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    Dietary thiamine supplementation modulates ruminal microbiota and partly restores lactation performance in lactating Hu ewes under heat-stress conditions
    (Elsevier, 2024) Ma, Yi; Yang, Peng; Li, Pengfei; Elsabagh, Mabrouk; Cheng, Long; Chen, Huayou; Feng, Yong
    This study aimed to investigate the impact of dietary thiamine supplementation on milk production, rumen microbiota profile and inflammatory response of Hu ewes under heat-stress conditions. Twenty-seven multiparous pregnant and lactating Hu ewes of 71.6 +/- 1.4 kg body weight, 11 +/- 0.5 months gestation age, 31 +/- 1 days in milk, 1.68 +/- 0.15 L/d milk yield, and 2.14 +/- 0.12 kg of daily dry matter intake (DMI), were used in the study. Following an acclimation period of 7 days, ewes were divided into 3 blocks of 9 each (one Hu ewe per pen), in a complete randomized design and assigned to one of three environmental temperature conditions for 15 days: thermoneutrality without supplementation (CON), heat-stressed without supplementation (HS) or heat-stressed with dietary thiamine supplementation (200 mg/kg of DMI; HST). The results indicated that the HS group experienced notable declines in milk protein, fat, and lactose content from day 10-15 (P < 0.05) compared to the CON group. In contrast, thiamine supplementation significantly elevated milk protein content from day 13-15 and raised milk fat and lactose content on days 14 and 15 (P < 0.05) compared to the HS group, thereby enhancing milk quality to a certain extent. Additionally, thiamine supplementation (HST group) significantly increased the circulating thiamine and Immunoglobulin A (IgA) concentrations accompanied by a significant decline in LPS-binding protein, interleukin-1 (IL-1), and serum amyloid A protein (SAA) levels compared to the HS group (P < 0.05). Rumen microbial composition analysis revealed that thiamine supplementation increased the abundance of Pyramidobacter, Butyrivibrio, Bacteroides, and Saccharofermentans. In conclusion, heat exposure during lactation in Hu ewes lowered milk production and quality, affecting rumen microbes. Dietary thiamine supplementation could improve rumen fermentation, mitigate heat stress-induced inflammation, and restore milk production in Hu ewes under heat stress conditions.
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    Melatonin modulates lipopolysaccharides-induced inflammatory response and maintains circadian rhythm associated with histone H3 acetylation in bovine mammary epithelial cells
    (Elsevier, 2024) Ma, Yi; Cheng, Long; Gao, Xingliang; Elsabagh, Mabrouk; Feng, Yong; Li, Zelin; Khanaki, Hassan
    Lipopolysaccharides (LPS) can disrupt the barrier function of mammary epithelial cells, leading to mastitis. The protective effects of melatonin (MT) have been demonstrated against various infections, but the underlying mechanism remains unclear in LPS-induced bovine mastitis. This study, therefore, aimed to investigate the modulatory effect of melatonin (MT) on LPS-induced inflammation in bovine mammary epithelial cells (BMECs), its influence on the disruption of circadian rhythms triggered by this inflammation, and the potential underlying molecular mechanisms. BMECs extracted from lactating cows underwent one of 4 treatments in triplicates for 12 h simultaneously: Control (CON), LPS (exposed to LPS at 1 mu g/mL), MT (exposed to MT at 40 mu mol/L), or LPS + MT (LMT, exposed to both LPS at 1 mu g/mL and MT at 40 mu mol/L). The flow cytometry results demonstrated that MT reduced the ratios of cells in the G0/G1 phase but increased those in the G2/M phase (P < 0.05). Additionally, MT inhibited p65 phosphorylation levels, leading to a decreased cellular inflammatory response (P < 0.05). Treatment with MT elevated the acetylation levels of histone H3 in BMECs compared to the LPS treatment (P < 0.05). The circadian rhythm analysis revealed a significant increase in the gene expression levels of BMAL1, PER1, CRY1, and CRY2 at the 12 h mark in LMT compared to the LPS treatment (P < 0.05). Additionally, this study assessed the fluctuations in clock-related genes PER2 and CLOCK over 24 h under various treatment conditions. The results demonstrated that BMECs exposed to LMT treatment exhibited a significant increase in the expression levels of CLOCK and PER2 genes from 4 to 24 h in comparison to the LPS treatment (P < 0.05). Moreover, cells in the LMT treatment displayed a more regular circadian rhythm cycle compared to those in the LPS treatment. Overall, the data suggest that MT could alleviate the inflammatory response in BMECs by upregulating histone H3 acetylation, thereby maintaining the physiological circadian rhythm of BMECs.