METABOLIC PARAMETERS AND METHANOGENESIS IN THE RU-MEN LIQUID IN in vitro TESTING EXPERIMENTAL DIETS SUPPLEMENTED WITH PHYTOBIOTICS AND CoCl2

. These compounds are mostly administered separately. This paper is the first to describe the metabolic changes during in vitro incubation of the Kazakh white-headed bull ruminal liquid (RL) with feed compositions (biosubstrates) containing phytopreparations and cobalt chloride. The most effective combinations and dosages of these additives are evaluated. It was found out that Artemisiae absinthil herba (2.0 g/kg DM) + CoCl 2 (1.5 mg/kg DM) increases digestibility of feed dry matter (by 2.1 %), the activity of digestive enzymes and the concentration of metabolites in the RL while decreases methane production by 33.9 %. Salviae folia (1.6 g/kg DM) + CoCl 2 (1.5 mg/kg DM) provide the maximum reduction in methane emissions (by 46.3 %). Plant preparations increase the activity of RL amylase 2.6-4.0-fold and RL proteases 3.6-fold compared to control. Our goal was to reveal the effect of herbal preparation and cobalt chloride combination on the metabolic changes assessed in RL by in vitro technique. The experiments were carried out in 2021 at the BST RAS (Orenburg). Rumen liquid (RL) was sampled from four Kazakh white-headed bulls ( Bos taurus taurus ) weighing 250-265 kg at the age of 9-10 months. The samples were collected 12 h after feeding, through a chronic rumen fistula. The control ration (variant I) was 70 % coarse feed (mixed meadow hay) and 30 % concentrated feed (crushed barley). Test rations II was added with CoCl 2 (1.5 mg/kg DM; OOO NPK Ascont+, Russia),