This thesis describes the creation of substituted diphenylacetic acids and their results.

A distribuição espacial e o histórico deposicional de poluentes orgânicos persistentes (POPs) em sedimentos foram avaliados no ecossistema marino-estuarino da Ilha do Marajó, Pará. Os pesticidas predominantes nos sedimentos da camada superficial foram os HCHs (<0,04 e 0,90 ng g-1) e DDTs (<0,02 - 2,72 ng g-1), em peso seco. PCBs e PBDEs não foram detectados. HCHs predominaram no Estuário do Rio Paracauari indicando uso recente provavelmente relacionado à atividade madeireira. DDTs foram detectados na Praia do Pesqueiro e nos testemunhos sedimentares (<0,02 - 12,31 ng g-1 peso seco) do Mercado, Fazenda e Paracauari. Os valores máximos de DDT ocorreram entre 1982 e 2008 e são associados com campanhas de saúde púbica. Há uma redução gradativa até o presente que coincide com a substituição do DDT por piretróides. A razão &#931;DDDs / &#931;DDEs, predominantemente < 1, indicou a ocorrência de processos decomposicionais aeróbicos. No geral, as condições ambientais não favorecem o acúmulo de pesticidas nos sedimentos, sendo que os valores estão abaixo do limite provável para causar efeitos adversos exceto para HCHs no Estuário do Rio Paracauari. O presente trabalho estabeleceu a distribuição de POPs na Ilha do Marajó e poderá contribuir para o processo de gestão costeira e ambiental da região. / The spatial distribution and depositional history of persistent organic pollutants (POPs) in sediments were evaluated in marino-estuarine ecosystem of Marajó Island, Pará. The predominant pesticides in sediments of the surface layer were HCHs (<0.04 and 0, 90 ng g-1) and DDTS (<0.02 to 2.72 ng g-1) by dry weight. PCBs and PBDEs weren\'t detected. HCHs predominated in Paracauari Estuary indicating recent use probably related to logging. DDTs were detected in Praia do Pesqueiro and sediment cores (<0.02 to 12.31 ng g-1 dry weight) Mercado, Fazenda and Paracauari. Maximum levels of DDT residues occurred between 1982 and 2008 and are associated with pubic health campaigns. There is a gradual reduction up to the present which coincides with the substitution of the DDTs by pyrethroids. The ratio &#931;DDDs / &#931;DDEs predominantly < 1 indicated the occurrence of decomposicional processes under aerobic conditions. Overall, the environmental conditions do not favor the accumulation of pesticides in sediments, and the values are below the threshold likely to cause adverse effects except for HCHs in Paracauari Estuary. This work established the distribution of POPs in Marajó Island and could contribute to the process of coastal and environmental management in the region.

A distribuição espacial e o histórico deposicional de poluentes orgânicos persistentes (POPs) em sedimentos foram avaliados no ecossistema marino-estuarino da Ilha do Marajó, Pará. Os pesticidas predominantes nos sedimentos da camada superficial foram os HCHs (<0,04 e 0,90 ng g-1) e DDTs (<0,02 - 2,72 ng g-1), em peso seco. PCBs e PBDEs não foram detectados. HCHs predominaram no Estuário do Rio Paracauari indicando uso recente provavelmente relacionado à atividade madeireira. DDTs foram detectados na Praia do Pesqueiro e nos testemunhos sedimentares (<0,02 - 12,31 ng g-1 peso seco) do Mercado, Fazenda e Paracauari. Os valores máximos de DDT ocorreram entre 1982 e 2008 e são associados com campanhas de saúde púbica. Há uma redução gradativa até o presente que coincide com a substituição do DDT por piretróides. A razão &#931;DDDs / &#931;DDEs, predominantemente < 1, indicou a ocorrência de processos decomposicionais aeróbicos. No geral, as condições ambientais não favorecem o acúmulo de pesticidas nos sedimentos, sendo que os valores estão abaixo do limite provável para causar efeitos adversos exceto para HCHs no Estuário do Rio Paracauari. O presente trabalho estabeleceu a distribuição de POPs na Ilha do Marajó e poderá contribuir para o processo de gestão costeira e ambiental da região. / The spatial distribution and depositional history of persistent organic pollutants (POPs) in sediments were evaluated in marino-estuarine ecosystem