Beyond soybean meal: investigating the effects of dietary protein alternatives on gut health, liver function and microbiota in traditional slow-growing chicken breeds

The use of soybean meal in animal feed is crucial for nutrition but has a significant environmental impact, especially related to deforestation and biodiversity loss. With the increasing demand for sustainable agricultural practices, it becomes essential to explore alternatives to soybean meal. This study evaluated the effect of a soy-free diet, replaced with fava beans and pea protein, on an Italian slow-growing chicken breed: the Bianca di Saluzzo. The results indicate that the experimental diet did not compromise the growth, final weight or intestinal health of the animals, demonstrating a good tolerance and adaptability of the breed to these alternative ingredients. Furthermore, the analysis of the intestinal microbiota showed a positive impact, with an increase in organic acids such as succinic and citric, which could improve intestinal health and metabolic efficiency. Some changes in liver enzyme levels were observed, such as the increase in glutamate-oxaloacetate transaminase, an enzyme involved in amino acid metabolism. This increase could indicate a higher efficiency in protein metabolism, suggesting that the diet based on alternative ingredients could support an improvement in liver metabolism. Although this aspect deserves further investigation, it could represent a positive effect of the diet on liver function and overall health of the animals. Further studies are needed to fully understand the long-term implications of these dietary modifications, particularly in relation to the gut microbiota and metabolism.