Olive Milling Byproducts May Improve Animal Feed

Diets including olive tree leaves and olive oil pomace did not negatively impact the health of sheep or their milk quality while decreasing methane emissions.
By Simon Roots
Apr. 22, 2024 22:19 UTC

A recent study pub­lished in the Italian Journal of Animal Science high­lights the poten­tial of olive milling byprod­ucts in rumi­nant diets, improv­ing the sus­tain­abil­ity of both pro­duc­tion chains with­out neg­a­tively affect­ing the ani­mals.

Results indi­cate that olive tree leaves and olive oil pomace, the two main byprod­ucts of the olive oil pro­duc­tion process, have min­i­mal impact on micro­bial com­mu­ni­ties in sheep rumens and pro­mote sus­tain­abil­ity in feed­ing strate­gies.

Sustainability is para­mount in the live­stock sec­tor, respon­si­ble for an esti­mated 14.5 per­cent of total anthro­pogenic green­house gas emis­sions.

See Also:Asphalt Made with Olive Oil Byproducts Used to Pave a Highway in Spain

This has led to research into alter­na­tive feed sources that align with cir­cu­lar econ­omy prin­ci­ples and do not com­pete with human nutri­tion.

As a result, numer­ous agri­cul­tural by-prod­ucts are being explored as uncon­ven­tional com­po­nents in rumi­nant diets to mit­i­gate the eco­log­i­cal foot­print of food pro­duc­tion.

Edible agro-indus­trial byprod­ucts have emerged as promis­ing ingre­di­ents to reduce envi­ron­men­tal impact while meet­ing ani­mal nutri­tional require­ments.

They can poten­tially mod­u­late rumen micro­bial activ­ity, improv­ing energy-pro­tein bal­ance and digestibil­ity and reduc­ing nitro­gen excre­tions or methane emis­sions.


The rumen is a spe­cial­ized stom­ach cham­ber found in the diges­tive sys­tem of rumi­nant ani­mals like cows, sheep, and goats. It’s the first and largest com­part­ment of their multi-cham­bered stom­ach, where micro­bial fer­men­ta­tion breaks down fibrous plant mate­r­ial into nutri­ents.

Olive oil pro­duc­ers dis­pose of mil­lions of tons of olive tree leaves and olive oil pomace annu­ally, an addi­tional cost and logis­ti­cal chal­lenge for many mills.

Olive oil pomace and olive tree leaves con­tain polyphe­nols and fatty acids, mak­ing them attrac­tive dietary sup­ple­ments for rumi­nants.

Their inclu­sion in diets may replace con­ven­tional ingre­di­ents, includ­ing roughage or con­cen­trate, which sep­a­rate research found could lower feed­ing costs by 75 per­cent.

Olive oil pomace, rich in water-sol­u­ble polyphe­nols and fatty acids, has improved digestibil­ity com­pared to ear­lier forms, over­com­ing pre­vi­ous lim­i­ta­tions in ani­mal feed­ing.

Though lower in fiber qual­ity, olive tree leaves con­tain valu­able com­pounds like oleu­ropein and oleic acid, sug­gest­ing poten­tial ben­e­fits in rumen micro­bial activ­ity and milk qual­ity.

The researchers con­ducted two in vitro tri­als to assess the impact of olive milling byprod­ucts on rumen fer­men­ta­tion and micro­biome ecol­ogy.

The chem­i­cal com­po­si­tion of olive tree leaves and olive oil pomace makes them hypo­thet­i­cal mod­u­la­tors of rumen fer­men­ta­tion thanks to the high pres­ence of polyphe­nols that can influ­ence the activ­ity of rumen microor­gan­isms,” the researchers wrote.

Olive tree leaves were col­lected post-milling from a local mill and dried at 40 ºC to pre­vent oxi­da­tion, while olive oil pomace was derived from a two-half-phase milling sys­tem.

The first exper­i­ment included a con­trol feed with­out olive tree leaves and an exper­i­men­tal feed with 9.2 per­cent olive tree leaves of total diet dry mat­ter.

The sec­ond exper­i­ment included a con­trol feed with­out olive oil pomace and an exper­i­men­tal feed with eight per­cent olive oil pomace.

All feeds had the same amount of pro­tein and calo­ries as their con­trol diets, with the amount of olive tree leaves and olive oil pomace based on pre­vi­ous stud­ies.

Rumen fluid was col­lected from three ewes (female sheep) fol­low­ing a 15-day diet reg­i­men before slaugh­ter­ing.

Olive tree leaves and olive oil pomace inclu­sion in the diet at the tri­al’s adopted lev­els caused min­i­mal changes in the rumen envi­ron­ment. However, they influ­enced the rel­a­tive abun­dance of bac­te­r­ial species.

The researchers found that the con­trol and olive tree leaf feed com­po­si­tions showed sim­i­lar nutri­tional value and digestibil­ity.

They also found that diets with olive pomace oil and olive tree leaves fos­tered microor­gan­ism com­mu­ni­ties with bal­anced ratios of cel­lu­lolytic and non-cel­lu­lolytic bac­te­ria.

The researchers wrote, In the rumen, cel­lu­lolytic bac­te­ria pro­vide non-cel­lu­lolytic microor­gan­isms with cel­lodex­trins and cel­lobiose pro­duced dur­ing cel­lu­lose catab­o­lism, ensur­ing com­plete fiber diges­tion.”

Separate research has shown that com­plete fiber diges­tion in rumi­nants sig­nif­i­cantly reduces methane pro­duc­tion.

Olive pro­cess­ing by-prod­ucts can be reused as novel ingre­di­ents in the diet of rumi­nants so that to improve the sus­tain­abil­ity of both pro­duc­tion chains,” the researchers wrote.

Data reported in this study con­firmed that olive tree leaves and olive oil pomace from olive post-milling can be con­sid­ered good uncon­ven­tional ingre­di­ents in rumi­nant feed­ing strat­egy and that their impact on the micro­bial com­mu­nity is min­i­mal,” they con­cluded.


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