Genetic parameters for production traits, resistance and resilience to Nematode parasites under different worm burden challenges in Corriedale sheep

Marques, Camila Balconi; Goldberg, Virginia; Ciappesoni, Gabriel

doi:10.1016/j.vetpar.2020.109272

Cited by 9 publications

(12 citation statements)

References 16 publications

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“…In the case of FD, the 50K SNP chip didn´t increase mean accuracies probably due to the low number of genotyped animals (0.8%), and also because FD is a trait with higher heritability compared to FEC (h 2 =0.50 versus h 2 =0.18), so the margin to increase accuracies is much lower. FEC and FD reported heritability estimates for this study agree with previous ones in Corriedale breed in Uruguay (30) (47)(48) . Heritability is a factor that influences estimated breeding value accuracy: higher trait heritability, higher accuracies.…”

Section: Discussionsupporting

confidence: 91%

SNP arrays evaluation as tools in genetic improvement in Corriedale sheep in Uruguay

G.¹

2022

Agrocienc Urug

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One control strategy for gastrointestinal nematodes (GIN) is genetic selection. This study´s objective was to compare eggs per gram of feces (FEC) and fiber diameter (FD) estimated breeding values (EBV) and genomic EBV (GEBV) in Corriedale breed. Analysis included 19547 lambs with data, and 454, 711 and 383 genotypes from 170, 507 and 50K SNP chips, respectively. A univariate animal model was used for EBV and GEBV estimation, which included contemporary group, type of birth and dam age as fixed effects, and age at recording as covariate. Differential weights (α) were considered in the genomic relationship matrix (G), and the best fit models were identified using Akaike´s Information Criterion (AIC), which were later used for GEBV and accuracies estimation. The use of α only impacted on low density SNP chips. No differences were observed in mean accuracies for the whole population. However, in the genotyped subgroup accuracies increased by 2% with the 170 SNP chip (α=0.25), and by 5% (α=0.5) and 14% (α=0.75) with the 507 SNP chip. No differences were observed in FD EBV and GEBV mean accuracies. These results show that it is possible to increase GEBV accuracies despite the use of low-density chips.

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Section: Discussionsupporting

confidence: 91%

SNP arrays evaluation as tools in genetic improvement in Corriedale sheep in Uruguay

G.¹

2022

Agrocienc Urug

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“…Based on the current results of estimated genetic correlations between LFEC and FAMACHA, there is no clear indication for usefulness for genetic selection for FAMACHA to genetically reduce the FEC in sheep. However, previous studies with Corriedale sheep found moderate genetic correlation estimates between Log e (FEC + 100) and FAMACHA scores (0.55 ± 0.12) suggesting these two traits could be used together for selection toward more resilient or resistant sheep ( Balconi Marques et al, 2020 ). In relation to resilience, it is possible for animals with low FAMACHA scores and high levels of FEC to be tolerant to parasite infections and, therefore, FAMACHA could contain additional information beyond FEC.…”

Section: Resultsmentioning

confidence: 92%

“… van Wyk and Bath (2002) cited perfect correlation of 1.00. The different estimates for genetic correlations reported in the literature could be due to: 1) the level of infection, where higher worm environmental challenge leads to an increase in the heritability and genetic correlation estimates for FAMACHA and FEC traits; 2) data handling, specifically in relation with subjective clinical scoring for FAMACHA or the number of McMaster chambers counted; and 3) the different transformation methods of the raw FEC data in the different studies (e.g., Box–Cox transformation, log transformations, ln transformations; Riley and van Wyk, 2009 ; Silva et al, 2012 ; Balconi Marques et al, 2020 ). Based on the current results of estimated genetic correlations between LFEC and FAMACHA, there is no clear indication for usefulness for genetic selection for FAMACHA to genetically reduce the FEC in sheep.…”

Section: Resultsmentioning

confidence: 99%

Comparison between methods for measuring fecal egg count and estimating genetic parameters for gastrointestinal parasite resistance traits in sheep

