タイトル無し

概要

論文の詳細を見る
Sexual behavior and reproductive efficiency of beef cattle were investigated in the free-ranging condition where a Japanese Black bull (5 years old) was introduced into a group of 15 heifers of same breed in a paddock of 10m×15m for about 2 days. The heifers were injected with PGF<SUB>2α</SUB> analogue (ICI, Estrumate) intramuscularly twice at 10 days interval to induce estrus. The observation was initiated 47 hours after the second injection of PGF<SUB>2α</SUB> analogue, when the first estrus appeared. Mounting and mount-receiving behaviors were observed in 15 and 14 heifers, respectively. The frequencies of those behaviors within heifers were av. 48 (7115) times per head for mounting and av. 51 (3113) for mount-receiving. The duration of estrus, estimated by the mount-receving behavior, was 19.2±9.0 hours. The bull mounted to 13 heifers 176 times and ejaculated to 10 heifers 21 times in order of the occurrence of estrus during the period of observation. However, the bull was puzzled for selecting a proper heifer to serve when the heifers were almost synchronized with estrus during the first half of the observation. Seven of ten heifers conceived as the result of the trial.
日本繁殖生物学会の論文