FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Objetivou-se com esse trabalho avaliar os efeitos da intensificaÃÃo da produÃÃo de leite, via nÃveis de intensificaÃÃo do sistema, em pastagens de capim-mombaÃa (Panicum maximum Jacq. cv. MombaÃa) no trÃpico Ãmido, durante o perÃodo das Ãguas. Os tratamentos consistiram de quatro nÃveis de intensificaÃÃo, determinados pela combinaÃÃo de nÃveis de adubaÃÃo e nÃvel de produÃÃo dos animais. Foram eles, na sequÃncia crescente de intensificaÃÃo: 1  adubaÃÃo com 400 kg de NÃha-1Ãano-1, com vacas de baixa produÃÃo; 2 adubaÃÃo com 800 kg de NÃha-1Ãano-1, com vacas de baixa produÃÃo; 3 adubaÃÃo com 400 kg de NÃha-1Ãano-1, com vacas de alta produÃÃo; 4 adubaÃÃo com 800 kg de NÃha-1Ãano-1, com vacas de alta produÃÃo. As vacas eram sem raÃas definidas, em mÃdia de terceira cria, com partos ocorridos em outubro/novembro de 2009. No inÃcio das avaliaÃÃes de produÃÃo de leite, encontravam-se com aproximadamente 110 dias de lactaÃÃo. O perÃodo experimental foi de 24 de dezembro de 2009 a 10 de maio de 2010. Para as medidas relacionadas à morfogÃnese e estrutura, foi utilizado o delineamento inteiramente casualizado, com medida repetida no tempo. Quatro tratamentos, com quatro ciclos e quatro repetiÃÃes (piquetes), avaliando a interaÃÃo entre tratamentos e ciclos. Para a avaliaÃÃo do comportamento dos animais, foi utilizado o delineamento inteiramente casualizado, com quatro tratamentos, oito perÃodos e quatro repetiÃÃes (animais), avaliando a interaÃÃo entre tratamentos e perÃodos. Na avaliaÃÃo da distribuiÃÃo de fezes, foi utilizada a anÃlise geoestatÃstica, com quatro tratamentos e trÃs repetiÃÃes (piquetes). Nas anÃlises de produÃÃo dos animais, foi utilizado delineamento inteiramente casualizado simples (placas de fezes, total de fezes, consumo de forragem e consumo total), com medidas repetidas no tempo (escore de condiÃÃo corporal e peso vivo) e com medidas repetidas no tempo, sendo o tempo medida de controle local (produÃÃo de leite por vaca, peso vivo, taxa de lotaÃÃo e produÃÃo de leite por hectare). O perÃodo de descanso utilizado foi o necessÃrio para que fosse possÃvel a expansÃo de 2,5 novas folhas e o resÃduo equivalente ao IAF residual 2,0. O maior fornecimento de nitrogÃnio nÃo proporcionou elevaÃÃo nas variÃveis TAlF, TAlH, TSFant e TSFpost. NÃo foram observadas diferenÃas entre tratamentos em funÃÃo dos tipos de animais. A TAlF segue, em parte, a disponibilidade de Ãgua oriunda da precipitaÃÃo. NÃo houve diferenÃa na TAlH em funÃÃo dos tratamentos. Esse efeito, sendo reflexo do perÃodo de descanso adotado (2,5 novas folhas à perfilho-1), reduziu o nÃvel de interceptaÃÃo da radiaÃÃo fotossinteticamente ativa para valores inferiores a 95%. A intensificaÃÃo apresenta pouco reflexo nas variÃveis estudadas (MSFT, MSFV, MSLV e MSCV). A altura prÃ-pastejo apresentou crescimento do primeiro para o segundo ciclo e posterior declÃnio atà o Ãltimo ciclo, sendo esse o que apresentou os menores valores, para todos os tratamentos. A elevaÃÃo da oferta de nitrogÃnio proporcionou maiores nÃveis de produÃÃo em determinados momentos, quando da oferta de Ãgua em nÃveis adequados. A disponibilidade de Ãgua influenciou a resposta da produÃÃo das pastagens ao longo dos ciclos. Houve relaÃÃo do teor de matÃria orgÃnica do solo e o desempenho produtivo das pastagens. Quanto ao comportamento dos animais, foi observado interaÃÃo entre os tratamentos e os perÃodos do dia, com exceÃÃo do âcomportamento urinandoâ que sà apresentou efeito de perÃodo. A adubaÃÃo influenciou positivamente no âcomportamento pastejandoâ, elevando o tempo gasto na expressÃo do mesmo. Para Outras atividades, o efeito foi negativo, diminuindo o tempo de deslocamento dos animais. A adubaÃÃo e a interaÃÃo a adubaÃÃo à suplemento proporcionaram maior tempo de utilizaÃÃo de sombra pelos animais. A utilizaÃÃo de alimento concentrado elevou o nÃmero de defecaÃÃes, com concentraÃÃo durante os perÃodos de maior permanÃncia no pasto. O perÃodo do dia influenciou o âcomportamento bebendoâ, causando maior consumo de Ãgua nos perÃodos de maiores temperaturas, assim como os tratamentos intermediÃrios apresentaram maiores consumos. No que se refere à distribuiÃÃo de fezes, os dados apresentaram coeficientes de assimetria positiva e de