Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this research was to evaluate of three pasture-based systems with bermudagrass (BG) + 200 kg of N/ha; BG + 100 kg of N/ha and common vetch; BG + 100 kg of N/ha + forage peanut. The experiment was carried out from May 2011 to may 2012. Holstein cows receiving 4 kg-daily complementary concentrate feed were used in the evaluation. The actual mean value of forage on offer was 7.2 kg of dry matter/100 kg live weight. Herbage mass, botanical and structural composition, daily dry matter accumulation rate, forage production, disappearance of forage mass and stocking rate were evaluated. Nine grazing cycles were performed during the experimental period (365 days). The mean value of forage production and stocking rate were 21.05; 21.8 and 16.1 t/ha; 5.1; 5.3 and 4.5 animal units/ha/day for respective pasture systems. Superior result were found on BG + 100 kg of N/ha + common vetch and BG + 200 kg of N/ha pasture systems. / Objetivou-se com essa pesquisa avaliar três sistemas forrageiros constituídos por capim bermuda (CB) + 200 kg de N/ha; CB + 100 kg de N/ha e ervilhaca comum e CB + 100 kg de N /ha + amendoim forrageiro. O experimento foi realizado entre maio de 2011 e maio de 2012. Para avaliação foram utilizadas vacas em lactação da raça Holandesa, que receberam individualmente 4 kg/dia de concentrado. A oferta de forragem foi de 7,2 kg de matéria seca /100 kg de peso vivo. Foram avaliadas a massa de forragem, a composição botânica e estrutural, a taxa de acúmulo diário de matéria seca, a produção de forragem e o desaparecimento de massa de forragem e a taxa de lotação. Durante o período experimental (365 dias) foram realizados nove ciclos de pastejo. O valor médio da produção de forragem e a taxa de lotação foram de 21,05; 21,8 e 16,1 t/ha; 5,1; 5,3 e 4,5 unidades animais/ha/dia para os respectivos sistemas forrageiros. Resultados superiores foram encontrados nos sistemas forrageiros constituídos por CB+ 100 kg de N/ha + ervilhaca comum e CB + 200 kg de N/ha.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The milk production systems, mostly, use the pastures as the main source of forage for cattle, usually, consisting only of grasses. This strategy simplifies the management of pastures, however, implies high production costs, notably the high use of nitrogen fertilizers. An alternative to become the pasture systems more sustainable is the introduction of forage legumes, allowing a better distribution forage mass over time and reduce fertilizer costs. Thus, the objective of this research was to evaluate of three grazing systems (GS) with elephant grass (EG), Italian ryegrass (IR) and spontaneous growing species (SGS), as GS1 (control); EG + IR + SGS + arrowleaf clover, as GS2; and EG + IR + SGS + forage peanut, as GS3; during a crop year. The elephant grass was established in rows with a distance of 4m between rows. In winter period, Ryegrass was sowed between rows of EG; and considering respective treatments the arrowleaf clover was sowed and the forage peanut was preserved. Lactating Holstein cows were used in the evaluation. Experimental design was completely randomized with three treatments (grazing systems), three replicates (paddocks) with repeated measures (grazing cycles/seasons). Eight grazing cycles were performed during the experimental period (365 days), two in each season. The forage mass, botanical composition; daily accumulation dry matter rate, production and forage intake; grazing efficiency, stocking