| Abstract: | Bovine colostrum is important for neonates' health due to its nutritive and non-nutritive components. Heat treatment of colostrum is a well-established management tool, but it may influence colostrum components and affect the health status of calves. In our previous studies, we had shown that colostrum proteome and serum proteome of calves were altered by heat treatment to different degrees. Our objectives in this study were to investigate the effects of heat treatment on colostrum metabolome and the effect of feeding heat-treated colostrum on the serum metabolome of newborn calves. Further, the changes in serum metabolome from before to after colostrum feeding were characterized. Newborn Holstein female calves (n = 10) were randomized within pairs and fed heat-treated (n = 5; 60 °C, 60 min) or raw (n = 5) colostrum at 8.5% of birth BW by esophageal feeder within 1 h of birth. After a single colostrum feeding, calves were not fed until after the 8 h time point. Blood samples were taken immediately prior to feeding (0 h) and 8 h after feeding. The colostrum and serum metabolome were first analyzed using reverse-phase chromatography and tandem MS, and serum metabolome was then further analyzed using hydrophilic interaction chromatography and tandem MS. In colostrum metabolome, 458 features were identified and 328 were annotated and a trend of separation between raw and heat-treated colostrum could be observed through multivariate analysis. In serum metabolome, 3 360 features were identified and 1 439 were annotated, but no trend of separation was observed between the two groups of calves fed raw colostrum vs. heat-treated colostrum. The serum metabolome presented substantial differences comparing before (0 h) and after colostrum feeding (8 h); in particular, a tripeptide, β-homovaline-β-homoalanine-β-homoleucine, and 1-(2-acetamido-2-deoxy-α-d-glucopyranosyl)-1D-myo-inositol had higher concentrations after colostrum feeding than before, along with other metabolites that were not fully annotated. Based on a relatively small sample size, our findings point to the effect of heat treatment on the change of colostrum metabolome, but not on the change of serum metabolome of calves fed raw colostrum vs. heat-treated colostrum. Further studies using larger sample size and complementary analytical techniques are warranted to further explore potential heat treatment-induced alterations in colostrum metabolome. |
