Essential oil blends, organic acids viable antimicrobial alternative, study results show

By Lilian Schaer for Livestock Research Innovation Corporation

Farmers can feed cattle essential oil blends and organic acids without any negative impacts on animal performance or beef quality characteristics.

That’s the outcome of a multi-year study by Prof. Ben Bohrer of the University of Guelph’s Department of Food Science, who looked at the impact of replacing antibiotics and ionophores in cattle diets with feed additives like essential oil blends and benzoic acid.

“This is an important finding – you can feed alternatives and not expect any off-flavours in the meat or changes in storability or sensory attributes,” says Bohrer.

The sector is actively seeking alternatives to antibiotics that will maintain the health, welfare and production efficiency of beef cattle while also contributing to decreased antimicrobial use.

The project included a live animal component looking at growth performance and feed efficiency, as well as a focus on fresh beef that evaluated shelf-life in whole muscle and ground beef products and sensory attributes like flavour and tenderness.

Meat from three different groups of animals from the University of Guelph’s Elora Research Station was tested first for colour and lipid stability, and then went through a sensory testing panel. According to Bohrer, panel participants received two weeks of training around all the parameters of interest and were then ultimately asked to score samples based on tenderness, flavour, juiciness and off flavour.

In 2017, five groups of steers were each fed a common high moisture corn and alfalfa silage based diet with a different antimicrobial supplement: control (no added antimicrobials), traditional ionophore/antibiotic, benzoic acid, essential oil, and a combination of both oil and acid.

This was repeated in 2018, but with a minor change: two different commercially available blends of essential oils were tested both by themselves and in combination with the acid to check for performance impacts.

“We found no difference between the blends; it was similar to the 2017 results which helped further confirm that we wouldn’t see any differences (between antimicrobials and the alternatives),” he says. “The results were shockingly consistent, which means producers can be confident to feed these products.”

Results from 2019 are still being analyzed; that trial included feeding the benzoic acid in combination with a live yeast culture, teaming Bohrer’s efforts with work being done by Dr. Katie Wood of Guelph’s Department of Animal Biosciences.

According to Bohrer, the antimicrobial properties of essential oils and benzoic acids have already shown some success in boosting immune systems in poultry and pigs as livestock farmers move away from antibiotic use.

“If you think you will have health challenges (in your herd) or ruminal acidosis and would traditionally want to feed products like Rumensin or Tylan, maybe you can try to steer away from those in the diet and feed products with similar antimicrobial properties or rumen-altering properties,” he adds.

The alternative products are currently slightly more expensive than traditional antimicrobials, but since inclusion levels are fairly small – one gram of essential oil blend per head per day and benzoic acid at 0.5% of the dietary inclusion – producer feed costs are not expected to be significantly higher.  

And while meat from animals given antibiotics is safe and not different than meat from animals not given antibiotics, antibiotic resistant bacteria can be produced during livestock production. This makes enhanced antimicrobial stewardship important for the future of livestock farming.

Canadian rules governing the use of antibiotics in livestock production tightened in December 2018. For example, farmers now need a veterinary prescription to purchase medicated feed as well as antibiotics medically important for human health and feed mills can no longer sell bags of bulk medication for on-farm mixing.

BFO funded the growth performance and carcass characteristics portion of the project. The research was supplemented by support from the Ontario Agri-Food Innovation Alliance (formerly the Ontario Ministry of Agriculture, Food and Rural Affairs - University of Guelph Partnership) to evaluate meat quality and beef retail shelf life.

Bohrer also received a Weston Seeding Food Innovation Grant to fund the sensory panel to determine consumer reaction to the meat from cattle raised using the oil blend and acid additives.  

This article is provided by Livestock Research Innovation Corporation as part of LRIC’s ongoing efforts to drive innovation in livestock production and report on Canadian livestock research developments and outcomes.