Master of Science / Department of Animal Sciences and Industry / Evan C. Titgemeyer / Two experiments quantified effects of supplemental protein and energy on forage digestion and urea kinetics in beef cattle. In experiment 1, energy treatments included: control, 600 g glucose dosed ruminally once daily, and 480 g VFA infused ruminally over 8 h daily. Casein was dosed ruminally once daily (120 or 240 g). Cattle (208 kg) had ad libitum access to low-quality hay (5.8% protein). Infusion of VFA decreased forage intake by 27%. Glucose decreased NDF digestibility. Microbial N flow was greater for 240 than for 120 g/d casein, but was not affected by energy. Retained N increased with casein supply. Urea-N entry rate (UER) and gut entry of urea-N (GER) were not affected by energy, casein, or interactions, but GER/UER was less when 240 rather than 120 g/d casein was provided. Compared to VFA, glucose tended to increase GER/UER. Glucose led to more microbial uptake of recycled urea than VFA. In these young calves, changes in N and energy supply did not greatly impact urea kinetics, likely because increased N was largely retained. In experiment 2, treatments included: 0 or 1.2 kg glucose, and 240 or 480 g casein. Cattle (391 kg) were fed low-quality hay (4.7% protein). Glucose reduced forage intake by 18%, whereas casein did not affect it, and depressed fiber digestion. Microbial N flow to the duodenum and retained N increased as casein increased, but neither was affected by glucose. Increasing casein increased UER 50%. Urinary urea-N increased as casein increased; moreover, GER numerically increased 25% as casein increased. GER/UER decreased as casein increased. Glucose decreased urinary urea, but did not change UER or GER. Microbial uptake of recycled urea was least for steers receiving 480 g/d casein with no glucose, reflecting that this treatment exceeded ruminal requirement for N. In these more mature steers, increases in N intake increased UER, reflecting that only small proportions of the increased N intake were retained. Thus, as steer maturity increased, UER and GER increased, likely because less N was retained. These studies demonstrate the influence of urea recycling in meeting N needs of cattle fed low-quality forage.

Master of Science / Department of Chemistry / Mark D. Hollingsworth / Most urea inclusion compounds (UICs) are known to share a common packing arrangement in which the urea host forms helical ribbons held together by hydrogen bonds to form a series of linear, hexagonal tunnels. Because UICs can encapsulate a wide variety of linear guest molecules, they serve as useful model systems for probing mechanisms of crystal growth and molecular recognition. In this thesis, the syntheses (or attempts thereof) of six compounds that will serve as consequential guest molecules in studies of UICs are presented. These compounds are (5S,6S)-2,9-decanedione-d2, 1,6-dicyanohexane-1,1,6,6-d4, 1,11-undecanedioic acid, bis(3-oxobutyl) adipate, 2,16-heptadecanedione, and 2-eicosanone. With the exception of (5S,6S)-2,9-decanedione-d2, whose synthesis remains incomplete, detailed synthesis and crystal growth of the UICs of these compounds are discussed. Ongoing studies with the UICs containing these guests include the determination of the absolute configuration of UICs, the study of guest conformer population changes via solid-state NMR, the development and identification of novel ferroelastic UICs, and the classification of guest ordering in a series of alkanedione UICs.

