Citation: Buryakov, N.P.; Sycheva, L.V.; Trukhachev, V.I.; Zaikina, A.S.; Buryakova, M.A.; Nikonov, I.N.; Petrov, A.S.; Kravchenko, A.V.; Fathala, M.M.; Medvedev, I.K.; et al. Role of Dietary Inclusion of Phytobiotics and Mineral Adsorbent Combination on Dairy Cows Milk Production, Nutrient Digestibility, Nitrogen Utilization, and Biochemical Parameters. Vet. Sci. Simple Summary: The development of dairy cattle breeding is impossible without improving the technologies of raising, feeding, and high-quality breeding work. An important role in the development of cattle milk production is played by local breeds of cows, which have a sufficiently high genetic variability necessary for adaptations to future climate changes, consumer demand, and improvement of economically important traits. Low productivity is a crucial factor in the loss of local livestock breeds, as they are replaced by highly productive foreign cross breeds, which makes many countries, for example, Russia, Serbia, etc., dependent on imported breeds. This study investigated the effect of the inclusion of natural dry grits from Fucus vesiculosus and mineral adsorbent from the heat-treated mineral shungite extracted only in Russia in feeding native Suksun breed, and their effect on milk yield, the use of nutrients and nitrogen balance in the diet, and biochemical parameters of the blood. Abstract: Our research purpose was to study the effect of the inclusion of a combination of phytobi-otics in the form of dry Fucus vesiculosus grits (FG) and a mineral adsorbent from the heat-treated mineral shungite (TMS) on milk productivity, nutrient digestibility, and biochemical parameters of the Suksun dairy cows. A total of 80 dry-hardy cows of the Suksun breed were divided into four groups (20 heads each), balanced primarily by breed, age, body weight, body condition score, and indicators of milk yield for the previous lactation. The selected cows were with an average live body weight of 512.0 ± 1.28 kg, BCS 3.0-3.5, and parities of 6250 kg milk. The control group (CON) were fed the basic ration only; the second (TMS), third (FG), and fourth (TMS + FG) groups were fed the basic ration provided by 50 g of the mineral adsorbent from heat-treated shungite, 100 g of Fucus grits (Fucus vesiculosus), 50 g of the mineral adsorbent from heat-treated shungite, and 100 g of dry grits from Fucus vesiculosus, respectively. The total protein content in milk was significantly higher in the group receiving Fucus vesiculosus by 0.05% and the group receiving a combination of mineral adsorbent and Fucus vesiculosus by 0.03%. The percentage of milk fat content recorded the highest significant value in (TMS) group when compared to the control and represented (4.37 vs. 3.95). The group of cows that received (TMS + FG) revealed a significant difference in the digestibility of both ether extract and crude fiber when compared to the control group and represented (54.74 Vet. Sci. 2023, 10, 238. https://doi.org/10.3390/vetsci10030238 https://www.mdpi.com/journal/vetsci Vet. Sci. 2023, 10, 238 2 of 18 vs. 51.71 and 60.68 vs. 55.15%), respectively. The cows supplemented with a mineral adsorbent or a combination of mineral adsorbent and Fucus vesiculosus revealed a significant difference in the digestibility of ether extract and crude fiber in the group receiving TMS + FG by 3.0% (p < 0.05) and 5.5% (p < 0.05), respectively. The intake of nitrogen with the diet increased in (FG) and (TMS + FG) groups by 11.3 g (p < 0.05) and 13.4 g (p < 0.05) of nitrogen. There was an increase (p < 0.05) in the concentration of rumen ammonia in the control group compared to the other groups. The glucose content of those cows that received FG and TMS + FG combination increased (p < 0.05) by 0.76 mmol/L and 0.90 mmol/l in relation to the control group. The globulin, albumin/globulin ratio, and the level of triglycerides revealed a significant difference between the different experimental groups. In brief, the inclusion of a combination of phytobiotics in the form of dry Fucus vesiculosus grits and a mineral adsorbent from the heat-treated mineral shungite in Suksun dairy cows' diets improved milk composition, digestibility of nutrients, utilization of nitrogen, and did not cause deleterious effects on blood biochemical indicators.