Achieving sustainable agricultural systems will require transformative changes in markets, policies, and science.

Heavy metals such as zinc (Zn), copper (Cu), chromium (Cr), arsenic (As), cadmium (Cd), and lead (Pb) are potential bioaccumulative toxins of the dairy production system. The heavy metal content of dairy feeds, however, remains poorly documented, particularly in the United States. This survey determined the heavy metal content of 203 typical dairy ration components sampled from 54 dairy farms in Wisconsin. Lowest heavy metal concentrations were found in homegrown alfalfa (Medicago sativa L.) hay and haylage, and corn (Zea mays L.) grain and silage. Highest metal concentrations were found in purchased feeds, particularly mineral supplements, and to a lesser extent corn- or soybean-based concentrates. Zinc and Cu were found at the highest concentration in complete dairy (total mixed and aggregated component) rations and reflected the deliberate addition of these metals to meet animal nutrient requirements although more than half the farms fed Cu and Zn above US recommended levels. Concentrations of Cr, As, Cd, and Pb were present in much lower concentrations and decreased in the order Cr > As > Pb > Cd. No complete Wisconsin dairy ration contained heavy metal concentrations above US maximum acceptable concentrations and would be unlikely to induce any toxic effects in dairy cattle. Concentrations of Cd in complete dairy rations were closest to US maximum acceptable concentrations, suggesting the greatest potential long-term risk to exceed US maximum acceptable concentrations if whole farm levels of Cd were to increase in the future. With the exception of Pb, the main sources of Zn, Cu, Cr, As, and Cd in the complete dairy feed ration originated from imported feed. The continued importation of heavy metals in dairy feed is likely to be associated with accumulation of these metals in soils where manure is applied. Although the cycling of many heavy metals through the dairy food chain will be limited by factors such as a soil's cation exchange capacity, pH, salinity, and phytotoxicity of the metal, these may be less limiting for Cd. It is important that sources of Cd in the dairy system are identified and minimized to prevent problems associated with Cd accumulation in the dairy soil system arising over the long-term.

Wisconsin dairy producers who modernized their operations between 1994 and 1998 had positive feelings about their expansion experiences, accompanied by increased production and improved profitability and quality of life. The average herd in this survey experienced increased production during the 5-yr period studied. Nearly all producers were satisfied with their expansion experience. The negative effect on milk production normally associated with expansion was minimal for most years and did not exist if all herds were summarized together. Managing labor appeared to be the most daunting challenge facing producers following expansion. Respondents who built all new facilities observed higher production, greater labor efficiency, and satisfaction with measures of profitability and quality of life than respondents who modified facilities or added no new facilities. As herd size increased, milk production, labor efficiency, and satisfaction with herd performance, profitability, and quality of life increased. Producers who built all new facilities spent less time on farm work, more time managing employees, and had less difficulty finding, training, supervising, and keeping farm employees than producers who modified facilities or added new facilities to existing operations. Larger herds were associated with an increased reliance on nonfamily labor. Managing labor appears to be an easier task for managers of larger herds. The most difficult challenges for producers who modernized their operations were with labor management, financing, and loan procurement, construction and cost overruns, and feet and leg health. Difficulties with expansion differed little between expansion types (same type, some new, or all new facilities) or herd sizes.