Poor udder health status can have a detrimental effect on milk yield and reproductive performance, leading to reductions in the dairy farm profit. The objective of this retrospective longitudinal study was to assess the associations of somatic cell count (SCC) with daily milk yield and reproductive performance. A database with 1,930,376 lactations from 867 Argentinean grazing dairy herds records collected for 14 years was used. The association of the evolution of SCC (healthy vs. new case vs. cured vs. chronic; with 150,000 SCC/mL as threshold) and of the severity of SCC [mild (150,000--400,000 SCC/mL) vs. moderate (400,000-1,000,000 SCC/mL) vs. severe (>1,000,000 SCC/mL)] with the odds for conception were estimated. Finally, the associations of the linear score of SCC (LS-SCC) with daily milk yield were estimated depending on parity and milk production quartile. The odds ratios (CI 95%) for conception at first service were 0.921 (0.902-0.941), 0.866 (0.848-0.884), and 0.842 (0.826-0.859) for the new case, cured, and chronic cows compared with healthy cows, respectively. Also, the odds ratios (CI 95%) for conception were 0.902 (0.881-0.925), 0.837 (0.808-0.866) and 0.709 (0.683-0.736) for mild, moderate and severe cases compared with healthy cows, respectively. An increase of one point of LS-SCC was associated with decreases of 0.349, 0.539, and 0.676 kg in daily milk yield for first-, second-, and third-lactation cows, respectively. In conclusion, SCC is negatively associated with the risk for conception and with daily milk yield in grazing dairy cows. This negative relationship with conception is higher when SCC increase occurs after the service date and it is influenced by severity of mastitis, and in the case of milk yield, the negative association is influenced by parity, milk production quartile, and severity of mastitis.

In this study we developed an indirect ELISA to detect antibodies against Minute Virus of Mice (MVM) using an antigen produced from BHK-21 cells infected with a prototype strain of the virus. The optimal antigen concentration and serum dilutions were established. In order to analyze variability in the laboratory, reproducibility and repeatability within and between plates were determined. Then, a panel of 460 sera from conventional facilities and previously classified as positive or negative by the indirect fluorescent antibody assay was analyzed. The cutoff value was determined by a receiver operating characteristic (ROC) curve. The results of the indirect ELISA were compared with those of the indirect fluorescent antibody assay. The ELISA assay showed 100% sensitivity and 99% specificity. ELISA is a useful tool to be developed in standard virology laboratories and can be used for screening animals faster than the traditional indirect fluorescent antibody assay. Se desarrolló un ELISA indirecto para detectar anticuerpos contra el virus diminuto del ratón (Mice minute virus [MVM]), utilizando un antígeno producido a partir de células BHK-21 infectadas con la cepa prototipo del virus. Se establecieron las diluciones óptimas de antígeno y el suero a utilizar. Para analizar la variabilidad en el laboratorio, se determinaron la reproducibilidad y la repetibilidad dentro de una placa y entre placas. Luego se analizaron 460 sueros provenientes de bioterios convencionales y clasificados previamente como positivos o negativos por inmunofluorescencia indirecta. El valor de corte se determinó mediante una curva ROC. Los resultados se compararon con los obtenidos con la prueba de inmunofluorescencia indirecta. El ELISA mostró 100% de sensibilidad y un 99% de especificidad. Esta técnica demostró ser una herramienta útil para desarrollar en laboratorios de virología estándar y puede utilizarse como prueba tamiz para seleccionar animales de manera más rápida que con la tradicional prueba de inmunofluorescencia indirecta.

Objective To assess the efficacy of antibiotic usage for the treatment of puerperal metritis (PM) and its association with reproductive performance, a retrospective cohort study including a total of 9168 records of cows from a dairy farm in Argentina was run. Material and methods Cows having a PM3 (metricheck, scale 0–3) and treated with ceftiofur (ceftiofur crystalline free acid, 6.6 mg/kg) at 0–21 days postpartum (p. p.) (n = 2688), and cows having a PM 1–2 and not treated with an antibiotic at 0–21 days p. p. (n = 6480) were included in the study. All cows were reexamined with metricheck to assess the clinical cure (vaginal discharge [VD] score 0), partial cure (VD score similar or lower than previous), no cure (VD score higher than previous). Cows with a metricheck VD1–3 after 0–21 days p. p. were diagnosed as clinical endometritis (CE) 1–3. The occurrence of PM1–3, cure rate, calving to conception interval, the hazard of pregnancy, odds for non-pregnancy, and odds for CE were analyzed using SAS software. Results A total of 8876 PM1–3 records were included, 2435 records of PM3 treatments with ceftiofur (27.43 %), and 6441 records of PM1–2 (72.57 %) with no treatment. Cows having PM1 and PM2 became pregnant 14 and 12 days earlier than cows with PM3 (p < 0.001). The PM3 ceftiofur treated cows had a clinical cure of 24.85 % (PM0); 53.63 % had a partially cure; and 18.52 % no cure. Conversely, cows with PM1–2 had a 51.96 %, 20.70 %, and 24.53 % cure rate, respectively (p < 0.001). Cows having complete cure became pregnant 13 and 11 days earlier than cows having partial cure and no cure (p < 0.001). Cows that had PM3 during the first 21 days p. p. had twice the chances of developing CE compared to cows having PM1–2 (41.28 % vs. 24.14 %, p < 0.001). After 21 days p. p., less than 1 % of cows with clinical cure developed CE compared to 63.32 % that developed CE with partial cure, and 38.21 % with no cure (p < 0.001). Conclusion and clinical relevance After ceftiofur treatment, 78 % of cows were cured when measured by disappearance of fetid VD but only 25 % of cows had clinical cure when measured by appearance of a clear VD. The cows that remained with clinical metritis had more chances of having CE after 21 days p. p. and had more days open than cows with clear normal VD.

