The purpose of this study was to examine whether Urea could be an option as a nitrogen source for young cattle, the study was limited to risks related to feeding, growth and feed efficiency. Microbes in ruminants have the ability to convert nitrogen to protein, this has been highlighted by beef producers as they are in search of cheap protein feed resources. Urea can be a worthy source of nitrogen for growing young animals, because of its high nitrogen content and the low price. Studies have shown that the replacement of a portion of the total protein content by Urea in diets with low content of crude protein, like corn silage, may improve animal growth and feed efficiency. Replacement of all the true protein with Urea can result in reduced feed intake and microbial growth.

Safe retrieval of nutrients from human excreta to fertilize crops in order to gain adequate yields will increase food security and sustainability in agriculture areas with nutrient-poor fields. Safe and nutritious food will meet the dietary needs of the individual which promotes public health and the ability of an active life. Human excreta should be considered as a resource instead of being assumed as waste. Human faeces and urine is excellent fertilizers which may close the nutrient loop if utilized properly. However, sanitation of the excreta is required to prevent disease transmission by reducing the content of gastrointestinal pathogens such as bacteria, viruses and parasites. The objective of this study was to in small scale evaluate the sanitation in a combined liquid compost and Urea treatment by monitor the inactivation of bacteria and viruses at the combination three start temperatures, 45, 40 and 35 °C, and three additions of Urea, 0.5, 0.75 and 1 % and reference, 0 % Urea addition.

The aim of this thesis is to improve the control of Urea injection at the combined power and heating plant Framtidens Gärstad (FTG). Tekniska Verken i Linköping AB is the owner of the plant.The FTG plant consists of a boiler where garbage combustion is done. From the combustion nitrogen oxides are emitted. These nitrogen oxides are hazardous to the environment. To reduce the nitrogen oxides, injection of Urea into the boiler is used.

The aim of this literature study was to analyze how milk Urea concentration is working as a measure of the nitrogen supply to rumen microbes and indicator of the environmental load. Questions included in this literature study were how to improve the dairy cattle nitrogen efficiency and what correlations there are between milk Urea, nitrogen efficiency and crude protein content in the feed. Effects on the reproduction from high ration protein content are also addressed. Dairy cattle are today fed with large proportions of protein which could lead to high expenditure of feed and environmental pollutions. The nitrogen can be lost to the environment by different pathways; leaching, denitrification or by emission to the air.

The aim of this literature study was to analyze how milk Urea concentration is working as a measure of the nitrogen supply to rumen microbes and indicator of the environmental load. Questions included in this literature study were how to improve the dairy cattle nitrogen efficiency and what correlations there are between milk Urea, nitrogen efficiency and crude protein content in the feed. Effects on the reproduction from high ration protein content are also addressed. Dairy cattle are today fed with large proportions of protein which could lead to high expenditure of feed and environmental pollutions. The nitrogen can be lost to the environment by different pathways; leaching, denitrification or by emission to the air.

The purpose of this work was to provide a better understanding of Urea?s decomposition and byproduct formation in an SCR system on heavy trucks. In my experimental setup with TGA-DSC-FTIR (a combination of two thermal analysis methods and a method for gas phase detection), an FTIR method for Urea in the gas phase was developed for the qualitative and quantitative determination of Urea and its decomposition products. Chemicals such as Urea, biuret, cyanuric acid and melamine of p.a. quality were used in this method development. Beforehand, there was no FTIR method available to detect these substances; hence, the aim of this work was to develop an FTIR method to understand the degradation chain of Urea. The combination of TGA and DSC was used for analysis of different samples, where Urea, biuret, cyanuric acid and melamine in varying amounts have been weighted in for various experiments in order to study the temperature at which a phase transition or reaction occurs, i.e.

A growing population together with a change in food habits to a more diverse diet containing more animal products such as meat and milk makes the possibility to produce and sell products of cattle a growing market. And at the same time there is an ongoing debate about global warming, where raising cattle is questioned due to their high production of enteric methane. To be able to raise animals in a more environmental friendly way and at the same time improve productivity in a developing country such as Vietnam would be favorable. The use of feed additives with high electron affinity could decrease the methane production and at the same time improve the gross energy digested. Nitrate and Sulfur are both good electron acceptors, but due to its toxic effects the use of nitrate in feed has been neglected.

Root rot is a big hurter and a huge economic problem for the Swedish and European forestry. The severest hurter is Heterobasidion annosum (Fr.) Bref and it occurs as two different species in Sweden. Commonly referred to as the P-type (Heterobasidion annosum s.s. (Fr.) Bref.) and the S-type (Heterobasidion parviporum Niemelä & Korhonen). Therefore a lot of research has been carried out in this topic to find a solution and reduce this problem, one alternative that have shown to be profitable is stump treatment in thinnings.

