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Estimation of genetic parameters for reproductive traits in Korean dairy cattle |
Jae-Gu Lee1,a 
, Jeongwoo Seo2,3,a
, Mahboob Alam1
, Hyungjun Song4
, Seokhyun Lee4
, Joohyeon Cho4
, Chang-Gwon Dang1,*
, Joonho Lee2,*
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1Animal Breeding and Genetics Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea
2GeneApps Co., Ltd., Seoul 06105, Korea
3Current affiliation: Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
4Dairy Cattle Improvement Center of NHAgri Business Group, National Agricultural Cooperative Federation, Goyang 10292, Korea |
Correspondence:
Chang-Gwon Dang, Tel: +82-41-580-3372, Fax: +82-41-580-3369, Email: gkgkgki@korea.kr
Joonho Lee, Tel: +82-02-556-2895, Fax: +82-02-542-7736, Email: joonho@gene-apps.com
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Received: 1 July 2024 • Revised: 25 July 2024 • Accepted: 6 September 2024
aThese authors contributed equally to this work. |
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| Abstract |
Objective
In Korea, dairy cattle breeding programs have historically prioritized productive, conformation traits, leading to positive improvements, yet reproductive traits have lagged in development. This study was conducted to develop the breeding program of key reproductive traits in the Korean dairy cattle population.
Methods
Utilizing data from 7,596 farms and over seven million observations, we conducted quality control to rectify manual entry errors and selected traits in line with international genetic evaluation standards. Traits analyzed included heifer conception rate (HCR), interval from calving to first insemination (CF), cow conception rate (CCR), interval from first to last insemination (FL), and days open (DO). Genetic parameters were estimated using a single trait animal model for HCR and a multiple lactation animal model for CF, CCR, FL, and DO, considering contemporary group of herd-insemination year, insemination month, and monthly age as fixed effects.
Results
Results showed low heritability estimates, ranging from 0.007 to 0.035 across different traits and lactations. Theoretical reliability appears to be low on average due to the influence of heritability, but it showed sufficiently high reliability in some sires (over 0.8). In terms of genetic and phenotypic trends, capacity for reproductive traits declined for a long time until around 2014. In recent individuals, improved trend can be found.
Conclusion
This study addressed the critical need for enhancing reproductive efficiency to complement the existing breeding goals, thereby supporting sustained economic viability in the dairy industry. The results underscore the need for improved data quality and methodological adjustments for reproduction records to enhance the genetic evaluation of dairy cattle in Korea. |
| Keywords:
Genetic Correlation; Heritability; Korean Holstein Cattle; Multiple Lactation Animal Model; Reproductive Traits |
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