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Resumo: As pastagens naturais, um dos principais ecossistemas do mundo, estão ameaçadas e as espécies nativas são desejáveis quando se trata de restauração. Os principais processos para o sucesso da restauração das pastagens são o estabelecimento das plantas e a adição de sementes no solo. Assim, isso requer a superação das barreiras que impedem a germinação e estratégias de dispersão de sementes. Este trabalho teve como objetivo avaliar o potencial germinativo, tratamentos para superar a dormência de sementes e a dispersão por endozoocoria de espécies nativas forrageiras por bovinos. Sementes de 21 espécies nativas das quatro famílias botânicas mais comuns (Poaceae, Asteraceae, Fabaceae e Cyperaceae) foram coletadas em uma área de pastagem natural (Bioma Pampa) e utilizadas nos experimentos. Experimento I: foi realizada a germinação em condições controladas de todas as espécies e comparada com a da forragem comercial (Paspalum notatum cv. "Pensacola"). Experimento II: foram testados três tratamentos para superação da dormência das sementes (escarificação mecânica e química e priming) em seis espécies. Experimento III: foi avaliada a recuperação, viabilidade e germinação das sementes das espécies nativas Paspalum notatum Flüggé e Desmodium incanum DC em fezes de gado. Os resultados mostram que Paspalum umbrosum Trin. e Saccharum angustifolium Nees apresentam alto potencial germinativo quando comparadas à forragem comercial. Os tratamentos para superar a dormência das sementes aumentaram a germinação de D. incanum, Paspalum plicatulum Michx. e Paspalum dilatatum Poir. A recuperação total de sementes de 15% (P. notatum) e 26% (D. incanum), sem afetar a viabilidade das sementes, mostra que os bovinos são capazes de suprir o banco de sementes do solo com espécies nativas. O potencial germinativo, tratamentos para superar a dormência de sementes e dispersão endozoocórica de espécies nativas forrageiras podem ser explorados na restauração de pastagens naturais. [ABSTRACT FROM AUTHOR]

Natural grasslands, one of the main ecosystems worldwide, are under threat and native species are desired when addressing restoration issues. The main processes for grasslands restoration success are plant establishment and seed addition in the soil. Thus, it requires overcoming barriers that prevent germination and seed dispersal strategies. This study aimed to assess the germination potential, treatments to overcome seed dormancy and endozoochory dispersal of forage native species by cattle. Seeds from 21 native species from the four most common botanical families (Poaceae, Asteraceae, Fabaceae and Cyperaceae) were collected in a natural grassland area (Pampa Biome) and used in the experiments. Experiment I: germination under controlled conditions of all species was carried out and compared to commercial forage (Paspalum notatum cv. "Pensacola"). Experiment II: three treatments to overcome seed dormancy (mechanical and chemical scarification; priming agent) were tested in six species. Experiment III: the recovery, viability and germination of native P. notatum Flüggé and Desmodium incanum DC seeds from cattle faeces were evaluated. The results show that Paspalum umbrosum Trin. and Saccharum angustifolium Nees have high germination potential when compared to commercial forage. The treatments to overcome seed dormancy increased the germination of D. incanum, Paspalum plicatulum Michx. and Paspalum dilatatum Poir. Total seed recovery of 15% (P. notatum) and 26% (D. incanum), without affecting seed viability, show that cattle are able to supply the soil seed bank with native species. Germination potential, treatments to overcome seed dormancy and endozoochory dispersal of forage native species may be exploited in natural grassland restoration. [ABSTRACT FROM AUTHOR]

A supplementation trial was accomplished with rumen fistulated steers with the objective of verifying the coated urea use as a source of nitrogen of slower and uniform release throughout the time, as well as its effect on cellular wall degradability. The treatments were: hay + mineral supplement; hay + protein supplement with common urea; hay + protein supplement with coated urea formula 1; hay + protein supplement with coated urea formula 2. The forage used was Tifton (Cynodon dactylon L.) hay of low quality (CP: 4.62% and NDF: 83.46%). The measures were: ruminal pH and N-NH3, rumen degradability of NDF and ruminal degradation parameters. Effect (P<0.05) of the nitrogen supplementation on ruminal ammonia nitrogen concentration was verified; however the coated urea was not different (P>0.05) from the common urea. The data of ruminal pH and degradability of NDF were not affected by the treatments (P>0.05) when comparing supplemented or not supplemented diets with degradable protein and also when comparing non-protein nitrogen sources. The coated urea was not superior to the common urea, probably due low efficiency of its protection. The coated urea and the degradable protein supplementation had not been efficient in increasing the cellular wall degradability. [ABSTRACT FROM AUTHOR]

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