Raw material file: lemon tree (citrus limon) leaves

• The main residue generated by this industry is the leaves after pruning, approximately 3.92 tons of dry matter per cultivated hectare.
• Possible use is composting
• There is not much information of its utilization in animal feeding,
• Lemon leaves are used as forage for ruminants, especially goats.

How is it produced?

Adult lemon trees are pruned in spring if there is no danger of low temperatures. It is a manual activity and it is recommended to be done annually.

Pruning citrus trees renders a large volume of vegetal remains to be disposed. Normally, they are burnt, or crushed and incorporated to the soil.

• Burning is a dangerous operation and aggressive to the environment
• Crushing the remains and incorporating them to the soil reduce the need of fertilisation, improves soil structure, and avoids the risks of burning.
• Using this by-product in animal feeding, after separating and crushing the leaves, is an alternative to be considered, especially for goats. The leaves are offered directly on the trough. They preserve well, due to their high dry matter content (90%).

Chemical composition

Table 1 shows the energetic valorisation. The values were obtained using equations form the literature and the chemical composition shown in table 2.

Nutritional value of lemon tree leaves for goats

Feeding lemon tree leaves with Lucerne grass (alfalfa) hay

Perez-Baena, J.V. et al (2018) fed a mix of lemon tree leaves and alfalfa to goats. They observed significant differences in consumption of the total ration and its digestibility (Table 3), although there were no significant differences in milk production (Table 4).

Following the INRA energetic valorisation method, Perez-Baena et al. (2018) obtained a value of 0.77 UFL for lemon tree leaves, which was much higher than the 0.5 UFL calculated using their chemical composition (Table 2). This higher UFL value could be interpreted as a higher capacity of the goats for utilising this by-product. Fernández et al. (2018) found that the utilisation of metabolizable energy for milk ptoduction was significantly higher when feeding a mix of alfalfa and lemon tree leaves (63%) than when feeding alfalfa alone (60%)

Uses in animal feeding

Since it is utilised directly from pruning, its inclusion is limited to feeding ruminants.

An added value that all citruses leaves seem to have, and especially lemon tree leaves, is that they reduce the production of methane. Perez-Baena et al. (2018) found a reduction of 17.58% respect of alfalfa hay. The effect is associated with the presence of essential oils in the fat of lemon tree leaves.

Perhaps, the only precaution to consider when using pruning by-products to feed animals, is the time passed since the last phytosanitary treatment.

Conclusions

• Lemon tree leaf is a good by-product to be used as forage in animal feeding
• Although it cannot be used as an ingredient in feed mills, it can be crushed and incorporated in the troughs. It is a good solution for direct feeding of ruminants, mainly goats.
• Lemon tree leaves are used to complement grass or other forages, especially in areas where it is available locally. It is normally distributed ad libitum. It is part of the rations in the Mediterranean basin.
• The animals valorise this low-cost by-product, which would, otherwise, be wasted.

Acknowledgements

This work has been done thanks to the support of the project LOW CARBON FEED, of the program LIFE16/CCM/ES/000088.

This article was originally published in agriNews Spanish version as “Materia prima . Hoja de cítricos, subproducto de poda, ‘Citrus limon’“