of Marajó Island, Pará. The predominant pesticides in sediments of the surface layer were HCHs (<0.04 and 0, 90 ng g-1) and DDTS (<0.02 to 2.72 ng g-1) by dry weight. PCBs and PBDEs weren\'t detected. HCHs predominated in Paracauari Estuary indicating recent use probably related to logging. DDTs were detected in Praia do Pesqueiro and sediment cores (<0.02 to 12.31 ng g-1 dry weight) Mercado, Fazenda and Paracauari. Maximum levels of DDT residues occurred between 1982 and 2008 and are associated with pubic health campaigns. There is a gradual reduction up to the present which coincides with the substitution of the DDTs by pyrethroids. The ratio &#931;DDDs / &#931;DDEs predominantly < 1 indicated the occurrence of decomposicional processes under aerobic conditions. Overall, the environmental conditions do not favor the accumulation of pesticides in sediments, and the values are below the threshold likely to cause adverse effects except for HCHs in Paracauari Estuary. This work established the distribution of POPs in Marajó Island and could contribute to the process of coastal and environmental management in the region.

Diss. (sammanfattning) : Uppsala universitet, 2007. / Härtill 5 uppsatser.

This thesis describes three separate and unrelated chemical experiments. The first investigates analogs for the compound DDT. The second investigates the properties of O-substituted hydroxylamines. The third investigates the action of slight changes to the structure of an antihistaminic agent.

In D. melanogaster, resistance to DDT is conferred by the upregulation of a cytochrome P450 enzyme, CYP6G1. Resistant flies have tandemly duplicated Cyp6g1 alleles that possess the LTR (Long Terminal Repeat) of an Accord retrotransposon inserted in the cis-regulatory region, 291bp upstream of the transcription start site. This DDT resistance allele (DDT-R) has been shown to have pleiotropic fitness benefits for female flies in at least one genetic background and with evidence of sexually antagonistic selection at this locus. In this thesis, I first review the role of transposable elements in conferring insecticide resistance and the evidence to date regarding the pleiotropic effects of DDT-R in D. melanogaster. By conducting life history and behavioural tests on flies of two genetic backgrounds I examine the sex-specific effects of expressing DDT-R in the absence of DDT. Finally I develop a single locus population genetics model based on these sex-specific effects and test the model using replicate laboratory populations. The first main finding is that DDT-R incurred a male mating cost that depended on the genetic background in which DDT-R was found and that this cost coincided with strong epistasis between genetic background and DDT-R that influenced male size (Chapter 3). Following on from this result, it was confirmed that the effect of DDT-R on male size does contribute to lowered mating success but does not fully explain this fitness cost (Chapter4). Additionally, resistant males were found to have a lowered rate of courtship behaviour driven by aborted chasing of females and lower male-male aggression than susceptible males (Chapter 4). Fitness assays in wild caught strain females revealed that DDT-R confers a fecundity increase but unlike previous work, no offspring viability increases were detected (Chapter 5). Thus as with male costs, specific pleiotropic female fitness benefits to resistance depend on genetic background. Modelling of DDT-R using a simple single-locus approach (Chapter 6) provides, for the first time, a unifying explanation for past and present DDT-R frequencies in nature and in old laboratory populations. The model is consistent with an old origin for the original DDT-R mutation held at low equilibrium frequency through balancing selection of a sexually antagonistic nature. It is also consistent with continued near fixation of DDT-R long after discontinued use and matches empirical observations in laboratory populations of the Canton-S background.

published_or_final_version / Community Medicine / Master / Master of Public Health

No description available.