Faculty of Health Scicence School of Medicine 0100107g johannes.geyer@wits.ac.za / The 14C and 13C labelled urea breath tests (UBT) for detecting Helico-bacter pylori infection are well established but scope for improvement exists in both to reduce some of their shortcomings. For this study, the 14C UBT investigation focussed on reducing the quantity of radioactive tracer that is administered to the subject un-dergoing this test, with the aim of lowering the radiation dose to the patient, reducing the impact to the environment and exempting the test from radioactive materials licensing. Wider acceptance, availabil-ity, affordability to lower socio-economic groups and third party medi-cal treatment payers and using readily available equipment were fac-tors considered when developing the method. The principle of the method developed is to collect larger volume breath sample, quantitatively absorbing a defined volume of extracted breath CO2 in an efficient CO2 trapping agent using a specifically de-signed apparatus and measuring the activity with a low background β-spectrometer. A reduction in the quantity of 14C labelled urea administered to the pa-tient was achieved. The method also reduced the counting error mar-gin at a lower detection limit, improving discrimination between H. py-lori positive and negative patients. iii The 13C UBT is a non-radioactive test however, it is substantially more expensive. The 13C UBT investigation aimed to determine whether commercially available un-enriched urea could be used thus reducing the cost of the 13C UBT. A simple protocol with Isotope Ratio Mass Spectrometry (IRMS) for the measurement was used as opposed to the well-established 13C UBT protocol. The principle of the 13C UBT investigation was to detect the change of the breath δ13C (13C/12C) ratio after the administration of un-enriched urea with a δ13C different to the exhaled breath. Theoretical calculations showed that an administered dose of 500mg un-enriched urea with at least a 10‰ δ13C difference may be detectable using IRMS. In vitro investigations confirmed that levels of 0.01 to 0.001‰ δ13C were detectable by IRMS. A change in the δ13C of a standard breath CO2 was confirmed for a range between 0.14 to 50% v/v mixed CO2 samples, i.e. the projected range for in-vivo investigation. Results from the in-vivo investigation however were not able to distinguish positive from negative H. pylori patients. The use of the 1000mg dose of urea appears to have caused saturation of the enzyme. It was con-cluded that some enrichment of the 13C is necessary or less urea be used.

Tabelas de estágio embrionário podem ser utilizadas para detectar semelhanças e diferenças de caracteres entre grupos e como ferramenta para estudos baseados na fase embrionária. Neste estudo, ovos do lagarto Iguana iguana foram utilizados para a elaboração de uma tabela de estágios e para determinar o padrão de excreção durante o desenvolvimento. Iguana é um modelo conveniente por produzir numerosas desovas de ovos de tamanho grandes, propiciando um fácil manuseio e um bom número de réplicas. Após a oviposição, 18 estágios embrionários foram determinados durante os quais uréia foi o resíduo nitrogenado principal. Apesar do iguana ser o primeiro lagarto estudado, o padrão ureotélico é comum entre a maioria das espécies reptilianas estudadas até o momento. A casca pergaminácea permite que os ovos dobrem em massa devido à absorção de água, e o mecanismo pelo qual os embriões lidam com a diluição e osmolaridade resultante é um tema interessante para futuros trabalhos e comparações com espécies de cascas rígidas. Há evidência de desenvolvimento heterocrônico dos membros e o desenvolvimento de iguana é similar ao do lagarto Anolis sagrei, também do clado Iguania. Mais estudos de desenvolvimento de lagartos são necessários e a utilização de critérios morfológicos similares para facilitar a comparação de eventos embrionários. / A Table of embryonic stages can be used to detect similarities and differences in developmental features between groups and as a tool for studies based on embryonic phase. In this study, eggs of the lizard Iguana iguana were used to elaborate a staging table and to determine the nitrogen excretion pattern during the development. Iguana is a convenient model for having a large clutch of large eggs, allowing an easy handling and a good number of replicates. After oviposition embryonic stages were determined during which urea was the main nitrogen waste. Although iguana is the first lizard studied, the ureotelic pattern is common among the majority of reptilian species so far studied The pergaminaceous shell allows that the eggs double in mass due to water absorption, and the mechanism and how the egg deals with dilution and resultant osmolarity is an interesting issue for future works and comparisons with species of rigid eggshells. There is evidence of heterocronic development of the limbs and the development of iguana is similar to the lizard Anolis sagrei, also from the clade Iguania. Further studies on lizard evelopment are required and the use of similar morphological approach to facilitate comparisons of embryonic events

