Genotype by environment interaction of Swedish dairy cows in organic and conventional production systems

Abstract

Most dairy cows used in organic dairy production today are of high producing breeds, bred within the conventional production system. The aim of this study was to investigate the occurrence of genotype by environment (G×E) interactions between organic and conventional dairy production in Sweden, to see if they are of a magnitude justifying development of a separate breeding program for organic production. Records of production, fertility, and somatic cell count in Swedish Holstein and Swedish Red cows in first and second lactation, collected between 1998 and 2005 in 424 organic and 5564 conventional herds, were analyzed. Indications of G×E were only found for three fertility traits; calving interval, the interval from calving to last insemination, and pregnant at first insemination, in second lactation Swedish Holstein. This, together with the small organic population, does not justify development of a separate breeding program for cows in organic production in Sweden.

Keywords:

• Cattle
• fertility
• G×E
• udder health

Acknowledgements

The authors are grateful to the Swedish Dairy Association and the certification organization KRAV for providing the data. The Swedish Research Council Formas is acknowledged for financial support.