Olive Milling Byproducts May Improve Animal Feed

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.

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.

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.

• Sustainability