Boareki

Schenkel

Willoughby

et al. 2021

Journal of Animal Science

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Fecal egg count (FEC) is an indicative measurement for parasite infection in sheep. Different FEC methods may show inconsistent results. Not accounting for inconsistencies can be problematic when integrating measurements from different FEC methods for genetic evaluation. The objectives of this study were to evaluate the difference in means and variances between two fecal egg counting methods used in sheep, the Modified McMaster (LMMR) and the Triple Chamber McMaster (LTCM); to estimate variance components for the two FEC methods, treating them as two different traits; and to integrate FEC data from the two different methods and estimate genetic parameters for FEC and other gastrointestinal parasite resistance traits. Fecal samples were collected from a commercial Rideau-Arcott sheep farm in Ontario. Fecal egg counting was performed using both Modified McMaster and the Triple Chamber McMaster methods. Other parasite resistance trait records were collected from the same farm including eye score (FAMACHA ©), body condition score (BCS), and body weight (WT). The two FEC methods were highly genetically (0.94) and phenotypically (0.88) correlated. However, the mean and variance between the two FEC methods were significantly different (P < 0.0001). Therefore, re-scaling is required prior to integrating data from the different methods. For the multiple trait analysis, data from the two fecal egg counting methods were integrated (LFEC) by using records for the LMMR when available and replacing missing records with re-standardized LTCM records converted to the same mean and variance of LMMR. Heritability estimates were 0.12 ± 0.04, 0.07 ± 0.05 , 0.17 ± 0.06, and 0.24 ± 0.07 for LFEC egg count, FAMACHA ©, BCS, and WT, respectively. The estimated genetic correlations between fecal egg count and the other parasite resistance traits were low and not significant (P>0.05) for FAMACHA © (r= 0.24 ± 0.32) and WT (r= 0.22 ± 0.19), and essentially zero for BCS (r= -0.03 ± 0.25), suggesting little to no benefit of using such traits as indicators for LFEC.

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“…Especially supplementary feeding of protein has been shown to enhance the host’s immune response against H. contortus infections [ 34 , 40 , 41 , 42 ]. Genetic selection for traits that lead to host resistance and/or resilience is a further promising strategy of IPM, as such traits are often highly hereditary [ 10 , 34 , 43 , 44 , 45 ]. Vaccination against haemonchosis offers a further perspective for parasite control (see Section 4 ).…”

Section: Current Control Strategiesmentioning

confidence: 99%

Haemonchosis in Sheep and Goats, Control Strategies and Development of Vaccines against Haemonchus contortus

Adduci

Sajovitz

Hinney

et al. 2022

Animals

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The evolutionary success of parasitic worms causes significant economic losses and animal health problems, including in the small ruminant industry. The hematophagous nematode Haemonchus contortus is a common endoparasite that infects wild and domestic ruminants worldwide, especially in tropical and subtropical regions. To date, the most commonly applied control strategy is the administration of anthelminthic drugs. The main disadvantages of these chemicals are their ecotoxic effects, the necessary withdrawal period (especially important in dairy animals) and the increasing development of resistance. Vaccines offer an attractive alternative control strategy against Haemonchus infections. In previous years, several potential vaccine antigens prepared from H. contortus using the latest technologies have been assessed in clinical trials using different methods and strategies. This review highlights the current state of knowledge on anti-H. contortus vaccines (covering native, recombinant and DNA-based vaccines), including an evaluation, as well a discussion of the challenges and achievements in developing protective, efficient, and long-lasting vaccines to control H. contortus infection and haemonchosis in small ruminants. This paper also addresses novel developments tackling the challenge of glycosylation of putative candidates in recombinant form.

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Genetic parameters for production traits, resistance and resilience to Nematode parasites under different worm burden challenges in Corriedale sheep

Cited by 9 publications

References 16 publications

SNP arrays evaluation as tools in genetic improvement in Corriedale sheep in Uruguay

SNP arrays evaluation as tools in genetic improvement in Corriedale sheep in Uruguay

Comparison between methods for measuring fecal egg count and estimating genetic parameters for gastrointestinal parasite resistance traits in sheep

Haemonchosis in Sheep and Goats, Control Strategies and Development of Vaccines against Haemonchus contortus

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