Linseed oil supplementation in pre-weaned calves: Effects on oxidative stress, immunity, and performance | Dellait

Álvaro García

Oxidative stress: An invisible challenge in young calves

The first weeks of life represent one of the most delicate phases in a calf’s development. During this period, the animal must rapidly adapt to a new environment while its immune and antioxidant systems are still immature. This imbalance creates a window where even well-managed calves can struggle to cope with disease pressure, environmental stress, and nutritional transitions.

At the center of this challenge is oxidative stress. This condition arises when the production of reactive oxygen species exceeds the calf’s ability to neutralize them through its antioxidant defenses. While these molecules are a normal part of metabolism and immune function, excessive levels can damage tissues, impair immune responses, and reduce growth efficiency.

In practice, oxidative stress rarely appears as a standalone problem. Instead, it amplifies usual challenges such as diarrhea, respiratory disease, temperature fluctuations, and handling stress. Under these conditions, nutrients that would normally support growth are redirected toward immune function, resulting in slower development and increased need for intervention.

Supporting the calf from the inside: The role of omega-3 fatty acids

Because oxidative stress and inflammation are linked, nutritional strategies that influence both processes have gained increased attention. Among these, omega-3 polyunsaturated fatty acids stand out for their ability to modulate immune responses while supporting antioxidant capacity.

Linseed oil is a rich source of α-linolenic acid, an omega-3 fatty acid that influences inflammatory pathways. Rather than simply adding energy to the diet, it alters how immune cells respond to challenges, helping prevent excessive inflammatory reactions. This results in a more controlled immune response, allowing calves to cope with stress without unnecessary physiological cost.

The use of ethyl esters derived from linseed oil further improves the practicality of this approach. These forms are easier to mix into milk replacer and are less prone to oxidation than raw oils, making them more suitable for consistent use under farm conditions.

In research settings, fatty acids derived from linseed oil are sometimes provided as ethyl esters, which improve stability and mixing in liquid feeds. Under practical farm conditions, however, linseed oil is typically used in its natural triglyceride form. Although the form differs, high-quality linseed oil still provides a rich source of omega-3 fatty acids and can support similar biological responses when properly managed.

Table 1: Typical fatty acid composition of linseed oil

What research has shown

A recent study by Baba and colleagues (2026) evaluated the effects of supplementing milk replacer with increasing doses of linseed-derived polyunsaturated fatty acids in pre-weaned calves, providing practical insight into how this strategy performs under real farm conditions. Calves receiving 30 mL per day showed the most consistent improvements, including higher body weight gain, better feed efficiency, and fewer days requiring veterinary treatment. At the same time, indicators of inflammation were reduced and antioxidant capacity improved, suggesting a stronger ability to cope with early-life stress.

These results are particularly relevant because they go beyond simple energy supplementation. The improvement in feed efficiency indicates that calves were using nutrients more effectively, due to a better physiological balance between immune activity and growth. In practical terms, linseed-derived omega-3 supplementation stabilizes calf performance during a biologically stressful period. While it does not eliminate disease challenges, it improves the calf’s ability to respond to them more efficiently.

The most consistent responses have been observed at approximately 30 mL per day. Lower inclusion levels may not produce a visible effect, which can lead to the mistaken conclusion that the strategy is ineffective. When applied correctly, the benefits are typically reflected in more uniform growth, fewer health interventions, and a smoother rearing process overall.

The effectiveness of this approach depends heavily on the quality of the oil used. Linseed oil is highly unsaturated and therefore prone to oxidation, meaning that poor-quality or improperly stored products can quickly lose their biological response. 

For this reason, farmers and nutritionists should prioritize feed-grade linseed oil sourced from reputable suppliers, such as oil mills, feed manufacturers, or agricultural distributors. Freshness and proper storage are critical. Exposure to air, heat, or light accelerates oxidation, reducing effectiveness. Using non-feed-grade or degraded oil is one of the most common reasons supplementation programs fail to deliver expected results.

Even well-designed strategies can fail if implementation is inconsistent. A frequent issue is expecting supplementation to compensate for weak colostrum management, poor hygiene, or inadequate housing conditions.

Take-home message

Oxidative stress and inflammation are key drivers of calf health and performance during the preweaning period, even when they are not immediately visible. Supporting the calf’s ability to manage these challenges is essential for achieving consistent growth and reducing disease pressure.

Supplementation with omega-3 fatty acids from linseed oil, when applied correctly and at effective inclusion levels, offers a practical way to enhance antioxidant capacity and regulate immune function. Although research often uses refined forms of these fatty acids, high-quality linseed oil can provide similar biological benefits under farm conditions when adequately managed. When combined with strong management, this approach can improve resilience, reduce treatment needs, and support better overall performance through to weaning.

The full list of references used in this article is available upon request.

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