Management of trace elements and vitamins in organic ruminant livestock nutrition in the context of the whole farm system

摘要

There is a wealth of information on the vital role of trace minerals in ruminant health. This information gives some reasonable indications of the levels required by dairy and beef animals to maintain good health though there is much less information available for sheep. There is also a wealth of information available on the role played by trace elements in the major diseases of ruminants, particularly mastitis and the problem of high somatic cell counts. There is also information available on the effects of trace mineral supplementation on fertility and production. This information should be used by organic farmers and their advisors to assess trace mineral status of animals under their care and to design strategies to help ensure that the trace element requirements of the ruminant are met and that good health status can be established and maintained. This should enable them to better resist the every day challenges by pathogenic organisms responsible for many of the current infections such as mastitis. However, currently we only have enough information to be able to do this with any degree of certainty by using dietary supplementation with appropriate trace elements which is a conventional approach and does not sit well with organic philosophy. There are indications from a very small number of studies that there may be a more “sustainable, organic” way to achieve the same objective by increasing the diversity of the pastures used as the major food source for ruminant livestock. However, much more information is needed on the levels of trace elements present in these plants, how the level varies with soil trace element content and health status of the soil and how the level varies with stage of growth through the season. Only when we have this more detailed information can we design pastures that provide for the animal’s requirements. An additional benefit of such pastures is that they may result in a much greater diversity of wildlife. Attention also needs to be paid to the management and nutrition of the livestock in order to reduce both physical and nutritional stress to a minimum.