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Smith LA, Fox NJ, Marion G, Booth NJ, Morris AMM, Athanasiadou S, Hutchings MR. Animal Behaviour Packs a Punch: From Parasitism to Production, Pollution and Prevention in Grazing Livestock. Animals (Basel) 2024; 14:1876. [PMID: 38997988 PMCID: PMC11240309 DOI: 10.3390/ani14131876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/06/2024] [Accepted: 06/20/2024] [Indexed: 07/14/2024] Open
Abstract
Behaviour is often the fundamental driver of disease transmission, where behaviours of individuals can be seen to scale up to epidemiological patterns seen at the population level. Here we focus on animal behaviour, and its role in parasite transmission to track its knock-on consequences for parasitism, production and pollution. Livestock face a nutrition versus parasitism trade-off in grazing environments where faeces creates both a nutritional benefit, fertilizing the surrounding sward, but also a parasite risk from infective nematode larvae contaminating the sward. The grazing decisions of ruminants depend on the perceived costs and benefits of the trade-off, which depend on the variations in both environmental (e.g., amounts of faeces) and animal factors (e.g., physiological state). Such grazing decisions determine the intake of both nutrients and parasites, affecting livestock growth rates and production efficiency. This impacts on the greenhouse gas costs of ruminant livestock production via two main mechanisms: (1) slower growth results in longer durations on-farm and (2) parasitised animals produce more methane per unit food intake. However, the sensitivity of behaviour to host parasite state offers opportunities for early detection of parasitism and control. Remote monitoring technology such as accelerometers can detect parasite-induced sickness behaviours soon after exposure, before impacts on growth, and thus may be used for targeting individuals for early treatment. We conclude that livestock host x parasite interactions are at the centre of the global challenges of food security and climate change, and that understanding livestock behaviour can contribute to solving both.
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Affiliation(s)
- Lesley A Smith
- Animal and Veterinary Sciences, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK
| | - Naomi J Fox
- Animal and Veterinary Sciences, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK
| | - Glenn Marion
- Biomathematics and Statistics Scotland (BioSS), Kings Buildings, Edinburgh EH9 3FD, UK
| | - Naomi J Booth
- Animal and Veterinary Sciences, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK
| | - Alex M M Morris
- Animal and Veterinary Sciences, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK
| | - Spiridoula Athanasiadou
- Animal and Veterinary Sciences, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK
| | - Michael R Hutchings
- Animal and Veterinary Sciences, Scotland's Rural College (SRUC), West Mains Road, Edinburgh EH9 3JG, UK
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Siero E, Siteur K, Doelman A, Koppel JVD, Rietkerk M, Eppinga MB. Grazing Away the Resilience of Patterned Ecosystems. Am Nat 2019; 193:472-480. [PMID: 30794443 DOI: 10.1086/701669] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ecosystems' responses to changing environmental conditions can be modulated by spatial self-organization. A prominent example of this can be found in drylands, where formation of vegetation patterns attenuates the magnitude of degradation events in response to decreasing rainfall. In model studies, the pattern wavelength responds to changing conditions, which is reflected by a rather gradual decline in biomass in response to decreasing rainfall. Although these models are spatially explicit, they have adopted a mean-field approach to grazing. By taking into account spatial variability when modeling grazing, we find that (over)grazing can lead to a dramatic shift in biomass, so that degradation occurs at rainfall rates that would otherwise still maintain a relatively productive ecosystem. Moreover, grazing increases the resilience of degraded ecosystem states. Consequently, restoration of degraded ecosystems could benefit from the introduction of temporary small-scale exclosures to escape from the basin of attraction of degraded states.
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Fox NJ, Marion G, Davidson RS, White PCL, Hutchings MR. Climate-driven tipping-points could lead to sudden, high-intensity parasite outbreaks. ROYAL SOCIETY OPEN SCIENCE 2015; 2:140296. [PMID: 26064647 PMCID: PMC4453250 DOI: 10.1098/rsos.140296] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 04/23/2015] [Indexed: 05/27/2023]
Abstract
Parasitic nematodes represent one of the most pervasive and significant challenges to grazing livestock, and their intensity and distribution are strongly influenced by climate. Parasite levels and species composition have already shifted under climate change, with nematode parasite intensity frequently low in newly colonized areas, but sudden large-scale outbreaks are becoming increasingly common. These outbreaks compromise both food security and animal welfare, yet there is a paucity of predictions on how climate change will influence livestock parasites. This study aims to assess how climate change can affect parasite risk. Using a process-based approach, we determine how changes in temperature-sensitive elements of outbreaks influence parasite dynamics, to explore the potential for climate change to influence livestock helminth infections. We show that changes in temperate-sensitive parameters can result in nonlinear responses in outbreak dynamics, leading to distinct 'tipping-points' in nematode parasite burdens. Through applying two mechanistic models, of varying complexity, our approach demonstrates that these nonlinear responses are robust to the inclusion of a number of realistic processes that are present in livestock systems. Our study demonstrates that small changes in climatic conditions around critical thresholds may result in dramatic changes in parasite burdens.
