Reproductive status and blood biochemical parameters of Holstein cows with different milk productivities in connection with the dynamics of lipid metabolism during the postpartum period

In the early period of lactation, the energy needs of high-yielding dairy cows sharply increase, which leads to a negative energy balance. For it compensation, the organism spends its internal resources, mainly lipid reserves. Normalization of cholesterol production at the beginning of the postpartum period is obviously associated with an increase in the animal reproductive ability. However, it remains unclear what role in the regulation of the reproductive function can play a change in the blood level of triglycerides. Here, we compared for the first time the duration of the calving to conception interval in Holstein cows with medium (MP) and high milk productivity (HP) depending on the increase or decrease in the blood concentration of triglycerides from the end of month 1 to the end of month 2 of lactation. Furthermore, we found a connection between the calving to conception interval, the serum content of triglycerides, and some other indexes of metabolism. Cows ( Bos taurus taurus ) of the Holstein breed of the 1st calving with milk yield of 6336±160 kg per 305-day lactation ( n = 19; EKH Klyonovo-Chegodaevo, settlement Klyonovskoe, Moscow) and of the 2nd-3rd calving with milk yield of 10007±420 kg per 305-day lactation ( n = 14; PZ Prinevskoe, Vsevolozhsk Region, Leningrad Province) were used in the experiments...