A metabolomics approach for the study of long-term progesterone in domestic sheep and physiological processes in domestic and bighorn sheep
Herrygers, Melissa Rashelle
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Metabolomics allows for a snapshot of global metabolisms by studying metabolic intermediates and products of cellular metabolism. Experiments 1 and 2's objectives were to evaluate the effects of long-term P4 treatment, independent of the influence of the placenta and fetus, on changes in feed efficiency, BW, body composition, NEFA, metabolic hormones, and metabolites identified through nuclear magnetic resonance (NMR) metabolic profiling in mature Rambouillet ewes. Thirty, multiparous, 5- and 6-yr-old Rambouillet ewes were stratified by age and metabolic BW and assigned randomly to receive long-term P4 administration using controlled intravaginal releasing devices (CIDR) or no P4 (CIDRX; CIDR backbone only). Sera samples and body weights were collected every 14-d, along with CIDR/CIDRX replacement. Sera samples were assayed for metabolic hormones, NEFA, and metabolites. There were no differences in BW, RFI, STDMI, body composition, or temporal patterns of T3, T4, NEFA, or metabolites between CIDR- and CIDRX-treated ewes. Insulin concentrations were greater in CIDR-treated ewes than in CIDRX-treated ewes. Long-term P4 did not affect metabolism or body composition, independent from the presence of a fetus or placenta. Progesterone may increase tissue sensitivity to INS. In Experiment 3, the primary aim was to determine if NMR metabolic profiling has the potential to serve as a management tool for evaluating herds of bighorn (Ovis canadensis) sheep. Bighorn sheep herds were sampled between December of 2014 to March of 2015 in Montana and Wyoming. The sampling included 240 bighorn sheep ewes from 13 herds from geographically distinct locations at different times of the year. Metabolites identified by NMR in bighorn sheep serum were analyzed by pathway enrichment analyses, PLS-DAs, and biomarker analyses to determine if bighorn sheep herds can be distinguished by pregnancy status, geographic location, or time of year. NMR metabolic profiling could not distinguish between pregnant and non-pregnant bighorn sheep. Metabolic profiling did differentiate bighorn sheep herds and identified a subset of potential biomarkers that discriminated distinct geographic locations and time of year. Thus, NMR metabolic profiling has the potential to develop a suite of metabolites that wildlife managers can use to assess bighorn sheep nutrition and overall health.