Estrus and conception rate following estrous synchronization in heifers by using new PRIDs [progesterone releasing intravaginal devices and re-used PRIDs]
1985
Nareerat Viseshakul | Wantanee Srikosak | Pichit Pisansarakit (Chulalongkorn Univ., Bangkok (Thailand). Faculty of Veterinary Science)
Sixty seven from 2,500 of fifty percent Freisian-native crossbred heifers at "The Promotion of Calves Rearing Project", Chantuk, Nakhon Ratchasima were treated with new PRIDs, (Progesterone Releasing Intravaginal Devices) attached with 10 mg. oestradiol benzoate capsule. PRIDs were inserted for 12 days, then removed. The animals were divided into 2 groups, treated with PRIDs and PRIDS plus PMSG 500 i.u. intramuscular injection on the day of removal. Percentage of synchronized oestrus heifers of those two groups were 54.84 and 88.89 respectively. Removed PRIDs were inserted to another 38 heifers, 19.05 % became heat when treated with PRIdS alone and 29.14 % became heat when combined with PMSG. All animal received a fixed time insemination at 56h after PRIDs removal. The conception rates at the induced oestrus were 17.86 %, 37.15 %, 21.05 % and 6.25 % in heifers treated with new PRIDs, new PRIDs plus PMSG, reused PRIDs and reused PRIDs plus PMSG respectively.
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