Two experiments were designed to study endometritis in postpartum dairy cows. In the first experiment, 30 cows 28 to 41 days in milk (DIM) and without evidence of clinical endometritis were sampled using cytobrush cytology. Cytobrush sampling provided sufficient endometrial material to prepare cytologic specimens and to extract endometrial mRNA. Pro-inflammatory cytokines were analyzed in harvested endometrial tissue taken from cows with and without endometritis. Cytokine expression varied between experimental groups with 30-fold higher IL-6 expression levels (P=0.01), greater than 50-fold higher IL-8 expression levels (P=0.0001), and 20-fold higher TNF-α expression levels (P=0.001) in endometritis-positive versus negative cows. Regression analysis of cytokine expression levels (Ct) and the percentage of PMNs in subclinical endometritis-positive cows showed that for each additional threshold cycle required for IL-8 detection, which corresponded to two-fold less mRNA, the percentage of PMN decreased by 3.3% (P=0.00001). Similarly, for each additional threshold cycle required to detect IL-6 and TNF-α, the percentage of PMNs in endometritis-positive cows decreased by 2.3% (P=0.015) and 2.4% (P=0.054), respectively. Cows with > 18% PMNs required significantly fewer amplification cycles to detect IL-6 (P = 0.01), IL-8 (P =0.0001) and TNF-α (P=0.053) mRNA than cows with <18% PMNs (endometritis-negative). There was a highly significant positive correlation between the expression of individual pro-inflammatory cytokines when comparing IL-8 and IL-6 (P=0.0001), IL-8 and TNF-α (P=0.00001), and finally IL-6 and TNF-α (P=0.0002). In the second experiment, 340 cows 28 to 41 days in milk were examined using cytobrush cytology and transrectal ultrasonography of the uterus and ovaries. One-half of the cows were treated with benzathine cephapirin uterine infusion to determine the lowest PMN percentage where a significant improvement in reproductive performance occurred. Subclinical endometritispositive (>15%) cows in this study were defined as those with the lowest percentage of PMNs that was associated with a significant positive treatment effect. Treated cows with >15% PMNs required 31 fewer days (P=0.041) to become pregnant and had 2.5 times fewer services per conception (P=0.0001) than untreated cows with >15% PMNs. The likelihood of there being CLs at the time of examination in cows with >15% PMNs in endometrial cytobrush cytology was 2.3 times significantly higher (P=0.04). The treatment of cows with ultrasonographically detectable fluid in the uterine lumen with benzathine cephapirin had no effect on days open compared to treatment of cows without fluid in the uterus (P=0.39). Cervical diameter and endometrial thicknesses did not differ between groups of cows with >, < 15%PMNs (P=0.46, P=0.36, respectively). In summary, based on the response to a single treatment with benzathine cephapirin, and the analysis of pro-inflammatory cytokine gene expression, we recommend that a threshold of >18% PMNs be used to define endometritis-positive disease status in cows 28 to 41 DIM. Cervical diameter, ultrasonographic evidence of uterine fluid and ultrasonographic measurement of endometrial thickness were not useful for diagnosing benzathine cephapirin responsive endometritis.

