The Influence of Selected Factors on the Nutritional Value of the Milk of Cold-Blooded Mares: The Example of the Sokólski Breed

SIMPLE SUMMARY: Mare milk, as well as fermented products produced from it, are recognized as having medicinal effects. Mare milk has been consumed for hundreds of years in Central Asia and Eastern Europe. In Europe it became popular in the 1990s. However, in many European countries, including Poland, the milking of mares remains marginal. Nevertheless, the group of consumers interested in purchasing mare milk is gradually growing. The horse population in Poland is about 300,000, of which half are cold-blooded horses. Native breeds of cold-blooded horses, including the Sokólski horse, are included in a genetic resources conservation programme. These horses are used in diverse ways, including for meat. For ethical and cultural reasons, however, the slaughter of horses is negatively perceived in Poland. An alternative to this type of use could be the acquisition of milk from mares. Therefore, the aim of the study was to determine the effect of selected factors (access to pasture, lactation number, and sex of the foal) on the proximate composition, whey protein profile, and fatty acid profile of milk from mares of the Sokólski breed. The results may be useful for those managing herds of Sokólski mares and other mares of cold-blooded breeds that are in good condition. ABSTRACT: This study assessed the effect of access to pasture, lactation number, and foals’ sex on the nutritional value of milk (79 samples) from nine mares. The following were analysed: content of dry matter, protein, fat, lactose, and ash; percentages of α-lactalbumin (α-La), β-lactoglobulin (β-Lg), serum albumin (SA), immunoglobulins (Ig), lactoferrin (Lf), and lysozyme (Lz) in the total protein; and the fatty acid profile. Mares without access to pastures were shown to produce milk with a higher dry matter content, including fat, lactose, and ash; higher percentages of β-Lg, α-La, Ig, and Lf; and a better fatty acid profile. The milk from mares with access to pasture contained more protein, including higher percentages of SA and Lz. Milk from mares in lactations 4–6 had the highest fat and protein concentrations and the lowest lactose concentration. The α-La level was highest in lactation 1, Lf in lactations 2–3, and Lz in lactations 4–6. Milk from mares in lactations 4–6 had the best fatty acid profile (the lowest concentration of saturated fatty acids (SFAs) and the highest concentration of monounsaturated fatty acids(MUFA) and polyunsaturated fatty acids (PUFA)). Milk from mothers of female offspring had higher dry matter, fat, and protein concentrations, a higher share of lysozyme, and a better fatty acid profile.