Metabolomics Analysis Across Multiple Biofluids Reveals the Metabolic Responses of Lactating Holstein Dairy Cows to Fermented Soybean Meal Replacement

Cooling redistributed endotoxin across different biofluids via modulating the ruminal microbiota and metabolome without altering quorum sensing signal levels in heat-stressed beef bulls

BACKGROUND

Cooling is one of the most common and economical methods to ameliorate heat stress (HS), and it has been discovered to alter the lipopolysaccharide (LPS) endotoxin level in ruminants. However, whether the endotoxin variation induced by cooling relates to the quorum sensing (QS) within the ruminal microflora remains unknown. The current study was consequently performed to examine whether cooling could influence the endotoxin distribution across different biofluids, ruminal microbiota, and ruminal metabolisms through affecting the QS of rumen microorganisms in beef cattle exposed to HS. Thirty-two Simmental bulls were used as experimental animals and randomly assigned to either the control (CON) group, or the mechanical ventilation and water spray (MVWS) treatment. The temperature-humidity index (THI) was recorded throughout this trial, and samples of the rumen liquid, blood, and urine were collected.

RESULTS

Cooling significantly lowered (P < 0.05) the temperature-humidity index (THI), ruminal endotoxin, and endotoxin concentration and excretion in urine, and significantly raised endotoxin level in blood (P < 0.05), but did not change the ruminal concentrations of QS signals including 3-OXO-C6-HSL and the AI-2 (P > 0.05). The linear discriminant analysis effect size (LEfSe) analysis revealed that Prevotellaceae, Rikenellaceae, Monoglobales and their affiliated members, as well as other bacterial taxa were significantly differently (P < 0.05) enriched between the two treatments. The Tax4Fun2 prediction suggested that QS function was upregulated in MVWS compared to CON. The metabolomic analysis indicated that cooling altered the ruminal metabolism profile and downregulated the pathways of lysine degradation, phenylalanine, tyrosine and tryptophan biosynthesis, and ubiquinone and other terpenoid-quinone biosynthesis. The significant (P < 0.05) correlations of the differential bacteria and metabolites with endotoxin and QS molecules were also demonstrated through Spearman analysis.

CONCLUSIONS

Based on the results of this trial, it could be speculated that the cooling reshaped the endotoxin distribution across different biofluids through manipulating ruminal microbiota and metabolome, which might involve the participation of QS. Further investigations are warranted to disclose and verify the mechanisms for those correlations found in this study.

Effects of maternal calcium propionate supplementation on offspring productivity and meat metabolomic profile in sheep

This study determined the effect of dietary calcium propionate (CaPr) as a source of energy supplementation during the First Half of Gestation (FMG), the Second Half of Gestation (SMG), and during All Gestation (AG), on offspring post-weaning growth performance, meat quality, and meat metabolomic profile. Thirty-one pregnant ewes were assigned to one of four treatments: a) supplementation of 30 gd-1 of CaPr during the first half of gestation (day 1 to day 75, n = 8) (FMG); b) supplementation of 30 gd-1 of CaPr during the second half of gestation (day 76 to day 150, n = 8) (SMG); c) supplementation of 30 gd-1 of CaPr during all gestation (AG, n = 8); d) no CaPr supplementation (control; CS, n = 7). The ewes were ad libitum fed a basal diet based on oat hay and corn silage. Ewes were distributed in a completely randomized unbalanced design to four treatments. The FMG group had lower (P ≤ 0.05) birth weight and weaning weight than the CS group. However, the average daily gain was similar across all treatments. Empty body weight and FMG had lower values (P ≤ 0.05) than the other groups. Both FMG and AG had lower hot carcass weight (P ≤ 0.05) compared to CS, while CaPr treatments resulted in reduced hot carcass yield (P ≤ 0.05). Meat color and texture were similar among treatments. A principal component analysis between gestation stages showed a trend for separating CS and FMG from SMG and AG, and that was explained by 93.7% of the data variability (PC1 = 87.9% and PC2 = 5.8%). Regarding meat metabolomic profile, 23 compounds were positively correlated between all treatments. Only 2 were negatively correlated (eicosane and naphthalene 1,2,3); but tetradecanoic acid, hexadecane, undecane 5-methyl, (-)-alpha, hexadecenoic acid, octadecanoic acid, and octadecane had a highly significant correlation (P ≤ 0.05). Overall, dam supplementation with CaPr during different periods of gestation provoked changes in meat metabolites related to the biosynthesis of fatty acids in lambs without negative changes in lamb's growth performance and carcass quality.