A utilização de uréia na alimentação de fêmeas bovinas pode prejudicar o desempenho reprodutivo destes animais, provavelmente decorrente do aumento do teor de nitrogênio uréico plasmático (NUP). O objetivo deste estudo foi avaliar se alimentação com uréia por curto prazo oferecida a novilhas, e conseqüente aumento de NUP, exerce influência sobre a quantidade, qualidade e competência dos complexos cumulus-oócito (CCO). O experimento teve duração de 62 dias, dividido em oito semanas e dois períodos. Foram utilizadas 40 novilhas mestiças mantidas a pasto, alocadas a dois tratamentos, utilizando-se delineamento \"cross-over\": dieta sem uréia (SU): 5 kg (matéria original) de silagem de milho e 1 kg de concentrado/animal/dia ou dieta com uréia (U): 5 kg de silagem de milho e 1 kg de concentrado contendo 75 g de uréia/animal/dia. Os animais selecionados a cada semana receberam as dietas por seis dias, uma única vez ao dia. No sexto dia de oferecimento das dietas, foram realizadas aspiração folicular (OPU) e colheita de sangue, em jejum e 3 horas após a alimentação. Imediatamente após a OPU, foi realizada contagem total de CCO recuperados e classificação dos mesmos em viáveis e inviáveis. Apenas os viáveis foram destinados à produção In vitro de embriões. Em relação ao teor de NUP, houve efeito de interação entre tratamento e tempo de colheita (P=0,04) e dentro de cada tempo foi observado aumento significativo (P<0,01) para os animais do tratamento U. Não foi observado efeito de tratamento em relação ao número total de CCO recuperados por animal (média ± EPM: SU=9,15 ± 0,82 vs. U=8,82 ± 0,95), nem sobre a porcentagem de CCO viáveis sobre total de CCO recuperados por animal (SU=73,61% ± 2,47 vs. U=70,26% ± 2,31). A taxa de clivagem obtida no dia 3 após a inseminação In vitro (IIV) e as taxas de blastocisto nos dias 6, 7 e 9 após a IIV, não foram influenciadas pelo tratamento. Porém, no 11º pós IIV, houve diminuição (P=0,04) da taxa de blastocistos eclodidos para o tratamento U (SU=82,50% ± 0,05 vs. U=64,33% ± 0,07). Apesar do aumento do teor de NUP observado nas novilhas do tratamento U, a quantidade, qualidade e competência dos CCO durante as primeiras clivagens até atingirem o estádio de blastocisto In vitro não foram influenciadas pelo oferecimento de 75 g de uréia na dieta, durante seis dias. Porém, foi observada redução da taxa de eclosão dos blastocistos das novilhas do tratamento U. / Urea feeding offered to bovine dams may damage their reproductive performance, probably due to an increase in levels of plasmatic urea nitrogen (PUN). The aim of this study was evaluate if short-term urea feeding of heifers, following high PUN levels, would have an influence on the quantity, quality and competence of cumulus-oocyte complexes (COC). Trial lasted 62 days, divided into eight weeks and two periods. Forty crossbred grazing heifers were allocated to one of two treatments, using a cross-over design: diet without urea (WU): 5 kg (as fed) of corn silage and 1 kg of concentrated/animal/day, or diet with urea (U): 5 kg of corn silage and 1 kg of concentrated with 75 g of urea/animal/day. Heifers selected in each week received these diets once a day, for six days. On the sixth day of diets? offer, ovum pick-up (OPU) and blood sampling at fasting and 3 hours after feeding were carried out. Immediately after OPU, total COC recovered was counted and classified as either viable or unviable. Only viable were destined to In vitro embryo production. In relation to PUN level, there was a significant interaction between treatment and sampling time (P=0.04) and a significant (P<0.01) increase in animals undergoing U treatment for each of the test times. No significant effect was observed relative to either the total number of recovered COC per animal (mean ± SEM: WU=9.15 ± 0.82 vs. U=8.82 ± 0.95), or the viable COC as a percentage of total recovered COC per animal (WU=73.61% ± 2.47 vs. U=70.26% ± 2.31). Cleavage ratio assessed on day 3 post In vitro insemination (IVI) and blastocyst ratio on days 6, 7 and 9 post IVI were not influenced by treatments. However, there was a significant treatment effect (P=0.04) in relation to hatched blastocysts on day 11 after IVI (WU=83% ± 0.05 vs. U=64% ± 0.07). Even though higher PUN levels were observed in animals from treatment U, quantity, quality and competence of the COC during first cleavages until reaching the blastocyst stage In vitro were not influenced by adding 75 g of urea on the diet offered to heifers, during six days. Neverthless, a decline in hatched blastocysts rate was observed in heifers of treatment U.

