Diurnal variation of NMR based blood metabolites in calves fed a high plane of milk replacer: a pilot study

Host metabolome and faecal microbiome shows potential interactions impacted by age and weaning times in calves

BACKGROUND

Calves undergo nutritional, metabolic, and behavioural changes from birth to the entire weaning period. An appropriate selection of weaning age is essential to reduce the negative effects caused by weaning-related dietary transitions. This study monitored the faecal microbiome and plasma metabolome of 59 female Holstein calves during different developmental stages and weaning times (early vs. late) and identified the potential associations of the measured parameters over an experimental period of 140 days.

RESULTS

A progressive development of the microbiome and metabolome was observed with significant differences according to the weaning groups (weaned at 7 or 17 weeks of age). Faecal samples of young calves were dominated by bifidobacterial and lactobacilli species, while their respective plasma samples showed high concentrations of amino acids (AAs) and biogenic amines (BAs). However, as the calves matured, the abundances of potential fiber-degrading bacteria and the plasma concentrations of sphingomyelins (SMs), few BAs and acylcarnitines (ACs) were increased. Early-weaning at 7 weeks significantly restructured the microbiome towards potential fiber-degrading bacteria and decreased plasma concentrations of most of the AAs and SMs, few BAs and ACs compared to the late-weaning event. Strong associations between faecal microbes, plasma metabolites and calf growth parameters were observed during days 42-98, where the abundances of Bacteroides, Parabacteroides, and Blautia were positively correlated with the plasma concentrations of AAs, BAs and SMs as well as the live weight gain or average daily gain in calves.

CONCLUSION

The present study reported that weaning at 17 weeks of age was beneficial due to higher growth rate of late-weaned calves during days 42-98 and a quick adaptability of microbiota to weaning-related dietary changes during day 112, suggesting an age-dependent maturation of the gastrointestinal tract. However, the respective plasma samples of late-weaned calves contained several metabolites with differential concentrations to the early-weaned group, suggesting a less abrupt but more-persistent effect of dietary changes on host metabolome compared to the microbiome.

Preweaning nutrient supply alters serum metabolomics profiles related to protein and energy metabolism and hepatic function in Holstein heifer calves

Lifting the preweaning milk restriction in dairy calves has been causally associated with beneficial effects on growth and future lactation performance. However, the biological mechanisms linking early-life nutrient supply and future performance remain insufficiently understood. Thus, the objective of this study was to characterize growth and the metabolic profiles of calves fed a restricted (RES) and an elevated (ELE) milk supply preweaning. A total of 86 female Holstein Friesian calves were blocked in pairs by maternal parity and received identical colostrum supply within block. Treatments randomized within block consisted of a milk replacer (MR; 24% crude protein, 18% crude fat, and 45% lactose) supplied at either 5.41 Mcal of ME in 8 L of MR/d (ELE) or 2.71 Mcal of ME in 4 L of MR/d (RES) from d 2 after birth until they were stepped down by 50% during wk 7 and fully weaned at wk 8. All calves had ad libitum access to pelleted calf starter (17.3% crude protein, 24.4% neutral detergent fiber, 2.0% crude fat, and 18.2% starch), chopped wheat straw, and water. At 2 and 49 d of age, blood samples were taken for metabolomics analysis. The ELE group by design consumed more milk replacer, resulting in a lower starter intake and a greater body weight and average daily gain. The ELE calves consumed 20.7% more ME and 9.7% more crude protein. However, efficiency of growth was not different between groups. Metabolomic profiling using 908 identified metabolites served to characterize treatment-dependent biochemical differences. Principal component analysis revealed clearly distinct metabolic profiles at 49 d of age in response to preweaning milk supply. Changes in energy (fatty acid metabolism and tricarboxylic acid metabolites), protein (free AA, dipeptides, and urea cycle), and liver metabolism (bile acid and heme metabolism) were the main effects associated with the dietary differences. The ELE group consumed proportionately more glucogenic nutrients via milk replacer, whereas the RES group consumed proportionately more ketogenic nutrients from the digestion of the calf starter, comprising a larger portion of total intake. Associated with the higher growth rate of the ELE group, hepatic changes were expressed as differences in bile acid and heme metabolism. Furthermore, energy metabolism differences were noted in fatty acid and AA metabolism and the urea cycle. The metabolic profile differences between the ELE and RES groups reflect the broad differences in nutrient intake and diet composition and might point to which metabolic processes are responsible for greater dairy performance for cows fed a greater milk supply preweaning.

24-h variations of blood serum metabolites in high yielding dairy cows and calves

BACKGROUND

Blood profile testing is commonly used to monitor herd health status, diagnose disorders, and predict the risk of diseases in cows and calves, with subsequent optimization the production of dairy herds. By understanding the physiological ranges of serum metabolites relative to age, lactation stage, and the sampling time in healthy cows and calves, the dairy practitioners can accurately diagnose abnormalities with a blood test. The effect of sampling time on the variation of serum metabolites within 24 h were evaluated in 83 cattle. All animals were originated from a dairy herd, where the animals, based on their ages and lactation stages, were classified into eight groups. The blood samples were collected from each animal every 4 h within a day.

RESULTS

The time of sampling within the day showed significant influences on the serum concentrations of glucose, β-hydroxybutyric acid (BHBA) and urea. BHBA was the most metabolite that showed day variation among cows' groups. Furthermore, the concentrations of total cholesterol were the most stable metabolite in all groups. The mean values of albumin, total proteins, glucose, non-esterified fatty acids (NEFA), BHBA, total cholesterol, total bilirubin, urea, and creatinine revealed significant variations among the different studied groups.

CONCLUSIONS

A certain suitable time of blood sample collection cannot be recommended. However, care shall be taken for the time of sampling for measurements of glucose, NEFA, BHBA and urea, otherwise the comparative values of these metabolites at different sampling time points may differ significantly from each other's, without a disease cause. It may be recommended, for metabolic assessment of dairy herds, classification the subjects into different groups based on lactation stages and ages of animals.

1H nuclear magnetic resonance-based plasma metabolomics provides another perspective of response mechanisms of newborn calves upon the first colostrum feeding

The first meal of a neonatal calf after birth is crucial for survival and health. Blood IgG levels remarkably increase in neonatal calves after the first colostrum feeding. However, there is little comprehensive information on blood small-molecule metabolites in neonatal calves at that time. In this study, the changes in plasma metabolites of neonatal calves after the initial colostrum feeding were first examined with comprehensive 1H nuclear magnetic resonance (NMR). Sixteen plasma samples obtained from 8 calves before and after feeding were analyzed with 1H NMR. Multivariate analyses revealed a significant difference in metabolic profiles. After feeding, acute phase N-acetylated glycoproteins and 13 other plasma metabolites decreased, whereas 19 plasma metabolites increased. Metabolomics pathway analysis of these metabolites revealed that a global metabolic response on the first colostrum feeding was reflected by alterations of 13 metabolic pathways including lipid, carbohydrate, and amino acid metabolism in neonatal calves. These results suggested that besides meeting energy demand, a 4.0 L of high-quality colostrum feeding within 4 h after birth had a positive effect on relieving the postnatal stress in neonatal calves. This study provides another perspective of response mechanisms of newborn calves upon the first colostrum feeding.