By Gretchen Rops, Dordt College-Sioux Center, Iowa; Brad Rops and Bob Thaler, South Dakota State University
With the expansion of the veterinary feed directive in 2017, U.S. pork producers have lost the use of most feed-grade antibiotics for growth promotion. Also, with producers promoting the responsible use of antibiotics in pork production, they are making changes in management, nutrition, biosecurity, environment, etc., to decrease the need for those products with relatively good success. One tool that has been receiving close attention by U.S. producers recently is the use of essential oils in swine diets.
Essential oils have been used in Europe as a replacement for antibiotics, and have been reported to possess antimicrobial and antioxidant activities for both pigs and poultry. Data from research trials have been mixed, but it appears that essential oils can be effective in improving pig health and growth performance.
The objectives of this trial were to see if an oregano-based essential oil would improve finishing pig performance, and also if pelleting had an effect on the essential oil response.
Materials and methods
A total of 90 crossbred pigs weighing approximately 180 pounds were randomly allotted to one of three treatments based on weight and sex. There were six replicates per treatment and two dietary phases were used (180-230 pounds and 230-280 pounds). The three dietary treatments were:
Control — meal
Essential oil — meal
Essential oil — pellet
All diets were identical except that the essential oil was added in the place of ground corn at the rate of 0.5 pounds per ton of complete feed. Pellets were made at the South Dakota State University feed mill and are shown in the photo above.
There were five pigs per pen, and pig weights and feed consumption were measured every two weeks. Feed was offered ad libitum through a two-hole dry feeder, and water was provided via a nipple waterer.
The data shown in the table are raw means and have not been statistically analyzed yet.
In the first phase (180-230 pounds), it appears that feed efficiency was not different between treatments, but feed intake was numerically increased by the addition of essential oil. Also, the pigs with the largest daily gains were the pigs fed the pelleted essential oil diet.
In the second phase (230-280 pounds), numerically the pigs fed diets supplemented with essential oil ate more feed, grew faster and were more efficient than the Control. This difference was the greatest when the essential oil diet was pelleted versus meal form.
For the overall trial (180-280 pounds), pigs fed the pelleted, essential oil supplemented diets exhibited the best growth performance.
From this trial it appears that an oregano-based essential oil is beneficial to finishing pig performance, and that the effect is enhanced by pelleting. The authors have no explanation as to the benefit from pelleting, but are planning follow-up trials to re-confirm those results and to answer those questions.