Para comparar o risco de intoxicação por uréia granulada (G) e extrusada (E) 24 garrotes, nunca alimentados com uréia, foram distribuídos em quatro grupos de seis animais, onde foi administrada, de uma só vez, (G) ou (E) em duas diferentes doses: alta (A; 0,5 g/kg PV) ou padrão (B; 0,22 g/kg PV). Em seguida, foram acompanhados o pH e os teores de amônia no rúmen, as concentrações sangüíneas de amônia, uréia, creatinina, glicose, lactato-L, potássio, as atividades de gama glutamiltransferase, aspartato aminotransferase e creatina quinase, perfil hemogasométrico e hematócrito, além de acompanhamento quadro clínico no decorrer de 240 min após as administrações de G ou E. Alguns animais dos grupos GB e EB tiveram um discreto quadro de intoxicação, se recuperando sem quaisquer tratamentos. Por outro lado, cinco garrotes de ambos grupos GA e EA tiveram severo quadro tóxico que exigiram tratamento, sendo que um animal GA sucumbiu. A velocidade de hidrólise ruminal da uréia G e E foi semelhante, embora as manifestações clínicas tenha sido iniciadas mais tardiamente no grupo EA. Quanto mais intensa foi a hiperamoniemia mais destacada foi o grau de acidose metabólica, desidratação, a glicólise anaeróbica e a gliconeogênese. Pela análise das atividades enzimáticas comprovou-se que os danos bioquímicos foram intensos na musculatura, mas não nos hepatócitos. Concluiu-se que tanto a uréia G como E quando oferecidas subitamente, em especial em doses altas, podem oferecer igual risco de intoxicação por amônia. / To compare the toxicity potential of prilled urea (G) and extruded grain with urea (E), both were administered all at once in two different doses, high (A; 0,5 g/kg BW) or standard (B; 0,22 g/kg BW), to 24 steers divided into four groups of six animals, which had never been fed nonprotein nitrogen compounds. For 240 min after the administration of urea the following variables were determined: rumen fluid pH and ammonia level, blood ammonia, urea, creatinine, glucose, L-lactate, potassium, and activities of gama glutamiltranspeptidase, aspartate aminotransferase and creatine kinase, haemogasometric profile and hematocrit. The clinical picture was also followed. Some steers from groups GB and EB showed slight signs of ammonia toxicity, overcoming it without treatment. On the other hand, five steers from either groups GA and EA showed severe signs of ammonia toxicity that required treatment; even though one animal from group GA succumbed. The speed of ruminal urea hydrolysis of G and E was similar, although the clinical signs started later in group EA. The higher the hyperammonemia, the higher the metabolic acidosis, dehydration, anaerobic glycolysis and gluconeogenesis. The enzymatic profile showed that biochemical damage occurred in the striated muscular tissue, but not in the hepatocytes. The results showed that both G and E had similar potential to cause ammonia poisoning, principally when high doses were administered all at once.

