Characterisation of terminal sire sheep farm systems, based on a range of environmental factors: a case study in the context of genotype by environment interactions using Charollais lambs

McLaren, A; Lambe, N. R.; Morgan-Davies, C; Mrode, Raphael; Brotherstone, S.; Conington, J.; Morgan-Davies, J.; Bünger, L.

doi:10.1017/s175173111400072x

Cited by 6 publications

(8 citation statements)

References 36 publications

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“…Production traits have been combined in an environmental index in dairy (Haskell et al, ) and used with fertility and production indexes for the evaluation of G × E for fertility traits (Strandberg et al, ). Clustering techniques have also been used to categorize environments for the analysis of G × E multiple traits in sheep (McLaren et al, ) and in dairy cattle (Huquet, Leclerc, & Ducrocq, ; Windig, Calus, Beerda, & Veerkamp, ). Since there are varying degrees to which phenotypes can be impacted by different environmental factors, the combination of traits to derive environmental descriptors may provide a way to better capture environmental challenges.…”

Section: Discussionmentioning

confidence: 99%

Reaction norm analysis of pig growth using environmental descriptors based on alternative traits

Guy

Thomson

et al. 2019

J Animal Breeding Genetics

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Contemporary group (CG) estimates of different phenotypes have not been widely explored for pigs. The objective of this study was to extend the traits used to derive environmental descriptors of the growing pig, to include CG estimates of early growth between birth and start of feed intake test (EADG), growth during feed intake test (TADG), lifetime growth (ADG), daily feed intake (DFI), backfat (BF) and muscle depth (MD). Pedigree and performance records (n = 7,746) from a commercial Australian piggery were used to derive environmental descriptors based on CG estimates of these six traits. The CG estimates of growth traits described different aspects of the environment from the CG estimates of carcass traits (r < 0.10). These definitions of the environment then were used in reaction norm analysis of growth, to evaluate sire‐by‐environment interaction (Sire × E) for growth. The most appropriate reaction norm model to evaluate Sire × E for growth was dependent on the environmental descriptor used. If the trait used to derive an environmental descriptor was distinctly different from growth (e.g., BF and MD), CG as an additional random effect was required in the model. If not included, inflated common litter effect and sire intercept variance suggest there was unaccounted environmental variability. There was no significant Sire × E using any of the definitions of the environment, with estimated variance in sire slopes largest when environments were defined by BF (σfalse^bi2 = 97 ± 83 (g/day)2), followed by environments defined by DFI (σfalse^bi2 = 39 ± 101 (g/day)2). While there appears to be differences in ability to detect Sire × E, improved data structure is required to better assess these environmental descriptors based on alternative traits. The ideal trait, or combination of traits, used to derive environmental descriptors may be unique for individual herds. Therefore, multiple phenotypes should be further explored for the evaluation of Sire × E for growth in the pig.

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Section: Discussionmentioning

confidence: 99%

Reaction norm analysis of pig growth using environmental descriptors based on alternative traits

Guy

Thomson

et al. 2019

J Animal Breeding Genetics

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“…Questions posed covered aspects such as farm location and land cover; sheep numbers and breed; management of the flock throughout the year; health treatments and the use of labour. The questionnaire and results have been discussed in detail by McLaren et al (2014). Data collected from the 40 Texel flocks that responded were used in the current study.…”

Section: Fe Definitionmentioning

confidence: 99%

“…Genotypes are considered 'plastic' if they demonstrate highly variable phenotypes across environments or 'robust' if they remain relatively constant (de Jong and Bijma, 2002;Bryant et al,the phenotype expressed by a certain genotype over a number of different environments and can be particularly useful when environments are described along a continuous scale or gradient (de Jong and Bijma, 2002). The use of a continuous scale to define the environment also means that there is less reliance on genetic connections between each individual environment, thus removing some of the problems observed by McLaren et al (2014). When environments were not well connected, the estimation of reliable genetic correlations proved difficult.…”

