Browsing by Person "Kononov, Susanne Ursula"

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Dietary L-carnitine affects leukocyte count and function in dairy cows around parturition
(2022) Kononov, Susanne Ursula; Meyer, Jennifer; Frahm, Jana; Kersten, Susanne; Kluess, Jeannette; Bühler, Susanne; Wegerich, Anja; Rehage, Jürgen; Meyer, Ulrich; Huber, Korinna; Dänicke, Sven
In early lactation, an energy deficit leading to a negative energy balance (NEB) is associated with increased susceptibility to disease and has been shown to be an important factor during transition in dairy cows. L-carnitine as a key factor in the mitochondrial transport of fatty acids and subsequently for β-oxidation and energy release is known to modulate mitochondrial biogenesis and thus influence metabolism and immune system. In the current study, we characterized hematological changes around parturition and investigated the potential effects of dietary L-carnitine supplementation on immune cell functions. For this approach, dairy cows were assigned either to a control (CON, n = 30) or an L-carnitine group [CAR, n = 29, 25 g rumen-protected L-carnitine per cow and day (d)]. Blood samples were taken from d 42 ante partum (ap) until d 110 post-partum (pp), with special focus and frequent sampling from 0.5 to72 h post-calving to clarify the impact of L-carnitine supplementation on leukocyte count, formation of reactive oxygen species (ROS) in polymorphonuclear cells (PMN) and peripheral mononuclear cells (PBMC) and their phagocytosis activity. Blood cortisol concentration and the capacity of PBMC proliferation was also investigated. All populations of leukocytes were changed during the peripartal period, especially granulocytes showed a characteristic increase up to 4 h pp. L-carnitine supplementation resulted in increased levels of eosinophils which was particularly pronounced one day before to 4 h pp, indicating a possible enhanced support for tissue repair and recovery. Non-supplemented cows showed a higher phagocytic activity in PBMC as well as a higher phagocytic capacity of PMN during the most demanding period around parturition, which may relate to a decrease in plasma levels of non-esterified fatty acids reported previously. L-carnitine, on the other hand, led to an increased efficiency to form ROS in stimulated PMN. Finally, a short period around calving proved to be a sensitive period in which L-carnitine administration was effective.
The influence of L-carnitine on hematology and functional blood parameters of dairy cows with special focus on high resolution data around parturition
(2023) Kononov, Susanne Ursula; Huber, Korinna
The transition period, defined as three weeks before to three weeks after parturition, is one of the most critical times in the production cycle of dairy cows. On the one hand, cows have to cope with increased energy demand, while on the other hand, feed intake decreases due to stress and pain during parturition. This results in an negative energy balance and, consequently, at the beginning of body fat tissue mobilization. Lipomobilization increases the blood concentration of NEFA. This is accompanied by an increase in the blood concentration of ketone bodies, such as BHB. In addition to changes in energy metabolism, alterations in the immune function of dairy cows occur during the transition period. Stress and pain during calving lead to elevated blood levels of glucocorticoids, such as cortisol, which affect the immune system. Furthermore, the immune system is affected by increased concentrations of NEFA and BHB. At the same time, oxidative stress occurs due to an imbalance between the production of reactive oxygen species (ROS) and the activity of the antioxidative system. In general, the period around calving and its consequences constitute a very complex process influenced by many interdependent factors. One key factor in energy production is the quaternary amine L-carnitine (LC), which is necessary for the transport of short-chain fatty acids from the cytosol to the mitochondrial matrix. Furthermore, several studies have demonstrated the antioxidant and membrane-stabilizing effects of LC. This study aimed to investigate the effects of dietary LC supplementation on energy metabolism, hematology, and immune functions of dairy cows during the transition period. In addition, the first 72 h after calving were observed at high resolution to show the characteristic courses of the examined parameters, which, to the best of our knowledge, have not yet been analyzed. To attain this aim, 60 pluriparous Holstein Friesian cows were assigned to two groups based on their lactation number, body weight, body condition score, and fat-corrected milk yield from previous lactation. The LC group (CAR) received 25 g of rumen-protected LC. The study started 42 days before excepted calving and ended 110 days after parturition. To evaluate the performance and health of the animals, feed and milk samples were collected regularly, and feed intake, milk yield, body weight, and BCS were documented (Manuscript I). Additionally, NEB was calculated, and NEFA, BHB, and triglyceride concentrations in the blood were determined (Manuscript I). Also, the concentration of LC in the blood as well as that of the precursors γ-butyrobetaine (γBB), Nε-trimethyllysine (TML), and acetylcarnitine (ACA) was examined (Manuscript I). Red blood cell counts and antioxidant enzyme activity were measured to obtain more information on the oxygen supply and antioxidant status of the animals (Manuscript II). To evaluate the immunological status and inflammatory response, white blood cell count, phagocytic activity, ROS production, and lymphocyte populations were analyzed (Manuscript III). Dietary supplementation with LC increases blood LC, γBB, and ACA concentrations. Furthermore, LC supplementation resulted in better utilization of NEFA and TG. This was manifested by an increased blood concentration of triglycerides and a lower concentration of NEFA. Moreover, increased levels of platelets and eosinophils were detected in the CAR group, confirming the membrane-stabilizing effect of LC and the associated longer cell lifespan. Additionally, immunological functions were affected by LC supplementation. The ability of polymorphonuclear cells (PMN) to phagocytose bacteria was analyzed by the mean fluorescence intensity (MFI) of ROS-producing PMN, and the phagocytic capacity decreased compared to the CON group. Simultaneously, the efficiency of ROS production by PMN increased in CAR cows. These results suggest an altered immune function around calving, but not suppression, as is often described in the literature. In addition, this study showed that calving affected almost all analyzed data. The strongest changes in hematology and cell function were found four hours after calving. Furthermore, the influence of LC supplementation on immunological parameters was observed in the first few hours after parturition, indicating that LC supplementation may have an effect at energetically critical times. In conclusion, the present study showed that dietary LC supplementation affected energy metabolism, cell vitality, and cell function during the critical period around calving. However, this study also showed the clear influences of calving, which may be even more pronounced than animal-specific differences. Future studies should record the LC supply of cells to enable a more detailed description of the energetic situation of cells such as blood cells.