Two experiments were designed to study endometritis in postpartum dairy cows. In the first experiment, 30 cows 28 to 41 days in milk (DIM) and without evidence of clinical endometritis were sampled using cytobrush cytology. Cytobrush sampling provided sufficient endometrial material to prepare cytologic specimens and to extract endometrial mRNA. Pro-inflammatory cytokines were analyzed in harvested endometrial tissue taken from cows with and without endometritis. Cytokine expression varied between experimental groups with 30-fold higher IL-6 expression levels (P=0.01), greater than 50-fold higher IL-8 expression levels (P=0.0001), and 20-fold higher TNF-α expression levels (P=0.001) in endometritis-positive versus negative cows. Regression analysis of cytokine expression levels (Ct) and the percentage of PMNs in subclinical endometritis-positive cows showed that for each additional threshold cycle required for IL-8 detection, which corresponded to two-fold less mRNA, the percentage of PMN decreased by 3.3% (P=0.00001). Similarly, for each additional threshold cycle required to detect IL-6 and TNF-α, the percentage of PMNs in endometritis-positive cows decreased by 2.3% (P=0.015) and 2.4% (P=0.054), respectively. Cows with > 18% PMNs required significantly fewer amplification cycles to detect IL-6 (P = 0.01), IL-8 (P =0.0001) and TNF-α (P=0.053) mRNA than cows with <18% PMNs (endometritis-negative). There was a highly significant positive correlation between the expression of individual pro-inflammatory cytokines when comparing IL-8 and IL-6 (P=0.0001), IL-8 and TNF-α (P=0.00001), and finally IL-6 and TNF-α (P=0.0002). In the second experiment, 340 cows 28 to 41 days in milk were examined using cytobrush cytology and transrectal ultrasonography of the uterus and ovaries. One-half of the cows were treated with benzathine cephapirin uterine infusion to determine the lowest PMN percentage where a significant improvement in reproductive performance occurred. Subclinical endometritispositive (>15%) cows in this study were defined as those with the lowest percentage of PMNs that was associated with a significant positive treatment effect. Treated cows with >15% PMNs required 31 fewer days (P=0.041) to become pregnant and had 2.5 times fewer services per conception (P=0.0001) than untreated cows with >15% PMNs. The likelihood of there being CLs at the time of examination in cows with >15% PMNs in endometrial cytobrush cytology was 2.3 times significantly higher (P=0.04). The treatment of cows with ultrasonographically detectable fluid in the uterine lumen with benzathine cephapirin had no effect on days open compared to treatment of cows without fluid in the uterus (P=0.39). Cervical diameter and endometrial thicknesses did not differ between groups of cows with >, < 15%PMNs (P=0.46, P=0.36, respectively). In summary, based on the response to a single treatment with benzathine cephapirin, and the analysis of pro-inflammatory cytokine gene expression, we recommend that a threshold of >18% PMNs be used to define endometritis-positive disease status in cows 28 to 41 DIM. Cervical diameter, ultrasonographic evidence of uterine fluid and ultrasonographic measurement of endometrial thickness were not useful for diagnosing benzathine cephapirin responsive endometritis.

Two experiments were designed to study endometritis in postpartum dairy cows. In the first experiment, 30 cows 28 to 41 days in milk (DIM) and without evidence of clinical endometritis were sampled using cytobrush cytology. Cytobrush sampling provided sufficient endometrial material to prepare cytologic specimens and to extract endometrial mRNA. Pro-inflammatory cytokines were analyzed in harvested endometrial tissue taken from cows with and without endometritis. Cytokine expression varied between experimental groups with 30-fold higher IL-6 expression levels (P=0.01), greater than 50-fold higher IL-8 expression levels (P=0.0001), and 20-fold higher TNF-&#945; expression levels (P=0.001) in endometritis-positive versus negative cows. Regression analysis of cytokine expression levels (Ct) and the percentage of PMNs in subclinical endometritis-positive cows showed that for each additional threshold cycle required for IL-8 detection, which corresponded to two-fold less mRNA, the percentage of PMN decreased by 3.3% (P=0.00001). Similarly, for each additional threshold cycle required to detect IL-6 and TNF-&#945;, the percentage of PMNs in endometritis-positive cows decreased by 2.3% (P=0.015) and 2.4% (P=0.054), respectively. Cows with > 18% PMNs required significantly fewer amplification cycles to detect IL-6 (P = 0.01), IL-8 (P =0.0001) and TNF-&#945; (P=0.053) mRNA than cows with 15%) cows in this study were defined as those with the lowest percentage of PMNs that was associated with a significant positive treatment effect. Treated cows with >15% PMNs required 31 fewer days (P=0.041) to become pregnant and had 2.5 times fewer services per conception (P=0.0001) than untreated cows with >15% PMNs. The likelihood of there being CLs at the time of examination in cows with >15% PMNs in endometrial cytobrush cytology was 2.3 times significantly higher (P=0.04). The treatment of cows with ultrasonographically detectable fluid in the uterine lumen with benzathine cephapirin had no effect on days open compared to treatment of cows without fluid in the uterus (P=0.39). Cervical diameter and endometrial thicknesses did not differ between groups of cows with >, < 15%PMNs (P=0.46, P=0.36, respectively). In summary, based on the response to a single treatment with benzathine cephapirin, and the analysis of pro-inflammatory cytokine gene expression, we recommend that a threshold of >18% PMNs be used to define endometritis-positive disease status in cows 28 to 41 DIM. Cervical diameter, ultrasonographic evidence of uterine fluid and ultrasonographic measurement of endometrial thickness were not useful for diagnosing benzathine cephapirin responsive endometritis.

