The Instituto de Ganadería de Montaña (IGM), a joint center of the CSIC and the University of León, is working to improve the health properties of sheep’s milk, an objective it has achieved by introducing vegetable and fish oils and marine microalgae into the animals’ diet. However, this innovation reduces the percentage of milk fat, which is decisive for the price the farmer obtains for the milk. Now, new research is analyzing thousands of sheep genes in an attempt to find the keys to combining the two aspects, health and profitability.
The idea behind the work of the Ruminant Nutrition area of the IGM is that, given the high incidence of cardiovascular and metabolic diseases that have their origin in an inadequate diet, it is necessary to develop foods that are potentially beneficial to health. Milk and its derivatives are but could still increase their properties. To achieve this, “we have carried out a number of studies to improve the nutritional value of milk fat, in a natural and effective way, through changes in cattle feed,” researcher Pilar de Frutos explains to DiCYT.
One avenue has been to improve the diet of dairy sheep with vegetable oils rich in unsaturated fatty acids, e.g., sunflower, olive or flax oil. This increases the content of certain bioactive compounds in milk, especially conjugated linoleic acid (CLA). Scientists have found that this also decreases the amount of some potentially more negative saturated fatty acids for consumers.
On the other hand, they have also incorporated into the diet a small amount of lipids of marine origin, such as microalgae and fish oil, which give the same results as vegetable oils and, in addition, increase the content of n-3 polyunsaturated fatty acids, known as omega-3.
In this way, sheep’s milk becomes a functional food, i.e. specifically aimed at improving health, and its taste remains unchanged. However, “milk fat depression syndrome occurs,” says the expert, which is a problem for the practical application of these supplements in the sheep’s diet, since “the price of milk is determined by its percentage of solids, basically fat, protein and lactose”.
Researchers are now trying to solve the problem, which varies greatly among sheep even if they follow the same diet. For this reason, they have conducted a nutrigenomics study in collaboration with the Department of Animal Production of the University of León. The results have been published in the prestigious scientific journal Scientific Reports and provide very relevant information.
Food and genes
“Diet can cause changes or repression in the expression of certain genes involved in fat synthesis in the mammary gland,” explains Pilar de Frutos. Therefore, the research sought to find out how diet, specifically the addition of a small amount of fish oil, affected them.
For this purpose, a massive sequencing technique was used, which allowed the analysis of more than 14,000 genes in each sample. “This is the first time this new generation methodology has been used in the study of milk fat depression syndrome and the improvement of milk fatty acid composition,” he stresses.
The study included four ewes receiving the enriched diet and four ewes receiving the control diet, i.e. without the oil, and the analyses were performed at the National Center for Genomic Analysis. As this is such a novel study, it has been published in a high-impact journal and “is generating valuable information that will contribute to the understanding and management of fat depression syndrome,” says the IGM researcher.
“We are currently continuing with this line and are investigating what explains the different individual response of sheep,” he stresses. The usefulness of dietary supplementation with lipids of marine origin to improve the healthfulness of milk fatty acids has been demonstrated, but the drop in fat percentage is the main stumbling block to its practical application, but the study of genetic factors may make a solution possible.