Esta pesquisa foi realizada para avaliar criticamente a recomendação clássica proposta por Huber (1978), que há necessidade de se promover novo período de adaptação à uréia dietética se os bovinos se abstiverem de receber este nutriente por mais de três dias. Vinte e cinco garrotes foram alimentados com dieta baixa em proteína bruta (10%) e sem uréia dietética e em seguida distribuídos aleatoriamente em cinco grupos iguais, ou seja: controle (O) dieta basal; grupos A, B, C e D alimentados durante 21 dias com a dieta basal e uréia (1% MS). Todos os grupos foram desafiados com uma infusão intravenosa de solução de cloreto de amônio (1,5 M) até o surgimento da convulsão, quando esta foi interrompida. O desafio no grupo A ocorreu no 22o dia do recebimento de uréia; nos grupos B, C e D os desafios foram respectivamente nos dias 4, 15 e 30 dias da abstinência da uréia dietética. O exame clínico e a coleta de amostras de sangue e urina total foram realizados durante a infusão e nas três horas seguintes. Os animais adaptados à uréia (A, B, C e D) necessitaram de maior quantidade de cloreto de amônio para manifestarem convulsão (p<0,001), e demoraram mais para exibirem este sintoma que o grupo controle. Em relação ao grupo controle, os garrotes adaptados, com exceção do grupo C, tiveram um quadro clínico mais brando, se recuperaram mais prontamente e não necessitaram de tratamento médico após o término do experimento. Isto ocorreu devido a maior queda na concentração de amônia sangüínea, causada por uma maior atividade do ciclo da uréia, maior volume urinário e eliminação de amônio neste. Demonstrou-se ainda que a maior produção e eliminação de uréia pelos rins provocou maior diurese, que por sua vez estimulou maior excreção de amônio pela urina, aumentando a eficiência de desintoxicação, especialmente no momento mais crítico do quadro (até uma hora pós-convulsão). Concluiu-se que os animais alimentados previamente com uréia e com abstinência desta na dieta por até um mês não necessitam de novo período de adaptação, contrariando o axioma preconizado por Huber (1978). / This study was carried out to investigate the recommendation stated by Huber (1978) that there is a need to re-adapted cattle that were fed previously with dietary urea, but subsequently were deprived of this nutrient for more than 3 d. Twenty four steers fed a low crude protein ration, deprived of urea, were randomly distributed into 5 equal groups, and were fed as follows: O (control; basal diet); the remaining groups (A,B, C and D) were fed the basal diet + urea (1% D.M.) for 21 d; afterwards the groups B,C and D were fed only the basal diet for 4, 15 and 30 d, respectively. Thereafter, all steers were challenged with an intravenous infusion of ammonium chloride (1.5 M) up to the outcome of convulsion when the infusion was stopped. Throughout the infusion and for 3 h later clinical examination was carried out; blood samples and whole urine were also collected. The steers adapted to urea (A,B,C and D) needed a greater amount of ammonium chloride to cause convulsion (p < 0.001) and took longer to exhibited this symptom than the control group. As compared to the control, all the adapted groups, but the C, had a less severe clinical picture and recovered sooner, and did not require any medical treatment after the end of the experiment. This resistance was due a faster fall in the blood ammonia level, caused by a greater activity of the urea cycle, excretion of a higher excretion of ammonium and urinary volume. It was demonstrated that the higher the production and excretion urea by the kidneys, the greater the diuresis, that by its turn increased the excretion of ammonium into the urine improving the efficiency of detoxification, principally at the most critic moment of the poisoning (from the convulsion up to 1st h later). It was concluded that cattle fed previously with urea and afterwards restricted of urea for up to 30 d do not require a new re-adaptation period, contradicting Huber\'s axiom.

No description available.

