The impacts of lipid metabolites on the immune mediation of peripheral blood leukocytes and incidence of postpartum diseases in dairy cows

報告時間：2024-06-21
報告地點：Room 407
指導老師：Chien-Kai Wang and Peng-Wen Chan
學生： Cheng-Yan, Li
摘要

The transition period for dairy cows is typically defined as the three weeks before and after calving. During this period, cows undergo physiological changes such as calving and onset lactation, which increase energy demand rapidly and lead to negative energy balance (NEB) status. At NEB status, cows mobilize lipids to produce non-esterified fatty acids (NEFA) to meet the additional energy demands, and generate metabolites such as β-hydroxybutyric acid (BHBA) in liver NEFA and BHBA therefore are considered as good indicators for identifying NEB status. Severe NEB status reduces dry matter intake and delays the resumption of feed intake, and also impacts milk productivity. Both the incidences of postpartum disorders and culling rates are increased in these NEB cows. Therefore, this study aims to investigate the association of lipid metabolites on cattle health at NEB status. First, the relationship between lipid metabolite concentrations, NEFA and BHBA, and the incidence of postpartum diseases was examined, and found a higher risk of subclinical endometritis, purulent vaginal discharge, and delayed time to first ovulation with increased NEFA/BHBA levels during the transition period. The increase of infection diseases at postpartum suggests that immune capability may be affected at NEB status. Therefore, this study further investigated the effects of NEFA and BHBA on cytokine expression in peripheral blood leukocytes (PBL). The expression of inflammatory cytokines (including IL-1β, TNF-α, and IL-8) in PBL was upregulated by NEFA treatment. Moreover, NEFA treatment further enhanced liposaccharide (LPS) induced inflammatory cytokine expression in PBL, when LPS represented an infectious stimuli. Since inflammatory responses are a series complicate processes to against infectious pathogens, overreaction of inflammatory responses lead to disruption inthe resumption of feed intake and postpartum recovery in cows. In summary, higher levels of lipid metabolites, NEFA and BHBA, increase the health risks of postpartum diseases, and it is likely due to the excessive expression of pro-inflammatory cytokines in PBL, which may suppress feed intake and delay postpartum recovery. Therefore, controlling the NEB statusmay help to alleviate inflammatory responses and allow cows to navigate the transition period successfully.

Keywords: transition period, negative energy balance, postpartum disorders, inflammatory cytokines, dairy cows, NEFA, BHBA
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