The successful development of a PRID regime for oestrous synchronization in New Zealand beef cattle

J.F. Smith, H.R. Tervit

Ruakura Animal Research Station, Hamilton

Proceedings of the New Zealand Society of Animal Production. 1980, 40: 272-279

A series of trials to study factors affecting the efficacy of the PRID treatment is described. The PRID is more readily retained in the vagina than are intravaginal sponges. The conception rate to insemination (AI) 56 h after PRID removal was affected by the time of onset of oestrus, with the highest rates achieved in cows exhibiting oestrus between PRID removal and AI. Short-term treatment (10 days) resulted in more cows showing oestrus between PRID removal and AI and higher conception rates to a fixed-time AI than did longer treatments (14 or 20 days).

Oestrogen pre-treatment at PRID insertion increased the proportion of animals showing oestrus by AI compared with non-treated animals, and increased the conception rate to the timed AI. Oestradiol valerate (5 mg) administered intramuscularly at PRID insertion was superior to oestradiol benzoate (10 mg) administered intravaginally through a gelatin capsule. Temporary removal of calves from cows for the 56 h between PRID removal and AI(Shang treatment) increased both the incidence of cows showing oestrus by AI and the conception rate to the time AI. The efficiency of the PRID treatment was also affected by the interval from calving to PRID insertion, with poor conception rates obtained in animals treated prior to 40 days post partum.

The use of a 10 day PRID treatment augmented with oestrogen at the time of insertion and accompanied by temporary calf removal for the 56 h period between removal and AI is a very satisfactory technique for the synchronization of oestrus in suckling beef cows in New Zealand. Provided the treated animals are at least 40 days post partum and in good condition, approximately, 60% of them can be expected to conceive to a single timed AI after this regime.

Keywords: NZSAPAB;

Last Updated 12-09-1998