The effects of a plant-based and a plant- and marine-based n-3 oil supplement on behavioural reactivity, heart rate variability, and plasma fatty acid profile in young healthy horses.
Abstract: Behavioural reactivity in horses poses a welfare and safety risk to both the horse and the handler, however, beneficial effects have been observed when dietary fat is increased in replacement of sugar. Supplementation with the fatty acids (FA) eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) appear to improve negative behaviours in rodents and humans, but the effect of α-linolenic acid (ALA), EPA, and DHA, specifically, on reactivity in horses is unknown. The objective of this study was to evaluate the effects of camelina oil (CAM; ALA-enriched) and a mix of camelina and algal oil (ALG; ALA-, EPA-, and DHA-enriched) both fed at a dose of 0.37 g oil/kg body weight on plasma FA, behaviour, and heart rate variability (HRV) in young horses compared to a negative control (CON). Thirty-four client-owned horses aged 7 months - 6 years were enrolled. Horses were assigned to either CAM, ALG, or CON and underwent a novel object test (NOT) before and after a 6-week supplementation period. Prior to each NOT, blood was collected for evaluation of plasma FA profile (n = 28). During the NOT, behaviour was recorded using a pre-determined ethogram and assessed in BORIS software by two raters (n = 29). Electrocardiogram (ECG) data was collected at baseline, during the NOT, and after the NOT (recovery). The ECG data was analyzed in Kubios software for determination of heart rate (HR) and several HRV parameters (n = 24). The treatment oils were treated as fixed effects, baseline measurements as covariates, and location as a random effect. Plasma DHA (P < 0.01) was greater and n-6:n-3 ratio (P < 0.01) was reduced in ALG than in CAM and CON, while ALA and EPA were similar among treatments (P > 0.05). When treatments were pooled, the maximum HR (P < 0.01) and the low frequency to high frequency ratio HRV parameter (P < 0.01) were greater during the NOT compared to baseline and recovery. Bucking (P = 0.03) and backing (P = 0.02) behaviours were reduced in the CAM group compared to the CON group, but neither group differed from ALG. All other behaviours, HR, and HRV parameters were similar among treatments (P > 0.05). Our results suggest that the NOT was successful in creating acute stress, however, feeding either CAM or ALG at this dose did not reduce reactivity in this cohort of horses. Further research is needed to understand the effects of specific FA, if any, on behaviour and HRV in more specific populations of horses and specifically those deemed highly reactive.
© The Author(s) 2025. Published by Oxford University Press on behalf of the American Society of Animal Science.
Publication Date: 2025-04-08 PubMed ID: 40202435DOI: 10.1093/jas/skaf117Google Scholar: Lookup
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Summary
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The study investigates the impact of oil supplements sourced from plants and marine life on the behavioural reactions, heart rate variability, and plasma fatty acid profile of young, healthy horses. The research does not find any significant reduction in reactivity with the supplement doses used in the study.
Introduction and Objectives
- This research was primarily motivated by a concern for horse welfare and safety. Excessive behavioural reactivity in horses can pose risks to animals and their handlers.
- Previous studies have suggested positive benefits of dietary fat replacing sugar on horse behaviour. Moreover, certain fatty acids (namely eicosapentaenoic (EPA) and docosahexaenoic acid (DHA)) have been found to improve negative behaviours in humans and rodents.
- This study aimed to assess the effects of camelina oil, which is rich in α-linolenic acid (ALA), and a mix of camelina and algal oil, enriched in ALA, EPA, and DHA, on horses’ behaviour, heart rate variability, and plasma fatty acid profile. The effects were compared with a negative control group.
Methodology
- The study involved 34 horses aged between 7 months and 6 years, owned by clients of the researchers.
- The horses were exposed to a novel object test (NOT), which is a test of behaviour, both before and after a period of supplementation with one of the two types of oil or no oil (control).
- The behaviours of the horses were recorded and analyzed by designated software, and blood samples were obtained to evaluate their plasma fatty acid profiles.
- Additionally, electrocardiograms (ECGs) were conducted at various stages to assess heart rate and heart rate variability.
Results
- The results showed a notably greater amount of DHA and a reduced n-6:n-3 ratio in the algal group compared to the camelina-only and control groups. However, the ALA and EPA levels did not greatly differ across the groups.
- There was a significant rise in maximum heart rate and a key heart rate variability parameter during the NOT compared to baseline and recovery. This suggests that the horses experienced acute stress during this period.
- Two specific behaviours, bucking and backing, were marginally reduced in the camelina group compared to the control, but there was no significant difference between these groups and the algal group.
- All other measured behaviours, heart rate, and heart rate variability parameters were not dramatically different across the supplement feeding groups.
Conclusions and Further Research
- The study concludes that while the NOT successfully induced acute stress in the horses, the dosages of camelina oil or the mix of camelina and algal oil did not significantly decrease reactivity within the horse sample.
- The researchers call for further investigation into how specifics fatty acids may affect horse behaviour and heart rate variability, particularly in horses that are known to be highly reactive.
Cite This Article
APA
Hartwig S, Rankovic A, McCrae P, Gagliardi K, Burron S, Ellis J, Ma DWL, Shoveller AK.
(2025).
The effects of a plant-based and a plant- and marine-based n-3 oil supplement on behavioural reactivity, heart rate variability, and plasma fatty acid profile in young healthy horses.
J Anim Sci, skaf117.
https://doi.org/10.1093/jas/skaf117 Publication
Researcher Affiliations
- Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
- Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
- Department of Research and Development, Myant Inc., Toronto, ON M9W 1B6, Canada.
- Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
- Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
- Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
- Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
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