The cumulative evidence that perinatal events have long-lasting ripple effects through the life of livestock animals should impact future nutritional and management recommendations at the farm level. The implications of fetal programming due to malnutrition, including neonatal survival and lower birth weights, have been characterized, particularly during early and mid-gestation, when placental and early fetal stages are being developed. The accelerated fetal growth during late pregnancy has been known for some time, while the impact of maternal stressors during this time on fetal development and by extent its postnatal repercussions on health and performance are still being defined. Maternal stressors during late pregnancy cannot only influence colostrogenesis but also compromise adequate intestinal development in the fetus, thus, that further limits the newborn’s ability to absorb nutrients, bioactive compounds, and immunity (i.e., immunoglobulins, cytokines, and immune cells) from colostrum. These negative effects set the newborn calf to a challenging start in life by compromising passive immunity and intestinal maturation needed to establish a mature postnatal mucosal immune system while needing to digest and absorb nutrients in milk or milk replacer. Besides the dense-nutrient content and immunity in colostrum, it contains bioactive compounds such as growth factors, hormones, and cholesterol as well as molecular signals or instructions [e.g., microRNAs (miRNAs) and long non-coding RNAs (lncRNAs)] transferred from mother to offspring with the aim to influence postnatal gut maturation. The recent change in paradigm regarding prenatal materno-fetal microbiota inoculation and likely the presence of microbiota in the developing fetus intestine needs to be addressed in future research in ruminants. There still much to know on what prenatal or postnatal factors may predispose neonates to become susceptible to enteropathogens (e.g., enterotoxigenic Escherichia coli), causing diarrhea. From the host-side of this host-pathogen interaction, molecular data such as fecal RNA could, over time, help fill those gaps in knowledge. In addition, merging this novel fecal RNA approach with more established microbiome techniques can provide a more holistic picture of an enteropathogenesis and potentially uncover control points that can be addressed through management or nutrition at the farm level to minimize preweaning morbidity and mortality.

中文翻译：

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新生奶牛的肠道健康、压力和免疫力：宿主与病原体相互作用的宿主方

累积的证据表明，围产期事件对家畜的一生具有长期的连锁反应，这应该会影响农场层面未来的营养和管理建议。营养不良对胎儿编程的影响，包括新生儿存活率和出生体重较低，已经得到了表征，特别是在妊娠早期和中期，此时胎盘和早期胎儿阶段正在发育。怀孕后期胎儿生长加速的现象早已为人所知，而在此期间母体压力源对胎儿发育的影响以及其对健康和表现的产后影响仍在确定中。妊娠后期的母亲应激源不仅会影响初乳生成，还会损害胎儿肠道的充分发育，从而进一步限制新生儿从初乳中吸收营养、生物活性化合物和免疫（即免疫球蛋白、细胞因子和免疫细胞）的能力。这些负面影响使新生犊牛在生命的开始时充满挑战，因为它损害了建立成熟的产后粘膜免疫系统所需的被动免疫和肠道成熟，同时需要消化和吸收牛奶或代乳粉中的营养物质。除了初乳中丰富的营养成分和免疫力外，它还含有生物活性化合物，如生长因子、激素和胆固醇，以及从母亲传给后代，目的是影响产后肠道成熟。最近关于产前母胎微生物群接种的范式的变化以及发育中的胎儿肠道中可能存在微生物群需要在未来的反刍动物研究中得到解决。关于哪些产前或产后因素可能使新生儿容易受到肠道病原体（例如产肠毒素大肠杆菌）的影响，从而引起腹泻，目前仍有很多问题需要了解。从宿主与病原体相互作用的宿主角度来看，粪便 RNA 等分子数据随着时间的推移可以帮助填补这些知识空白。此外，将这种新颖的粪便 RNA 方法与更成熟的微生物组技术相结合，可以更全面地了解肠道发病机制，并有可能发现可以通过农场水平的管理或营养来解决的控制点，以最大限度地减少断奶前发病率和死亡率。