Overapplication of manure in sensitive watersheds is an issue of increasing environmental concern due to increased nutrient loading and antibiotic release into aquatic environments. Manure is typically surface applied, leaving nutrients and antibiotics vulnerable to loss at the soil surface. Elevated nutrient and antibiotic loading into water bodies can increase the rate of eutrophication and occurrence of antibiotic resistance genes in areas of high animal agriculture production, such as the Chesapeake Bay watershed. Manure injection is a new technology that incorporates manure into the soil with minimal disturbance, and management strategies that reduce manure loss from agricultural fields could prevent the transport of nutrients and antibiotics to sensitive waterways. However, little is known about the efficacy of dry litter injection to decrease nitrogen (N) loss when compared to surface application. Also, there are no studies that determine the effects of injection on antibiotic transport and transformation after manure application. Therefore, this project focused on changes in N cycling, orchardgrass hay yield and quality, and transport and transformation of pirlimycin and cephapirin, two common antibiotics in dairy production, when manure is injected. Subsurface injection eliminated ammonia volatilization and N loss in runoff and increased soil inorganic N when compared to surface application after volatilization, incubation, and rainfall simulation studies. Although these benefits did not translate to higher yields in orchardgrass hay, protein increased when poultry litter was injected, indicating greater N uptake. Injection of dairy manure decreased losses of pirlimycin to levels of the control when compared to surface application. Although, pirlimycin had a slower degradation rate within the injection slit compared to surface application, potentially increasing the amount of time soil microbes are exposed to antibiotics. In an incubation study, pirlimycin concentrations decreased after 7 days, but concentrations increased sharply after 14 days. This indicates that conjugates formed in the liver or digestive tract of dairy cows may revert back to the parent compound after manure application. With increased retention of nutrients and antibiotics, injection could be a best management practice used to reduce the loss of these compounds to the environment while increasing the quality of crops produced. / Ph. D.

No description available.

La reproduction est un pilier majeur de la productivité des fermes laitières. Dans ce contexte, il est pertinent d’identifier à l’avance les animaux à risque d’avoir des performances en reproduction sous-optimales, surtout si un traitement efficace est disponible pour améliorer ces performances. Les endométrites clinique et subclinique sont des conditions définies selon leur impact sur les performances en reproduction subséquentes et donc, des outils très intéressants de surveillance de la santé utérine. Le premier objectif de cette étude était de déterminer simultanément des seuils diagnostiques pour les endométrites clinique (diagnostiquée par le Metricheck) et subclinique (diagnostiquée par la cytologie endométriale ou par l’estérase leucocytaire) selon leur impact sur les performances en reproduction à la première saillie. L’écoulement vaginal purulent a été identifié comme seuil pour l’endométrite clinique, alors que les seuils identifiés pour l’endométrite subclinique ont été un pourcentage de polymorphonucléaires de 6% à la cytologie et une « forte quantité de leucocytes » à l’estérase leucocytaire. Le second objectif de l’étude était d’évaluer l’effet d’un traitement intra-utérin de céphapirine sur les performances à la première saillie des animaux sains et atteints d’endométrite. Aucun effet du traitement n’a été observé chez les vaches saines ou atteintes d’endométrite clinique, alors qu’une tendance à l’amélioration des performances a été associée au traitement chez celles atteintes d’endométrite subclinique. L’anovulation post-partum prolongée pourrait altérer l’efficacité du traitement de céphapirine, surtout chez les vaches atteintes d’endométrite clinique. / Reproduction is a major concern in the dairy industry. In this context, it is relevant to have an early identification of cows at risk of altered subsequent reproductive performance, especially if a treatment is available and effective to improve this performance. Clinical and subclinical endometritis are defined based on their impact on reproductive performance and are interesting tools for reproductive tract health surveillance. The