuracy of the phenotypic measurements and genomic association study. Additionally, we sought to identify a novel udder and teat trait composite risk index to determine loci with potential pleiotropic effects related to mastitis. This approach was aimed at improving the biological understanding of the genetic factors influencing mastitis. Cows (N = 471) were genotyped on the Illumina BovineHD777k beadchip and scored for front and rear teat length, width, end shape, and placement; fore udder attachment; udder cleft; udder depth; rear udder height; and rear udder width. We used principal component analysis to create a single composite measure describing type traits previously linked to high odds of developing mastitis within our cohort of cows. Genome-wide associations were performed, and 28 genomic regions were significantly associated (Bonferroni-corrected p < 0.05). Interrogation of these genomic regions revealed a number of biologically plausible genes whicht may contribute to the development of mastitis and whose functions range from regulating cell proliferation to immune system signaling, including ZNF683, DHX9, CUX1, TNNT1, and SPRY1. Genetic investigation of the risk composite trait implicated a novel locus and candidate genes that have potentially pleiotropic effects related to mastitis.
Short Communication: artificially reared ewes cannot be distinguished from natural reared ewes based on observed maternal behavior or lamb weaning weights
(Oxford University Press, 2024-09) Posbergh, Christian J.; Miles, Asha M.; Pettifor, Natasha L.; Thonney, Michael L.
Artificially rearing lambs is an important component of United States sheep production as some flocks select for increasing litter size to boost productivity. However, there is a conception among shepherds that artificially reared ewe lambs will ultimately result in poor mothers since they were not naturally raised. The objective of this study was to determine if differences in maternal behavior could be detected between ewes raised artificially and those raised naturally and if dam rearing type had an impact on lamb growth performance. Forty-eight ewes were enrolled comprised of 4 equal sized groups: artificially reared primiparous, naturally reared primiparous, artificially reared multi-parous, and naturally reared multi-parous. Ewes were observed using remote cameras to record maternal behaviors toward the lambs during and shortly after parturition. Behavior of 29 ewes during the first hour after parturition was analyzed. Independent multivariable regression models were evaluated for: proportion of time spent grooming, proportion of time spent helping the lambs nurse, number of helpful bouts, and the number of negative bouts. No statistically significant difference (P < 0.05) was detected between artificially reared and naturally reared ewes for the proportion of time spent grooming and the proportion of time spent helping the lambs nurse. Historical flock data were utilized to evaluate lamb growth between artificially and naturally reared ewes. No detrimental associations between artificially reared ewes and lamb weaning weights were observed. This study shows that artificially reared ewes are no different in terms of mothering behaviors and may be used as potential replacement candidates.