Minoru Sakaguchi

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.

The number of cows in estrus often influences estrus behavior; however, the effects of social order are not well documented. This study examined the effects of social order on the expression of behaviorally-scored and pedometer-detected estrus, combined with the effects of the number of cows in estrus. In a herd comprising 13 or 15 beef cattle, cows with orders 1st–7th were defined as dominant and the remaining cows as subordinate. Sole or simultaneous estrus was induced by prostaglandin F2α analog injection and/or intravaginal progesterone treatment. Ovulation timing was determined using ultrasonography at 6-hour intervals. Estrous signs and steps of the cows were recorded 49 h before ovulation using video monitoring and a pedometer, respectively. Among the 59 treated cows, 56 behaviorally-scored estruses (27 sole and 29 simultaneous) were detected. In the sole estrus, 61.5% of the dominant-rank cows had no zero-point period; however, 35.7% of the subordinate-rank cows had that period. The dominant-rank cows in estrus alone had a significantly shorter duration of scored estrus than those in simultaneous estrus (P < 0.05). Among the 50 pedometer-detected estruses (24 sole and 26 simultaneous), the subordinate-rank cows in sole estrus had a shorter interval from estrus onset to ovulation than the dominant-rank cows in simultaneous estrus (P < 0.05). The effects of social order varied in response to the number of cows in estrus, which might have influenced determining the optimal time for artificial insemination.

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.

Accelerating age at first calving (AFC) is a strategy for sustainable dairy farming, whereas the impact of a reduction in AFC on long-term performance remains unclear. In this study, longevity and milk productivity until the end of the third lactation period were investigated retrospectively according to AFC. A total of 169 cows were categorized according to AFC as young, moderate, old, and very old (< 22.5, 22.5 –< 24.0, 24.0 –< 25.5, and ≥ 25.5 months). The young AFC group had approximately 70 kg lower body weight before first calving (620 vs. 695 kg, P < 0.05) and experienced their first calving approximately 4.2 months earlier than the very old AFC group (21.9 vs. 26.1 months, P < 0.05). The survival rate at the third calving stage was 61% in the young AFC group, which was higher than those in the moderate (42%), old (35%), and very old (33%) AFC groups. In the young AFC group, no cows were culled because of low productivity and hoof disease, compared to 5.0–8.1% of older AFC cows. The young AFC group had a higher overall lifetime milk yield (cumulative milk yield/days from birth to the end of final lactation) than the old AFC group (14.3 vs. 8.7 kg/d, P = 0.11). The cows that survived the third calving had better reproductive performance than non-surviving cows; however, no statistical difference was detected among the AFC groups. In conclusion, AFC as early as 22.5 months could be associated with better survivability and higher overall lifetime milk yield than older AFC without impairing reproductive performance. Our results suggest that accelerating AFC may lead to higher profitability.

It has been suggested that domestication has turned cattle from seasonal breeders to annual breeders. This study examined the seasonal differences in early postpartum ovulation and subsequent reproductive performance in 542 Holstein cows. Cows displaying corpora lutea in the ovary at 26 days postpartum were defined as early ovulators. Factors affecting the occurrence of early ovulation were analyzed, and subsequent reproductive traits were compared between cows with and without early ovulation. During the summer season, 70.5% of calving cows showed early ovulation, whereas 48.7, 39.2, and 47.2% presented this condition in autumn, winter, and spring, respectively (P < 0.01). Third parity cows showed early ovulation more often than their first parity counterparts (P < 0.05). Cows with a 2.50 to 3.00 or > 3.00 body condition score (BCS) more frequently became early ovulators than those with BCSs < 2.50 (P < 0.001). Calving year was a risk factor, and uterine abnormalities were also often risk factors for early ovulation. The survival analysis showed that seasonal differences in the occurrence of early ovulation did not completely affect the time to first service and pregnancy. Proportional hazard regression analysis revealed that calving year, parity, and early ovulation were risk factors for the time to first service and that calving year was a risk factor for the time to pregnancy. In conclusion, domesticated dairy cows maintain seasonality in postpartum ovarian activity but not in subsequent fertility.

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.