rate and nutritive value were evaluated. Samples from hand-plucking method were collected to analyze neutral detergent fiber (NDF), crude protein (CP), in situ dry matter digestibility (ISDMD) and total digestible nutrients (TDN). The values of forage mass and stocking rate were 3.46, 3.80 and 3.91 t ha-1 and 2.89, 3.39 and 3.20 animal unit ha-1, respectively for GS. Better results were found on grazing systems mixed with forage legumes. The average of NDF, CP, ISDMD and TDN of EG were 62.4, 61.5 and 60.2 %; 16.7, 16.7 and 18.1 %; 79.6, 79.8 and 79.1 %; 71.4, 71.2 and 69.9 %; and of the forage between rows of EG were 60.3, 60.3 and 52.4 %; 13.7, 15.7 and 19.5 %; 75.0, 72.8 and 81.1 %; 67.9, 65.3 and 72.9 %, respectively for treatments. Higher value of CP, ISDMD and TDN and lower of NDF were observed for the grazing systems mixed with forage peanut, especially on winter. Better results to nutritive value of elephant grass were found on spring. / Os sistemas de produção leiteira, em sua maioria, utilizam as pastagens como base da alimentação dos animais, geralmente, constituídas apenas por gramíneas. Essa prática simplifica o manejo dos pastos, contudo, implica em custos elevados de produção, notadamente pelo uso de adubos nitrogenados. Uma alternativa para tornar os sistemas forrageiros mais sustentáveis é a introdução de leguminosas, possibilitando melhor distribuição de forragem no decorrer do tempo, além de reduzir custos com adubação. Assim, a presente pesquisa teve como objetivo avaliar três sistemas forrageiros (SF) com capim elefante (CE), azevém (AZ), espécies de crescimento espontâneo (ECE), como SF1 (testemunha); CE + AZ + ECE + trevo vesiculoso (TV), como SF2; e CE + AZ + ECE + amendoim forrageiro (AF), como SF3; durante um ano agrícola. O capim elefante foi estabelecido em linhas afastadas em 4m. No período hibernal realizou-se a semeadura do azevém entre as linhas do CE; e considerando os respectivos tratamentos o trevo vesiculoso foi semeado e o amendoim forrageiro, foi preservado. Para avaliação foram usadas vacas da raça Holandesa. O delineamento experimental utilizado foi o inteiramente casualizado, com três tratamentos (SF), três repetições (piquetes) com medidas repetidas (pastejos/estações). Durante o período experimental (365 dias) foram realizados oito pastejos, dois em cada estação. Foi avaliada a massa de forragem, composição botânica; taxa de acúmulo diário, produção e consumo de foragem; eficiência de pastejo, taxa de lotação e valor nutritivo da forragem. Amostras de simulação de pastejo foram coletadas para análise de fibra em detergente neutro (FDN), proteína bruta (PB), digestibilidade in situ da matéria seca (DISMS) e nutrientes digestíveis totais (NDT). Os valores de massa de forragem e taxa de lotação foram de 3,46; 3,80 e 3,91 t ha-1 e 2,89; 3,39 e 3,20 unidades animais ha-1, respectivamente para os SF. Melhores resultados foram obtidos nos sistemas forrageiros consorciados com leguminosas. Os valores médios para FDN, PB, DISMS, e NDT do CE foram de 62,4; 61,5 e 60,2 %; 16,7; 16,7 e 18,1 %; 79,6; 79,8 e 79,1 %; 71,4; 71,2 e 69,9 %; e para forragem presente na entrelinha foram de 60,3; 60,3 e 52,4 %; 13,7; 15,7 e 19,5 %; 75,0; 72,8 e 81,1 %; 67,9; 65,3 e 72,9 %, para os respectivos tratamentos. Maiores valores para PB, DISMS e NDT e menores para FDN foram observados no sistema forrageiro consorciado com amendoim forrageiro, em especial no inverno. Melhores resultados de valor nutritivo para o capim elefante foram obtidos na primavera.

