Testing the Induction of Metritis in Healthy Postpartum Primiparous Cows Challenged with a Cocktail of Bacteria

Abstract

Metritis is a postpartum uterine disease with greater incidence in primiparous than in multiparous cows. In primiparous cows, the impact on production and health is lessened, presumably due to a superior immune response. Here, we tested whether an in vivo model of clinical metritis induction developed for postpartum multiparous Holstein cows would produce similar results in primiparous cows. Thirty-six cows were randomly assigned to one of three groups and received intrauterine infusion within 24 h of parturition. The controls were infused with sterile saline; the low-dose group received a bacterial cocktail containing 10³ cfu of Escherichia coli, Trueperella pyogenes, and Fusobacterium necrophorum; and the high-dose group were infused with 10⁶ cfu of the same cocktail. Production, health traits, and the vaginal discharge culture were assessed daily, from enrollment until 14 d in milk. Clinical metritis occurred in 64% of high-dose cows, 33% of the controls, and 42% of low-dose cows, with no significant difference of incidence between groups. However, when accounting by time, high-dose cows had a 2.7 times greater hazard of metritis compared with the controls. The bacterial challenge affected milk production and dry matter intake tended to decrease. In the high-dose group, a greater growth of F. necrophorum in the selective medium was also observed, suggesting an association with metritis. Therefore, this study suggests intrauterine inoculation with 10⁶ cfu of this bacterial cocktail elicits physical and clinical outcomes consistent with clinical metritis.

Keywords: challenge; dairy cow; metritis; microbiota; primiparous.

Figure 1

Kaplan–Meier survival curves for calving to metritis diagnosis of cows challenged intrauterine with a bacterial inoculum containing 10³ cfu (n = 12) or 10⁶ cfu (n = 11) of E. coli, T. pyogenes, and F. necrophorum, and controls (n = 12).

Figure 2

Clinical signs during the study period. Rectal temperature (A), milk production (B), and dry matter intake (C) during the first 14 days of lactation of cows challenged intrauterine with a bacterial inoculum containing 10³ cfu (n = 12) or 10⁶ cfu (n = 11) of E. coli, T. pyogenes, and F. necrophorum, and controls (n = 12). Results are presented as LSM ± SEM. TRT = treatment.

Figure 3

Plasma concentration of IL-6 (A) and IL-8 (B) during the first 14 d of lactation of cows challenged with low-dose (n = 12) and high-dose (n = 11) of bacterial inoculum or controls (n = 12). Results are presented as LSM ± SEM. TRT = treatment.

Figure 4

Bacterial cultures of total anaerobes (A) and F. necrophorum (B), and relative abundance of the genus Fusobacterium (C) from vaginal content during the first 14 d of lactation of cows challenged intrauterine with a bacterial inoculum containing 10³ cfu (n = 12) or 10⁶ cfu (n = 11) of E. coli, T. pyogenes, and F. necrophorum, and controls (n = 12). Results are presented as LSM ± SEM. TRT = treatment.

Figure 5

Bacterial cultures of total aerobes (A) and E. coli (B), and relative abundance of the genus Escherichia (C) from vaginal swabs during the first 14 d of lactation of cows challenged intrauterine with a bacterial inoculum containing 10³ cfu (n = 12) or 10⁶ cfu (n = 11) of E. coli, T. pyogenes, and F. necrophorum, and controls (n = 12). ln = natural log. Results are presented as LSM ± SEM. TRT = treatment.

Figure 6

Bacterial cultures of total facultative anaerobes (5% CO₂; (A)) and T. pyogenes (B), and relative abundance of the genus Trueperella (C) from vaginal content during the first 14 d of lactation of cows challenged intrauterine with a bacterial inoculum containing 10³ cfu (n = 12) or 10⁶ cfu (n = 11) of E. coli, T. pyogenes, and F. necrophorum, and controls (n = 12). Results are presented as LSM ± SEM. TRT = treatment.

Figure 7

Bacterial cultures of F. necrophorum (A) and relative abundance of the genus Fusobacterium (B) from vaginal content during the first 14 d of lactation of cows diagnosed with metritis (n = 16) and cows diagnosed as healthy (n = 19). * p = 0.05 (non-metritic vs. metritic). Results are presented as LSM ± SEM. TRT = treatment.

Figure 8

Bacterial cultures of T. pyogenes (A) and relative abundance of the genus Trueperella (B) from vaginal content during the first 14 d of lactation of cows diagnosed with metritis (n = 16) and cows diagnosed as healthy (n = 19). * p = 0.05 (non-metritic vs. metritic). Results are presented as LSM ± SEM. TRT = treatment.

Figure 9

Bacterial cultures of E. coli (A) and relative abundance of the genus Escherichia (B) from vaginal swabs during the first 14 d of lactation of cows diagnosed with metritis (n = 16) and cows diagnosed as healthy (n = 19). * p = 0.05 (non-metritic vs. metritic). Results are presented as LSM ± SEM. TRT = treatment.