Section: Introductionmentioning

confidence: 99%

The effects of different farm environments on the performance of Texel sheep

McLaren

Brotherstone

Lambe

et al. 2015

Animal

Self Cite

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In order to assess the extent of genotype by environment interactions (G × E) and environmental sensitivity in sheep farm systems, environmental factors must be identified and quantified, after which the relationship with the traits(s) of interest can be investigated. The objectives of this study were to develop a farm environment (FE) scale, using a canonical correlation analysis, which could then be used in linear reaction norm models. Fine-scale farm survey data, collected from a sample of 39 Texel flocks across the United Kingdom, was combined with information available at the national level. The farm survey data included information on flock size and concentrate feed use. National data included flock performance averages for 21-week-old weight (21WT), ultrasound back-fat (UFD) and muscle (UMD) depths, as well as regional climatic data. The FE scale developed was then combined with 181 555 (21WT), 175 399 (UMD) and 175 279 (UFD) records from lambs born between 1990 and 2011, on 494 different Texel flocks, to predict reaction norms for sires used within the population. A range of sire sensitivities estimated across the FE scale confirmed the presence of genetic variability as both 'plastic' and 'robust' genotypes were observed. Variations in heritability estimates were also observed indicating that the rate genetic progress was dependent on the environment. Overall, the techniques and approaches used in this study have proven to be useful in defining sheep FEs. The results observed for 21WT, UMD and UFD, using the reaction norm models, indicate that in order to improve genetic gain and flock efficiency, future genetic evaluations would benefit by accounting for the G × E observed.Keywords: sheep, reaction norms, genotype × environment interactions, environmental sensitivity ImplicationsAlthough there are a wide range of different sheep farming systems in the United Kingdom, there is relatively little information with regards to the extent of genotype by environment interactions and environmental sensitivity present within the industry. This study has demonstrated an approach for defining sheep farm environments (FEs), which was then used in the reaction norm analyses of Texel sheep. A range of sire sensitivities were observed across the different environments. The ability to identify this variation in sensitivities could allow the identification and selection of sires predicted to best suit specific FE, thus improving flock performance.

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“…Sheep flocks each tend to have their own unique set of resources, management schemes and challenges facing them [ 2 ]. In order to study how blackloss might be impacting the flocks of questionnaire respondents, it would be valuable to classify the respondents into different groups, based on variables related to their hill systems.…”

Section: Introductionmentioning

confidence: 99%

Investigating hill sheep farmers and crofters’ experiences of blackloss in the Highlands and Islands of Scotland

McAuliffe,

McLaren,

Sargison

et al. 2024

PLoS ONE

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Hill sheep farming is an important component of Scottish agriculture and comprises a significant land use in much of the Highlands and Islands. However it faces significant challenges due to the natural constraints of the landscape. Hill sheep farming uses hardy traditional breeds, such as the Scottish blackface and North Country Cheviot to graze extensive areas, where the sheep are not housed and tend to lamb on the open hill. Flocks are gathered several times a year for stock checks, husbandry, and health treatments. Between these handling events, stock will disappear and be unaccounted for. These unexplained losses are known as blackloss in the Highlands and Islands. Previously reported figures for annual lamb blackloss give an average of 18.6%. These losses are in addition to the known losses of lambs and represent a significant welfare and sustainability issue. High parasite burdens, predation, a photosensitisation disease known as plochteach or yellowses, and poor nutrition are often given as presumed reasons for blackloss. A questionnaire was developed to assess the experiences, impacts and understanding flock managers have of blackloss. Typology analysis using partitioning around medoids was used to cluster respondents into three distinct groups: 1- very large extensive farms and Sheep Stock Clubs, 2- medium sized farms, and 3- small-scale crofts. The responses of these groups were subsequently analysed to see if their experiences and perceptions of blackloss differed with relation to lamb health challenges and predation impacts. The groups reported similar health challenges, apart from Group 1 which had a significantly higher plochteach challenge. In terms of predators, Group 1 also perceived white-tailed eagles (Haliaeetus albicilla) as a much higher threat to their lambs than the other groups. It was observed that many of the respondents believed blackloss is inevitable and that predators pose a large threat to lambs. However, most agreed that reducing these losses is important and that understanding the causes would enable them to do so.

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Characterisation of terminal sire sheep farm systems, based on a range of environmental factors: a case study in the context of genotype by environment interactions using Charollais lambs

Cited by 6 publications

References 36 publications

Reaction norm analysis of pig growth using environmental descriptors based on alternative traits

Reaction norm analysis of pig growth using environmental descriptors based on alternative traits

The effects of different farm environments on the performance of Texel sheep

Investigating hill sheep farmers and crofters’ experiences of blackloss in the Highlands and Islands of Scotland

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