Department of Animal Physiology, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati-781 022, India.
*Part of the MVSc Thesis of the first author approved by AAU Khanapara Guwahati-22.
Fifteen healthy cyclic indigenous cows of Assam at first and/or second lactation were randomly divided into three groups viz. I, II and III, each comprising of five cows. Group I cows were kept as untreated control. The cows under group II and III were treated with “Iliren” (a PGF2 analogue) and “Crestar” (3 mg Norgestomet, 5 mg Estradiol valerate) respectively. All experimental animals of group II exhibited oestrus between 96 and 108 hrs with a mean of 99.00 ± 3.00 hrs following treatment while 4 cows under group III, responded to treatment. Mean interval between withdrawal of Crestar ear implant and exhibition of oestrus was 29.80 ± 0.91 hrs with a range from 24 to 48 hrs. The physical symptoms of oestrus were similar in hormonally treated and control animals. Duration of oestrus was found to be significantly higher (p<0.01) in “Iliren” treated (26.50 ± 1.89 hrs) and “Crestar” implanted cows (36.00 ± 3.89 hrs) than that of the control cows (18.20 ± 2.13 hrs).
Cows, Crestar, Iliren, Oestrus, Synchronization
