The administration of olive leaves in the sheep ration improves the milk yield for the production of a cheese with exceptional nutritional qualities. The discovery is the result of a recent study carried out by the Special Animal Husbandry research unit of the Department of Agricultural, Food and Environmental Sciences of the University of Perugia. (1)
Long live by-products
The category of ruminants (whose main bred representatives are cattle, sheep and goats) has physiological characteristics particularly suitable for the use of by-products derived from agro-industry.
Ruminants they are in fact capable of converting sources of fiber unsuitable for human consumption into products with a high nutritional value, such as meat and milk (2).
The use of by-products makes it possible to reduce waste management costs, environmental impact and the cost of animal diet, also improving the welfare of the animals themselves (3).
A systematic review
The olive leaves they are suitable for integration into the diet of ruminants (sheep, in this case), as well as being a source of polyphenols, vitamins and unsaturated fatty acids. The study by the researchers from Perugia focused on integrating this by-product into the diet of pasture-raised sheep.
To the animals, 20 divided into two homogeneous groups, daytime access to pasture was allowed. The first group was fed a commercial pellet feed during the milking phase, while the experimental group was supplied with a feed supplemented with 28% dried olive leaves.
From milk produced a cheese was made from the sheep which was then aged for 60 days. Chemical and sensorial analyzes were carried out on the cheese which produced particularly interesting results.
The milk yield in cheese increased for the group whose feed was supplemented with dried olive leaves, as a result of the higher protein and fat content.
For the latter component, quality is a fundamental aspect that affects human health. The fat composition of the two cheeses was different.
Less saturated fat
The cheese made with milk obtained from animals that received the integration of olive leaves showed a lower percentage of saturated fatty acids.
Some saturated fatty acids they are known to increase the risk of cardiovascular pathologies, and they are precisely those that were present in lower percentages in the experimental cheese.
The monounsaturated fatty acids, including oleic acid (characteristic of olive oil), on the contrary, were higher in the cheese made with the milk of animals fed with the leaves.
Also several polyunsaturated fatty acids showed the same trend, with particular reference to those of the omega-3 series, known for their positive effects.
Consequently, the indices relating to thrombogenicity and atherogenicity (related to the risks for the cardio-circulatory system) of the experimental cheese were lower than those of the traditional cheese.
The antioxidant capacity it was also better for the cheese derived from the group of sheep fed with olive leaves.
This can present an advantage both for the consumer, who benefits from the metabolically available compounds, and for the product, which is defended from the oxidizing action to which polyunsaturated fatty acids are particularly subject, thus improving its shelf life.
Some bioactive compounds some olive leaves were then successfully transferred to the cheese, arriving directly on the consumer's plate.
The appreciation of panel
Il panel tests performed on cheeses revealed that consumers are aware of the high residual value of olive leaves and tend to attribute added value to them even when used in an unconventional way.
After a taste 'blindly', in fact, no significant differences were found in the appreciation of the two types of cheese by the panel. Conversely, once the differences in the diet provided to the two groups of animals were revealed, the tasters showed a greater appreciation for the cheese derived from the olive leaf diet.
This data it could also be directly related to an idea of greater sustainability: consumers appreciate the use of by-products rather than a diet based solely on raw materials which compete with human nutrition and which require additional space and resources to be obtained .
Innovation in tradition
in the Mediterranean areas, historically suited to olive growing and sheep breeding, this study could have a significant impact and practical utility, favoring the competitiveness of a more sustainable breeding, conducted in marginal areas and which allows the reduction of feed-to-food competition.
The needs of the modern consumer require greater attention from producers and the market in general, and evaluating more "traditional" rather than "conventional" alternatives could have an interesting economic impact, on the one hand reducing the food costs of farms and increasing willingness to pay of buyers on the other.
In conclusion, a greater awareness of consumers and producers can provide a higher quality, healthier product that is sustainable in economic, environmental and animal welfare terms: information and communication represent the best approach to achieve these common goals.
Customers they are increasingly attentive to the quality and sustainability of the products they consume, and animal products are even more subject to the critical eye of the buyer. It is essential that research accompanies the new needs of the food market to provide information to support intelligent production as sustainable and of quality. Recent geopolitical events, however, have led to an alarming increase in the cost of cereals and soy for the livestock sector, which conventionally bases its production on concentrated feed obtained from these raw materials.
Footnotes to the story
(1) V. Bolletta, M. Pauselli, C. Pomente, A. Natalello, L. Morbidini, G. Veneziani, V. Granese, B. Valenti, Dietary olive leaves improve the quality and the consumer preferences of a model sheep cheese , International Dairy Journal, Volume 134 (2022)
(2) A. Natalello, A. Priolo, B. Valenti, M. Codini, S. Mattioli, M. Pauselli, et al., Dietary pomegranate by-product improves oxidative stability of lamb meat, Meat Science, 162 (2020) , Article 108037
(3) A. Campione, M. Pauselli, A. Natalello, B. Valenti, C. Pomente, M. Avondo, et al., Inclusion of cocoa by-product in the diet of dairy sheep: Effect on the fatty acid profile of ruminal content and on the composition of milk and cheese, Animal, 15 (2021) https://doi.org/10.1016/j.animal.2021.100243