Suitability of Purebred and Crossbred Dairy Cows for Organic Systems

S. Brotherstone, J. Santarossa and M.P. Coffey
Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, UK

Abstract
Organic livestock producers are required to choose breeds and crosses that are most suited to organic systems, in order to minimize the incidence of disease and other health and welfare problems.

To investigate any benefit of crossbreeding to organic farmers, data on milk production, somatic cell count (SCC), calving interval and survival from first to second lactation were extracted for a variety of pure and first-cross cows.

No useful heterosis was found for any of the production traits, but useful heterosis was found for SCC in all first-cross animals for all breeds. Similar genes control SCC and mastitis, so by crossbreeding, advantage can be taken of heterosis for SCC to reduce the incidence of mastitis in the herd.

Heterosis for calving interval in the Ayrshire-Jersey cross indicates that fertility is better in this cross than in either purebred Ayrshires or purebred Jerseys.

Economic values for traits of interest were calculated twice, using assumptions applicable to conventional and organic systems. From an economic perspective, and irrespective of system, Holsteins performed best but Shorthorns ranked last.

If maximizing profitability is their primary objective, it is not evident that farmers running organic systems should consider crossbreeding as a first option.

Source
"Organic Farming: Science and Practice for Profitable Livestock and Cropping"
Proceedings of Symposium No. 37, British Grassland Society, 2004
Association of Applied Biologist & Colloquium of Organic Researchers

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Posted October 2007