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Abstract
Estrous synchronization and AI are tools that enhance reproductive management in cattle and allow more cows to become pregnant early in the breeding season, which is essential to maintain 365 days calving interval. This also allows more time for cows to resume estrous cyclicity before the beginning of the subsequent breeding season. Moreover, estrous synchronization improves uniformity of a calf crop (Dziuk and Bellows, 1983).
Recently, effective estrous synchronization protocols are developed in order to increase the use of AI, in addition estrous synchronization protocols should be designed to reduce time and labor inputs by limiting cattle handlings and reducing or eliminating estrus detection (Larson, Lamb, Stevenson, Johnson, Day, Geary, Kesler, DeJarnette, Schrick, DiCostanzo and Arseneau, 2006).
The application of Al is difficult in buffaloes undergoing spontaneous estrus and ovulation due to the relatively low expression of estrous behavior, variable duration of estrus from 4 to 64 h, and difficulty in predicting the time of ovulation (Seren, Panneggiani and Campanile, 1995; Ohashi, 1994). Moreover; Barkawi, Bedeir and EI Wardani 1993; De Rensis and Lopez- Gatius (2007) found that, one reason for variable responses between bovine and buffalo to estrous synchronization protocols could be that buffalo cows have a higher degree of variability in the interval from the pre ovulatory LH surge to ovulation than bovine cows in both naturally and hormonally induced ovulations. For that reason, various protocols to synchronize estrus and ovulation have been evaluated in buffaloes in an attempt to overcome the difficulty of applying Al in spontaneously ovulating animals. Another factor must be take in consideration the commonly occurrence of non-cyclic condition in buffaloes, therefore protocols used to synchronize estrus and ovulation in buffaloes should be effective in both cyclic and non-cyclic animals and should result in high pregnancy rates to fixed-time AI (Baruselli, 2001)
A timed insemination protocol Ovsynch has been developed in dairy cows to specifically control the time of ovulation (Pursley, Mee and Wiltbank, 1995; Yaniz, Murugavel and Lopez-Gatius, 2004).Although, the Ovsynch protocol was found to be effective in buffaloes, particularly cyclic buffalo cows, for both double and single fixed-time AI (Neglia, Gasparrini, Palo, Rosa, Zicarelli and Campanile, 2003; Paul and Prakash, 2005)
Aim of study
The main purpose of this study was to evaluate the effect of different synchronization protocols such as PGF2α double injection, Ovsynch and progesterone supplementation in the course of Ovsynch protocol on some hematological parameters, serum hormonal concentration (P4 and estradiol) and pregnancy rate in both cows and buffaloes.