The inclusion of soyabean and linseed oils in the diet of dairy cows improves milk quality, according to new research reported by news service ScienceX on 7 May.

It also increased the proportions of omega-6 and omega-3 in milk, the report said.

Led by Arlindo Saran Netto, a professor at the University of São Paulo’s School of Animal Science and Food Engineering (FZEA-USP) in Pirassununga, the research showed that consumption of these oils by dairy cows reduced the level of saturated fatty acids in their milk and increased the level of unsaturated fatty acids, which helped reduce low-density lipoproteins LDL, known as “bad cholesterol”, ScienceX wrote.

The study was one of a series led by Netto with the aim of improving food quality and developing novel types of milk and meat, the report said.

“The quality of the milk available on the market is good. In our research, we aim to create more opportunities to make sure milk benefits human health in novel ways. Many consumers want to go on a specific diet,” Netto was quoted as telling the São Paulo Research Foundation (FAPESP).

Humans, like other mammals, cannot synthesise omega-6 or omega-3 and must obtain them from food.

Higher levels of omega-6 impair the metabolisation of omega-3 and can raise blood pressure and triglyceride levels while omega-3 can exert anti-inflammatory action and reduce blood lipids.

Recent research had shown that diets with the right amounts of omega-3 and omega-6 played an important role in disease prevention, ScienceX wrote.

The researchers worked with 18 lactating Holstein dairy cows for 94 days. All animals were fed the same diet for the first 10 days, followed by three experimental periods of 28 days.

A regular dairy cow diet with no oil additions was used as the control.

Soyabean oil was added at 2.5% as a source of omega-6, with 2.5% linseed oil as a source of omega-3. Both oils corresponded to 2.5% of total dry matter, replacing corn.

The oil levels were chosen as earlier studies by the group had shown they enhanced the fatty acid profile of the milk without significantly altering yield. Milk samples were then analysed for fat, protein, lactose, and total solids.

The study showed that supplementing the cows' feed with the oils resulted in an omega-6/omega-3 ratio of 2.7:1 in their milk. The World Health Organization (WHO) recommends between 5:1 and 10:1.

“Future studies should evaluate the health benefits of omega-enriched milk in the human diet,” the article concluded.

The results of the study, which was supported by FAPESP, was reported in an article published in PLOS One.

Earlier research by Netto's group, published in 2016, had shown that adding canola oil to the diet of dairy cows also altered the fatty acid profile of their milk, making it healthier, ScienceX reported.

Another study, also funded by FAPESP, had experimented with supplementation comprising sunflower oil, organic selenium and vitamin E. This had led to improvements to animal health and milk yield while showing that children who consumed the milk had increased levels of selenium and vitamin E in their blood, the report said.