Valorisation of CITrus byproducts by a sustainable utilisation in RUMinant feeding: a way to recycle wastes, reduce the impact of feedstuff transport and improve milk and meat quality
ProjectCitrus fruits are the most produced fruit in the world, with a global production of over 140 million tons (in 2019; FAO, 2020). Of
these, about one third is processed (FAO, 2017a) to obtain mainly juice, but also pectin and essential oils. The industrial processing
of citrus fruits produces non-edible biomasses, consisting in peels, pomaces, and seeds. These by-products of citrus industry (BPCI)
represent 50% to 70% of fresh fruits, depending on the technology adopted and fruit cultivar (Zema et al., 2018), which means an
estimated worldwide production of 28 million tons of BPCI (as much as the world production of pineapples or melons). Disposal of
BPCI requires high costs and can potentially cause soil and water bodies pollution (Zema et al., 2018). Therefore, the valorisation of
BPCI is fundamental to protect the environment and reduce waste management costs. The upcycling of by-products is indeed a
research priority for Horizon Europe (PNR 2020) and is a crucial step for the achievement of sustainable development (UN, 2015).
The principal application of BPCI is as a feed for ruminants, which can use the fibre contained in BPCI as an energy source. Diets
containing up to 15% of BPCI generally have no adverse effects on animal performance (Tayengwa & Mapiye, 2018), but even higher
amounts can be successfully fed (Lanza et al., 2015; Scerra et al., 2021). This adds further importance to BPCI valorisation in a
perspective of sustainable agriculture. Indeed, a transformation of farming management is needed to ensure a secure and healthy
future for all people and the entire planet (FAO, 2017b) and this transformation must involve the feeding of ruminants. Most of the
environmental impact of ruminant farming is due to feed production (Gerber et al., 2013). With a growing population and an
increasing demand for animal-derived food (FAO 2017), it is of paramount importance to reduce the impact of feed production and
the feed-to-food competition. In this scenario, increasing the quota of non-edible by-products in the diet of ruminants is a key
strategy.
Unfortunately, the strategy of feeding ruminants with BPCI is practically adopted rarely, without criteria, and without making the
most of its potential (Tayengwa & Mapiye, 2018). Although over the past 20 years research has investigated the inclusion of BPCI in
the diet of ruminants, there are still many blind spots that need to be studied to ensure that this practice is solidly adopted by
farmers.
The first problem is that BPCI are considered as a single product in literature, which contributes to the great confusion about their
use in practice. Instead, different citrus species (e.g., orange, tangerine, lemon, bergamot) and different industrial processes (e.g.,
juice extraction, essential oils extraction, phenolic compounds extraction) generate different by-products with specific
characteristics.
Second, a multidisciplinary approach in touch with the practical reality is essential. Communication with stakeholders is necessary to
understand needs and limitations of both citrus industry and ruminant farmers in order to direct research and obtain practical
advice. Furthermore, it is critically importance to quantify the impact that this feeding strategy have on farming costs and consumer
acceptance, including organoleptic characteristics.
Last, while the suitability of BPCI in terms of ruminant digestion and animal performance is sufficiently documented, there is a lack of
more in-depth information about their effect on animal welfare and product quality (Tayengwa & Mapiye, 2018). Indeed, the peculiar
composition of most BPCI includes polyunsaturated fatty acids, phenolic compounds, flavonoids, and vitamins. Therefore, BPCI have
the potential to naturally enhance animal welfare (Havlin & Robinson, 2015), food nutritional quality (Scerra et al., 2021; Lanza et al.,
2015), and food shelf-life (Gravador et al., 2014; Luciano et al., 2017), fitting the goals of the 2030 Agenda for Sustainable
Development (UN, 2015).
