Question: Write a study description for the study titled 'Effect of chromium propionate supplementation in prepartum dairy cow diets on neonatal oxidative stress in calves: a multi-omics investigation'.
Answer: Background:Neonatal oxidative stress at birth in calves represents a significant challenge for livestock farmers, directly affecting calf survival, health status and subsequent growth performance. Chromium propionate (CrPro), a chelate formed between propionate and Trivalent chromium [Cr (III)], has been shown to improve heat stress, energy balance, metabolism and milk production in adult dairy cows. However, the potential benefits of supplementing CrPro in the prepartum diet of dairy cows in alleviating neonatal oxidative stress in calves and the underlying mechanisms remain unclear.Results:In this study, 30 Holstein cows with similar age, parity (1.53 ± 0.09), body condition scores (3.48±0.03) and expected date of parturition were randomly divided into 3 groups, Con, CrL and CrH, 21 days before parturition and fed CrPro supplementation according to 0, 1 and 2 g/d/head [0, 4, and 8 mg of “Cr (III)”d/head], respectively. On the day of calving, blood samples were collected from the jugular vein of the neonatal calves to assess plasma Cr (III) concentration, oxidative stress markers and conduct untargeted metabolomic sequencing. Meconium sample was subjected to metagenomic sequencing. It was found that CrPro supplementation to the diet of pre-peripartum dairy cows had ameliorative effects on neonatal oxidative stress in calves, with 2 g/d/head [8 mg of “Cr (III)”d/head] being the most effective. Untargeted metabolomic sequencing revealed that organoheterocyclic compounds played a crucial role in the metabolic regulation of CrPro’s protective effects against neonatal oxidative stress in calves. Moreover, CrPro may exert its anti-neonatal oxidative stress function by modulating the absorption pathway of minerals with anti-oxidative stress function in feed. Metagenomic sequencing indicated that CrPro supplementation in the prepartum diet of dairy cows influenced the restructuring of the meconium microbiota in neonatal calves. Species-level analysis identified six species (Streptococcus sp000187445, Schaedlerella sp004556565, UBA1181 sp900769555, Muriiphilus lacisalsi and Aliidongia dinghuensis) that were significantly correlated with Cr (III) content, as well as with antioxidant markers (GSH, T-AOC, CAT). Further analysis of the meconium samples revealed that functional genes ENO, KRAB, ARNTL2, and the signaling pathway HIF-1 were involved in the regulation of neonatal oxidative stress. Furthermore, integrated network analysis revealed that antioxidant markers were closely associated with changes in the microbial species and plasma metabolites. Notably, Cr (III) and MDA were identified as key contributors to this integrated network, playing a crucial role in the protective effects of CrPro against neonatal oxidative stress.Conclusion:The results of this study suggest that supplementing CrPro in the prepartum diet of dairy cows can improve neonatal oxidative stress in calves by modulating their meconium microbiota and plasma metabolites. This study provides a practical method to improve the neonatal oxidative stress in calves and initially reveals its potential mechanism, which is beneficial to the development of the livestock industry.