Apesar do ambiente epifítico ser caracterizado como bastante desfavorável para o desenvolvimento de vegetais devido à falta intermitente de água e escassez de nutrientes, uma grande diversidade de bromélias o ocupam com sucesso. Uma série de características adaptativas, tanto morfológicas, anatômicas e fisiológicas, está presente nessas plantas e as capacitam a utilizar com grande eficiência os recursos disponíveis de maneira escassa e temporária. O enfoque deste trabalho foi direcionado à compreensão das estratégias adotadas pela bromélia epífita com tanque Vriesea gigantea para a utilização da ureia, uma fonte de nitrogênio não usual para a maioria das plantas terrestres. Em decorrência da frequente associação com anfíbios em ambiente natural, a ureia é um recurso disponibilizado ocasionalmente e durante um curto período na água do tanque. Foram isolados 2 cDNAs completos de aquaporinas potencialmente envolvidos no transporte de ureia: VgPIP1,5 e VgTIP2, que codificam proteínas de membranas plasmática e de tonoplasto, respectivamente. Ambos os genes tiveram expressão mais acentuada nas bases foliares e foram pouco afetados pelo regime de luz. Além disso, a expressão desses genes foi estimulada na presença de ureia, o que não foi observado para em relação às fontes inorgânicas amônio e nitrato. A assimilação de ureia pareceu ser, em grande parte, dependente de hidrólise prévia em NH4+ e CO2, reação essa catalisada pela urease. Foi demonstrado que ambos os produtos dessa reação são incorporados rapidamente, formando aminoácidos (principalmente via GDH, GS/GOGAT e subseqüentes transaminases) e esqueletos carbônicos Infelizmente, a incorporação direta de ureia via reação inversa da arginase não foi confirmada, embora esse resultado possa estar relacionado a limitações metodológicas para a análise de arginina. Ainda assim, evidências sugerem que, se não pela arginase, outras vias alternativas de assimilação direta de ureia possam estar envolvidas. Além da sua importância da urease na hidrólise citossólica de ureia, foi demonstrada, de forma inédita em plantas, a presença dessa enzima nas frações de membranas e parede celular de V. gigantea. É muito provável que, além da capacidade de secreção da urease para a região do tanque, a presença dessa enzima em regiões próximas à superfície celular torne mais rápido e eficiente o processo de assimilação de ureia pelas células. Embora seja caracterizada como um recurso de disponibilidade ocasional e de curta duração e por ser alvo de intensa competição interespecífica, a ureia ainda assim é a fonte de N preferencial para Vriesea gigantea. É provável que um dos motivos que levou essa espécie a utilizar preferencialmente a ureia seja a vantagem de se obter, simultaneamente, tanto carbono quanto nitrogênio, ambos presentes em quantidades limitantes no seu habitat natural. / Although the growth conditions in epiphytic habitats are unfavourable for plant growth due to water and nutrient limitations, a great diversity of bromeliads successfully occupy this environment. These plants have evolved a variety of morphological, anatomical and physiological adaptations allowing them a highly efficient use of available resources. The main objective of the present work was to elucidate the strategies of the epiphytic tank bromeliad Vriesea gigantea to utilize urea, a nitrogen source generally considered to be uncommon for most terrestrial plants. Although in natural environments urea is frequently excreted by amphibians that are associated with the tank of these plants, the availability of this nitrogen source is nevertheless short-lived and unpredictable. Two complete cDNA sequences encoding plasma membrane and tonoplast aquaporin proteins, which are potentially involved in urea transport, were isolated from leaf tissues of Vriesea gigantea: VgPIP1,5 and VgTIP2, respectively. Both genes were mainly expressed in the leaf bases and were not affected by light conditions. Moreover, the expression of these aquaporins was stimulated in the presence of urea in the culture medium, while no effect was observed with ammonium and nitrate as nitrogen source. Urea assimilation is thought to be strongly dependent on precedent hydrolysis of urea to NH4+ and CO2 mediated by urease. Both products of this reaction were quickly assimilated and incorporated into amino acids (mainly via GDH, GS/GOGAT and subsequent transaminases) and carbon skeletons. On the contrary, the direct incorporation of urea via a reverse reaction of arginase could not be confirmed due to the methodological limitation of analyzing double-labelled (13C-,15N-) arginine. However, there is strong evidence suggesting that arginase or other alternative assimilation pathways may be involved in urea assimilation. Despite the importance of urease in the cytosolic hydrolysis of urea, the present work demonstrates for the first time that this enzyme is present in both, membrane and cell wall fractions of V. gigantea. Consequently, besides the capacity of this plant to excrete urease into the tank water, the close association of this enzyme to urea uptake regions could further increase the rate and efficiency of urea assimilation by plant cells. Although urea is characterized as an occasional and only short-lived nutrient source, which is furthermore subject to intense interspecific competition, urea can be considered to be a preferential nitrogen source for Vriesea gigantea. One reason for the preferential use of urea could be the advantage of simultaneously gaining carbon and nitrogen, two limiting resources in the natural habitat of epiphytic bromeliads.