Considering all the above, the CIT-RUM project intends to adopt a comprehensive research model that can effectively consolidate the
use of BPCI as feed for ruminants. The CIT-RUM project aims to achieve this objectives thanks to the strategical position of the team
– Sicily, Calabria, and Apulia together produce 90% of Italian citrus fruits (RRN, 2020) –, the collaboration with stakeholders, and the scientific excellence of the team in the fields of animal nutrition, food quality, and agricultural economics.
these, about one third is processed (FAO, 2017a) to obtain mainly juice, but also pectin and essential oils. The industrial processing
of citrus fruits produces non-edible biomasses, consisting in peels, pomaces, and seeds. These by-products of citrus industry (BPCI)
represent 50% to 70% of fresh fruits, depending on the technology adopted and fruit cultivar (Zema et al., 2018), which means an
estimated worldwide production of 28 million tons of BPCI (as much as the world production of pineapples or melons). Disposal of
BPCI requires high costs and can potentially cause soil and water bodies pollution (Zema et al., 2018). Therefore, the valorisation of
BPCI is fundamental to protect the environment and reduce waste management costs. The upcycling of by-products is indeed a
research priority for Horizon Europe (PNR 2020) and is a crucial step for the achievement of sustainable development (UN, 2015).
The principal application of BPCI is as a feed for ruminants, which can use the fibre contained in BPCI as an energy source. Diets
containing up to 15% of BPCI generally have no adverse effects on animal performance (Tayengwa & Mapiye, 2018), but even higher
amounts can be successfully fed (Lanza et al., 2015; Scerra et al., 2021). This adds further importance to BPCI valorisation in a
perspective of sustainable agriculture. Indeed, a transformation of farming management is needed to ensure a secure and healthy
future for all people and the entire planet (FAO, 2017b) and this transformation must involve the feeding of ruminants. Most of the
environmental impact of ruminant farming is due to feed production (Gerber et al., 2013). With a growing population and an
increasing demand for animal-derived food (FAO 2017), it is of paramount importance to reduce the impact of feed production and
the feed-to-food competition. In this scenario, increasing the quota of non-edible by-products in the diet of ruminants is a key
strategy.
Unfortunately, the strategy of feeding ruminants with BPCI is practically adopted rarely, without criteria, and without making the
most of its potential (Tayengwa & Mapiye, 2018). Although over the past 20 years research has investigated the inclusion of BPCI in
the diet of ruminants, there are still many blind spots that need to be studied to ensure that this practice is solidly adopted by
farmers.
The first problem is that BPCI are considered as a single product in literature, which contributes to the great confusion about their
use in practice. Instead, different citrus species (e.g., orange, tangerine, lemon, bergamot) and different industrial processes (e.g.,
juice extraction, essential oils extraction, phenolic compounds extraction) generate different by-products with specific
characteristics.
Second, a multidisciplinary approach in touch with the practical reality is essential. Communication with stakeholders is necessary to
understand needs and limitations of both citrus industry and ruminant farmers in order to direct research and obtain practical
advice. Furthermore, it is critically importance to quantify the impact that this feeding strategy have on farming costs and consumer
acceptance, including organoleptic characteristics.
Last, while the suitability of BPCI in terms of ruminant digestion and animal performance is sufficiently documented, there is a lack of
more in-depth information about their effect on animal welfare and product quality (Tayengwa & Mapiye, 2018). Indeed, the peculiar
composition of most BPCI includes polyunsaturated fatty acids, phenolic compounds, flavonoids, and vitamins. Therefore, BPCI have
the potential to naturally enhance animal welfare (Havlin & Robinson, 2015), food nutritional quality (Scerra et al., 2021; Lanza et al.,
2015), and food shelf-life (Gravador et al., 2014; Luciano et al., 2017), fitting the goals of the 2030 Agenda for Sustainable
Development (UN, 2015).
Considering all the above, the CIT-RUM project intends to adopt a comprehensive research model that can effectively consolidate the
use of BPCI as feed for ruminants. The CIT-RUM project aims to achieve this objectives thanks to the strategical position of the team
– Sicily, Calabria, and Apulia together produce 90% of Italian citrus fruits (RRN, 2020) –, the collaboration with stakeholders, and the scientific excellence of the team in the fields of animal nutrition, food quality, and agricultural economics.