The objective of this experiment was to determine if nutrient utilization and energy partitioning by lactating dairy cows would differ in response to dietary corn grain (CG) types [steam-flaked corn (SFC) vs. high-moisture corn (HMC)] and to test if the types of CG would interact with slow-release urea (SRU) on lactational performance and energy utilization. Eight multiparous Holstein cows (32 ± 8.2 days-in-milk) were used in a duplicated 4 × 4 Latin square with one square consisting of ruminally cannulated cows. A 2 × 2 factorial arrangement was used to test 4 dietary treatments: SFC without SRU, SFC with SRU, HMC without SRU, and HMC with SRU. The experimental diets contained 60.5% dry matter (DM) of forages, whereas 12.9% or 14.4% DM of SFC or HMC was added in the diets, respectively. The SRU was supplemented at 0.46% DM, replacing a mixture of soybean meal and canola meal in a 50:50 ratio. Feeding HMC decreased intakes of DM, crude protein, and fiber compared with SFC. Supplementation of SRU did not affect intakes of DM and nutrients, whereas it tended to increase intakes of DM or increased crude protein intake under SFC but no effect under HMC, leading to CG ×SRU interactions on DM and crude protein intakes. Neither type of CG nor SRU supplementation affected milk production except that cows fed HMC-based diets tended to decrease energy-corrected milk yield compared to those fed SFC-based diets. Utilization of HMC in the diet had a tendency to increase dairy efficiency based on milk yield over SFC utilization. Cows fed HMC diets gained more body weight (BW) than those fed SFC diets, whereas supplementing SRU tended to reduce BW gain regardless of type of CG. Cows fed HMC diets shifted more net energy into BW compared with those fed SFC diets, whereas supplementing SRU tended to decrease a portion of net energy partitioned into BW gain under both SFC and HMC diets. Dietary treatments exerted minor impacts on ruminal fermentation profiles. Feeding HMC diets decreased fecal N excretion compared with SFC diets. In addition, supplementing SRU increased fecal N excretion under SFC, but it was decreased by SRU with HMC, leading to an interaction between CG and SRU. These collective results demonstrate that feeding HMC with SRU can be a practical option in high-forage lactation diets to maintain or improve nutrient and energy utilization efficiency and minimize negative environmental impacts.

Au cours des dernières années, une sélection génétique importante a été faite pour améliorer la production de lait des bovins, ceci au détriment des performances reproductives. Cette diminution de performance n’a cependant pas été rapportée chez la génisse présentant un même potentiel génétique. Cette immense production de lait et les changements métaboliques qui l’accompagnent ont donc un impact négatif sur l’efficacité reproductive des vaches laitières qui subissent un stress métabolique supérieur à celui des génisses. Le but de l’étude était d’acquérir une meilleure connaissance des différences moléculaires et métaboliques entre ces deux groupes d’animaux pour amener à une meilleure compréhension de la pathogenèse de l’infertilité chez la vache laitière. Pour ce faire, les vagues folliculaires de vaches en lactation (30-50 jours en lait; N = 12) et de génisses (N = 10) ont été synchronisées par ablation écho guidée des follicules et par traitement hormonal avec injection de prostaglandine et insertion d’un implant de progestérone. L’aspiration du liquide folliculaire et des cellules de la granulosa du follicule dominant a été faite au jour 6. Les paramètres métaboliques mesurés chez les animaux à partir de prises de sang, faites au jour 6, confirment un plus grand stress métabolique chez la vache, les niveaux de BHBA, acides biliaires et cholestérol étant plus élevés et le niveau de glucose plus bas chez celles-ci. Un total de six échantillons a été utilisé pour le séquençage d’ARN et des analyses bio-informatiques ont été effectuées. Plusieurs gènes et voies de signalisation ont présenté des différences entre les deux groupes d’animaux incluant le cycle cellulaire et la production d’hormones. Une confirmation des résultats par PCR en temps réel a été faite, mais la grande variation intragroupe a nui à l’obtention de résultats significatifs. Conjointement, une culture primaire de cellules de la granulosa a été réalisée pour évaluer l’effet des acides biliaires sur la stéroïdogenèse suite à la détection d’une plus grande quantité de ceux-ci chez la vache laitière. La présence d’acide biliaire dans la culture cellulaire cause une diminution de l’accumulation