Cows

In total, 1340 cows were sampled and included 682 Swedish Red (SRB), 460 Swedish Holstein (SLB) and 198 crossbreds between SLB and SRB (CRB). Parities ranged from 1 to 6 with 50% of the animals in first, 23% in second and 14% in third parity. During the sampling period, 504 cows calved twice and 29 calved three times.

Sampling of first milking colostrum was carried out by staff on the farms who recorded the time between birth and sampling for 1711 individual samples, but 29 of these were excluded due to labeling issues. In addition, pre-parturition serum and first test milk samples were obtained only from cows at the Lövsta center, among which there were 330 serum samples from January 2015 to June 2016 between days 1 and 23 before calving and 290 milk samples from February 2015 to March 2016 at 6 to 24 days in milk. All colostrum and milk samples were sent in sterile and pyrogen-free 50-mL Falcon tubes.

Information on milk production was provided by Växa Sverige for 1283 cows and comprised 305-day milk yield (kg), fat and protein percentage and lactation-average somatic cell score (LASCS) from lactations matching the corresponding colostrum sample. LASCS values were calculated from somatic cell count (SCC) measurements as described by Wijga et al. [25].