d before initiating treatments. Cows were blocked by lactation number and assigned randomly to 3 treatments consisting of variations of the Ovsynch protocol. Cows in Cosynch-48 and Ovsynch received injections of GnRH 7 d before and 48 h after a PGF injection. Fixed-time inseminations (TAI) were made at the time of the second GnRH injection (0 h; Cosynch-48) or 24 h (Ovsynch). Those in Cosynch-7...

This study was designed to evaluate the reproductive performance of Japanese black cows following the 3rd injection of gonadotropin releasing hormone (GnRH) analogue administered concurrently with Ovsynch-based treatment on day 6 (day 1 = the day of ovulation). In Experiment 1, 12 cows were allocated into three groups: a control group that was subjected to Ovsynch treatment and then injected wi...

Previous research indicates that high blood urea nitrogen (BUN) concentrations are associated with decreased fertility in lactating dairy cows.This experiment was done to evaluate the effects of equine chorionic gonadotropin (eCG) administration (with or without eCG) on fertility of lactating dairy cows with different levels of BUN subjected to fixed-time artificial insemination (FTAI).Ovulatio...

Introduction Reproductive physiologists had long searched to develop a synchronization program that could overcome the problems and limitations associated with visual estrus detection. Such a program was developed at the University of Wisconsin-Madison in 1995 (Pursley et al., 1995) and is now commonly referred to as Ovsynch. Ovsynch synchronizes follicular development, luteal regression and ov...

Background and Objective: Ineffective estrus detection is the foremost limiting factor in the fertility of farmed cattle worldwide. Therefore, this study investigates the effect of three synchronization protocols with Fixed Time Artificial Insemination (FTAI) on the pregnancy rate of crossbred dairy cows. Methodology: Ninety one cows were assigned to four groups where the Body Condition Score (...

The objective of the present study was to compare the impact of ovsynch and progesterone-based ovulation synchronization protocol on ovarian response and conception in buffalo (n=19) exhibiting subestrus during low-breeding season (maximum ambient temperatures and relative humidity ranging from 36-45°C and 30-80%, respectively). Group I buffalo (n=10) were administered ovsynch protocol (d 0 and...

The objective was to compare pregnancy rates and pregnancy losses in lactating dairy cows that were diagnosed not pregnant and re-inseminated following either the Ovsynch or Heatsynch protocols. Also evaluated were the effects of stages of the estrous cycle, ovarian cysts and anestrus on pregnancy rates for both treatments. Non-pregnant cows (n = 332) as determined by ultrasonography on day 27 ...

The objective of this study was to compare the effectiveness of the Ovsynch and controlled internal drug releasing (CIDR) protocols under commercial conditions for the treatment of cystic ovarian disease in dairy cattle. A total of 401 lactating dairy cows with ovarian cysts were alternatively allocated to two treatment groups on the day of diagnosis. Cows in the Ovsynch group were treated with...

Background: Ovsynch is one of the most adopted estrus synchronization protocols used for ovulation and fixed-time artificial insemination however, new corpus luteum (CL) induced by first GnRH treatment in inappropriately regressed with a single prostaglandin F2α. Inadequate CL regression reduces fertility. Considering this rationale, present research was implemented effect second F2 alpha durin...

Dairy cow infertility negatively affects profit of dairy production enterprises around the world, and enhancing conception rates of dairy cows is a critical management issue to resolve. It appears that conception rates of dairy cows are attenuated due to reduced progesterone concentrations in circulation during growth of the ovulatory follicle. It is not clear how reduced progesterone influence...