first objective of this research project was to determine simultaneously diagnostic criteria for clinical (diagnosed by Metricheck) and subclinical (diagnosed by endometrial cytology or leukocyte esterase testing) endometritis based on their impact on reproductive performance at first service. Clinical endometritis was defined as presence of purulent vaginal discharge whereas subclinical endometritis was defined as presence of ≥ 6% of polymorphonuclear cells using endometrial cytology or the presence of “large amount of leukocytes” using leukocyte esterase testing. The second objective of this research project was to determine the effect of an intrauterine infusion of cephapirin on the reproductive performance at first service in cows with clinical endometritis, subclinical endometritis, and in cows unaffected by endometritis. Cephapirin treatment had no effect on first service pregnancy risk in unaffected cows or in cows affected by clinical endometritis. However, there was a tendency of a positive effect of the treatment in cows affected by subclinical endometritis. Presence of prolonged postpartum anovulation in cows may reduce the efficacy of the cephapirin treatment, especially in cows affected by clinical endometritis.

La reproduction est un pilier majeur de la productivité des fermes laitières. Dans ce contexte, il est pertinent d’identifier à l’avance les animaux à risque d’avoir des performances en reproduction sous-optimales, surtout si un traitement efficace est disponible pour améliorer ces performances. Les endométrites clinique et subclinique sont des conditions définies selon leur impact sur les performances en reproduction subséquentes et donc, des outils très intéressants de surveillance de la santé utérine. Le premier objectif de cette étude était de déterminer simultanément des seuils diagnostiques pour les endométrites clinique (diagnostiquée par le Metricheck) et subclinique (diagnostiquée par la cytologie endométriale ou par l’estérase leucocytaire) selon leur impact sur les performances en reproduction à la première saillie. L’écoulement vaginal purulent a été identifié comme seuil pour l’endométrite clinique, alors que les seuils identifiés pour l’endométrite subclinique ont été un pourcentage de polymorphonucléaires de 6% à la cytologie et une « forte quantité de leucocytes » à l’estérase leucocytaire. Le second objectif de l’étude était d’évaluer l’effet d’un traitement intra-utérin de céphapirine sur les performances à la première saillie des animaux sains et atteints d’endométrite. Aucun effet du traitement n’a été observé chez les vaches saines ou atteintes d’endométrite clinique, alors qu’une tendance à l’amélioration des performances a été associée au traitement chez celles atteintes d’endométrite subclinique. L’anovulation post-partum prolongée pourrait altérer l’efficacité du traitement de céphapirine, surtout chez les vaches atteintes d’endométrite clinique. / Reproduction is a major concern in the dairy industry. In this context, it is relevant to have an early identification of cows at risk of altered subsequent reproductive performance, especially if a treatment is available and effective to improve this performance. Clinical and subclinical endometritis are defined based on their impact on reproductive performance and are interesting tools for reproductive tract health surveillance. The first objective of this research project was to determine simultaneously diagnostic criteria for clinical (diagnosed by Metricheck) and subclinical (diagnosed by endometrial cytology or leukocyte esterase testing) endometritis based on their impact on reproductive performance at first service. Clinical endometritis was defined as presence of purulent vaginal discharge whereas subclinical endometritis was defined as presence of ≥ 6% of polymorphonuclear cells using endometrial cytology or the presence of “large amount of leukocytes” using leukocyte esterase testing. The second objective of this research project was to determine the effect of an intrauterine infusion of cephapirin on the reproductive performance at first service in cows with clinical endometritis, subclinical endometritis, and in cows unaffected by endometritis. Cephapirin treatment had no effect on first service pregnancy risk in unaffected cows or in cows affected by clinical endometritis. However, there was a tendency of a positive effect of the treatment in cows affected by subclinical endometritis. Presence of prolonged postpartum anovulation in cows may reduce the efficacy of the cephapirin treatment, especially in cows affected by clinical endometritis.