National Academy of Agricultural Sciences (NAAS)
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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcmas@gmail.com / submit@ijcmas.com Editor-in-chief: Dr.M.Prakash Index Copernicus ICV 2018: 95.39 NAAS RATING 2020: 5.38 |
Improvement of conception following GnRH treatment during oestrus has been attributed to the prevention of ovulation failure or to reduced variation in the interval to ovulation. The objective of the present study was to assess the efficacy of GnRH administration subsequent to earliest recognition of dominance of preovulatory follicle in repeat breeder (RB) crossbred (CB) cows with prolonged oestrus. All the selected animals (n=20) were observed for oestrous signs twice a day in the morning and evening. Cows in Group I (n=10) were treated with 20 microgram of GnRH analogue (Buserelin acetate) intramuscularly, when the diameter of preovulatory follicle reached the persistent dominant follicular (DF) size. All the animals were inseminated with frozen-thawed semen 8 h after administration of GnRH. In group I animals, ovulation occurred within 30 h of GnRH administration.Cows in Group II (n=10) were inseminated with frozen-thawed semen, when the diameter of preovulatory follicle reached the persistent DF size. Further re-inseminations were carried out at 24 h interval till ovulation was confirmed by trans-rectal ultrasonography (TRUS). The average number of inseminations in group II animals were 2.60.Pregnancy diagnosis was performed by TRUS on day 28and confirmation was done on day 60 post AI in both the groups. The conception rates in GnRH treated animals were 60 and 20 per cent respectively in group I and II. The present study concluded that administration of GnRH at the time of persistence of preovulatory follicle at its dominant size improves the conception rate in RB cows with prolonged oestrus.
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