Evaluation of the effectiveness of the AST Ketoz feed supplement to prevent metabolic disorders in high-yielding cows during transition period

Abstract

The results of a farm trial evaluating the efficacy of the AST Ketoz feed supplement in preventing metabolic disorders in highly productive Holstein cows during the transition period are discussed. The trial was conducted in 2025 at the OOO Zazerkale agricultural enterprise in the Vologda Region. The animals were given the supplement at a dose of 300 g per head per day individually for 28 days. The energy metabolism indices were monitored five times a week by a rapid test measuring β-hydroxybutyric acid and blood glucose levels. The specific results indicated that the average β-hydroxybutyric acid level in the group remained within the subclinical range throughout all stages varying from 0.64 ± 0.236 to 1.014 ± 0.258 mmol L and never exceeding the threshold of 1.2 mmol L. After the first week of supplement use, a 21.4% decrease of the average β-hydroxybutyric acid level was recorded from 0.814 to 0.64 mmol L. The physiological increase of β-hydroxybutyric acid level and the decrease of glucose after calving (from 4.43 to 3.6 mmol L) did not lead to the development of clinical ketosis. All calvings were without any complications. Individual analysis revealed that two cows with the highest previous productivity (Makushka and Angliya) experienced single exceedances of the threshold levels of β-hydroxybutyric acid (up to 1.4 mmol L) confirming their increased predisposition, but the indices remained within the subclinical form. Thus, the use of AST Ketoz feed supplement at a dose of 300 g per head per day demonstrated its effectiveness in controlling ketone body levels and preventing metabolic stress in highly productive cows during the critical transition period.