Chan Kam Che. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 199-219). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.iii / 摘要 --- p.v / Contents --- p.vii / List of figures --- p.xiv / List of tables --- p.xix / Abbreviations --- p.xxii / Chapter Chapter I --- Introduction --- p.1 / Chapter 1.1 --- Persistent organic pollutants --- p.1 / Chapter 1.2 --- DDT and DDE --- p.2 / Chapter 1.2.1 --- Background --- p.2 / Chapter 1.2.2 --- Health effects --- p.4 / Chapter 1.2.3 --- Environmental exposure of DDE --- p.4 / Chapter 1.2.4 --- Level of DDE in human --- p.9 / Chapter 1.2.5 --- Biodegradation of DDE --- p.10 / Chapter 1.3 --- Remediation methods --- p.11 / Chapter 1.3.1 --- Physical/ chemical treatment --- p.11 / Chapter 1.3.2 --- Bioremediation --- p.13 / Chapter 1.4 --- Fungal Bioremediation --- p.14 / Chapter 1.5 --- Ligninolytic enzymes --- p.15 / Chapter 1.5.1 --- Laccase --- p.15 / Chapter 1.5.2 --- Peroxidases --- p.20 / Chapter 1.5.2.1 --- Manganese Peroxidase (MnP) --- p.20 / Chapter 1.5.2.1 --- Lignin Peroxidase (LiP) --- p.24 / Chapter 1.6 --- Cultivation of Pleurotus pulmonarius --- p.27 / Chapter 1.7 --- Enzyme technology on environmental cleanup and its limitation --- p.28 / Chapter 1.8 --- Aims and objectives of this study --- p.29 / Chapter Chapter II --- Materials and Methods --- p.30 / Chapter 2.1 --- Organism and growth conditions --- p.30 / Chapter 2.2 --- Cultivation and the expression of the ligninolytic enzyme-coding genes during solid-state-fermentation of edible mushroom Pleurotus pulmonarius --- p.30 / Chapter 2.3 --- Treatment of DDE by living P. pulmonarius --- p.31 / Chapter 2.3.1 --- Optimization of DDE removal in broth system --- p.31 / Chapter 2.3.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.32 / Chapter 2.3.1.2 --- Effects of inoculum size on the removal of DDE --- p.33 / Chapter 2.3.1.3 --- Effects of incubation time on the removal of DDE and transcriptional profiles of the ligninolytic enzyme-coding genes --- p.33 / Chapter 2.3.2 --- Optimization of DDE removal in soil system --- p.34 / Chapter 2.3.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.34 / Chapter 2.3.2.2 --- Effects of inoculum size on the removal of DDE --- p.35 / Chapter 2.3.2.3 --- Effects of incubation time on the removal of DDE --- p.35 / Chapter 2.3.2.4 --- Transcription of the ligninolytic enzyme-coding genes --- p.35 / Chapter 2.4 --- Treatment of DDE by 1st SMC of p. pulmonarius grown on straw-based compost --- p.36 / Chapter 2.4.1 --- Optimization of DDE removal in soil system --- p.36 / Chapter 2.5 --- Treatment of DDE by crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.36 / Chapter 2.5.1 --- Optimization of DDE removal in broth system --- p.36 / Chapter 2.5.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.37 / Chapter 2.5.1.2 --- Effects of amounts of crude enzyme preparations on the removal of DDE --- p.37 / Chapter 2.5.1.3 --- Effects of incubation time on the removal of DDE --- p.37 / Chapter 2.5.2 --- Optimization of DDE removal in soil system --- p.37 / Chapter 2.5.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.38 / Chapter 2.5.2.2 --- Effects of amount of crude enzyme preparations on the removal of DDE --- p.38 / Chapter 2.5.2.3 --- Effects of incubation time on the removal of DDE --- p.38 / Chapter 2.6 --- Soil characterization --- p.39 / Chapter 2.6.1 --- Identification of organic contaminants in soil sample from Gene Garden using Gas Chromatography/Mass Spectrometry (GC/MS) --- p.39 / Chapter 2.6.2 --- Determination of soil texture --- p.42 / Chapter 2.6.3 --- Fresh soil/air-dried sample moisture --- p.44 / Chapter 2.6.4 --- "Soil pH, electrical conductivity & salinity" --- p.44 / Chapter 2.6.5 --- Total organic carbon contents --- p.44 / Chapter 2.6.6 --- Total nitrogen and total phosphorus --- p.44 / Chapter 2.6.7 --- Available nitrogen --- p.45 / Chapter 2.6.8 --- Available phosphorus --- p.45 / Chapter 2.6.9 --- Potassium value --- p.46 / Chapter 2.7 --- Quantification of residual DDE level --- p.47 / Chapter 2.7.1 --- Preparation of DDE stock solution --- p.47 / Chapter 2.7.2 --- Extraction and quantification of DDE using Gas Chromatography with Electron Capture Detector (GC/μECD) --- p.47 / Chapter 2.7.3 --- Identification of DDE breakdown products by GC/MS --- p.50 / Chapter 2.8 --- Extraction of protein and ligninolytic enzymes --- p.53 / Chapter 2.8.1 --- Protein assay --- p.53 / Chapter 2.8.2 --- Laccase assay --- p.53 / Chapter 2.8.3 --- Manganese peroxidase assay --- p.54 / Chapter 2.8.4 --- Calculation of activity and specific activity of laccase and manganese peroxidase --- p.54 / Chapter 2.9 --- Estimation of fungal biomass --- p.55 / Chapter 2.9.1 --- Preparation of ergosterol standard solution --- p.56 / Chapter 2.9.2 --- Analysis of ergosterol content --- p.56 / Chapter 2.10 --- Expression of the ligninolytic enzyme-coding genes --- p.58 / Chapter 2.10.1 --- Preparation of ribonuclease free reagents and apparatus --- p.58 / Chapter 2.10.2 --- RNA isolation and purification --- p.58 / Chapter 2.10.3 --- cDNA synthesis --- p.59 / Chapter 2.10.4 --- Semi-quantification of ligninolytic enzyme-coding gene expression by RT-PCR --- p.59 / Chapter 2.11 --- Preparation of crude enzyme preparations from P. pulmonarius compost --- p.63 / Chapter 2.12 --- "Assessment criteria: removal efficiency, RE, and removal capacity, RC" --- p.63 / Chapter 2.13 --- Statistical analysis “ --- p.64 / Chapter Chapter III --- Results --- p.65 / Chapter 3.1 --- Soil characterization --- p.65 / Chapter 3.2 --- Cultivation and the expression of the ligninolytic enzyme-coding genes during solid-state-fermentation of edible mushroom Pleurotus pulmonarius --- p.66 / Chapter 3.2.1 --- Mushroom yield --- p.66 / Chapter 3.2.2 --- Protein content --- p.66 / Chapter 3.2.3 --- Specific ligninolytic enzymes activities --- p.66 / Chapter 3.2.4 --- Ergosterol content --- p.69 / Chapter 3.2.5 --- Ligninolytic enzymes productivities --- p.69 / Chapter 3.2.6 --- Expression of the ligninolytic enzyme-coding genes during solid-state-fermentation --- p.72 / Chapter 3.3 --- Treatment of DDE by living P. pulmonaruis --- p.78 / Chapter 3.3.1 --- Optimization of DDE removal in broth system --- p.78 / Chapter 3.3.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.78 / Chapter 3.3.1.1.1 --- Effects of DDE on biomass development --- p.78 / Chapter 3.3.1.1.2 --- Protein content --- p.78 / Chapter 3.3.1.1.3 --- Specific ligninolytic enzyme activities --- p.78 / Chapter 3.3.1.1.4 --- Ligninolytic enzyme productivities --- p.79 / Chapter 3.3.1.1.5 --- DDE removal and removal capacity --- p.79 / Chapter 3.3.1.2 --- Effects of inoculum sizes on the removal of DDE --- p.84 / Chapter 3.3.1.2.1 --- Effects of DDE on biomass development --- p.84 / Chapter 3.3.1.2.2 --- Protein content --- p.84 / Chapter 3.3.1.2.3 --- Specific ligninolytic enzyme activities --- p.85 / Chapter 3.3.1.2.4 --- Ligninolytic enzyme productivities --- p.85 / Chapter 3.3.1.2.5 --- DDE removal and removal capacity --- p.85 / Chapter 3.3.1.3 --- Effects of incubation time on the removal of 4.0 mM DDE/g biomass --- p.89 / Chapter 3.3.1.3.1 --- Effects of DDE on biomass development --- p.89 / Chapter 3.3.1.3.2 --- Protein content --- p.89 / Chapter 3.3.1.3.