Can Omega-3 Fatty Acids Improve Piglet Health?

In swine production weaning is the most stressful time in a piglet’s life. At this time piglets are removed from the sow, moved to a new room in the same barn or offsite, mixed with unfamiliar pen mates, and they begin consuming an unfamiliar diet. These stressors (social, environmental and nutritional) contribute to what the industry refers to as the ‘post-weaning growth lag’ which can affect piglet welfare. This growth lag is characterized by anorexia, reduced or negative growth and increased susceptibility to pathogens. In some cases piglets do not eat for 24-48 hours. It has been shown that during weaning, some piglets undergo an inflammatory reaction triggered by these stresses (the stress and immune response pathways are closely linked in the body). Although a certain degree of immune response is beneficial, an over-production of immune cells can become detrimental to the animals, leading to reduced muscle growth or even muscle degradation and thus the post-weaning growth lag.

Over the years we have seen many nutritional strategies implemented with the goal of improving piglet performance and welfare at the time of weaning. Some of these strategies include the use of feed in the farrowing room (this is called “creep” feed and it is supposed to encourage piglets to eat solid food prior to weaning), the use of highly palatable protein sources in starter diets and even the use of novel feed ingredients to encourage piglets to eat immediately post-weaning. Recently the Prairie Swine Centre (Saskatoon, SK) conducted a series of experiments and continues to research how nutritional modulation using Omega-3 fatty acids can improve piglet health and performance at weaning. 

Omega-3 (n3) and Omega-6 (n6) fatty acids are long chain polyunsaturated fatty acids. Depending on the source (plant or fish), the n3 or n6 fatty acids will differ slightly in structure and function. The metabolites of these fatty acids are highly active in the body. The n6 products are generally considered pro-inflammatory (cause inflammation) and the n3 products are antiinflammatory (prevent inflammation). In other words, the n3 fatty acids may assist in regulating the body’s immune response, and thus may help alleviate the stress-induced immune response generated at weaning. 

Recently at the Prairie Swine Centre an experiment was conducted to determine how altering the n6 to n3 fatty acid ratio (n6:n3) in sows’ diets would affect the inflammatory responses of their piglets. Sows were fed one of 5 diets with varied n6:n3 fatty acid ratios: A control (tallow based) diet, plant based ratios of 10:1, 5:1 and 1:1 in the diet, or a fish based 5:1 ratio. Piglets were weaned on day 26 of lactation onto a common commercial starter diet. A total of 100 piglets were used; 20 in each of the 5 dietary treatment groups.

On day 7 post-weaning the piglets underwent an immune challenge. Half of the piglets in each dietary treatment group were injected with a portion of E.Coli bacteria (called LPS) to trigger a short-lived (approximately 24 hours) immune response. The E. coli LPS trigger is widely used in both animal and human trials because it is non-pathogenic, meaning it does not cause disease, but it does elicit a short-term immune response. In the context of this experiment it was used to mimic the inflammatory responses of piglets that occur at weaning. The other half of the piglets in each dietary treatment group received an injection of saline (control group). Rectal temperatures were recorded at 0, 1, 2, 3, 4, 5, 6, 12 and 24 hours post injection, and blood samples were collected at 0, 2, 6 and 12 hours post injection. 

Results indicated that an injection of E. Coli LPS was effective in generating an immune reaction, thus mimicking weaning stress.

Varying dietary ratios of Omega-6 to Omega-3 fatty acids had a significant effect on body temperature (fever response). Piglets born from sows that ate the 1:1 diet had greater body temperatures than those born from sows that ate the control, 10:1 or 5:1 plant based diets. The body temperatures of piglets born from sows consuming the 5:1 fish based diet were intermediate. Markers of inflammation in the blood were also elevated in piglets born from sows that ate the 1:1 plant based and 5:1 fish based diets. 

These results were contrary to what we expected: that a higher Omega-6 to Omega-3 fatty acid ratio in the diet would result in increased body temperatures (fever) and immune response in piglets. 

Our experiment demonstrated that what is fed to the sow can affect how her piglets respond to immune challenges at weaning. It appears that altering the Omega-6 to Omega-3 fatty acid ratio in sow diets can affect fever and inflammatory cell responses of their piglets when challenged with E. Coli LPS post-weaning.

When sows ate a diet with a 1:1 ratio of Omega-6 to Omega-3 fatty acids, their piglets had elevated body temperatures and a greater response to the immune challenge compared to piglets from sows that ate the other diets. In other words, the 1:1 diet piglets were more stressed and fevered at weaning.

This led us to conclude that perhaps Omega-6 fatty acids were not as inflammatory as we originally thought; or alternatively, perhaps there is an “optimal” ratio of Omega- 6 to Omega-3 in the diet, after which point the immune response generated becomes a hindrance to piglet productivity and health. It is important to reiterate that an immune reaction is a good bodily defense mechanism against foreign invaders, but an overly active immune system can be harmful.

Based on these preliminary results, we can recommend that farmers do not feed their sows less than a 5:1 Omega-6 to Omega-3 fatty acid ratio in the diet. Further experiments are being conducted to determine the consequences of these immune responses to the animals, and the resulting implications on animal health, performance and welfare. Once these additional trials are completed, more concrete recommendations can be made. 

Strategic program funding was provided by Sask Pork, Alberta Pork, Manitoba Pork Council and Saskatchewan Agriculture and Food Development Fund. Specific funding for this project was provided by Alberta Livestock and Meat Agency (ALMA) and Vandeputte s. a., Belgium.