@article{oai:miyazaki-u.repo.nii.ac.jp:00003372,
 author = {邉見, 広一郎 and Henmi, Koichiro and Kobayashi, Ikuo and 小林, 郁雄 and 加治佐, 誠 and Kajisa, Makoto and 北原, 豪 and Kitahara, Go and 福山, 喜一 and 上村, 俊一 and Kamimura, Shunichi and 邉見, 広一郎 and Henmi, Koichiro and 加治佐, 誠 and Kajisa, Makoto and Fukuyama, Kiichi and 上村, 俊一 and Kamimura, Shunichi},
 journal = {宮崎大学農学部研究報告, Bulletin of the Faculty of Agriculture University of Miyazaki},
 month = {Feb},
 note = {Effect of time lapse from the onset of estrus detected by data transmissible pedometer (Gyuho, Comtec, Miyazaki, Japan) until artificial insemination (AI) and estrous synchronization on calf sex ratio was investigated in Japanese Black Cows. A total of 80 Japanese Black Cows were installed with pedometers, which store the number of steps per hour and transmit the date for 24 hours. The onset of estrus was defined when the number of each hour steps in cows exceeded more than double of the maximum steps in recent 15 days. Cows were randomly assigned to either timed AI program with estrus synchronization using progesterone-releasing intravaginal device (PRID®) (n = 33) or AI using AM/PM rule (n = 47). Cows were subdivided into three groups retrospectively based on the time lapse from the onset of estrous until AI ; 0-8h (n = 8), 9-16h (n = 43), 17-24h (n = 29).
Estimating the onset of estrus using pedometers revealed that only a small number of cows showed estrus during daytime hours (08:00～18:00), whereas many cows commenced estrus at night-time (18:00～08:00) (daytime 23.7 % vs. night-time 76.3 % : P<0.01). There was no significant difference between groups in conception rate (timed AI 45.5 % vs. estrus AI 63.8 % : P=0.10), which showed estrus synchronization using PRID® could be useful to improve reproductive performance in Japanese Black Cows. Male calf ratio was lower in early AI group (0 % in 0-8 h, 75.0 % in 9-16h and 46.7 % in 17-24h), which indicated calf sex ratio might be affected by the time lapse from the onset of estrus until AI. However, there was no such tendency in the synchronized timed AI cows., 1時間毎の歩数量を受信機に自動送信できる歩数計を黒毛和種牛に装着することにより, 発情の開始時刻を特定し,発情開始後人工授精(AI)までの経過時間が子牛の性比に及ぼす影響を検討した. 今回,歩数計(牛歩®,コムテック,宮崎)に記録された1時間毎の歩数量が,過去15日間の最大歩数の2倍以上に増加した時点を発情開始時刻とし,発情開始後AIまでの経過時間により牛群を0～8時間群(短い群,n=8), 9～16時間群(中間群,n=43), 17～24時間群(長い群,n=29)の3つに分けた. AIの実施では,プロジェステロン徐放剤(PRID®)による発情同期化後,定時AIを行う群(定時AI群,n=33)と,発情発見の12時間後にAM-PM法でAIを行う群(発情時AI群,n=47)に分けた.
その結果,牛が発情を開始する時間は昼間より夜間が多かった (08:00～18:00 : 23.7%, 18:00～08:00 : 76.3%, P<0.01). 発情同期化処置の有無によるAIでは受胎率に差はなく(定時AI群:45.5%, 発情時AI群:63.8%, P=0.10), PRID®の使用は分娩後早期のAIを可能とし,繁殖管理に有効であった. 発情時AI群では,発情開始後AIまでの経過時間が短い群で雄子牛の比率が低く(0～8時間 : 0%, 9～16時間 : 75.0%, 17～24時間 : 46.7%), 発情開始後AIまでの経過時間と出生子牛の性比との関連が示唆された. 一方,発情同期化処置を行った定時AI群では,その傾向はみられなかった.},
 pages = {93--99},
 title = {歩数計測による発情開始から人工授精までの時間と発情同期化が黒毛和種子牛の性比に及ぼす影響},
 volume = {57},
 year = {2011},
 yomi = {ヘンミ, コウイチロウ and コバヤシ, イクオ and カジサ, マコト and キタハラ, ゴウ and フクヤマ, キイチ and カミムラ, シュンイチ and ヘンミ, コウイチロウ and カジサ, マコト and カミムラ, シュンイチ}
}