The study aimed to describe pregnancy losses within the same lactation in a large commercial dairy herd in Argentina. A retrospective study was completed using 25,019 lactation records from 11,263 cows with at least 1 artificial insemination-declared pregnant (AIDP) by ultrasound at 28 to 42 d post AI. Each AIDP was identified according to the corresponding parity number, which was sequentially numbered and related to a pregnancy number within the same lactation. In each lactation, the uterine health events (UTE), retention of fetal membranes, puerperal metritis, and clinical endometritis, as well as the nonuterine health events (NUTE), clinical mastitis, and clinical lameness were recorded. The health status for each lactation was categorized according to the site of inflammation, such as healthy cows, cows with UTE, cows with NUTE records, and cows with both UTE and NUTE. Pregnancy loss was defined by: (1) detection of heat with blue paint rubbed off after having been previously diagnosed pregnant and subsequently diagnosed open by ultrasound at the next herd visit 14 d later; (2) observed abortion; or (3) diagnosis open by ultrasound pregnancy diagnosis 5 mo after AI of pregnancy to reconfirm pregnancy status. The occurrence of pregnancy loss was reported for the whole study period and 21-d periods. The risk of pregnancy loss was analyzed using a Cox proportional hazards model that included parity number, AIDP, season, health status, DIM to AIDP, and daily milk production to AIDP as covariates. Herd persistence was used to assess the risk of cows leaving the herd before the next lactation due to pregnancy loss, with the last pregnancy within each lactation, parity number, and pregnancy loss as covariates. The occurrence of pregnancy loss was 22.5%; the occurrence of pregnancy loss per 21 d was 3.7%. The median day of gestation and median DIM for the first, second, and third pregnancy losses were 98, 108, 121 d and 224, 394, and 552 d, respectively. Cows with UTE diseases had a higher hazard of pregnancy loss than healthy cows (hazard ratio [HR] 1.24, 95% CI 1.13-1.36); conversely, cows in second or third parity did not have a higher hazard of pregnancy loss than first parity cows (HR 1.03, 95% CI 0.95-1.11; HR 1.00, 95% CI 0.92-1.08; respectively). Similarly, cows with 2 and 3 AIDP had a lower hazard of pregnancy loss than cows with only 1 AIDP (HR 0.90, 95% CI 0.83-0.97; HR 0.92, 95% CI 0.85-0.99, respectively). Cows with AIDP in fall and winter had a lower HR of pregnancy loss than those with AIDP in summer (HR 0.84, 95% CI 0.77-0.91; HR 0.82, 95% CI 0.75-0.89). In conclusion, health events during lactation affect pregnancy loss within the same lactation and herd persistence to the next lactation in dairy cows. The risk of pregnancy losses within a lactation may not increase with parity number and higher AIDP, but conversely, it may increase with higher milk production (HR 1.02, 95% CI 1.01-1.02; 1%/1 kg increase in test-day milk yield closest to the AIDP).

This study aimed to evaluate the association between colostrum quality, as indicative of the immune status of the cows, and peripartum disease risk occurrence in a herd of grazing dairy cows. A prospective cohort study was conducted on a grazing dairy farm with 3000 Holstein milking cows from 15 March 2022 to 15 March 2023. Multivariable binary logistic models evaluated the association between colostrum quality (expressed in Brix grades as a continuous predictor) and the risk of peripartum diseases (including dystocia, stillbirth, retention of fetal membranes, metritis, and clinical endometritis). We found that colostrum quality was negatively associated with the risk of dystocia (p = 0.02), stillbirth (p < 0.01), clinical endometritis (p = 0.02), and total peripartum diseases (p < 0.01). Conversely, colostrum quality was not related to the risk of retention of the placenta (p = 0.25) or metritis (p = 0.76). Additionally, we found that the calving season affected colostrum quality (p < 0.01). Conversely, parity number, dry period length, and milk yield in previous lactation did not affect it (p > 0.10). We concluded that colostrum quality, expressed in Brix grades, is negatively associated with peripartum disease risk in dairy cows and could be a useful indicator of the immune status of the cow.