Genetic Correlations Between Milk Production and Health and Fertility Depending on Herd Environment

• Published in: Journal of dairy science 2006-05, Vol.89 (5), p.1765-1775
• Main Authors: Windig, J. J, Calus, M. P. L, Beerda, B, Veerkamp, R. F
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animal productions; Animals; Biological and medical sciences; Breeding; Cattle - genetics; Cell Count; dairy cows; dairy herds; Environment; Female; female fertility; Fertility - genetics; Food industries; Fundamental and applied biological sciences. Psychology; genetic correlation; health and fertility; Health Status; herd environment; herd health; Insemination, Artificial - veterinary; Lactation - genetics; Milk - cytology; Milk and cheese industries. Ice creams; milk yield; Netherlands; Pedigree; Phenotype; postpartum interval; Pregnancy; pregnancy rate; Quantitative Trait, Heritable; reaction norm model; Regression Analysis; selection criteria; selection response; Selection, Genetic; somatic cell count; Terrestrial animal productions; Time Factors; Vertebrates
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(06)72245-7

High milk production in dairy cattle can have negative side effects on health and fertility traits. This paper explores the genetic relationship of milk yield with health and fertility depending on herd environment. A total of 71,720 lactations from heifers calving in 1997 to 1999 in the Netherlands were analyzed. Herd environment was described by 4 principal components: intensity, average fertility, farm size, and relative performance indicating whether herds had good (poor) health and fertility despite a high (low) production. Fertility was evaluated by days to first service and number of inseminations (NINS); somatic cell score was used as a measure of udder health. Data were analyzed with a multitrait reaction norm model. Genetic correlation within traits across environments ranged from 0.84 to unity. Genetic correlations of the 3 traits with milk yield were antagonistic but varied over environments. Genetic correlation of milk yield with days to first service varied from 0.30 in small herds to 0.48 in herds with low average fertility. Correlations with NINS varied from 0.18 in large herds to 0.64 in high fertility herds, and with somatic cell score from 0.25 in herds with a high fertility relative to production to 0.47 in herds with a relative low fertility. Selection in environments of average value resulted in different predicted responses over environments. For example, selection for a decrease of NINS of 0.1 in an average production environment decreased milk yield by 35kg in low production herds, but by 178kg in high production herds.