Genetics and breeding of sheep in Brazil

McManus, Concepta; Paiva, Samuel Rezende; Araújo, Ronyere Olegário de

doi:10.1590/s1516-35982010001300026

Cited by 83 publications

(65 citation statements)

References 58 publications

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“…This result may be due to the small sample population (15 individuals), and due to the population being consolidated with planned genetic crosses established from breeding programs. Several studies using locally adapted or native breeds confirmed that these breeds have more number of loci in HWE when compared to more specialized breeds (McManus et al, 2010;Paiva et al, 2011a;Tolone et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Genetic diversity of locally adapted sheep from Pantanal region of Mato Grosso do Sul

Crispim¹,

Grisolia²,

Seno³

et al. 2013

Genet. Mol. Res.

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ABSTRACT. Sheep of the Pantaneiro breed and seven other breeds, raised in the State of Mato Grosso do Sul, Brazil, were genotyped using eight microsatellite loci. The aim of the present study was to determine the genetic variability, phylogenetic relationship, and patterns of gene introgression and miscegenation among the animals surveyed, to obtain information about the genetic structure of locally adapted sheep in Mato Grosso do Sul. A total of 195 animals were used for genetic analysis. The Pantaneiro breed had the largest average number of alleles/locus (9.25), and higher allelic richness (6.95), while the Dorper population had the lowest values for these parameters (4.88 and 3.86, respectively). Analysis of genetic distance values and genetic structure between populations made it possible to characterize these animals with regard to distinct genetic groups. Average expected heterozygosity ranged from 0.72 (Pantaneiro) to 0.55 (Dorper), while average observed heterozygosity ranged from 0.63 (White Dorper) to 0.54 (Dorper). On the basis of the statistical parameters evaluated, it 5459 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (4): 5458-5466 (2013) Genetic diversity in Pantaneiro sheep was possible to demonstrate that when compared to other populations, the Pantaneiro breed represented a reservoir of genetic diversity with rare and useful alleles for genetic improvement, emphasizing the importance of preserving the breed.

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Section: Discussionmentioning

confidence: 99%

Genetic diversity of locally adapted sheep from Pantanal region of Mato Grosso do Sul

Crispim¹,

Grisolia²,

Seno³

et al. 2013

Genet. Mol. Res.

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“…Despite data showing that several alterations outside the 136/154/171 codons, the relationship between the alteration and scrapie resistance could be speciϐic to the breed analyzed (Colussi et al 2010;McManus et al 2010). Therefore, it is vital to determine genotype for codons other than the classical ones associated with scrapie resistance and susceptibility for the different ovine breeds, establishing guidelines for genetic programmes aiming at scrapie epidemic risk reduction.…”

Section: Discussionmentioning

confidence: 99%

Single nucleotide polymorphisms at 15 codons of the prion protein gene from a scrapie-affected herd of Suffolk sheep in Brazil

et al. 2011

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Scrapie is a transmissible spongiform encephalopathy of sheeps and goats, associated with the deposition of a isoform of the prion protein (PrPsc). This isoform presents an altered conformation that leads to aggregation in the host's central nervous and lymphoreticular systems. Predisposition to the prion agent infection can be influenced by specific genotypes related to mutations in amino acids of the PrPsc gene. The most characterized mutations occur at codons 136, 154 and 171, with genotypes VRQ being the most susceptible and ARR the most resistant. In this study we have analyzed polymorphisms in 15 different codons of the PrPsc gene in sheeps from a Suffolk herd from Brazil affected by an outbreak of classical scrapie. Amplicons from the PrPsc gene, encompassing the most relevant altered codons in the protein, were sequenced in order to determine each animal's genotype. We have found polymorphisms at 3 of the 15 analyzed codons (136, 143 and 171). The most variable codon was 171, where all described alleles were identified. A rare polymorphism was found at the 143 codon in 4% of the samples analyzed, which has been described as increasing scrapie resistance in otherwise susceptible animals. No other polymorphisms were detected in the remaining 12 analyzed codons, all of them corresponding to the wild-type prion protein. Regarding the risk degree of developing scrapie, most of the animals (96%) had genotypes corresponding to risk groups 1 to 3 (very low to moderate), with only 4% in the higher risks group. Our data is discussed in relation to preventive measures involving genotyping and positive selection to control the disease.

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“…According to Paiva et al (2011), the use of only one class of marker (typically microsatellites) to inform maintenance and management policies is not desirable because one marker cannot provide all of the necessary genetic information. Studies involving Morada Nova sheep have been developed using RAPD (Paiva et al, 2005a), PCR-RFLP (Paiva et al, 2005b), microsatellites, and mtDNA (Paiva, 2005;McManus et al, 2010) markers. Paiva (2005) analyzed microsatellite genetic divergence between two herds of White and Red varieties and identified significant differences between them.…”

Section: Discussionmentioning

confidence: 99%

Genetic diversity and population structure of different varieties of Morada Nova hair sheep from Brazil

Js¹,

Paiva²,

Ec³

et al. 2014

Genet. Mol. Res.

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ABSTRACT. The aim of this study was to analyze genetic diversity and population structure among varieties of White (N = 40), Red (N = 32), and Black (N = 31) Morada Nova hair sheep from flocks in the northeastern Brazilian semiarid region. Fifteen nuclear microsatellite markers and two regions of mitochondrial DNA were used. The intra-population analysis demonstrated that the White variety had higher diversity, while the Red variety had the lowest values. The Bayesian analysis to assess the genetic population structure allowed differentiation between White, Red, and Black varieties, and revealed a tendency towards sub-structuring in the White variety flocks from the States of Ceará and Paraíba. The results of analyses of molecular variance showed that the greatest genetic structure was found when comparing flocks rather than varieties (8.59 vs 6.64% of the total variation, P < 0.001). Based on genetic distance, Dtl, both the dendrogram analysis and the principal coordinate analysis showed the formation of two main groups: one composed of White and another of Black and Red individuals. Five and two haplotypes were found for the D-loop region and the ND5 gene, respectively. A haplotype unique to the Red variety was found in the D-loop region and a variety haplotype unique to the Black variety was found in the ND5 gene; however, these frequencies were low and therefore require further validation. These results support the existence of substantial differences between the Red and White varieties and should be used as separate genetic resources and to improve conservation programs.

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Genetics and breeding of sheep in Brazil

Cited by 83 publications

References 58 publications

Genetic diversity of locally adapted sheep from Pantanal region of Mato Grosso do Sul

Genetic diversity of locally adapted sheep from Pantanal region of Mato Grosso do Sul

Single nucleotide polymorphisms at 15 codons of the prion protein gene from a scrapie-affected herd of Suffolk sheep in Brazil

Genetic diversity and population structure of different varieties of Morada Nova hair sheep from Brazil

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