Retraction to: PSVIII-10 Genome-wide CNV analysis unravels a deletion associated with parasite resistance in Florida native sheep

Abstract 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 < 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.

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PSVIII-8 Genetic parameters for parasite resistance in an endangered and heritage sheep breed from Florida

Journal of Animal Science ◽

10.1093/jas/skab235.441 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 242-242

Author(s):

Zaira M Estrada-Reyes ◽

Jorge A Hidalgo Moreno ◽

Brittany N Diehl ◽

Ibukun M Ogunade ◽

Andres A Pech-Cervantes ◽

...

Keyword(s):

Body Condition ◽

Genetic Parameters ◽

Body Condition Score ◽

Genetic Correlations ◽

The United States ◽

Parasite Resistance ◽

Southern Us ◽

Condition Score ◽

Native Sheep ◽

Resistance Traits

Abstract 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.

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