curtose platicÃrtica. Para o coeficiente de variaÃÃo verificou-se uma elevaÃÃo acentuada, com as Ãreas de descanso, apresentando maiores valores e piquetes com maior nÃvel de adubaÃÃo e menores valores. Os fatores climÃticos radiaÃÃo, temperatura e umidade relativa influenciaram significativamente na dispersÃo e localizaÃÃo das fezes. No que se refere ao grau de dependÃncia espacial (GDE), foi verificado classificaÃÃo, variando de moderado a forte. O alcance foi de 14,0 e 12,7 m para as Ãreas de descanso e piquetes, respectivamente. A adubaÃÃo e o fornecimento de concentrado influenciaram a deposiÃÃo e a perda de nitrogÃnio via fezes, elevando seus valores na medida em que se elevou o aporte nutricional. Observou-se heterogeneidade na deposiÃÃo das fezes, ocorrendo zonas de maior concentraÃÃo, como sombra, entrada de piquetes e malhadouro, mostrando picos de deposiÃÃo que chegaram a 1.051,2 kg de N à ha- à ano- e mÃdia variando de 148,8 a 210,7 kg de N à ha- à ano-Â. Houve crescimento das produÃÃes diÃrias e por Ãrea de leite, na medida em que intensificou o sistema. Com a intensificaÃÃo houve maior persistÃncia da lactaÃÃo, observado por meio da relaÃÃo obtida pela divisÃo do coeficiente angular pelo intercepto, resultando em percentual diÃrio de diminuiÃÃo da lactaÃÃo. A persistÃncia da produÃÃo dos animais respondeu diretamente à intensificaÃÃo do sistema, como reflexo da maior intensificaÃÃo (melhoria da dieta). A produÃÃo por Ãrea respondeu mais fortemente ao nÃvel de produÃÃo individual diÃria e segue comportamento quadrÃtico, de acordo com a distribuiÃÃo das chuvas. A produÃÃo fecal cresceu no sentido do maior nÃvel de intensificaÃÃo, resultando em maiores estimativas de consumo. O maior aporte de nutrientes (mais intensivo) possibilitou elevar os nÃveis de produtividade por animal, por Ãrea, em relaÃÃo à mÃo-de-obra e à produÃÃo total diÃria. A maior intensificaÃÃo possibilitou elevar as receitas, todavia elevou os custos totais mensais, apresentando melhor relaÃÃo nos nÃveis intermediÃrios de intensificaÃÃo. Na medida em que se elevou a Ãrea utilizada, o nÃvel menos intensivo apresentou margem bruta positiva. Os custos operacionais efetivos elevaram-se com a intensificaÃÃo dos sistemas. Jà os custos operacionais totais diminuÃram com a intensificaÃÃo, voltando a crescer no nÃvel mais intensivo. A alimentaÃÃo representou por volta de 70% dos custos operacionais efetivos. Os sistemas apresentaram-se inviÃveis no mÃdio-longo prazo, e no curto prazo, foram menos atrativos que o observado na amostra de produtores utilizada nesse estudo. / This study aimed at analyzing the intensification effects via different enhancement levels of the system of milk production in Mombasa grass pastures (Panicum maximum Jacq. cv. MombaÃa) in the humid tropics, during the water period. Treatments consisted of four enhancement levels, determined by combining fertilization levels and production level of the animals. Treatments were in increasing sequence of fertilization, as follow: 1  fertilization with 400 kg of NÃha-1Ãyear-1, with low yield dairy cows; 2 fertilization with 800 kg of NÃha-1Ãyear-1, with low yield dairy cows; 3 fertilization with 400 kg of NÃha-1Ãyear-1, with high yield dairy cows; 4 fertilization with 800 kg of NÃha-1Ãyear-1, with high yield dairy cows. It was used mixed breed cows, on average of third calving, and the births had occurred in October/November 2009. At the beginning of the evaluation of milk production, the cows had around 110 days of lactation. The experiment was conducted between December 24th, 2009 and May 10th, 2010. For the measures related to the morphogenesis and structure, we used a completely randomized design with repeated measurements over time. Four treatments, with four cycles, and four replicates (paddocks) were used to assess the interaction between treatments and cycles. To evaluate the behavior of the animals, we used a completely randomized design, with four treatments, eight periods and four replicates (animals) to evaluate the interaction between treatments and periods. In the evaluation of the distribution of feces, a geostatistical analysis was applied, with four treatments and three replicates (paddocks). In the analysis of animal production, a simple completely randomized design (feces patches, total feces, forage intake and total consumption), with repeated measures over time (body condition score and live weight) and with repeated measures over time; the time considered the measure of local control (milk yield per cow, live weight, stocking rate, and milk production per hectare). The rest period was the necessary to enable the expansion of 2.5 new leaves and the residue equivalent to the residual leaf area index 2.0 (residual LAI 2.0). The greater supply of nitrogen has not provided increase in the following variables: leaf elongation rate (TAlF), stem elongation rate (TAlH), anterior leaf senescence rate (TSFant) and posterior leaf senescence rate (TSFpost). There was no difference among treatments as a function of the type of animals. The TAlF partly had followed the availability of water from the rainfall. It was observed a variation in the organic matter content throughout the area, reflected in the ability to store water and nutrients, which influenced their availability to the pastures. No difference was detected in TAlH in function of treatments. This effect was a result of the rest period adopted (2.5 new leavesÃtiller-1), reducing the capture level of photosynthetically active radiation to values below 95%. The intensification has little consequence on studied variables (total forage dry mass, green forage dry mass, green leaf blade dry mass, and green stem dry mass). The pre-grazing height presented growth from the first to the second cycle and a subsequent decline until the last cycle, considering that this had the lowest values for all treatments. The increase in nitrogen availability promoted higher yield levels at certain moments, when water was supplied at suitable levels. Water availability influenced the yield response of pasture over the cycles. A relationship was verified between the soil organic matter content and yield performance of pastures. Regarding the animals behavior, it was registered interaction between treatments and day periods, except for urinating behavior that was only affected by the period. The fertilization had positive influence on the grazing behavior, increasing the time spent to expressing it. For the other activities the effect was negative, reducing the displacement time of animals. The fertilization and the interaction fertilization x supplement provided a longer use of shading by the animals. The use of concentrate feed increased the number of defecations, especially during the periods of longer permanence in the pasture. Day period influenced the drinking behavior, leading to a higher consumption of water in the periods with higher temperatures, as well as intermediate treatments presented higher consumption. In relation to the feces distribution, the data had coefficients of positive skewness and platicÃrtica kurtosis. For the coefficient of variation, we verified a great variation, with the rest areas presenting higher values, and paddocks with higher fertilization level presenting the lowest values. Climatic factors radiation, temperature and relative humidity have significantly influenced the dispersal and location of the feces. Regarding the degree of spatial dependence (GDE) it was verified classification ranging from moderate to strong, with higher proportion of GDE. The range was between 14.0 and 12.7m for rest areas and paddocks, respectively. The fertilization and supply of concentrate influenced the deposition and loss of nitrogen via feces, increasing its values to the extent that it increased the nutrient input. We observed heterogeneity in deposition of feces, with areas of higher concentration, as shadow, entrance of paddocks, and rest area, presenting peaks of deposition reaching 1,051.2kg NÃha-ÂÃyear-Â, and average varying between 148.8 and 210.7 NÃha-ÂÃyear-Â. There was increase in milk daily production and per area, as it intensified the system, via enhancement. With the intensification there was a greater persistence of lactation, observed through the relationship obtained by dividing the slope per intercept, resulting in a daily percentage of decrease in lactations. The persistence of animalsâ production responded directly to the system intensification, as a consequence of higher enhancement (improved diet). The production per area