Porcine Respiratory Complex (PRC): Prevention from functional nutrition

The Porcine Respiratory Complex (PRC) is one of the most relevant pathologies in intensive pig production; It has a significant impact on the technical, economic and health indicators of farms. Due to its multifactorial nature, involving viral and bacterial pathogens and environmental factors, a comprehensive control strategy is required.

Traditionally, control of this issue has been closely linked to the use of antimicrobials. However, legislative and social pressure to reduce their use, coupled with the emergence of resistance, makes finding safe and effective alternative solutions necessary. Functional nutrition is emerging as a key tool in this regard, as it can promote an adequate immune response, improve the state of the respiratory epithelium and modulate inflammation.

According to the study carried out by Pérez F. (2017), in an analysis of clinical cases of PRC in Spain, the most frequent combinations of pathogens were:

These combinations result in significant clinical variability, which makes diagnosis and the establishment of effective treatments difficult in many cases.

In the analysed clinical cases, Pérez's (2020) pathological findings predominantly consisted of lung lesions classified as bronchointerstitial pneumonia (37.8%), interstitial pneumonia (30.5%), and purulent bronchopneumonia (20.7%), in descending order. In most cases, the exclusive use of antibiotics was insufficient without a comprehensive approach, highlighting the need to implement additional preventive strategies.

The main non-infectious factors that predispose to the development of PRC are:

Feeding plays a productive role and can support animals' resilience to challenges such as PRC. This is particularly useful in cases of porcine respiratory complex.

These plant-derived compounds (such as plant extracts, essential oils and other aromatic compounds) have multiple properties, including antimicrobial, anti-inflammatory, mucolytic and antioxidant properties. Inclusion in the diet or drinking water has been shown to:

1.            Stimulation of mucus expulsion and fluidification.

2.            Modulation of respiratory microbiota activity.

3.            Decreasing oxidative stress in the respiratory system.

4.            Reduction of clinical severity during respiratory infections

5.            Improved convalescence and post-respiratory disease recovery periods.

1.            Eucalyptol: Mucolytic, expectorant and antimicrobial properties (Boukhatem et al., 2014).

2.            Thymol and carvacrol: Bacterial membrane disruptors with a modulatory effect on the immune response (Michiels et al., 2008).

3.            Menthol stimulates the respiratory reflex and reduces heat stress by activating TRPM8 receptors (thermosensitive ion channels that are activated by cold and produce a sensation of freshness).

4.            Garlic extract (rich in allicin): It has antibacterial, expectorant and antioxidant properties (Amagase et al., 2001).

In vivo studies have demonstrated that diets supplemented with a combination of these compounds can reduce coughing, improve conversion rates and lessen the severity of lung lesions (Windisch et al., 2008).

Respiratory infections trigger an exacerbated inflammatory response involving the release of reactive oxygen species (ROS), which damage the lung epithelium. An effective strategy is to include antioxidants that neutralise free radicals, preserve the integrity of cell membranes, and promote lung tissue healing. Some micronutrients, such as vitamins and minerals, can help in this regard. Additionally, natural polyphenols, flavonoids, and tannins with powerful antioxidant properties are of particular interest (Daglia, 2012).

Modulating the immune response provides greater resistance to viral and bacterial infections, particularly during critical periods such as weaning. Nutritional components such as algae and yeast extracts, nucleotides and MOS (mannan-oligosaccharides) can support and modulate the immune response in animals. Strategic use of these components can help reduce the impact of mixed infections, such as PRRSv–PCV2, where immunosuppression is a key factor in disease progression.

A preventive and comprehensive approach to controlling CRP is essential given that, once the problem has become established, costs increase exponentially, affecting not only the number of casualties caused by these pathogens, but also important production parameters such as the conversion rate and the length of time that animals spend in breeding and fattening facilities, as well as spending on medicines.

The prevention of PRC in pigs requires a holistic approach combining: 1) biosecurity and vaccination; 2) adequate environmental management; and 3) a functional nutritional strategy based on plant compounds with demonstrated biological and immunological activity, as well as antioxidants.

These approaches can improve animal resilience, reduce the use of antimicrobial drugs and ensure more sustainable and efficient production.