Heat treatment of bovine colostrum: effects on colostrum metabolome and serum metabolome of calves

Bovine colostrum is important for neonates' health due to its nutritive and non-nutritive components. Heat treat-ment of colostrum is a well-established management tool, but it may influence colostrum components and affectthe health status of calves. In our previous studies, we had shown that colostrum proteome and serum proteomeof calves were altered by heat treatment to different degrees. Our objectives in this study were to investigate theeffects of heat treatment on colostrum metabolome and the effect of feeding heat-treated colostrum on theserum metabolomeof newborn calves. Further,the changes in serum metabolome from before to after colostrumfeeding were characterized. Newborn Holstein female calves (n= 10) were randomized within pairs and fedheat-treated (n= 5; 60 °C, 60 min) or raw (n= 5) colostrum at 8.5% of birth BW by esophageal feeder within1 h of birth. After a single colostrum feeding, calves were not fed until after the 8 h time point. Blood sampleswere taken immediately prior to feeding (0 h) and 8 h after feeding. The colostrum and serum metabolomewerefirst analyzed using reverse-phase chromatography and tandem MS, and serum metabolome was then fur-ther analyzed using hydrophilic interaction chromatography and tandem MS. In colostrum metabolome, 458 fea-tures were identified and 328 were annotated and a trend of separation between raw and heat-treated colostrumcould be observed through multivariate analysis. In serum metabolome, 3 360 features were identified and 1 439were 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 colostrumfeeding than before, along with other metabolites that were not fully annotated. Based on a relatively small sam-ple size, ourfindings point to the effect of heat treatment on the change of colostrum metabolome, but not on thechange of serum metabolome of calves fed raw colostrum vs. heat-treated colostrum. Further studies using largersample size and complementary analyticaltechniques are warranted to further explore potentialheattreatment-induced alterations in colostrum metabolome.