responded more strongly to the level of individual daily production and followed a quadratic trend, accompanying the rainfall distribution. The fecal production increased towards the highest level of enhancement, resulting in higher estimates of consumption. The greater input of nutrients (more intensive) allowed elevating the productivity levels per animal, per area, in relation to the labor and total daily production. The increase in area used for production improves the investment/production ratio, decreasing as enlarges the area. The greater enhancement enabled raising the revenues, but also raised the total monthly costs, presenting better relationship the intermediate levels of enhancement. To the extent that it has increased the area used, the lowest intensive level had a positive gross margin. The actual operating costs increased as the systems had been intensified. But the total operating costs decreased with the intensification, increasing again at the most intensive level. The feed represented around 70% of actual operating costs. Systems were unfeasible at medium-long terms, and at short term they were less attractive than observed in the sample of producers used in this study.

Depuis les années 1990, le secteur de l’élevage au Vietnam subit des transformations rapides et profondes. Les productions de viande et de lait sont passées d’un système d’élevage familial intégré aux activités agricoles à un mode plus intensif et largement industrialisé. Les grandes exploitations capitalistiques se substituent progressivement à la petite paysannerie. Cette évolution soulève un certain nombre d’enjeux spatiaux. Le développement des villes, l’implantation des usines d’alimentation animale dans les campagnes, la relocalisation des bassins de production et l’essor de la production de maïs entrainent une réorganisation complète de la géographie de l’élevage au Vietnam. Cette dynamique spatiale est largement méconnue alors même qu’elle s’accélère depuis l’entrée du pays dans l’OMC en 2007. Cette thèse s’intéresse en particulier à trois districts – Thong Nhat, Mai Son et Ba Vi – dans lesquels l’élevage est une composante majeure du développement local. Les principaux résultats de cette thèse montrent que la concentration spatiale des systèmes d’élevage industriel dans un nombre réduit de régions est de fait organisée par un partenariat étroit entre autorités politiques et firmes privées qui privilégient les bénéfices économiques de cette industrialisation. Cependant, les autorités locales et les firmes impliquées peinent à prendre en compte les préjudices à moyen-terme de l’agglomération des systèmes de production sur la durabilité des anthroposystèmes. La gestion des milieux apparait laissée à la charge des communautés locales, et les fonctions de l’agriculture évoluent progressivement vers le recyclage des externalités du système d’élevage industriel. / Since the 1990’s, livestock sector in Vietnam has been deeply changing. Meat and milk productions are mouving from a mixed farming system towards a more intensive and industrialized production model. Concentrated animal feeding operations are progressively replacing small-scale livestock farming. This transition raises specific spatial issues. Expansion of urban areas, location of feed mills in rural areas, relocation of intensive production areas lead to a complete reorganization of the geography of livestock sector in Vietnam. This spatial dynamic is becoming an issue, especially since Vietnam has joined WTO in 2007. This thesis focuses on three districts – Thong Nhat, Mai Son et Ba Vì – where livestock plays a major role in local development. We show that spatial concentration of industrial production systems occurs in a limited number of regions. This dynamics appears to be organized by a close partnership between local authorities and private firms, with a focus on economic benefit. However, those stakeholders seem not to be in condition to manage all medium term impacts of this concentration on anthroposystem sustainability. Most of the challenges related to the Environmental management of industrial livestock systems remains in the hands of local communities. The role of agriculture progressively evolves towards the recycling of industrial livestock systems effluents.