Resumo: O objetivo do trabalho foi analisar o Ajifer L40 como fonte alternativa de fertilizante nitrogenado na produção de matéria seca, nutrientes da folha e atributos químicos do solo da Brachiaria brizantha cv. Xaraés (capim-Xaraés). O experimento foi conduzido em área do Sindicado Rural no município de Araçatuba, localizado na região da Alta Noroeste do Estado de São Paulo, no período de outubro de 2005 a maio de 2009 em solo classificado como Latossolo Vermelho Amarelo. O delineamento experimental foi em blocos casualizados com 10 tratamentos e três repetições. Os tratamentos foram arranjados em esquema fatorial 3 x 3 + 1, sendo três doses de nitrogênio (100, 200 e 400 kg ha-1 ano-1) e três fontes (uréia, sulfato de amônio e Ajifer L40) e um tratamento adicional (testemunha com dose 0 de N). Os fertilizantes apresentaram resposta máxima média dos quatro anos de avaliação na dose de 322 kg ha-1 de N. O teor de proteína bruta na parte aérea do capim-Xaraés foi linearmente crescente até a dose de 400 kg ha-1 de N para as três fontes estudadas. O Ajifer L40 e o sulfato de amônio foram importante fonte de enxofre para a nutrição das plantas. As fontes nitrogenadas Ajifer L40 e sulfato de amônio apresentaram comportamento semelhante, proporcionando maior acidez na camada superficial do solo em relação à fonte uréia. A utilização dos fertilizantes Ajifer L40, sulfato de amônio e uréia não alterou a concentração de sódio e a condutividade elétrica no solo. A fonte alternativa Ajifer L40 é similar às outras fontes de fertilizantes convencionais / Abstract: The aim was to evaluate the Ajifer L40 as an alternative source of nitrogen fertilizer on dry matter production, leaf nutrients and soil chemical properties of Brachiaria brizantha cv. Xaraés (Xaraés-grass). The experiment was conducted in Syndicate Rural area in the municipality of Araçatuba, located in Upper Northwest of São Paulo, from October 2005 to May of 2009 in a soil classified as Latosol Yellow Red. The experimental design was randomized blocks with 10 treatments and three replications. The treatments were arranged in a 3 x 3 + 1, three nitrogen levels (100, 200 and 400 kg ha-1 yr-1) and three sources (urea, ammonium sulfate and Ajifer L40) and an additional treatment (control dose of 0 N). Fertilizers showed a mean maximum of four years of evaluation at a dose of 322 kg ha-1 N. The crude protein content in leaves of Xaraés-grass was increasing linearly with doses up to 400 kg ha-1 of N for the three sources studied. The Ajifer L40 and ammonium sulfate were an important source of sulfur for plant nutrition. The nitrogen sources, Ajifer L40 and ammonium sulfate were similar, providing greater acidity in the topsoil is in relation to urea. The use of fertilizers Ajifer L40, ammonium sulfate and urea did not alter the concentration of sodium and electrical conductivity in the soil. The alternative source Ajifer L40 is similar to other conventional sources fertilizers / Orientador: Cecílio Viega Soares Filho / Coorientador: Reges Heinrichs / Banca: Ana Cláudia Ruggieri / Banca: Sílvia Helena Venturoli Perri / Mestre