Adding pure linseed oil to the diet of Thoroughbred and Arabian horses in a study in Poland significantly reduced evidence of strongyle infection in their fecal samples.
“The results indicate that properly selected plant additives obtained from arable crops may be helpful in limiting the numbers of drug-resistant strongylids,” Aleksander Górniak and his fellow researchers reported in the journal Agriculture.
The researchers noted the decreasing effectiveness of common deworming medications because of the development of drug resistance by parasites. “Therefore, the application of feed additives possessing antiparasitic properties may be helpful in limiting the burden of parasites,” they said.
The study team noted that vegetable oils are widely used in horse nutrition because they are readily available sources of slow-release energy and high levels of unsaturated fatty acids.
Their study involved 15 Thoroughbreds and 12 Arabian horses fed a base diet of oats, muesli and roughage, given in meals three times a day. All the horses were healthy and housed individually in box stalls without access to pasture.
The animals were dewormed with ivermectin and praziquantel in February 2020.
The animals were individually assigned across four groups, three of which were supplemented with daily vegetable oil while the fourth group remained the oil-free control group.
One group received soybean oil, another group linseed oil (also known as flaxseed oil), and the third group was supplemented with both linseed oil and vitamin E. The oil was feed at a rate of 0.5 millilitres per day per kilogram of body weight. The horses had free access to water and mineral salt.
Four months later, in June, dung samples were collected from each horse to test for parasites, based on egg counts.
Evidence of parasites was found in 25 of the 27 horses, with strongyles predictably the most prevalent. A third of the horses also showed evidence of Strongyloididae – threadworm infection.
Additionally, eggs and larvae of botflies (Oestridae) were identified in one Arabian horse and one Thoroughbred. One Arabian also had a live Paramecium species in its sample.
The effects of the feed additives on the prevalence of parasites in the four experimental groups are shown in the graph below. The second group, supplemented with pure linseed oil, had the lowest prevalence of strongyles (71% versus 100% in other groups), the absence of Strongyloididae, and the lowest share of horses infested with botflies.
Average numbers of parasitic larvae and/or eggs in 1 gram of feces for each group of horses are shown in the second graph, below.
“The main conclusion arising from the results of the present paper is that the addition of pure linseed oil significantly reduces the burden of Strongylidae in examined horses,” the study team said.
Linseed oil, they said, warrants further investigation, including tests on other farm animals.
The study team comprised Wanda Górniak, Hanna Moniuszko, Konrad Wojnarowski, Aleksander Górniak, Paulina Cholewińska, Agnieszka Waliczek, Maria Soroko and Natalia Szeligowska, variously affiliated with the Wrocław University of Environmental and Life Sciences, Warsaw University of Life Sciences–SGGW, the Wroclaw University of Science and Technology, and the University of Agriculture in Krakow.
Górniak, W.; Moniuszko, H.; Wojnarowski, K.; Górniak, A.; Cholewińska, P.; Waliczek, A.; Soroko, M.; Szeligowska, N. Effect of Vegetable Oils Feed Additives on Endoparasites Associated with Dewormed Racing Horses. Agriculture 2021, 11, 525. https://doi.org/10.3390/agriculture11060525