Wei Sun1,2,3, Yunxia Li1,2,3, Jie Su3,4, Xiangnan Bao3, Rui Ding3, Gaoping Zhao3, Guifang Cao3,4, Shuxiang Hu3, Jianguo Wang1,2, Qingyuan Sun5, Haiquan Yu1,2, Xihe Li1,2,3. 1. College of Life Science, Inner Mongolia University, Hohhot 010070, P.R. China. 2. The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, Inner Mongolia University, Hohhot 010070, P.R. China. 3. Inner Mongolia Saikexing Institute of Breeding and Reproductive Biotechnology in Domestic Animal, Hohhot 011517, P.R. China. 4. College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, P.R. China. 5. Institute of Zoology Chinese Academy of Science, Beijing 100101, P.R. China.
Abstract
Objective: Owing to the lack of breeding index for efficient and quick fertility evaluations of Holstein bulls when using traditional or genome-wide detection methods, this study aimed to determine whether in vitro fertilization (IVF) could be used as an indicator of conception rate of artificial insemination (AI). Methods: Conventional and sexed frozen semen from nine bulls were used for IVF and AI. Results: The IVF and AI conception rates of each bull were confirmed to be positively correlated between the conventional frozen and sexed frozen semen. The correlation coefficient R values of nine bulls between IVF and AI methods were 0.73 and 0.97 for the conventional frozen and sexed frozen semen, respectively. The average conception rate of three bulls undergoing AI was 69.5% and 64.2%, 61.8% and 58.8%, and 48.2% and 46.2% in first-, second-, and third-born cows when conventional frozen and sexed frozen semen were used, respectively, which showed a positive correlation with the fertilization rate in the same parity. We propose an evaluation standard to assess the fertilization ability of bulls based on their IVF test results, which is categorized into three grades: grade one, normal fertility bull with an AI conception rate of 40% ± 5% and IVF rate of 45%-60%; grade two, higher fertility bull with an AI conception rate of 50% ± 5% and IVF rate of 61%-80%; and grade three, highest fertility bull with an AI conception rate of 60% ± 5% and IVF rate of >80%. Conclusion: These findings reveal that IVF results can be used as a breeding index for bulls to evaluate their AI conception ability, which may shorten the time required to select bulls for breeding.
Objective: Owing to the lack of breeding index for efficient and quick fertility evaluations of Holstein bulls when using traditional or genome-wide detection methods, this study aimed to determine whether in vitro fertilization (IVF) could be used as an indicator of conception rate of artificial insemination (AI). Methods: Conventional and sexed frozen semen from nine bulls were used for IVF and AI. Results: The IVF and AI conception rates of each bull were confirmed to be positively correlated between the conventional frozen and sexed frozen semen. The correlation coefficient R values of nine bulls between IVF and AI methods were 0.73 and 0.97 for the conventional frozen and sexed frozen semen, respectively. The average conception rate of three bulls undergoing AI was 69.5% and 64.2%, 61.8% and 58.8%, and 48.2% and 46.2% in first-, second-, and third-born cows when conventional frozen and sexed frozen semen were used, respectively, which showed a positive correlation with the fertilization rate in the same parity. We propose an evaluation standard to assess the fertilization ability of bulls based on their IVF test results, which is categorized into three grades: grade one, normal fertility bull with an AI conception rate of 40% ± 5% and IVF rate of 45%-60%; grade two, higher fertility bull with an AI conception rate of 50% ± 5% and IVF rate of 61%-80%; and grade three, highest fertility bull with an AI conception rate of 60% ± 5% and IVF rate of >80%. Conclusion: These findings reveal that IVF results can be used as a breeding index for bulls to evaluate their AI conception ability, which may shorten the time required to select bulls for breeding.