d’estradiol ainsi que de l’expression des gènes CYP19A1 et CYP11A1. Les résultats présentés dans ce mémoire indiquent une différence potentielle au niveau métabolique et moléculaire des follicules dominants entre la vache laitière et la génisse pouvant avoir une responsabilité dans la diminution de l’efficacité reproductive observée chez la vache laitière. / Over the last fifty or more years, genetic selection has been employed to improve milk production in dairy cattle. This selection was made at the expense of reproductive performance. The observed decrease in fertility does not occur in heifers with the same genetic merit. The enormous milk production and the metabolic challenge that accompany it have a negative impact on the reproductive efficiency due to the metabolic stress of lactation. The purpose of the study was to gain a better knowledge of the molecular and metabolic difference between the two groups of animals in order to better understand the pathogenesis of infertility in dairy cows. To do this, the follicular wave of twelve lactating cows (30-50 days in milk; N = 12) and ten heifers (N = 10) were synchronized by ultrasound guided follicle ablation and by hormonal treatment with injection of prostaglandin-F2α and insertion of a progesterone implant. Follicular fluid and granulosa cells of the dominant follicle were aspirated on day 6. The metabolic indicators BHBA, total bile acids, cholesterol and glucose, were measured in the animals from the blood samples also taken on day 6 confirming greater metabolic stress in the cows when compared to the heifers. A total of six samples were used for RNA sequencing and bioinformatics analyses were performed. Several genes and signaling and cellular function pathways were shown to differ between the two groups of animals, including the cell cycle signaling pathway and hormone production pathway. A confirmation of the results by real-time PCR was undertaken, but the great intragroup variation obviated significant results. In the second set of experiments, primary culture of granulosa cells was conducted to evaluate the effect of bile acids on steroidogenesis to further explore the larger amount of the bile acids in the dairy cows when compared to heifers. The results demonstrate a difference in the metabolic status of the animals; BHBA, total bile acids and cholesterol being higher and glucose being lower in the dairy cow relative to the heifer. Presence of bile acids in the granulosa cell culture caused a decrease in expression of CYP19A1, CYP11A1 and estradiol accumulation. The differences at the metabolic and molecular level of the dominant follicles between dairy cows and heifers may be implicated in the reduced reproductive efficiency of the dairy cows.

The objective of this research was to evaluate three grazing systems with Coastcross-1 (CC) + 100 kg N/ha/year + common vetch; CC + 100 kg N/ha/year + arrowleaf clover; and CC + 200 kg N/ha/year. The experiment was carried out from May 2013 to April 2014. Lactating Holstein cows were used in the evaluation. The grazing method was the rotative stocking, with one day of occupation. Thirteen grazing cycles were performed during the experimental period (313 days). The forage mass, botanical composition, leaf/stem ratio; daily accumulation rate, production and forage intake; grazing efficiency and stocking rate were evaluated. Experimental design was completely randomized with three treatments (grazing systems), three replicates (paddocks) in completely split-plot time (seasons). The average of forage production and stocking rate were 20.8, 17.6 and 19.7 t/ha/year; 7.0, 6.8 e 6.8 animal units/ha/day, respectively. Better results were found on CC + 100 kg of N/ha + common vech and CC + 200 kg of N/ha pasture systems. The presence of the legumes did not affect the structural composition of Coastcross-1, but implies delay in the development of this grass. / Objetivou-se com esta pesquisa avaliar três sistemas forrageiros constituídos por: Coastcross-1(CC) + ervilhaca comum + 100 kg de N/ha/ano; CC + trevo vesiculoso + 100 kg de N/ha/ano e CC + 200 kg de N/ha/ano. O experimento foi conduzido entre maio de 2013 e abril de 2014. Para avaliação foram utilizadas vacas em lactação da raça Holandesa. O método de pastejo utilizado foi o de lotação rotacionada, com um dia de ocupação. Durante o período experimental (313 dias) foram realizados treze pastejos. Foram avaliados a massa de forragem, composição botânica, relação folha/colmo; taxa de acúmulo diário, produção e consumo de foragem; eficiência de pastejo e taxa de lotação. O delineamento experimental utilizado foi o inteiramente casualizado com três tratamentos (sistemas forrageiros), três repetições (piquetes) e parcelas subdivididas no tempo (estações do ano). Os valores médios de produção de forragem e taxa de lotação foram de 20,8; 17,6 e 19,7 t/ha/ano; 7,0; 6,8 e 6,8 unidades animais/ha/dia, respectivamente. Melhores resultados foram encontrados nos sistemas forrageiros constituídos por CC + 100 kg de N/ha + ervilhaca comum e CC + 200 kg de N/ha. A presença das leguminosas não afetou a composição estrutural da Coastcross-1, mas implica em atraso no desenvolvimento dessa gramínea.