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.89 / Chapter 3.3.1.3.4 --- DDE removal and removal capacity --- p.90 / Chapter 3.3.1.3.5 --- Putative degradation derivatives --- p.90 / Chapter 3.3.1.3.6 --- Expression of the ligninolytic enzyme-coding genes during the removal of 4.0 mM DDE/g biomass --- p.94 / Chapter 3.3.1.4 --- Effects of incubation time on the removal of 10.0 mM DDE/g biomass --- p.100 / Chapter 3.3.1.4.1 --- Effects of DDE on biomass development --- p.100 / Chapter 3.3.1.4.2 --- Protein content --- p.100 / Chapter 3.3.1.4.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.100 / Chapter 3.3.1.4.4 --- Expression of the ligninolytic enzyme-coding genes during the removal of 10.0 mM DDE/g biomass --- p.102 / Chapter 3.3.2 --- Optimization of DDE removal in soil system --- p.107 / Chapter 3.3.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.107 / Chapter 3.3.2.1.1 --- Ergosterol content --- p.107 / Chapter 3.3.2.1.2 --- Protein content --- p.107 / Chapter 3.3.2.1.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.107 / Chapter 3.3.2.1.4 --- DDE removal and removal capacity --- p.108 / Chapter 3.3.2.2 --- Effects of inoculum sizes on the removal of DDE --- p.111 / Chapter 3.3.2.2.1 --- Ergosterol content --- p.111 / Chapter 3.3.2.2.2 --- Protein content --- p.111 / Chapter 3.3.2.2.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.111 / Chapter 3.3.2.2.4 --- DDE removal and removal capacity --- p.112 / Chapter 3.3.2.3 --- Effects of incubation time on the removal of DDE --- p.115 / Chapter 3.3.2.3.1 --- Ergosterol content --- p.115 / Chapter 3.3.2.3.2 --- Protein content --- p.115 / Chapter 3.3.2.3.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.115 / Chapter 3.3.2.3.4 --- DDE removal and removal capacity --- p.116 / Chapter 3.3.2.3.5 --- Putative degradation derivatives --- p.116 / Chapter 3.3.2.4 --- Transcription of the ligninolytic enzyme-coding genes --- p.121 / Chapter 3.4 --- Treatment of DDE by 1st SMC of p. pulmonarius grown on straw-based compost --- p.127 / Chapter 3.4.1 --- Optimization of DDE removal in soil system --- p.127 / Chapter 3.4.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.127 / Chapter 3.4.1.1.1 --- Ergosterol content --- p.127 / Chapter 3.4.1.1.2 --- Protein content --- p.127 / Chapter 3.4.1.1.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.127 / Chapter 3.4.1.1.4 --- DDE removal and removal capacity --- p.128 / Chapter 3.4.1.2 --- Effects of inoculum sizes on the removal of DDE --- p.132 / Chapter 3.4.1.2.1 --- Ergosterol content --- p.132 / Chapter 3.4.1.2.2 --- Protein content --- p.132 / Chapter 3.4.1.2.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.132 / Chapter 3.4.1.2.4 --- DDE removal and removal capacity --- p.133 / Chapter 3.4.1.3 --- Effects of incubation time on the removal of DDE --- p.136 / Chapter 3.4.1.3.1 --- Ergosterol content --- p.136 / Chapter 3.4.1.3.2 --- Protein content --- p.136 / Chapter 3.4.1.3.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.136 / Chapter 3.4.1.3.4 --- DDE removal and removal capacity --- p.137 / Chapter 3.4.1.3.5 --- Putative degradation derivatives --- p.137 / Chapter 3.5 --- Treatment of DDE by crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.142 / Chapter 3.5.1 --- The crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.142 / Chapter 3.5.2 --- Optimization of DDE removal in broth system --- p.143 / Chapter 3.5.