Short communication: Associations of udder edema with health, milk yield, and reproduction in dairy cows in early lactation.

Udder edema (UE) is a common condition of cows around calving, but its effects are not well characterized. The objectives of this study were to determine the associations of UE with the incidence of health disorders and with milk yield and reproduction in dairy cows in early lactation. On 3 commercial farms, UE was scored weekly on 1,346 cows, on a scale of 0 to 3, from 1 wk before calving to 3 wk after calving. Among cows with complete UE scores, 30% never had edema, 12% had edema only prepartum, 11% had it only postpartum, and 48% had edema prepartum and in at least 1 wk postpartum. Udder edema was associated with a greater incidence of clinical mastitis before 30 d in milk (5 vs. 2%). Subclinical ketosis (blood β-hydroxybutyrate ≥1.2 mmol/L) was more prevalent at wk 2 (11 vs. 6%) postpartum among cows with UE. No association was observed of UE with other diseases or culling in early lactation. In a subset of 912 cows with complete UE and 3 test-days of milk yield data, differences were observed in yield at test d 1 among UE categories. Cows with UE only prepartum produced less milk (39.9 kg/d) than cows with UE postpartum only (42.4 kg/d) and cows with UE both prepartum and postpartum (41.6 kg/d), none of which differed from cows without UE (40.9 kg/d). Udder edema was not associated with the prevalence of anovulation, or the time to or probability of pregnancy at first insemination, yet to 300 d in milk, cows that had UE postpartum had a shorter time from calving to pregnancy than cows without UE. The associations of UE with health and productivity are mixed, and the mechanisms underlying UE and its effects merit further investigation.