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Affiliation(s)
- Naomi J. Fox
- Disease Systems Team, SRUC, King's Building, West Mains Road, Edinburgh EH9 3JG, UK
- Biomathematics and Statistics Scotland, King's Buildings, West Mains Road, Edinburgh EH9 3JZ, UK
- Department of Environment, University of York, Heslington, York YO10 5DD, UK
| | - Glenn Marion
- Biomathematics and Statistics Scotland, King's Buildings, West Mains Road, Edinburgh EH9 3JZ, UK
| | - Ross S. Davidson
- Disease Systems Team, SRUC, King's Building, West Mains Road, Edinburgh EH9 3JG, UK
| | - Piran C. L. White
- Department of Environment, University of York, Heslington, York YO10 5DD, UK
| | - Michael R. Hutchings
- Disease Systems Team, SRUC, King's Building, West Mains Road, Edinburgh EH9 3JG, UK
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Fox NJ, Marion G, Davidson RS, White PCL, Hutchings MR. Modelling parasite transmission in a grazing system: the importance of host behaviour and immunity. PLoS One 2013; 8:e77996. [PMID: 24223133 PMCID: PMC3819330 DOI: 10.1371/journal.pone.0077996] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 09/14/2013] [Indexed: 11/18/2022] Open
Abstract
Parasitic helminths present one of the most pervasive challenges to grazing herbivores. Many macro-parasite transmission models focus on host physiological defence strategies, omitting more complex interactions between hosts and their environments. This work represents the first model that integrates both the behavioural and physiological elements of gastro-intestinal nematode transmission dynamics in a managed grazing system. A spatially explicit, individual-based, stochastic model is developed, that incorporates both the hosts' immunological responses to parasitism, and key grazing behaviours including faecal avoidance. The results demonstrate that grazing behaviour affects both the timing and intensity of parasite outbreaks, through generating spatial heterogeneity in parasite risk and nutritional resources, and changing the timing of exposure to the parasites' free-living stages. The influence of grazing behaviour varies with the host-parasite combination, dependent on the development times of different parasite species and variations in host immune response. Our outputs include the counterintuitive finding that under certain conditions perceived parasite avoidance behaviours (faecal avoidance) can increase parasite risk, for certain host-parasite combinations. Through incorporating the two-way interaction between infection dynamics and grazing behaviour, the potential benefits of parasite-induced anorexia are also demonstrated. Hosts with phenotypic plasticity in grazing behaviour, that make grazing decisions dependent on current parasite burden, can reduce infection with minimal loss of intake over the grazing season. This paper explores how both host behaviours and immunity influence macro-parasite transmission in a spatially and temporally heterogeneous environment. The magnitude and timing of parasite outbreaks is influenced by host immunity and behaviour, and the interactions between them; the incorporation of both regulatory processes is required to fully understand transmission dynamics. Understanding of both physiological and behavioural defence strategies will aid the development of novel approaches for control.
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Affiliation(s)
- Naomi J. Fox
- Disease Systems Team, SRUC, Edinburgh, United Kingdom
- Environment Department, University of York, York, United Kingdom
- Biomathematics and Statistics Scotland, Edinburgh, United Kingdom
| | - Glenn Marion
- Biomathematics and Statistics Scotland, Edinburgh, United Kingdom
- * E-mail:
| | - Ross S. Davidson
- Disease Systems Team, SRUC, Edinburgh, United Kingdom
- Biomathematics and Statistics Scotland, Edinburgh, United Kingdom
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Allometric scaling of resource acquisition by ruminants in dynamic and heterogeneous environments. Ecol Modell 2010. [DOI: 10.1016/j.ecolmodel.2010.07.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Smith L, Marion G, Swain D, White P, Hutchings M. The effect of grazing management on livestock exposure to parasites via the faecal–oral route. Prev Vet Med 2009; 91:95-106. [DOI: 10.1016/j.prevetmed.2009.05.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 05/25/2009] [Accepted: 05/26/2009] [Indexed: 10/20/2022]
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Using accelerometer, high sample rate GPS and magnetometer data to develop a cattle movement and behaviour model. Ecol Modell 2009. [DOI: 10.1016/j.ecolmodel.2009.04.047] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Inter- and intra-specific exposure to parasites and pathogens via the faecal-oral route: a consequence of behaviour in a patchy environment. Epidemiol Infect 2008; 137:630-43. [PMID: 18812011 DOI: 10.1017/s0950268808001313] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Livestock herbivores are at risk of inter- and intra-specific exposure to parasites/pathogens via the faecal-oral route during grazing. Each contact between livestock and faeces in the environment is a potential parasite/pathogen transmission event. Cattle grazing contact with faeces varies in relation to the species depositing the faeces and the distribution of the faeces. We used a foraging model to simulate the grazing behaviour of beef cattle in two grazing systems to compare the relative inter-specific and intra-specific exposure risks to parasites/pathogens. Overall, there is a greater level of intra- vs. inter-specific risk via the faecal-oral route. However, under certain conditions, particularly for microparasite infections, e.g. paratuberculosis in rabbits and bovine tuberculosis in badgers, wildlife may pose a significant exposure risk to parasites/pathogens. These risks can be enhanced when cattle are first turned out onto pasture and in situations where intra-specific variations in wildlife behaviour result in more dispersed defecation patterns.
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Wulder MA, White JC, Coops NC, Nelson T, Boots B. Using local spatial autocorrelation to compare outputs from a forest growth model. Ecol Modell 2007. [DOI: 10.1016/j.ecolmodel.2007.06.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Identifying mechanistic models of spatial behaviour using pattern-based modelling: An example from lizard home ranges. Ecol Modell 2007. [DOI: 10.1016/j.ecolmodel.2007.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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