Document Type : Original Article
Authors
1
Theriogenology, faculty of veterinary medicine,menofia
2
Position Faculty of Veterinary Medicine University of Sadat City Menofia, Egypt
3
Department of Anatomy and Embryology Faculty of veterinary Medicine, Menoufia University
4
Department of Biochemistry and Chemistry of Nutrition, Faculty of veterinary Medicine, Menoufia University
5
Animal Reproduction Research Institute, Giza, Egypt.
Abstract
The study aimed to determine the optimal timed artificial insemination protocol for high-yield Holstein dairy cows, examining the correlation between parity number, season, and post-synchronization fertility. Four oestrous synchronization protocols were applied: Double Ovisynch, Cider synch, Resynch, and Ovisynch56. During the winter season, the conception rates for mixed parity cows were (50.66%, 39%, 36.33%, and 35%) for Double Ovisynch, Cider synch, Resynch, and Ovisynch56 protocols, respectively. In first lactation cows, the rates were (56%, 46%, 44%, and 37%), and in second lactation season cows, the rates were (46%, 36%, 35%, and 34%). With Double Ovisynch, there were significant differences (p 0.05). During the summer season, the conception rates in mixed parity cows were (36%, 30%, 28%, and 22%) for Double Ovisynch, Cidersynch, Resynch, and Ovisynch56 protocols, respectively. In first lactation cows, the rates were (40%, 37%, 35%, and 33%), and in second lactation cows, the rates were (36%, 26%, 33% and 33%). In conclusion, it was found that the Double Ovisynch protocol was associated with a higher conception rate compared to the other protocols, regardless of parity or season.
Keywords
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