The Effect of Humic Mineral Substances from Oxyhumolite on the Coagulation Properties and Mineral Content of the Milk of Holstein-Friesian Cows

Simple Summary Global commodity milk production relies mainly on Holstein-Friesian cows. Intensive selection has made this breed highly productive, but deterioration of health, reduced longevity, and problems with milk quality have been observed. Much of the milk produced is used for cheese production, where its coagulation capacity is crucial. Dietary modifications are used to improve the health and milk quality of cows. Recent years have seen growing interest in humic substances in animal diets. Humic substances are natural organic substances formed in soil during humification of dead organic matter. Their main components are humic acids, fulvic acids and humins. Moreover, humic substances are a rich source of easily absorbed minerals. They are considered natural and safe feed additives with a number of positive effects, including improve of animal welfare and the quality of animal products. The literature lacks information on the results of the use of humic mineral substances in the diet of cows on the suitability of milk for cheese production. Therefore, the aim of the study was to assess the effect of the addition of humic mineral substances from oxyhumolite to the diet of high-producing cows on the chemical composition, mineral content and rennet clotting ability of milk. The study was conducted to determine the effect of humic mineral substances from oxyhumolite added to the diet of Holstein-Friesian cows on the coagulation properties, proximate chemical composition, and mineral profile of milk. The experiment was conducted on 64 cows divided into two groups of 32 each, control (CON) and experimental (H). The group H cows received the humic mineral substances as feed additive, containing 65% humic acids, for 60 days (100 g cow/day). Milk samples were collected twice, after 30 and 60 days. After 30 days no significant changes were observed in the chemical composition, somatic cell count (SCC), mineral content (except potassium), or curd texture parameters. However, the coagulation properties improved. The milk from group H after both 30 and 60 days coagulated significantly (15%) faster on average (p < 0.05), and the curd was about 36% and 28% firmer after 30 and 60 days, respectively (p < 0.05). After 60 days there was an increase in the content of fat (by 0.27 p.p.; p = 0.041), protein (by 0.14 p.p.; p = 0.012), and casein (by 0.12 p.p.; p = 0.029). SCC decreased by 20% (p = 0.023). The curds were significantly harder and less fracturable compared to the control. Calcium and iron content increased as well. The results indicate that humic mineral substances from oxyhumolite in the diet of cows can improve the suitability of milk for cheese production.