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this research was to evaluate the productivity and nutritive value of elephant grass pastures, subjected to conventional and organic production system. In the conventional system elephant grass was planted in rows 1.2 m apart from each other. In the organic system elephant grass was planted in rows 3 m apart from each other. In the space between rows, in cool season, annual ryegrass was sown; allowing the development of spontaneous growing species in the warm season. It was applied 100 kg of N/ha from chemical and organic fertilizers (manure of cattle and pig slurry) in the respective pastures. The grazing method was rotated with time to occupy the two days. Holstein cows receiving 0.9% of body weight complementary concentrate feed were used. Pre and post grazing forage mass, botanical and structural composition, forage production and stocking rate were evaluated. Hand-plucked samples were collected to analyze chemical composition and digestibility. Experimental design was completely randomized with two treatments (forage systems), three replicates (paddocks) and repeated measures (mean values of grazing cycles or season). Eight and seven grazing cycles were performed during the experimental period for respective systems. Organic system present best forage distribution thought the year and highest participation of elephant grass leaf blades on herbage mass. The pasture under conventional system presented higher forage mass and stocking rate. Similar value was found in the chemical composition and digestibility of elephant grass pastures in both pasture systems. The organic as much as conventional system showed high qualitative values considering the fertilization, manage and utilization time, in proposed strategy. The results show that the elephant grass can be used under the organic system proposed. / Objetivou-se com esta pesquisa avaliar a produtividade e o valor nutritivo de pastagens de capim elefante submetidas aos sistemas de produção orgânico e convencional. No sistema convencional, o capim elefante foi plantado em linhas afastadas a cada 1,2 m. No sistema orgânico, o capim elefante foi plantado em linhas afastadas a cada 3 m; no espaço entre as linhas, no período hibernal, foi semeado o azevém anual e, no período estival, permitiu-se o desenvolvimento de espécies de crescimento espontâneo. Foram utilizados 100 kg de N/ha com fertilizantes químico e orgânico (esterco de bovino e chorume de suínos) para os respectivos sistemas de produção. O método de pastejo adotado foi o rotacionado, com tempo de ocupação de um ou dois dias, utilizando vacas em lactação que receberam complementação alimentar com concentrado à razão de 0,9% do peso vivo. Foram avaliados a massa de forragem de pré-pastejo e pós-pastejo, composições botânica e estrutural, taxa de desaparecimento, e de acúmulo, produção de forragem e carga animal. Para a determinação da composição química e digestibilidade da forragem, foram retiradas amostras simulando o pastejo. O delineamento experimental foi o inteiramente casualizado com dois tratamentos (sistemas forrageiros), com três repetições (piquetes) e com medidas repetidas (valores médios dos pastejos em cada ciclo ou estação do ano). Durante o período experimental, foram conduzidos oito e sete pastejos para os respectivos sistemas. Na pastagem sob o sistema orgânico, houve melhor distribuição de forragem e maior participação de lâminas foliares do capim elefante na massa de forragem. Na pastagem sob o sistema convencional, verificaram-se maiores valores de produção de forragem e carga animal. Valores similares foram observados quanto à composição química e digestibilidade do capim elefante em ambos os sistemas. Na estratégia proposta, tanto no sistema orgânico quanto no convencional apresentaram teores qualitativos elevados, considerando-se a adubação, manejo e tempo de utilização. Os resultados demonstram que o capim elefante pode ser utilizado segundo o sistema de produção orgânico proposto.