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Effect of oestrous resynchronization on the reproductive efficiency of zebu cows
Author(s) -
Faleiro Nilson Shonholzer,
Neves Kedson Alessandri Lobo,
Pereira Luciano Leite,
Silva Cleidson Manoel Gomes da,
Vale William Gomes,
Minervino Antonio Humberto Hamad
Publication year - 2019
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/rda.13468
Subject(s) - estrous cycle , zebu , ovulation , artificial insemination , pregnancy , pregnancy rate , estradiol benzoate , medicine , zoology , estrus synchronization , andrology , biology , hormone , genetics , ovariectomized rat
Abstract The aim of this study was to develop a resynchronization strategy before the return of oestrus in cows diagnosed as not pregnant after fixed‐time artificial insemination (TAI). A total of 839 cows, approximately 45 days post‐partum, were synchronized using TAI. On day 0, intravaginal progesterone‐releasing devices were inserted and 2 mg of oestradiol benzoate was administered. Eight days later (D8), the progesterone‐releasing devices were removed and oestradiol cypionate (0.5 mg, eCG [300 IU]) and prostaglandin (7.5 mg) were administered. All cows were inseminated between 48 and 56 hr after device removal (D10). Thirty days after TAI, cows that were not diagnosed as pregnant by ultrasound were immediately resynchronized and again inseminated at a fixed time. The hormonal protocol used in the first and second rounds of TAI was the same. The pregnancy rate after the first TAI was 52%, and after the second TAI, it was 49%. The increase in the total pregnancy rate (synchronization + second oestrous synchronization) compared to a single synchronization was 23.5%. In conclusion, resynchronization of oestrus and ovulation in zebu cows that had previously undergone TAI protocols is effective in increasing the reproductive efficiency.