Nitrogen and phosphorus surpluses on Danish dairy and pig farms in relation to farm characteristics

This study is in two parts. In the first part, nitrogen (N) losses per unit of milk and meat in Danish conventional and organic pig and dairy farming were compared on the basis of farm data. In the second part, organic and conventional dairy farming were compared in detail, using modelling. N-surpluses at different livestock densities, fodder intensities, and soil types were simulated. Finally, simulated N-surpluses were used in national scenarios for conversion to organic dairy farming in Denmark. In Part one, pig farming was found to have a higher N-efficiency than dairy farming. Organic pig production had a lower N-efficiency and a higher N-surplus per kg meat than conventional pig production. The possibilities to reduce N-loss by conversion to organic pig production therefore appear to be poor. Organic dairy farming had a higher N-efficiency and a lower N-surplus per kg milk than conventional dairy farming. Conversion from conventional to organic dairy farming may therefore reduce N-losses. In Part two, a positive correlation between livestock density and N-surplus ha-1 was found for dairy farming. For all simulated livestock densities, fodder feeding intensities and soil types, organic systems showed a lower N-surplus per unit of milk produced than conventional systems. National scenarios for dairy farming showed that the present Danish milk production could be achieved with a 24% lower total N-surplus if converted from intensive conventional farming to extensive organic farming. At the same time, N-surplus ha-1 and N-surplus (t milk)-1 would be lowered by 50% and 25% respectively. Changing from intensive to extensive conventional dairy farming with a livestock density equal to that in the organic scenario resulted in a reduction in N-surplus ha-1 of 15%. It was concluded that a reduction in total N-loss from agriculture is possible by converting from conventional to organic dairy farming but at the cost of either lower production on the present dairy farm area, or the current production on a substantially larger area.

About half of all N and P loads to Swedish waters originate from agriculture and must decrease to reach environmental goals. Studying nutrient management at farm level can provide an understanding of nutrient recycling and the risk of losses. In a survey of organic and conventional dairy and arable farms in three southern counties of Sweden, farm-gate N and P balances and N use efficiency (NUE) were analysed. Crop distribution differed significantly between organic and conventional farms, with organic dairy farms having higher proportions of ley and pulse crops and organic arable farms having a much higher proportion of N-fixing crops than corresponding conventional farms. Conventional dairy and arable farms had on average 70% and 40% higher N surplus than corresponding organic farms. Farm-gate P surplus was larger on conventional dairy farms and much larger on organic arable farms, mainly due to purchase of P-rich organic fertilisers. Organic dairy farms had higher NUE than corresponding conventional farms, but the opposite was true for arable farms. However, in the southernmost county Skåne, where soil fertility and yield potential are high, NUE was similar on all arable farms. Total inputs of N and P were positively correlated with N and P surpluses, especially on dairy farms. Improved manure and crop residue management, reduced use of purchased mineral N fertilisers coupled to more uniform within-farm distribution of manure, use of catch crops, intercropping and organic fertilisers with appropriate N:P ratio are measures that can reduce farm nutrient surpluses and improve nutrient management on both organic and conventional farms.

Comparative analysis of the diversity of aerobic spore-forming bacteria in raw milk from organic and conventional dairy farms

Variations in nitrogen utilisation on conventional and organic dairy farms in Norway

The economic value of organic dairy farms in Vermont and Minnesota

Variations of energy intensities and potential for improvements in energy utilisation on conventional and organic Norwegian dairy farms

This study compares the energy return on investment (EROI) of organic and conventional farms in Iceland. It examines which farming method returns the highest amount of edible energy to society relative to the input required. Twenty farms were studied: two organic and 18 conventional. Real data were gathered directly from five farms (including both of the organic farms in the study). Further data from 15 conventional dairy farms of different sizes were collected from a database maintained by the Icelandic Farmers Association. One of the organic farms studied (Org1) was found to have an EROI of 2.68, whereas two conventional farms used as controls for comparison (Con1-a and Con1-b) had EROIs of 0.60 and 0.69, respectively. The second organic farm (Org2) had an EROI of 0.55, versus the control farm ratio of 0.27. On average, large (<170 hectares) conventional dairy farms had an EROI of 0.65, while medium (<70 hectares) and small (<40 hectares) conventional farms had average EROIs of 0.56 and 0.50, respectively. This limited analysis suggests that organic dairy farms may provide better EROIs than conventional farms, but that their dairy yields per hectare are lower.

Management Practices and Reported Antimicrobial Usage on Conventional and Organic Dairy Farms

Antimicrobial Susceptibility of Salmonella from Organic and Conventional Dairy Farms

