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A Competitive and Unpredictable Feeding Environment Pre-calving Increases Inflammation and Endometritis in Holstein Dairy Cows
Pre-calving management may influence the risk of disease after calving. Our objective was to determine the effects of a competitive and unpredictable feeding environment on inflammation and uterine health in dairy cows. Sixty-four animals were randomly assigned to treatment (n = 4 animals x 8 groups) or control groups (n = 4 animals x 8 groups). Each group consisted of 3 multiparous cows and 1 primiparous heifer. During a 1 wk baseline period (5 wk before calving) all groups had free access to 4 electronic feed bins (Insentec, Marknesse, Holland). From 4 wk before calving until calving, control cows were given ad libitum access to 6 feed bins. For treatment groups, 4 non-experimental cows were added to the pen; after 2 wk, treatment groups were moved into a pen with 4 new cows. Throughout the treatment period morning feeding times were delayed at random 0, 1 or 2 h on alternate days. Cows were excluded if they calved twins, aborted or calved > 2 wk early. Blood samples were taken at baseline and weekly thereafter until 1 wk after calving. Serum was analyzed for TNF-a using an ELISA. A uterine cytology smear was taken 3 to 5 wk post-calving. Smears were stained and examined under 400X magnification for presence of neutrophils and uterine epithelial cells; cows were considered to have endometritis if > 5% neutrophils were identified. Preliminary analysis revealed treatment*parity*week interactions so data were analyzed separately by parity. The percentage of endometritis cases per group was compared between treatments using a Mann-Whitney U test in SAS. Log-transformed TNF-a data were analyzed using a mixed model including baseline data as a covariate, treatment as a main effect, week as a repeated measure (wk -2, -1, 0, 1 relative to calving) and group as a random effect. There was no difference in the number of cases of endometritis or differences in TNF-a between control and treatment first-calf heifers. For cows, treatment groups had a higher percentage of endometritis cases (64% vs. 17% cases/group; P=0.02) and higher TNF-a (2.1 vs. 1.8 ± 0.06 log pg/ml; P=0.02) compared to controls. These results indicate that management practices that create a competitive and unpredictable feeding environment such as regrouping, overstocking, and variable feeding times can disrupt immune function and increase disease risk in cows but not first-calf heifers.
Keywords: stress, endometritis, parturition