Resumen
The aim of the experiment was to study the relationship between the age of cows, blood BHBA content, and CLA isomer (C18:2 cis9,trans11, CLA9; C18:2 trans10,cis12, CLA10) content during the first three weeks post-partum. For the experiment, 105 cows were selected from the entire herd and assigned to one of four groups: healthy primiparous (PH), healthy multiparous (MH) or ketotic primiparous (PK), ketotic multiparous (MK) based on their symptoms, and blood serum BHBA concentrations at 5 ± 2 days post-partum. Milk and blood samples were taken from the animals for a period of three weeks at weekly intervals on the same day. High levels of ketone bodies inhibit the activity of acetyl-CoA, thus decreasing the transport of acetyl-CoA, which may result in a decrease in CLA9 and CLA10 synthesis. Studies have shown that the age of the cows was an additional factor in determining the formation of CLA isomer levels during the early stage of lactation. The CLA9 content in the milk of PH cows in the first week of lactation was 32.75% higher than that of PK milk, while in MH milk, it was 67.7% higher than that of MK milk. The CLA10 content in the milk PH, when compared to the healthy groups, was 319% lower for primiparous cows. In summary, different reference limits in CLA9 and CLA10 content should be considered in the diagnosis of ketosis, taking into account, among other things, parity.