Hiromi Kusaka

Summary: We investigated the association between follicular development at 10 days postpartum and the presence of early ovulation until 26 days postpartum. Furthermore, the factors affecting the emergence of ≥15 mm follicles at 10 days postpartum were assessed. Cows with no follicles ≥10 mm in diameter exhibit a lower frequency of early ovulation. In contrast, early ovulation was more frequently observed in cows with at least one ≥15 mm follicle. Cows with high uterine abnormalities had a significantly lower frequency of ≥15 mm follicles than those with low and medium uterine abnormalities. The cows that calved in summer had a higher frequency of ≥15.0 mm follicle emergence than those that calved in winter and spring. The body weight loss and the parity of dams were significantly associated with the frequency of ≥15.0 mm follicle emergence. Although various factors affect the emergence of ≥15 follicles, an abnormal uterine status may have a more direct and negative impact on postpartum follicular development than other factors.

Background: Male pseudohermaphroditism is a developmental anomaly wherein animals are genetically and gonadally male, but their internal and/or external genitalia resemble those of females. In cattle, pseudohermaphroditism is often accompanied by multiple severe malformations. To the best of our knowledge, this is the first report of male pseudohermaphroditism in a complex malformed calf born with an acardius amorphous cotwin. Case presentation: This report describes the case of a three-day-old, male anurous Japanese Black calf born with an acardius amorphous cotwin, complete absence of the tail, agenesis of the anus, separate scrota, and umbilical hernia. Transthoracic echocardiography and computed tomography revealed serious malformations in the skeletal system and the circulatory, digestive, urinary, and genital organs. Necropsy revealed rectal atresia, immature testes, epididymis, and penis, but no male accessory gonads. Histological analyses revealed vaginal- and uterine-like tissues adjacent to or fused to the rectum. Fluorescence in situ hybridization detected X and Y chromosomes, and some cells presented two X-probe signals in the same nucleus. Conclusions: In contrast to the male genitalia, the female genitalia derived from the Müllerian ducts were difficult to detect by necropsy in the presented case. Many similar cases may be overlooked in clinical practice.

産褥期の牛における子宮の炎症反応は生理的な機構であるものの，正常な子宮修復過程の破綻によって炎症は病的なものへと変化する．乳牛において分娩後の子宮内膜炎は一般的な疾患である．子宮内膜炎はひとつの病原細菌によって引き起こされる疾病ではなく，複数の細菌の相乗効果によって病態は深刻化する．乳牛における子宮内膜炎のリスクファクターとしては，胎盤停滞，難産，低カルシウム血症，ケトーシスなどが重要である．さらに，泌乳ストレスによるエネルギーバランスの悪化が分娩後の免疫機能の低下に寄与する．分娩後のおおよそ15～20%の乳牛が子宮内膜炎に罹患していると考えられているが，子宮内膜炎の有病率は報告によって大きく異なり，国外では5～68%と大きな幅がある．このように有病率が報告間で大きく変動する原因として，子宮内膜炎の診断基準・診断ツール・検査の実施時期の違いが指摘されている．本稿では，乳牛の子宮内膜炎の診断と治療に関して概説する．

Background: Reducing the age at first calving (AFC) in dairy heifers may decrease replacement costs, while the acceleration of body growth could affect milk productivity. A lower bodyweight (BW) at first calving may increase calving problems and compromise the subsequent reproductive performance. Materials and methods: This retrospective study aimed to investigate the effect of AFC and BW prior to calving on milk productivity, the incidence of calving problems (difficult calving and stillbirth) and reproductive performance during the first lactation. Multivariate analysis was conducted using a total of 203 calving records from 1999 to 2012 for one herd of Holstein heifers. The AFC was categorised as young, moderate, old and very old (<22.5, 22.5 to <24.0, 24.0 to <25.5, ≥25.5 months) and the heifer BW before first calving was grouped into low, moderate, high and very high (≤625, 626–654, 655–683, ≥684 kg), respectively. Results: The incidence of difficult calving and the prevalence of stillbirth were significantly higher in the animals with low BW compared with the heifers with moderate and high BW. Even so, there was no adverse impact on reproductive performance. There was a significant association between the lifetime daily milk yield and AFC; the highest mean value for yield was recorded for the heifers in the young AFC group, which was significantly different from heifers in the moderate and old age groups. Conclusions: In this experimental herd, a reduction in AFC could increase the profitability during the first lactation.

