title: Associations between intrauterine bacterial infection, reproductive tract inflammation, and reproductive performance in pasture-based dairy cows.
abstract: Reproductive tract bacterial infections, particularly those caused by Escherichia coli and Trueperella pyogenes, can have a negative impact on reproductive performance. It has been hypothesized that the presence of E coli early postpartum may increase the risk of isolation of T pyogenes later postpartum. The objective of the present study was to examine associations between intrauterine bacterial infections with E coli and T pyogenes and any bacterial growth (irrespective of bacterial species), purulent vaginal discharge (PVD), cytologic evidence of endometritis (an increased proportion of polymorphonuclear cells [PMNs]), and reproductive performance. Dairy cows (n = 272) from six herds were examined at Days 0 (median, 2 days in milk), 21 and 42 postpartum. From each cow two intrauterine samples were collected via triple-guarded cytobrush at Days 0 and 21. The first cytobrush was used for bacteriologic culture. Escherichia coli and T pyogenes were isolated by culture, and E coli isolates were assigned to one of four phylogenetic groups using a two-step triplex polymerase chain reaction. In addition, T pyogenes was confirmed by polymerase chain reaction. The second cytobrush was used to prepare a cytology slide. Nucleated cells (n = 200) were categorized as epithelial cells, PMNs, or macrophages. Cows were also assessed for body condition score, PVD score, the presence of a CL, and pregnancy. Statistical analysis was performed using multivariable models. There was no association between the presence of E coli at Day 0 and probability of isolation of T pyogenes 3 weeks later; however, E coli positive cows at Day 0 were more likely to be diagnosed with E coli at Day 21 (relative risk [RR] = 2.0, P < 0.01). Escherichia coli at Day 0 or T pyogenes at Day 21 increased the risk of PVD diagnosis 3 weeks later (RR = 1.9; P = 0.04 and RR = 3.0; P = 0.05, respectively). Cows with any bacterial growth at Day 21, irrespective of species, were less likely to conceive within 3 weeks after the start of the seasonal breeding program (RR = 0.8; P = 0.05). Interestingly, cows with 25% PMNs or greater at Day 0 had shorter time to pregnancy (hazard ratio = 1.32; P = 0.05). Intrauterine bacterial infection may impair reproductive performance but the presence of E coli was not associated with isolation of T pyogenes 3 weeks later. Increased endometrial flux of PMNs in cows early postpartum may be a physiological process and improve reproductive performance.
authors: Cognosco, Anexa Animal Health, Morrinsville, New Zealand; Epicentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand. Electronic address: mdeboer@anexa.co.nz.
authors: Melvin
authors: M
authors: de Boer
authors: AgResearch, Hopkirk Research Institute, Grasslands Research Centre, Palmerston North, New Zealand.
authors: Bryce M
authors: BM
authors: Buddle
authors: Epicentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
authors: Cord
authors: C
authors: Heuer
authors: HJ Tasty Free Range Ltd, Pokeno, New Zealand.
authors: Hassan
authors: H
authors: Hussein
authors: AgResearch, Hopkirk Research Institute, Grasslands Research Centre, Palmerston North, New Zealand.
authors: Tao
authors: T
authors: Zheng
authors: Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
authors: Stephen J
authors: SJ
authors: LeBlanc
authors: Cognosco, Anexa Animal Health, Morrinsville, New Zealand.
authors: Scott
authors: S
authors: McDougall
mesh_terms: D000191:Actinomycetaceae; D000193:Actinomycetales Infections / Q000150:complications / Q000662:veterinary; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D004926:Escherichia coli; D004927:Escherichia coli Infections / Q000150:complications / Q000662:veterinary; D007246:Infertility / Q000150:complications / Q000382:microbiology / Q000662:veterinary*; D012098:Reproduction; D060737:Reproductive Tract Infections / Q000150:complications / Q000382:microbiology / Q000662:veterinary*; D061685:Time-to-Pregnancy
keywords: Conception; Endometritis; Escherichia coli; Polymorphonuclear cell; Purulent vaginal discharge; Trueperella pyogenes