Monitoring circulating progesterone (P4) concentration is an important component of basic and applied reproduction research and clinical settings. IMMULITE® 2000 XPi (Siemens) is a newly upgraded fully automated immunoassay system marketed for human use to measure concentrations of different analytes including P4. Our objective was therefore to characterize the analytical performance of the IMMULITE® 2000 XPi P4 immunoassay across the reportable range in ovine serum. This validation of analytical performance included determining (1) linearity, (2) precision through within-run, and between-run coefficient of variation (CV) calculations, (3) accuracy through bias calculations for spiking-recovery bias and interlaboratory (range and average based) bias for two laboratories across the reportable range (0.2–40 ng/mL). The average within-run and between-run precision (CV%) across the reportable range of the IMMULITE® 2000 XPi P4 immunoassay for serum P4 concentration were both <5%, ranging between 2–8%. The average Observed Total Analytic Error (TEo) reported here for serum P4 concentration across the reportable range was ~30%, ranging from 14.8–59.4%, regardless of the considered bias. Based on these data we conclude that the automated IMMULITE® 2000 XPi P4 immunoassay provides a precise, accurate, reliable, and safe method for measuring P4 concentration ovine serum.

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Florida Native sheep is an indigenous breed from Florida and expresses superior parasite resistance. Previous candidate and genome wide association studies with Florida Native sheep have identified single nucleotide polymorphisms with additive and non-additive effects associated with parasite resistance. However, the role of other potential DNA variants, such as copy number variants (CNVs), controlling this complex trait have not been evaluated. The objective of the present study was to investigate the importance of CNVs on resistance to natural Haemonchus contortus infections in Florida Native sheep. A total of 200 sheep were evaluated in the present study. Phenotypic records included fecal egg count (FEC, eggs/gram), FAMACHA score, and packed cell volume (PCV, %). Sheep were genotyped using the GGP Ovine 50K SNP chip. The copy number analysis was used to identify CNVs using the univariate method. A total of 170 animals with CNVs and phenotypic data were used for the association testing. Association tests were carried out using single linear regression and Principal Component Analysis (PCA) correction to identify CNVs associated with FEC, FAMACHA, and PCV. To confirm our results, a second association testing using the correlation-trend test with PCA correction was performed. Significant CNVs were detected when their adjusted p-value was &lt; 0.05 after FDR correction. A deletion CNV in chromosome 21 was associated with FEC. This DNA variant was located in intron 2 of RAB3IL gene and overlapped a QTL associated with changes in eosinophil number. Our study demonstrated for the first time that CNVs could be potentially involved with parasite resistance in this heritage sheep breed.

The Florida Native Sheep is one of the oldest sheep breeds in the United States. This heritage breed from Florida, naturally adapted to humid and hot climate conditions, is one of the most parasite resistant breeds from the Southern US. However, only approximately 1,000 individuals remain alive in the world. Therefore, conservation efforts and breeding programs are critical for survival of this breed. The objective of this research was to estimate genetic parameters for parasite resistance and body condition score in Florida Native sheep. The pedigree file contained 695 animals born between 2018 and 2020 and included 279 individuals with genotypes (38,429 SNP after quality control). The dataset contained 365 animals with phenotypic records at 38 days post-infection (natural Haemonchus contortus infection) for fecal egg count (FEC), blood packed count volume (PCV), FAMACHA score (FAM), and body condition score (BCS). Genetic parameters were estimated using a multi-trait model with a Bayesian implementation in the GIBBS3F90 program. Heritabilities were 0.38 0.07, 0.47 0.05, 0.27 0.04, and 0.52 0.07 for FEC, PCV, FAM, and BCS. Genetic correlations among parasite resistance traits were high and favorable: -0.82 0.06 (FEC-PCV), 0.83 0.07 (FEC-FAM), and -0.94 0.03 (PCV-FAM). Genetic correlations among parasite resistance traits and BCS were -0.42 0.11 (FEC-BCS), 0.75 0.09 (PCV-BCS), and -0.82 0.05 (FAM-BCS). Genetic progress for parasite resistance is possible in Florida Native sheep. The FAMACHA score is a phenotypic parameter easy to record in sheep; therefore, genetic selection for this trait can be effective to improve the remaining traits.