Background: : Postpartum endometritis can cause subfertility in cows and reduce the reproductive performance of dairy herds. Thus, there is a critical need to improve the accuracy of the diagnosis of this disease, particularly in dairy cows.Objectives: : This study confirmed the effects of the combined use of two non‐laboratory methods: Metricheck device (MT) and ultrasonography (UT) to detect signs of endometritis and therefore predict the likelihood of pregnancy.Methods: : The reproductive tract of 67 lactating Holstein cows (25 primiparous and 42 multiparous) was observed at 4 and 6 weeks postpartum using the MT and UT. The cows with flecks and more purulent material in the vaginal discharge were defined as MT‐positive, and the cows with uterine echogenic contents were defined as UT‐positive. The combined definition was also used; both the UT and MT results or either the UT or MT result had to be positive for the final decision to be positive. The true‐negative cows were determined as both MT‐UT‐negative.Results and discussion: When comparing the diagnostic results obtained by MT and UT, 37.3% and 32.8% of the total cows showed conflicting results at 4 and 6 weeks postpartum. The proportion of non‐pregnant cows until 200 days postpartum was significantly greater in both MT‐UT‐positive cows than in the true negative cows. The hazard ratios of pregnancy rate were 0.37 for both MT‐UT‐positives relative to the true negatives at 4 weeks postpartum. Similar significant differences were not detected using the MT or UT alone. These results indicate that a more severe effect on the chance of pregnancy could be detected in cows that are both MT‐UT‐positive compared with those positive for MT or UT alone.Conclusions: : The combined use of MT and UT could support veterinary practitioners in diagnosing endometritis, potentially improving the accuracy of predicting subsequent reproductive performance.

Background Uterine health status is a key factor for dairy management. Methods The uteri of 28 Holstein cows were assessed weekly by three different methods: ultrasonography (UT), Metricheck device (MT) and cytobrush (CYT), during two weeks to seven weeks postpartum. Results The percentage of cows with an MT-positive, UT-positive and CYT-positive result decreased dramatically at three weeks, four weeks and five weeks postpartum, respectively. The agreement of the results was poor or weak within six weeks postpartum (κ=0.09–0.35), and only at seven weeks moderate or good agreement was achieved (κ=0.60–0.70). When comparing the results obtained by UT and MT, 30 per cent or more of the total cows had conflicting results from postpartum three weeks to six weeks. The uterine health of cows was re-evaluated by the combined usage of UT and MT referring to CYT. The highest sensitivity was achieved when positive individuals were identified as either MT-positive or UT-positive, whereas the highest specificity occurred when results were positive by both MT- and UT- methods. Conclusion The accuracy of early postpartum uterine health status by three methods depended heavily on the time postpartum. The combined use of UT and MT is a practical candidate for cow-side monitoring method of uterine health.

After parturition, the ovary ipsilateral to the side of previous pregnancy exhibits lower functional activity than that exhibited by the contralateral ovary. The local inhibitory effects of the corpus luteum of the previous pregnancy, and/or the presence of a previous gravid uterine horn, may induce the ipsilateral suppression of folliculogenesis. We examined the influence of the side of previous pregnancy on ovulation and folliculogenesis, until completion of the third postpartum ovulation. The ovaries of 30 Holstein cows were scanned by ultrasonography, through the three postpartum ovulation sequences. No significant differences in the development of growing follicles, 5-8 mm in diameter, were detected between ipsilateral and contralateral ovaries. However, the total number of dominant follicles emerging ipsilaterally before the second postpartum ovulation were less than those emerging contralaterally (25 vs. 75%), and both the first and second ovulation occurred less frequently on the ipsilateral versus contralateral side (23 vs. 77% and 27 vs. 73%, respectively). Sequential observation in this study clearly indicated that the influence of the side of previous pregnancy persisted until the second postpartum ovulation, and this affected postpartum dominant follicle selection and ovulation, but not the development of growing follicles.