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.143 / Chapter 3.5.2.2 --- Effects of amounts of crude enzyme preparations on the removal of DDE --- p.145 / Chapter 3.5.2.3 --- Effects of incubation time on the removal of DDE --- p.147 / Chapter 3.5.2.4 --- Putative degradation derivatives --- p.147 / Chapter 3.5.3 --- Optimization of DDE removal in soil system --- p.151 / Chapter 3.5.3.1 --- Effects of initial DDE concentration on the removal of DDE --- p.151 / Chapter 3.5.3.2 --- Effects of amounts of crude enzyme preparations on the removal of DDE --- p.151 / Chapter 3.5.3.3 --- Effects of incubation time on the removal of DDE --- p.154 / Chapter 3.5.3.4 --- Putative degradation derivatives --- p.154 / Chapter Chapter IV --- Discussions --- p.158 / Chapter 4.1 --- Quantification of the expression of the ligninolytic enzyme-coding genes --- p.158 / Chapter 4.2 --- Artificial cultivation and the expression of the ligninolytic enzyme-coding genes during solid-state-fermentation of edible mushroom Pleurotus pulmonarius --- p.164 / Chapter 4.3 --- Treatment of DDE by living P. pulmonarius --- p.166 / Chapter 4.3.1 --- Optimization of DDE removal in broth system --- p.166 / Chapter 4.3.2 --- Optimization of DDE removal in soil system --- p.169 / Chapter 4.3.3 --- Phylogeny of the ligninolytic enzyme-coding genes --- p.170 / Chapter 4.3.3.1 --- Laccase coding genes --- p.170 / Chapter 4.3.3.2 --- MnP coding genes --- p.175 / Chapter 4.3.4 --- Transcription of the ligninolytic enzyme-coding genes --- p.178 / Chapter 4.4 --- Treatment of DDE by 1st SMC of P. pulmonarius grown on straw-based compost --- p.183 / Chapter 4.4.1 --- Optimization of DDE removal in soil system --- p.183 / Chapter 4.5 --- Treatment of DDE by crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.184 / Chapter 4.6 --- Cost-effectiveness of the bioremediation method --- p.185 / Chapter 4.7 --- Further investigations --- p.194 / Chapter Chapter V --- Conclusions --- p.197 / References --- p.199

Origin and purpose of research Dichloro-diphenyl-trichloroethane or DDT as it is more commonly known, was first used extensively by the armed forces in the Pacific Area during World War II. This insecticide is not only a very toxic contact and stomach poison, but also is quite residual on most types of surfaces. Because of these qualities, it was selected to control the malaria mosquito and thus aided in the conquest of many disease-ridden islands of the Pacific. When DDT became available to the general public after the war, it was found not only to be effective against mosquitoes but also many other types of insects. Among these insects are the alfalfa weevil (Hypera postica hon.) and lygus bugs (Lygus elisus Van D., Lygus hesperus Knight) that had previously impaired the production of alfalfa in Utah and other areas. Although treatment of alfalfa fields is usually confined to alfalfa for seed production, DDT-dusted alfalfa straw and DDT dusted alfalfa hay are fed to farm livestock. In ruminant animals, microorganisms play an important role in the synthesis of protein from nitrogenous non-protein compounds and also aid in the break-down of many complex plant materials so that they may be more fully utilized by these animals. The purpose of this study was to determine the effect of DDT upon the role played by the microflora and fauna of the rumen in the synthesis, digestion and utilization of certain nutrients by dairy calves. Scope Digestion and balance studies were conducted with Holstein bull calves fed different levels of DDT and protein equivalent in the ration. The experiment was designed so that each calf would receive one level of DDT throughout the experiment, and would receive a low protein basal diet plus three additional levels of protein equivalent. These additional protein levels were made up by adding a nitrogenous non-protein compound, urea, to the basal diet to give an increased level of protein equivalent in the diet. The nitrogen, calcium, and phosphorus balance and the digestibility of dry matter, protein, and ether extract were determined.