Antibiotic resistance is a global problem affecting both human and animal health. Ensuring the strategic and effective use of antibiotics is paramount to combatting the emergence and spread of resistance. This study explored New York State (NYS) dairy farmers’ perceptions regarding antibiotic use in dairy farming and antibiotic resistance. Dairy farmers’ perceptions were assessed through semi-structured, in-person interviews. Twenty interviews with farm owners and/or managers of 15 conventional and five USDA certified organic dairy farms with 40 to 2,300 lactating cows were conducted. Thematic analysis was used to assess, compare and contrast transcripts for farmers’ characterization of their beliefs, values, and concerns. Conventional dairy farmers had a low level of concern about the possible impacts of on-farm antibiotic resistance on human health and believed their antibiotic use was already judicious. Generally, they believed their cattle’s health would suffer if antibiotic use were further curtailed. Conventional farmers expressed frustration over the possibility of more stringent governmental, milk cooperative, buyer, or marketer requirements for antibiotic use and associated animal welfare in the future. They attributed expanding regulations in part to misinformed consumer preferences, that farmers felt were influenced by the marketing of organic dairy products. Organic dairy farmers were generally more concerned about issues related to antibiotic resistance than conventional farmers. Both conventional and organic farmers placed emphasis on disease prevention through herd health management rather than treatment. In conclusion, the conventional NYS dairy farmers in this study were skeptical of the need for and benefits of reduced antibiotic use on their dairy farms. Interventions for farmers, delivered by a trusted source such as a veterinarian, that provide training about proper antibiotic use practices and information of possible financial benefits of refining antibiotic use may hold promise.

A comparison of production and management between Wisconsin organic and conventional dairy herds

Comparing risk perceptions and risk management in organic and conventional dairy farming: empirical results from Norway

Dairy farming is a major source of greenhouse gas (GHG) emissions in agriculture. There are numerous scientific studies analysing GHG flows and testing GHG reduction methods in dairy farming, yet very few scientific papers cover all the relevant GHG flows. GHG flows that are difficult to quantify, such as C sequestration in soils, the effects of land-use change (LUC) or the energy input used to produce capital equipment, are not always considered.This paper describes the development and application of a model for energy and GHG accounting in dairy farming. This new model enables all relevant nutrient, energy and GHG flows to be modelled at farm level. This then forms the basis for system analysis and derivation of GHG mitigation strategies. The model was used on 18 organic and 18 con-ventional farms in Germany. Calculated CO2-eq emissions per kg of Energy Corrected Milk (ECM) were 995 g on average for organic farms (org) and 1,048 g on average for conventional farms (con). The largest contribution (55 % (org) and 43 % (con)) to total GHG emissions came from enteric methane emissions (549 g CO2-eq (kg ECM)-1 (org) and 449 g CO2-eq (kg ECM)-1 (con)). On the organic dairy farms, there was an increase in soil humus and therefore carbon storage and sequestration in soils, whereas the GHG emissions for the conventional farms included CO2 emissions from LUC due to soybean usage. The significantly higher energy input in the conventional systems resulted from the production of energy-intensive concentrates, mineral fertilisers and pesticides, and transportation (imported feed).This study shows that there are many factors that influence GHG emissions in dairy farming, and that these factors often interact with each other. An increase in productivity is one of several optimisation strategies; however, it must not be at the expense of productive lifetime or require an extremely high amount of concentrates. GHG reduction in dairy farming requires farm-specific optimisation approaches due to the heterogeneity of production systems.

The purpose of this paper is to explore whether differences in profitability and revenue efficiency exist between Norwegian organic and conventional dairy farms. With access to accountancy data from more than 1000 conventional farms, it was possible to compare the 59 organic farms with a matched group of 177 conventional farms. The two groups did not differ significantly with respect to share of turnover from milk, forage area, number of cows, milk quota, location, and share of robotic milking. Data spanned over the fiscal years 2014 to 2016. Stochastic frontier analysis was used to calculate revenue efficiency. The results confirmed that organic farms and conventional farms use different production technology, and therefore, we calculated efficiency on two different production frontiers. On average, organic dairy farms were 6.5 percentage points more revenue efficient than conventional farms. Although conventional farms appeared more profitable than organic farms, differences were not significant; however, conventional farms had a higher profitability potential than organic farms.

To describe the occurrence of fecal shedding, persistence of shedding over time, and serogroup classification of Salmonella spp on a large number of dairy farms of various sizes. Longitudinal study. 22,417 fecal samples from cattle and 4,570 samples from the farm environment on 110 organic and conventional dairy farms in Minnesota, Wisconsin, Michigan, and NewYork. 5 visits were made to each farm at 2-month intervals from August 2000 to October 2001. Fecal samples from healthy cows, calves, and other targeted cattle groups and samples from bulk tank milk, milk line filters, water, feed sources, and pen floors were collected at each visit. Bacterial culture was performed at 1 laboratory. Salmonella spp were isolated from 4.8% of fecal samples and 5.9% of environmental samples; 92.7% of farms had at least 1 Salmonella-positive sample. The 75th percentile for median within-herd prevalence of Salmonella spp in cattle for 5 sampling visits to a given farm was 2.0% and for maximum within-herd prevalence of Salmonella spp was 13.6%. Farms with a median within-herd prevalence of Salmonella spp of > or = 2.0% accounted for 76.3% of Salmonella-positive samples. There was no significant difference in the prevalence of Salmonella spp between conventional and organic farms. Seasonal differences in Salmonella shedding were observed. More farms had at least 1 serogroup B isolate than any other serogroup, whereas serogroup E1 was the most common among all Salmonella-positive samples. More than 1 serogroup was isolated on 76.4% of Salmonella-positive farms. Salmonella spp were isolated from > 90% of dairy farms; however, 25% of farms accounted for > 75% of Salmonella-positive samples. This information is critical for the direction of intervention strategies to decrease the prevalence of Salmonella spp on dairy farms.