Comparison of the timing of development of immunity in Romney lambs from resistant and resilient selection lines

Hamie, Joseph Chakana; McAnulty, Robin W.; Logan, Christopher M.; Lundberg, Sara S.; Greer, Andrew W.

doi:10.1016/j.vetpar.2019.04.014

Cited by 3 publications

(2 citation statements)

References 35 publications

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“…Differences between resilient and resistant animals are expressed in the immune response installation delay. In a study that compared the delay of immunity installation against gastro‐intestinal nematodes parasites in resistant and resilient selection lines of Romney lambs, authors found that resistant animals developed immunity earlier and these animals were more physiologically mature than resilient animals (Hamie, McAnulty, Logan, Lundberg, & Greer, 2019).…”

Section: Discussionmentioning

confidence: 99%

Individual variability among autochthonous sheep in Northern Tunisia to infection by abomasum nematodes and Babesia/Theileria parasites

Rouatbi

Romdhane

Bouaicha

et al. 2020

Veterinary Medicine & Sci

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In Tunisia, livestock plays an important role in the economy; unfortunately, Tunisian sheep population faces several health challenges. The aim of this trial was to study phenotypic variability of four local sheep breeds and strains to abomasum nematodes infection and to Babesia/Theileria parasites. Faeces, blood and abomasum contents were collected from 310 sheep slaughtered in eight commercial slaughterhouses across North Tunisia. Haematological and biochemical parameters were assessed. DNA was extracted and catch‐all primers were used to detect both Theileria spp. and Babesia spp. DNA. Faecal egg counts (FEC) was quantitatively assessed using simple flotation technique followed by McMaster technique. Male and female worms were collected from all abomasum contents and counted under a stereomicroscope. The percentage of faeces samples positive for GIN’s eggs was 30.82%. After worms’ recovery, the infection prevalence was estimated to 75.90%. The overall infection prevalence by Babesia spp. and Theileria spp. was 4.21%. The dispersion of observations plots obtained by principal component analysis (PCA) showed two clusters of individuals. The first cluster contains animals having positive Babesia/Theileria PCR, presence of nematodes in the abomasum contents and relatively low total worm count (TWC < 500) expect one animal which was found bearing high TWC (>500). In this same group, with a suspected form of resistance, animals showed normal values of albumin and normal haematological parameters (red blood cell count [RBC], haemoglobin [Hb] and packed cell volume [PCV]). The second cluster represents all the other observations in which subgroups of animals were distinguished on the basis of their potential resistance to abomasum nematodes. Multiple correlations showed significant positive correlations between RBC/Hb, RBC/PCV, PCV/Hb and FEC/TWC. Significant negative correlations were observed between TWC/RBC and TWC/Hb. It is concluded that the phenotypic variability among local sheep breeds is essential for more advanced genetic and genomic studies.

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Section: Discussionmentioning

confidence: 99%

Individual variability among autochthonous sheep in Northern Tunisia to infection by abomasum nematodes and Babesia/Theileria parasites

Rouatbi

Romdhane

Bouaicha

et al. 2020

Veterinary Medicine & Sci

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“…A previous study of our host–pathogen system but with non‐selected animals has clearly supported a Th2‐oriented immune response to H. contortus (Lacroux et al, 2006), as seen for other gastro‐intestinal nematode infection (Allen & Maizels, 2011). However, an accurate immune marker of the selected resistance against H. contortus may be particularly challenging to identify considering that the timing of immune response, rather than its magnitude, can be the most determinant aspect (Hamie et al, 2019). Moreover, no major effect QTL has been identified so far in our lines (Sallé et al, 2012, 2021).…”

Section: Discussionmentioning

confidence: 99%

The cost of host genetic resistance on body condition: Evidence from divergently selected sheep

Douhard

Doeschl‐Wilson

Corbishley

et al. 2022

Evolutionary Applications

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Trade-offs between host resistance to parasites and host growth or reproduction can occur due to allocation of limited available resources between competing demands.To predict potential trade-offs arising from genetic selection for host resistance, a better understanding of the associated nutritional costs is required. Here, we studied resistance costs by using sheep from lines divergently selected on their resistance to a common blood-feeding gastro-intestinal parasite (Haemonchus contortus). First, we assessed the effects of selection for high or low host resistance on condition traits (body weight, back fat, and muscle thickness) and infection traits (parasite fecal egg excretion and loss in blood haematocrit) at various life stages, in particular during the periparturient period when resource allocation to immunity may limit host resistance. Second, we analysed the condition-infection relationship to detect a possible trade-off, in particular during the periparturient period. We experimentally infected young females in four stages over their first 2 years of life, including twice around parturition (at 1 year and at 2 years of age). Linear mixed-model analyses revealed a large and consistent between-line difference in infection traits during growth and outside of the periparturient period, whereas this difference was strongly attenuated during the periparturient period. Despite their different responses to infection, lines had similar body condition traits. Using covariance decomposition, we then found that the phenotypic relationship between infection and condition was dominated by direct infection costs arising from parasite development within the host. Accounting for these within-individual effects, a cost of resistance on body weight was detected among ewes during their first reproduction. Although this cost and the reproductive constraint on resistance are unlikely to represent a major concern for animal breeding in nutrient-rich environments, this study provides important new insights regarding the nutritional costs of parasite resistance at different lifestages and how these may affect response to selection.

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Distinct immune response profile during rhipicephalus (boophilus) microplus infestations of guzerat dairy herd according to the maternal lineage ancestry (mitochondrial DNA)

Araújo

Ronda

Bittar

et al. 2019

Veterinary Parasitology

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Comparison of the timing of development of immunity in Romney lambs from resistant and resilient selection lines

Cited by 3 publications

References 35 publications

Individual variability among autochthonous sheep in Northern Tunisia to infection by abomasum nematodes and Babesia/Theileria parasites

Individual variability among autochthonous sheep in Northern Tunisia to infection by abomasum nematodes and Babesia/Theileria parasites

The cost of host genetic resistance on body condition: Evidence from divergently selected sheep

Distinct immune response profile during rhipicephalus (boophilus) microplus infestations of guzerat dairy herd according to the maternal lineage ancestry (mitochondrial DNA)

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