Protein and oligosaccharide composition of colostrum and transition milk from pasture-based dairy cows supplemented prepartum with inorganic selenium, organic selenium or rumen-protected choline

Prepartum diet and mineral supplementation can influence bovine colostrum proteins and oligosaccharides (OS). The objective of this study was to evaluate the effects of prepartum supplementation with 1) inorganic selenium (INORG), 2) organic selenium (ORG) or 3) rumen-protected choline (RPC) on these components. Fifty-seven (12 primiparous and 45 multiparous) cows were supplemented daily from 49 ± 12.9 d prior to calving until d of calving. Colostrum was collected within 1 h postpartum and transition milk (TM) samples 1–5 were collected over the following 2–3 d postpartum. Prepartum supplementation with INORG, ORG or RPC had no significant effect on the gross, OS or IgG composition of colostrum. Animals supplemented with ORG or RPC produced significantly higher concentrations of colostrum α_s2-Casein and β-Casein. Each milking postpartum had a significant effect on the protein and OS composition of milk. This research demonstrates that supplementing these micro-nutrients prepartum does not have a deleterious effect on subsequent colostrum or TM composition.