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. 2025 Jan 4:103:skaf117.
doi: 10.1093/jas/skaf117.

The effects of a plant-based and a plant- and marine-based n-3 oil supplement on behavioral reactivity, heart rate variability, and plasma fatty acid profile in young healthy horses

Samantha Hartwig  1 , Alexandra Rankovic  1 , Persephone McCrae  2 , Kiara Gagliardi  1 , Scarlett Burron  1 , Jennifer Ellis  1 , David W L Ma  3 , Anna K Shoveller  1
Affiliations

The effects of a plant-based and a plant- and marine-based n-3 oil supplement on behavioral reactivity, heart rate variability, and plasma fatty acid profile in young healthy horses

Samantha Hartwig et al. J Anim Sci. .

Abstract

Behavioral 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 behaviors 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, behavior, and heart rate variability (HRV) in young horses compared to a negative control (CON). Thirty-four client-owned horses aged 7 mo to 6 yr were enrolled. Horses were assigned to either CAM, ALG, or CON and underwent a novel object test (NOT) before and after a 6-wk supplementation period. Prior to each NOT, blood was collected for evaluation of plasma FA profile (n = 28). During the NOT, behavior was recorded using a predetermined ethogram and assessed in BORIS software by 2 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) behaviors were reduced in the CAM group compared to the CON group, but neither group differed from ALG. All other behaviors, 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 behavior and HRV in more specific populations of horses and specifically those deemed highly reactive.

Keywords: algal oil; behavior; camelina oil; equine nutrition; novel object test.

Plain language summary

Reactive behaviors in horses can impact the welfare and safety of both the horse and the handler. Reductions in reactivity have been observed in horses-fed diets with increased fat and low starch and sugar, but the effects of specific fatty acids on reactive behaviors in horses is unknown. Therefore, the objective of the study is to investigate the impacts of camelina oil (providing the plant-based α-linolenic acid, ALA) and a mix of camelina and algae oil (providing the marine-based eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA) on plasma fatty acids, heart rate variability, and reactive behaviors. Horses were supplemented with either camelina oil, a camelina and algae oil mix, or water (control) for 6 wk. All horses underwent a novel object test and plasma fatty acids, heart rate variability, and reactive behavior was assessed before and after supplementation. Plasma fatty acids were largely reflective of the oil consumed, however, heart rate variability and behavior did not differ among groups. Results suggest that supplementation with either camelina oil or a camelina and algae oil mix may not be effective in reducing reactive behaviors in otherwise healthy horses not experiencing chronic stress.

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Conflict of interest statement

All authors have no conflict of interest to disclose.

Figures

Figure 1.
Figure 1.
Images of the novel objects used during the baseline NOT (left) and the final NOT (right) for horses supplemented with 0.37 g/kg BW of either a placebo, camelina oil, or a camelina + algae oil mix for 6 wk, along with object dimensions. Note: images are not to scale.
See this image and copyright information in PMC

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