2019年になってしまいました。本年もマイペースに更新しますので、どうぞよろしくお願いします。2018年は学術面において達成できたことも多く、個人的には飛躍の年となった。今年もその勢いをどうにか止めないで行きたい。
さて、正月に執筆中の論文が一段落したので、久しぶりにJ. Dairy Sci.の論文読みを再開した。繁殖関連の論文しか読めていないが毎月4，5本は出るのですぐに溜まってしまう。
まずは、乳牛における自動活動量モニターによる発情発現が排卵のタイミング及び失敗に及ぼす影響を検討した論文(10.3168/jds.2018-15151)を読んでみた。
自動活動量モニターによって検出された発情発現が排卵のタイミング及び失敗に影響しているかを調べること。
The aim of this study was to determine if estrous expression, as measured by an automated activity monitor (AAM), affects timing and failure of ovulation of lactating Holstein dairy cows.
首につける活動量モニター（AAMC）と足につける活動量モニター（AAML）を分娩後10日から装着させた。293頭の850回分の発情発現を調査した。検知された牛はエコー装置で排卵までの時間を調べた（2回/日、最大3日間）。活動量モニターにおける「ピーク活動量」または発情の「時間」と、排卵や受胎率の関係を解析した。
Cows were equipped with 2 AAM, 1 neck-mounted (AAMC) and 1 leg-mounted (AAML), by 10 d postpartum and enrolled into the trial when their activity crossed the alert threshold on the AAMC. A total of 850 episodes of estrus from 293 different cows were used for this study. When cows were enrolled, their ovaries were scanned by transrectal ultrasonography and gait and body condition scored. Ovaries of cows detected in estrus were scanned twice daily for a maximum of 3 d to determine the disappearance of the preovulatory follicle (ovulation) and the interval from estrus to ovulation was calculated. Physical activity data recorded from the AAM were used to determine estrus behavior using 2 traits: (1) peak activity and (2) duration. Peak activity was only available for the AAML. Peak activity was defined as the maximum activity during an estrus episode. Duration of estrus was defined as the time the activity of the cow exceeded threshold values set by the AAM software.
AAMCによる警報のうち、87.8%は発情だった。警報から排卵までの時間は平均で25.8 ± 10.2時間（AAMC）と 24.7 ± 9.3時間（AAML）だった。どちらのAAMでも、活動量が低いと排卵までの時間が短い傾向にあった。排卵の失敗率は活動量により差があった（AAMCでの高活動量で1.9% vs. 低活動量で9.5%。AAMLでの高活動量で2.3% vs. 低活動量で6.2%。AAMCでの長活動時間で2.1% vs. 短活動時間で8.9%。）。さらに、受胎率は活動量により差があった（AAMCでの高活動量で42.3% vs. 低活動量で31.7%。AAMLでの高活動量で43.1% vs. 低活動量で36.3%。）
The AAMC correctly identified 87.8% of the estrus alerts, with 12.2% false positives. The average (±standard deviation) intervals from activity alert to ovulation were 25.8 ± 10.2 and 24.7 ± 9.3 h for the AAMC and AAML, respectively. Changes in estrous expression were associated with differences in the interval from alert to ovulation. Cows with short intervals to ovulation were found to have less intense estrous expression than cows with medium and long length intervals to ovulation using the AAMC, whereas using the AAML, cows with short intervals to ovulation exhibited less intense estrous expression than cows with medium but the same as those with long intervals to ovulation. Furthermore, irrespective of the AAM, estrus events with less estrous expression had increased odds of having a short interval to ovulation (below the median of 20 h) when compared with those having greater estrous expression (2.6 and 1.9 increased odds for the AAMC and AAML, respectively). Ovulation failure was affected by estrous expression because estrus events with greater peak activity or longer duration had reduced ovulation failure compared with those with less estrous expression (AAMC peak activity: 1.9 ± 1.4 vs. 9.5 ± 1.7%; AAML peak activity: 2.3 ± 1.4 vs. 6.2 ± 1.5%; AAMC duration: 2.1 ± 1.4 vs. 8.9 ± 1.7%). In addition, cows with more estrous expression had greater pregnancy per artificial insemination than those with less estrous expression with both the AAMC (42.3 ± 0.4 vs. 31.7 ± 0.4%) and the AAML (43.1 ± 0.4 vs. 36.3 ± 0.4%). Pregnancy per artificial insemination results were consistent even when removing cows that failed to ovulate.
自動活動量モニターによって検出された発情発現は、排卵までの時間、排卵失敗率、受胎率に影響していた。高活動量の牛では、警報から排卵までの時間が長く、排卵失敗率が低く、そして受胎率が高い。
In conclusion, expression of estrus was highly associated with ovulation timing, ovulation failure, and fertility when using 2 different AAM. Cows with greater estrous expression have longer intervals from activity alert to ovulation, experience less ovulation failure, and have greater pregnancy per artificial insemination.
AAMC にはHeatime, H-Tags（SCR Engineers, Netanya, Israel）を、AAMLにはBoumatic Heat-seeker-TX（Boumatic Dairy Equipment Co., Madison, WI）を使用している。活動量をモニターしているので、歩数を数えている牛歩などのシステムとはどうやら違うみたい。中身は3Dセンサーなのかな？反芻時間まで分かるみたいだからすごいなぁ。
酪農も自動モニターの時代に突入しているのをひしひしと感じる。