Nutrition and cattle and sheep welfare

Cattle and sheep evolved toutilise poor quality feeds, and have the potential to survive variation in feed supply through the use of body lipid reserves. Despite this beef cattle and sheep are susceptible to undernutrition because they are normally raised on marginal land that experiences climatic extremes. In regions with such marginal land, undernutrition is commonly regarded as the greatest welfare problem for extensively reared cattle and sheep. Dairy cows that have been bred fOr high milk outputare more likely to experience malnutrition in the form of macro- or micronutrient deficiencies. Feeding excessively high energy diets to reduce early lactation energy deficiencies can result in health risks, as well as behaviour problems as a result of insufficient oral stimulation. Cattle and sheep farmers will usually rectify known deficiencies if it is economic to do so, but the welfare impact of most clinical and subclinical disorders is not known. Toxic plants have immediate welfare.effects and are most common in extensive grazing situations. Increased weed seed trarismissionto novel grazing lands may increase this problem. Pollution may also contaminate grazing lands but is more likely to affect the welfare of hljmans consuming livestock, rather than the livestock themselves because of their short lives. It is anticipated that the importance of nutrition on the welfare of cattle and sheep is likely to increase, with the onset of global human food shortages and increased competition for resources