Use of polyethylene glycol to improve the utilisation of leguminous leaf meals in pigs: A review

The use of leguminous leaf meal as feed ingredients for pigs needs to be intensified and improved. Leguminous trees and shrubs are valuable sources of protein, amino acids, and dietary fibre for pigs. Leguminous leaf meals are abundant in the tropical regions and their use as alternate protein-rich feed ingredients for pigs is promising. In tropics, climate change and vegetation management practices have certainly increased the availability of shrub legumes compared to grasses. There is, therefore, a need to resort on harnessing abundant and cheap feed resources to cope with environmental changes and rise of feed prices. Leguminous leaf meals are invaluable feed ingredients for pigs because of their relatively high crude protein and they are highly available. The leguminous leaves also thrive in, and tolerate, adverse climatic and soil conditions. However, their utilisation is limited by presence of polyphenolic compounds, particularly condensed tannins that inhibit their efficient use by pigs. Other challenges for the utilisation of legume-based leaf meal diets are the presence of thorns and high fibre content. If leguminous leaf meals are included in the diet beyond optimum levels, polyphenolic compounds can suppress appetite, promote feed refusal, reduce digestibility, and can induce toxicity in pigs. This warrants investigation on the use of tannin-binding agents (TBA) to improve nutrient utilisation of leguminous leaf meal-containing diets fed to pigs. The inclusion level of polyethylene glycol (PEG) in livestock diets has a huge potential to neutralise negative effects of undesirable polyphenolic compounds. Therefore, the current review aimed to assess the potential of PEG to inactivate tannin and amount of PEG to include for optimum pig performance.Keywords: Leguminous leaf meals, performance, pigs, polyethylene glycol, polyphenolic compound