During the last decades the fertility of dairy cows has declined in the same rate as the milk yield has increased. This is a result of the negative genetic correlation between milk yield and fertility, failure to show estrous signs and metabolic problems in the cow. The purpose of this review was to investigate the function of metabolites and hormones as markers for disturbances in fertility, health and production in the dairy cow. There are several metabolites that are suggested to indicate the cow?s energy balance.

The aim of this study was to in laboratory experiments investigate how addition of Urea, ECOX and structural materials can optimize sanitization during composting of sewage sludge. Today we strive for a sustainable society and the importance of closing the nutrient loop increases. It has therefore become even more important to safely reuse plant nutrients from human excreta to agricultural land. Partly because it increases the sustainability of society as the world's supply of many nutrients are finite, partly because it promotes human health, both by reducing disease transmission and by increasing Agricultural production. An untapped resource such as sewage sludge that is rich in nutrients and humus-forming materials could replace parts of the commercial fertilizers used in Sweden today. owever, sewage sludge contains undesirable substances such as heavy metals and drug residues, and pathogenic microorganisms.

Bringing back the nutrients from the city to the country is becoming increasingly important, as the world?s stores of nutrients get more exhausted. Sewage sludge is an unapplied resource, rich in plant nutrients, which could replace parts of the commercial fertilizers used in Sweden today. Sewage sludge may contain large amounts of pathogens, such as Campylobacter and Salmonella, why use can cause severe spreading of infections, both to animals and humans. These pathogens have the ability to survive for a long time in soil and water and therefore some sort of treatment of the sludge is recommended before use.

Bovine Respiratory Syncytial Virus (BRSV) is a common cause of respiratory disease among young cattle. The virus causes severe losses; the herd mortality rate can sometimes be as high as 20 %. In this study the avidity (i.e the antigen binding force) of BRSV specific antibodies was measured to see if there was a difference between antibodies produced during an acute phase of infection and antibodies produced by earlier infected animals. A commercially available ELISA-testkit against BRSV-specific antibodies was used and an incubation step with 6M Urea was added. The effect of the Urea is that it breaks the weak bonds between antibodies and antigen while the stronger bonds remain intact. Four different groups of animals were included in this study; seven calves that were naturally infected, three acutely infected calves with known time of infection, five cows that were seropositive during several years and four experimentally infected calves that had been a part of a vaccine trial. The results of this study showed that antibodies produced during the acute phase of an infection had a low avidity and that the avidity increased with time after infection.

Snöröjningen och isbekämpningen på Kallax flygplats i Luleå sköts idag med hjälp av plogning, sopning, borstning med stålborstar och användning av isbekämpningsmedel som Urea. Det är en väldigt kostsam verksamhet och även miljöbelastande då Urea har en gödande effekt på sin omgivning. Det här examensarbetet undersöker ett alternativt sätt att hålla banan fri från snö och is. Genom att lägga ner rör i asfalten och i dessa rör cirkulera varmt vatten kan man värma upp banan så att den fallande snön smälter. Värmen utgörs av spillvärme som lagras i ett bergvärmelager från inköpstillfälle till användning, dvs från sommar till vinter.

På Luleå Flygplats används Urea som halkbekämpningsmedel eftersom det löser upp isbeläggningar genom att sänka vattnets fryspunkt. Urea finns naturligt i vattendrag och jordar som ett resultat av exkretion och nedbrytning i form av nukleinsyror och proteiner. Halterna är vanligtvis låga i det naturliga kretsloppet. Stora mängder Urea tillförs i och med halkbekämpningen (145 ton säsongen 2009/2010). Urea består av 46 % kväve som förekommer som ammonium vars utsläpp kan leda till övergödning och kan vara giftig för organismer i höga halter.

The price trend on rapeseed the latest years has led to an increasing interest to grow the crop among many farmers in Sweden. The price trend has resulted in more than a doubling of the oilseed area since the early 2000s. For many farmers it is an advantage to increase cultivation of rapeseed because of the high proportion of cereals in the crop rotation on many farms, but it is not just benefits. The risk of the fields being infected by clubroot increases within frequent rapeseed cultivation and it often leads to subtantial economic losses. Clubroot is caused by Plasmodiophora brassicae that is a soilborne pathogen in genus Protozoa and its resting spores can be found in the soil for up to 18 years.