Protocolo

Animal Reproduction Science 119 (2010) 17–23

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Animal Reproduction Science
journal homepage: www.elsevier.com/locate/anireprosci

Efficacy of Ovsynch protocol in cyclic and acyclic Egyptian buffaloes in summer
Aly M. Karen a,∗ , Samy A. Darwish b
a b

Department of Theriogenology, Faculty of Veterinary Medicine, Kafr El-Sheikh University,El-Gaish Street, 13561 Kafr El-Sheikh, Egypt Mehallat Mousa Buffalo Research Station, Animal Production Research Institute, Egypt

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a b s t r a c t
The aim of the present study was to evaluate the efficacy of an Ovsynch protocol in the cyclic and non-cyclic Egyptian buffaloes in the summer. The present study was carried out on 21 Egyptian pluriparous buffalo cows (11 cyclicand 10 acyclic) and 8 heifers (5 cyclic and 3 acyclic). All animals were administered 100 g GnRH i.m. at Day 0, 500 g of PGF2∝ i.m. at Day 7 and a second dose (100 g) of GnRH i.m. at Day 9. Ovarian structures of the animals were recorded by means of transrectal ultrasonography (6–8 MHz linear-array transducer) daily from Day 0 (before treatment) to Day 9 (the second GnRH administration) andthereafter, at 12-h interval till ovulation or for a maximum of 48 h. After ultrasound examination, a blood sample was taken daily from each animal for progesterone analysis. The buffalo cows were inseminated at 16–20 h after 2nd GnRH administration. After the first administration of GnRH, 46% (5 of 11) of cyclic and 50% (5 of 10) of acyclic cows and 40% (2 of 5) of cyclic and 33% (1 of 3) of acyclicheifers responded by ovulation or luteinization of the follicles. The mean diameters (±S.E.M.) of the follicles in the responding cows and heifers were significantly higher than those in non-responding animals (9.7 ± 0.4 mm vs. 6.7 ± 0.6 mm, P < 0.0001; 11.1 ± 1.5 mm vs. 7.3 ± 0.7 mm, P < 0.05, respectively). After the second administration of GnRH, 81% (9 of 11) of cyclic and 60% (6 of 10) of acycliccows and 80% (4 of 5) of cyclic and 33% (1 of 3) of acyclic heifers ovulated, respectively. Ovulations occurred earlier (P = 0.059) and over a wider range of time in the non-cyclic cows (26 ± 4.8 h; range: 12–36 h) and in a heifer (12 h,) than in the cyclic cows (34.7 ± 1.3 h; range 24–36 h) and heifers (33 ± 3 h; range: 24–36 h). The conception rate was 18% (2 of 11) and 0% (0 of 10) in cyclicand non-cyclic cows, respectively. In conclusion, the Ovsynch protocol could be used effectively for synchronization of ovulation in cyclic cows and heifers in summer. © 2009 Elsevier B.V. All rights reserved.

Article history: Received 29 April 2009 Received in revised form 30 November 2009 Accepted 7 December 2009 Available online 16 December 2009 Keywords: Buffaloes Ultrasound ProgesteroneOvsynch protocol Summer

1. Introduction Genetic improvement of Egyptian buffaloes for increasing milk yield can be achieved by application of artificial insemination (A.I.). Successful results of A.I. depend on accurate detection of estrus. However, buffalo cows rarely show mounting behavior (Baruselli et al., 2003) and experience poor estrus expression and variable duration of

∗ Correspondingauthor. Tel.: +20 473231311; fax: +20 473231311. E-mail address: alykaren@hotmail.com (A.M. Karen). 0378-4320/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2009.12.005

estrus (6–64 h) (Ohashi, 1994) making the prediction of time of ovulation difficult. Therefore, the application of A.I. in buffaloes has not been widely used (De Rensis and López Gatius,2007). Fixed-time A.I. could be the solution to overcome the difficulty of estrus detection in buffaloes. Fixed-time A.I. after administration of PGF2 cannot be applied in buffaloes (De Rensis and López Gatius, 2007). Interval to the ovulation is variable (60–156 h) depending on the size and the status (growing or regressing) of the dominant follicle at the time of PGF2 administration (Brito et...