Resumo Objetivou-se com o presente trabalho determinar o nível de excreção dos microminerais orgânicos cobre, ferro, manganês e zinco adicionados as dietas de frangos de corte em diferentes níveis de inclusão. Os tratamentos consistiram de uma dieta a base de milho e farelo de soja suplementada com minerais na forma inorgânica ou porcentagens de minerais orgânicos: os tratamentos consistiram em dieta basal contendo 0% de microminerais de fonte orgânica (MO), 50% MO, 75% MO e 100% MO. Os níveis de excreção de microminerais orgânicos variaram de forma quadrática em relação aos níveis de inclusão dos minerais orgânicos. Nos níveis de inclusão de 50% e 75% de minerais orgânicos os animais apresentaram os menores níveis de excreção de todos os microminerais avaliados. As variáveis de desempenho não sofreram qualquer influência dos tratamentos, mesmo quando a quantidade de minerais orgânicos foi o equivalente a 50% dos níveis recomendados. A dieta com a inclusão dos microminerais no nível de 50% na forma orgânica se mostrou mais eficiente já que proporcionou os menores níveis de excreção dos microminerais, mantendo o desempenho das aves.

Abstract The aim of this current study was to determine the excretion level of the trace organic minerals copper, iron, manganese, and zinc added to broiler diets at different inclusion levels. The treatments consisted of a corn and soybean meal based diet supplemented with inorganic minerals or levels of organic minerals: basal diet containing 0% of microminerals of organic source (MO), 50% MO, 75% MO, and 100% MO. Excretion levels of organic trace minerals varied quadratically in relation to the inclusion levels of organic minerals. The inclusion levels of 50% and 75% of organic minerals led to animals with lower excretion levels of all trace elements evaluated. The performance variables did not suffer any influence of treatments, even when the amount of organic minerals was equivalent to 50% of the recommended levels. The diet with the addition of trace organic minerals at the level of 50% is more efficient since it provides lower levels of trace minerals excretion keeping poultry performance.

Grazing management strategies affect not only herbage accumulation but also the efficiency of grazing. This study aimed to evaluate herbage accumulation (leaf, stem and dead material), grazing efficiency and losses of mulato grass (a Brachiaria ruziziensis × Brachiaria brizantha cv. Marandu hybrid) subjected to strategies of rotational stocking management. Treatments consisted of combinations between two post-grazing heights (15 and 20 cm) and two pre-grazing conditions (95 % and maximum canopy light interception (LI)) assigned to experimental units (1200-m² paddocks) according to a 2 × 2 factorial arrangement and a randomized complete block design, with four replications. The experiment was carried out from Jan 2008 to Mar 2009. Season of the year influenced almost all studied variables, resulting in a common pattern of response that was determined by pre- and post-grazing management targets. Herbage accumulation was greater on swards managed at 95 %, with higher accumulation of leaves and lower accumulation of stem and dead material in relation to those managed at maximum LI (99 %) during the entire experimental period. On the other hand, herbage removal by grazing was larger on swards managed at 99 % LI, which was compensated for by the smaller number of grazing cycles and larger losses due to grazing under those circumstances. Under rotational stocking, the pre-grazing LI of 95 % and post-grazing height of 20 cm resulted in efficient grazing and high producing leafy pastures, highlighting the potential of Mulato grass pastures for animal production.

Objetivou-se avaliar a produção de forragem e a composição morfológica de uma pastagem de coastcross (Cynodon dactylon, cv. Coastcross) consorciada com amendoim forrageiro (Arachis pintoi, cv. Amarillo) com e sem adubação nitrogenada e submetida a pastejo com lotação continua. Utilizou-se um delineamento experimental em blocos ao acaso com parcelas subdivididas no tempo, com duas repetições, para avaliação das seguintes combinações: coastcross + amendoim forrageiro + 200 kg/ha de N; coastcross + amendoim forrageiro + 100 kg/ha de N; coastcross + 200 kg/ha de N e coastcross + amendoim forrageiro. Para estimar a disponibilidade de massa de forragem e a produção de forragem, foram usadas as técnicas da dupla amostragem e do triplo emparelhamento, respectivamente, a cada 28 dias. Foram avaliadas as proporções de gramínea, leguminosas, invasoras, solo descoberto e liteira. O material da dupla amostragem foi separado em lâmina foliar, bainha+colmo e material morto. A massa de forragem foi menor na pastagem sem adubação com nitrogênio e maior na pastagem adubada com nitrogênio (200 kg/ha) sem amendoim forrageiro. A pastagem sem adubação foi a que apresentou a maior massa de amendoim forrageiro. A produção de forragem foi maior nas pastagens adubadas com nitrogênio na dose de 200 kg/ha, seguidas da pastagem adubada com 100 kg de N/ha. A taxa de acúmulo de forragem seguiu a mesma tendência da produção de forragem. Não foram observadas diferenças para solo descoberto, liteira e área descoberta entre as combinações avaliadas, porém na pastagem adubada com nitrogênio na dose de 200 kg/ha sem leguminosa, houve menor incidência de plantas invasoras. A razão folha/colmo, massa de folhas e massa de material morto não diferiu entre as pastagens, porém aquela adubada com 200 kg de N/ha sem leguminosa apresentou maior massa de colmos.

This experiment was carried out from July 2006 to June 2007. It was used an experimental design of random blocks with split plot in time, with two replications using the following treatments: Coastcross + peanut forage + 200 kg/ha of N; Coastcross + Peanut Forage + 100 kg/ha of N; Coastcross + 200 kg/ha of N and Coastcross + Peanut Forage in the following seasons: winter, spring, summer and autumn. To estimate the forage mass production availability, the double sampling and triple pairing technique, respectively, every 28 days was used. The proportions of grass, legumes, weeds, uncovered soil and litter were evaluated. The material from the double sampling technique was separated into leaf blade, stem + sheath and dead material fractions. Regarding of forage availability, the pasture submitted to treatment without nitrogen had the lower mass, while that submitted to 200 kg/ha of nutrient without the presence of legume had the highest forage mass. For the peanut forage mass, the pasture without fertilization presented the best result. The forage production was higher in pastures submitted to treatment with 200 kg of N/ha followed by that fertilized with 100 kg of N/ha. The grass accumulation rate followed the same trend of forage production. No difference were observed for uncovered soil, litter and uncovered area between treatments; however, the pasture submitted to the dose of 200 kg of N/ha without legume presented lower incidence of invasive plants. No differences were observed for the leaf/stem ratio, leaves mass and dead material mass between treatments; however, the grass submitted to 200 kg of N/ha without legume presented the greatest stems mass.