Evaluation of dysrhythmias and myocardial biomarkers in high and low-yielding dairy cows

BACKGROUND: Cardiovascular system is a very importantorgan that plays a vital role in tissue function. In farm animals,the growth and high milk production depends on function ofcardiovascular system. OBJECTIVES: Cardiovascular health inhigh and low-yielding dairy cows was investigated. METHODS:Fifty 4-year-old high- yielding Holstein dairy cows and fifty 4-year-old low- yielding Holstein dairy cows were used in thisstudy. Electrocardiogram was recorded by a base- apex lead, andblood samples were collected from the jugular vein for themeasurement of cardiac biomarkers (CK (Creatine Kinase), CKMB(Creatine Kinase-Myocardial Band), LDH (LactateDehydrogenase), and AST (Aspartate Aminotransferase) andtroponin I). RESULTS: Cardiac dysrhythmias were detected morein low- yielding Holstein dairy cows (62%) compared to highyieldingHolstein dairy cows (46%). The cardiac dysrhythmiasthat were observed in low- yielding Holstein dairy cows includedsinus arrhythmia (34.7%), wandering pacemaker (22.45%),sinus bradycardia (18.37%), sinus tachycardia (10.20%), atrialpremature beat (2.04%), sinoatrial block (2.04%), atrialfibrillation (8.16%), and atrial tachycardia (2.04%). The cardiacdysrhythmias were observed in high- yielding Holstein dairycows, including sinus arrhythmia (86.95%) and wandering pacemaker (13.05%). Also, notched P wave was observed in highandlow- yielding Holstein dairy cows, 30% and 14%respectively. The amount of cardiac biomarkers in the lowyielding cows was significantly higher than that of the highyielding cows. Further more, there was not any detectablesignificant difference of serum concentration of total CK betweenthe high and low- yielding Holstein cows. CONCLUSIONS:Despite significant differences in cardiac biomarkers and basedon the normal range of cardiac biomarkers in both groups, theincrease in cardiac dysrhythmias in low- yielding Holstein dairycows may be metabolic and electrolyte disorders.