Hristov, A. N., Hanigan, M., Cole, A., Todd, R., McAllister T. A., Ndegwa, P. and Rotz, A. 2011. Review: Ammonia emissions from dairy farms and beef feedlots. Can. J. Anim. Sci. 91: 1–35. Ammonia emitted from animal feeding operations is an environmental and human health hazard, contributing to eutrophication of surface waters and nitrate contamination of ground waters, soil acidity, and fine particulate matter formation. It may also contribute to global warming through nitrous oxide formation. Along with these societal concerns, ammonia emission is a net loss of manure fertilizer value to the producer. A significant portion of cattle manure nitrogen, primarily from urinary urea, is converted to ammonium and eventually lost to the atmosphere as ammonia. Determining ammonia emissions from cattle operations is complicated by the multifaceted nature of the factors regulating ammonia volatilization, such as manure management, ambient temperature, wind speed, and manure composition and pH. Approaches to quanti...

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Review: Ammonia emissions from dairy farms and beef feedlots1

We compare productivity and technical efficiency of organic and conventional dairy farms in the United States We address self-selection into organic farming by using propensity score matching and explicitly test the hypothesis that organic and conventional farms employ a single, homogeneous technology Utilizing the 2005 Agricultural Resource Management Survey on Dairy Costs and Returns Report (ARMS) data, we reject the homogeneous technology hypothesis and find that the organic dairy technology is approximately 13% less productive However, we find little difference in technical efficiency between organic and conventional farms when technical efficiency is measured against the appropriate technology

https://papers.ssrn.com/sol3/Delivery.cfm/AJAE_AJAEAJAEAAP018.pdf?abstractid=3569150&mirid=1

Technology Adoption and Technical Efficiency: Organic and Conventional Dairy Farms in the United States

The global dairy industry, the predominant pathogens causing mastitis, our understanding of mastitis pathogens and the host response to intramammary infection are changing rapidly. This paper aims to discuss changes in each of these aspects. Globalisation, energy demands, human population growth and climate change all affect the dairy industry. In many western countries, control programs for contagious mastitis have been in place for decades, resulting in a decrease in occurrence of Streptococcus agalactiae and Staphylococcus aureus mastitis and an increase in the relative impact of Streptococcus uberis and Escherichia coli mastitis. In some countries, Klebsiella spp. or Streptococcus dysgalactiae are appearing as important causes of mastitis. Differences between countries in legislation, veterinary and laboratory services and farmers' management practices affect the distribution and impact of mastitis pathogens. For pathogens that have traditionally been categorised as contagious, strain adaptation to human and bovine hosts has been recognised. For pathogens that are often categorised as environmental, strains causing transient and chronic infections are distinguished. The genetic basis underlying host adaptation and mechanisms of infection is being unravelled. Genomic information on pathogens and their hosts and improved knowledge of the host's innate and acquired immune responses to intramammary infections provide opportunities to expand our understanding of bovine mastitis. These developments will undoubtedly contribute to novel approaches to mastitis diagnostics and control.

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Changing trends in mastitis.

The global livestock industry is charged with providing sufficient animal source foods to supply the global population while improving the environmental sustainability of animal production. Improved productivity within dairy and beef systems has demonstrably reduced resource use and greenhouse gas emissions per unit of food over the past century through the dilution of maintenance effect. Further environmental mitigation effects have been gained through the current use of technologies and practices that enhance milk yield or growth in ruminants; however, the social acceptability of continued intensification and use of productivity-enhancing technologies is subject to debate. As the environmental impact of food production continues to be a significant issue for all stakeholders within the field, further research is needed to ensure that comparisons among foods are made based on both environmental impact and nutritive value to truly assess the sustainability of ruminant products.

The Role of Productivity in Improving the Environmental Sustainability of Ruminant Production Systems

Organic milk production has been one of the fastest growing segments of organic agriculture in the United States in recent years. Despite the growing number of organic dairy operations, the characteristics of organic dairy operations and the relative costs of organic and conventional milk production have been difficult to analyze. This study, using 2005 ARMS data for U.S. dairy operations, which include a targeted sample of organic milk producers, examines the structure, costs, and challenges of organic milk production. The analysis addresses economies of size, regional differences, and pasture use in organic milk production and compares organic and conventional milk production costs. The findings suggest that economic forces have made organic operations more like conventional operations and that the future structure of the industry may depend on the interpretation and implementation of new organic pasture rules.

G.H. Kamphuis

Papers

Organic dairy production systems in Pennsylvania: a case study evaluation.