Short communication: Genetic parameters of production traits in Chinese Holsteins using a random regression test-day model

• Published in: Journal of dairy science Vol. 92; no. 9; pp. 4697 - 4706
• Main Authors: Miglior, F., Gong, W., Wang, Y., Kistemaker, G.J., Sewalem, A., Jamrozik, J.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.09.2009; American Dairy Science Association; Am Dairy Sci Assoc; Elsevier
• Subjects: Animal productions; Animals; Biological and medical sciences; Cattle - genetics; Cattle - physiology; Cell Count; China; Chinese Holstein; dairy cows; dairy herds; Environment; Fats - analysis; Female; Food industries; Fundamental and applied biological sciences. Psychology; genetic parameter; Genetic Variation; heritability; Holstein; Lactation - genetics; lactation number; Male; Milk - chemistry; Milk - cytology; Milk and cheese industries. Ice creams; milk composition; milk fat; milk proteins; Milk Proteins - analysis; milk yield; Models, Genetic; parity (reproduction); Pregnancy; protein content; random regression model; Regression Analysis; somatic cell count; Terrestrial animal productions; Time Factors; traits; Vertebrates; China; genetic parameter; Chinese Holstein; random regression model; Regression model; Dairy industry; Production; Genetic parameter; Day
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2009-2212

The objective of this study was to estimate genetic parameters of production traits in the first 3 parities in Chinese Holsteins. Data were a random sample of complete herds (109,005 test-day records of 9,706 cows from 54 herds) extracted from the original data set, which included 362,304 test-day records of 30,942 Holstein cows from 105 herds. A test-day animal model with multiple-trait random regression and the Gibbs sampling method were used for parameter estimation. Regression curves were modeled using Legendre polynomials of order 4. The multiple-trait analysis included milk, fat, and protein yield, and somatic cell score (SCS). Average daily heritabilities ranged between 0.222 and 0.346 for the yield traits and between 0.092 and 0.187 for SCS. Heritabilities were higher in the third lactation for all traits. Within-parity genetic correlations were very high among the yield traits (>0.806) and were close to zero between SCS and yield traits, especially for first-parity cows. Results were similar to previous literature estimates from studies that used the same model as applied to this study. The estimates found in this study will be used to perform breeding value estimation for national genetic evaluations in Chinese Holsteins.