Biological and economic performance of animal genetic groups under different diets.

A grazing trial to evaluate biological and economic efficiencies for rearing young animals exclusively on pasture from weaning at 7 months of age, with average initial weight of 220 ± 12 kg, to slaughter was conducted from May 2006 to October 2007. Two levels of combined supplementation during the first dry period and four genetic groups (F1 Angus-Nellore; ½Braford-¼Angus-¼Nellore; ½Brahman-¼Angus-¼Nellore; and Charolais- Nellore) were used following a 4 by 2 factorial arrangement and eight replications in a completely randomized design. During both dry periods, eight paddocks of deferred Brachiaria brizantha were utilized. During the first dry period, concentrated mix (CM) and protein-mineral mixture (PMM) were provided in quantities of 0.8% and 0.2% of body weight (BW), respectively, for 142 days. During the subsequent rainy period, the animals were transferred to eight guinea grass paddocks for 197 days. During the second dry period, the animals were allocated to the same eight palisade grass paddocks used during the previous dry season. Steers had received supplementary diet with the same CM used before at 0.8% of BW. Animals supplemented with CM gained more BW than those supplemented with PMM; however, during the rainy season, steers supplemented with PMM performed better than those receiving CM during the preceding dry period. Using concentrate since the first dry season is a risky option in economic terms, as only the Angus-Nellore group showed a positive but small gain.Título em português: Desempenho biológico e econômico de grupos genéticos animais sob diferentes dietas

Eficiências biológica e econômica de bovinos em terminação alimentados com dieta suplementar em pastagem de capim-marandu.

O objetivo deste trabalho foi avaliar as eficiências biológica e econômica de novilhos em terminação, em pastagem, que receberam suplementação durante o período seco. Trinta novilhos ½ Braford ¼ Angus ¼?Nelore, separados em dois lotes com pesos corporais mÚdios (PC) de 365 e 410ákg, foram distribuÝdos em seis piquetes de capim-marandu, em delineamento experimental inteiramente casualizado, com trÛs tratamentos e dez repetiþ§es. Osátratamentos foram constituÝdos pelos suplementos: sal-amireia; 0,6 e 1% do PC de concentrado. Aácada 28 dias, os animais foram pesados, e a cobertura de gordura foi avaliada. Mensalmente, todos os piquetes foram amostrados para determinaþÒo da massa de forragem dos componentes morfol¾gicos e do valor nutritivo. Osáanimais com suplementaþÒo de 1% do PC de concentrado ganharam mais peso do que aqueles com 0,6% do PC, e estes ·ltimos mais do que aqueles que receberam sal-amireia. Consequentemente, houve relaþÒo inversa entre a dose de suplementaþÒo e o tempo necessßrio para os animais atingirem o ponto de acabamento. Independentemente do tratamento, os animais mais leves apresentaram margens lÝquidas superiores. Para os dois lotes, a maior margem lÝquida esteve associada Ó suplementaþÒo apenas com sal-amireia.Título em inglês: Biological and economic efficiencies of steers in finishing period fed with supplementary diet in a palisade grass pasture

Estrutura do dossel de capim-mombaça sob pastejo intermitente.

Comissão organizadora: Grácia Maria Soares Rosinha, Alexandra Rocha de Oliveir, Rodrigo Carvalho Alva

Morphogenetic and structural characteristics of guinea grass pastures submitted to three frequencies and two defoliation severities.

It was evaluated the morphogenic and structural characteristics of guinea grass under rotational at three grazing intervals and two defoliation intensities. Grazing intervals corresponded to the time needed by the forage canopy to reach 90, 95 or 100% of incident light interception during regrowth and they were evaluated combined to two defoliation severities (post-grazing conditions, 25 and 50 cm of height), being allocated to experimental units according to a complete randomized design, with three replicates and 3 × 2 factorial arrangement. The experiment was conducted from July 2003 to May 2004. For evaluation of morphogenetic and structural characteristics, ten tillers per experimental unit were selected. Morphogenetic and structural characteristics were strongly influenced by seasons of the year inasmuch as leaf elongation rate increased 3.5 fold from winter to summer. In addition to year season effect, there was also an effect of defoliation frequencies on tiller population density, which was greater in the defoliation period corresponding to 90% of light interception, especially if evaluated in relation to the interval corresponding to 100% of light interception. Defoliation frequency is determinant in expression of phenotypic plasticit, acting on the control of stem elongation

Morphogenetic and structural characteristics of guinea grass pastures submitted to three frequencies and two defoliation severities.

It was evaluated the morphogenic and structural characteristics of guinea grass under rotational at three grazing intervals and two defoliation intensities. Grazing intervals corresponded to the time needed by the forage canopy to reach 90, 95 or 100% of incident light interception during regrowth and they were evaluated combined to two defoliation severities (post-grazing conditions, 25 and 50 cm of height), being allocated to experimental units according to a complete randomized design, with three replicates and 3 × 2 factorial arrangement. The experiment was conducted from July 2003 to May 2004. For evaluation of morphogenetic and structural characteristics, ten tillers per experimental unit were selected. Morphogenetic and structural characteristics were strongly influenced by seasons of the year inasmuch as leaf elongation rate increased 3.5 fold from winter to summer. In addition to year season effect, there was also an effect of defoliation frequencies on tiller population density, which was greater in the defoliation period corresponding to 90% of light interception, especially if evaluated in relation to the interval corresponding to 100% of light interception. Defoliation frequency is determinant in expression of phenotypic plasticit, acting on the control of stem elongation

Dinâmica do acúmulo de forragem de BRS Zuri, BRS Quênia e BRS Tamani sob mob grazing.

As novas cultivares de Panicum maximum BRS Tamani, Quênia e Zuri foram liberadas para comercialização nos últimos anos. O processo de lançamento comercial de uma cultivar forrageira não engloba pesquisas acerca do manejo da cultivar, baseado no conceito de interceptação de luz pelo dossel, mesmo sendo essa informação relevante para a adoção da cultivar. Assim, o presente projeto foi concebido com o objetivo de avaliar a dinâmica do acúmulo de forragem das cultivares de P. maximum, submetidas a pastejo sob lotação intermitente

Grass and forage research indexed by the Web of Science from 2005 to 2015.

Beef and milk production in Brazil is mainly pasture-based (Assis et al., 2005; ABIEC, 2018; FERRAZ; FELÍCIO, 2010). There is around 160 million ha of pasturelands in Brazil, which represents 45% of the agricultural area (IBGE, 2017). Sown pastures represent around 70% of the total pasture areas and are located mainly in the North, Southeast and Center-West regions of Brazil (IBGE, 2018). Grass and forage research in Brazil has shifted focus along the years. Traditionally, grass and forage research focused mostly on topics related to forage and animal production. Currently, besides the search for increasing production to fulfill a growing worldwide animal protein demand, grass and forage research faces new challenges like land degradation, climate change, competing land use, environmental impacts, including natural resources utilization, deforestation, loss of biodiversity, fragmentation, and loss of habitats, reduction on ?labor force? in rural areas, sustainability, among others. Indicators on science and technology reflect the central tendencies on scientific, technological and innovative activities from a country, institution or knowledge area. The development of specific indicators on science and technology on grass and forage science may be helpful for planning and evaluating activities of research groups and policy-makers alike. Based on specific indicators on science and technology it is possible to identify the main topics and grass and forage science research groups, and also verify if their activity is related to the main problems from the pasturebased animal production sector. This information may contribute to the more efficient use of research resources and to the progress of scientific advance on pasture-based animal production sustainability and competitiveness