In this study, the prevalence, effectiveness of diagnosis, and treatment based on vaginal discharge score (VDS) of clinical endometritis in cattle were evaluated. To detect clinical endometritis and classify its severity, vaginoscopy was performed during 21 to 60 days postpartum in 164 Holstein cows consisting of 229 lactations. Groups were defined using the 4-point VDS scale. Study groups included the following: non-endometritis (VDS=0; no/clear mucus; NEM group; n=168); mild endometritis, no treatment (VDS=1; mucus containing flecks of white/off-white pus; NTR group; n=30); and severe endometritis, treated with PGF2α (VDS≥2; discharge containing 50% pus, and fluid or uterine horn asymmetry; TEM group; n=31). Cows treated with PGF2α that did not recover (VDS≥1, n=5) received intrauterine procaine penicillin and streptomycin. Prevalence of clinical endometritis (VDS≥1) was 26.6%. The NTR group required significantly more artificial inseminations per pregnancy than NEM and TEM groups (2.8 ± 1.8 vs 2.0 ± 1.3, 1.9 ± 0.8, P<0.05). In survival analysis, the proportion of non-pregnant cows was higher in the NTR group compared to the NEM (P=0.012) and TEM (P=0.076) groups. In the TEM group, calving to first artificial insemination interval tended to be higher in cows treated 41 to 60 days postpartum than cows treated 29 to 40 days postpartum (97.2 ± 27.1 vs 74.4 ± 19.7, P=0.084). Our study suggests that cows with VDS=1 may require treatment to recover fertility. Diagnosis and treatment of clinical endometritis based on a VDS grading system may improve dairy herd reproductive performance.

In this study, we evaluated the efficiency of a single measurement of plasma anti-Müllerian hormone (AMH) concentration in heifers in determining the number of oocytes recoverable by ovum pick-up (OPU), and compared AMH concentrations among sister heifers from the same parents. For this, blood samples from 50 embryo-transfer-derived female Japanese Black (JB) heifers (mean: 8.7 age in months) were collected and plasma AMH concentration was measured. At 13–15 months of age, both the number of follicles (2–9 mm) and the number of collected oocytes after OPU were counted and compared. Results indicated that the heifers with the highest AMH concentration had the highest number of follicles in their ovaries and gave the highest number of collected oocytes with OPU, thereby indicating that a single measurement of plasma AMH concentration is informative for the selection of OPU-donor heifers in herd breeding programs. The practice of performing a single AMH measurement may accelerate the intensive breeding of JB herds.

The objective of this study was to evaluate the metabolic profile of cattle fed with or without zearalenone (ZEN) and sterigmatocystin (STC)-contaminated diets using a gas chromatography-mass spectrometry metabolomics approach. Urinary samples were collected from individual animals (n = 6 per herd) from fattening female Japanese Black (JB) cattle herds (23 months old, 550–600 kg). Herd 1 had persistently high urinary ZEN and STC concentrations due to the presence of contaminated rice straw. Herd 2, the second female JB fattening herd (23 months old, 550–600 kg), received the same dietary feed as Herd 1, with non-contaminated rice straw. Urine samples were collected from Herd 1, two weeks after the contaminated rice straw was replaced with uncontaminated rice straw (Herd 1N). Identified metabolites were subjected to principal component analysis (PCA) and ANOVA. The PCA revealed that the effects on cattle metabolites depended on ZEN and STC concentrations. The contamination of cattle feed with multiple mycotoxins may alter systemic metabolic processes, including metabolites associated with ATP generation, amino acids, glycine-conjugates, organic acids, and purine bases. The results obtained from Herd 1N indicate that a two-week remedy period was not sufficient to improve the levels of urinary metabolites, suggesting that chronic contamination with mycotoxins may have long-term harmful effects on the systemic metabolism of cattle.

The relationships between changes in anti-Müllerian hormone (AMH) concentration and various traits, including milk somatic cell counts (SCC), were evaluated. Blood samples were collected from 43 Holstein cows 14 days before (D-14) and 10 (D10) and 28 days after (D28) parturition, and vaginal discharge score (VDS) and polymorphonuclear leukocyte (PMNL) percentages were assessed in endometrial samples at D28. Cows were separated into four quartiles (Q1–Q4) based on changes in AMH concentration during the peripartum period (AMH ratio: D28/D-14). Correlations between AMH ratio and each parameter were evaluated and classified into high-AMH (Q4, 1.83 ± 0.12, n = 11) and low-AMH (Q1, 0.83 ± 0.05, n = 11) groups. The AMH ratio was positively correlated with magnesium and non-esterified fatty acids levels, and the albumin/globulin ratio at D10 and D28, but negatively correlated with serum amyloid A (SAA) at D10. SAA and γ-globulin levels were significantly higher in the low-AMH group at D28. There was no significant difference in VDS, PMNL percentage, and milk SCC between the two groups. The decreasing AMH ratio from the prepartum to the postpartum period corresponds to high inflammation biomarker levels. Whether it subsequently affects the reproductive prognosis of postpartum cows needs further investigations.