Objetivou-se com esta revisão abordar os principais fatores que afetam as características morfogênicas e estruturais de plantas forrageiras. Dentro do sistema agropecuário brasileiro, predomina-se a criação de animais a pasto. Devido às condições favoráveis do território nacional, é possível produzir diversas espécies de plantas forrageiras. Neste sentido, o entendimento do comportamento do ecossistema de forragem frente às variações dos recursos naturais se torna uma ferramenta capaz de auxiliar na elaboração de metas de manejo sustentáveis. A morfogênese é utilizada para mensurar o aparecimento e expansão dos órgãos vegetais através do fluxo de tecidos que ocorrem dentro do dossel forrageiro. De maneira geral, as características estruturais de um dossel forrageiro dependem das características morfogênicas da espécie, que são determinadas geneticamente. No entanto, essas caraterísticas sofrem influência direta de fatores abióticos e bióticos que alteram o padrão de crescimento dessas plantas. Ademais, através da avaliação dos processos morfogenéticos envolvidos no ecossistema de pastagem, é possível elaborar metas de manejo sustentável do dossel forrageiro, contribuindo para elevar a produtividade dos sistemas agropecuários do Brasil.

The aim of this study was to evaluate the effects of protein-energy or mineral supplementation on the ingestive behavior of dairy steers on pasture in the post-weaning phase during the rainy to dry season transition. Twenty-two ½ Holstein–Zebu dairy steers with an average initial body weight of 234 ± 16 kg were distributed into a completely randomized design into two groups: protein-energy supplementation and mineral supplementation offered ad libitum. The steers receiving protein-energy supplementation showed higher (P < 0.05) intake of dry matter (DM) and neutral detergent fiber (NDF) than those fed diets composed of mineral salt only. In addition, the animals that received protein-energy supplementation had longer period in grazing and spent on average more time per period eating at the trough (P < 0.05), however no significant differences were observed in the time per period in rumination and time per period in idle (P > 0.05). The supply of protein-energy supplement does not change the feeding behavior, except for an increase in the time spent feeding at the trough. The intake of protein-energy supplement improved the of DM and NDF feed efficiencies in grazing cattle during the rainy to the dry season transition.

It is necessary to increase the rates of initial growth of pastures for use during the better planting period. Thus, two experiments were used to evaluate the effect of plant growth regulator (PGR; auxins, gibberellins and cytokinins) in seeds types (coated with polymer coating fungicide and conventional method) and nitrogen fertilization methods in Brachiaria decumbens cv. Basilisk on the germination, growth, development and physiological composition. From the regression estimates, lower levels of PGR (10.3; 12.8; 8.85 and 9.57 ml/kg for germination percentage, germination speed index, leaf and pseudostem, respectively) were recommended in coated seeds when compared to conventional method (untreated seeds, with polymer coating and fungicide). Leaf and pseudostem mass production had a significant interaction effect between seed type and the use of growth regulator. Coated seeds (with fungicide and polymers after scarification) had greater performance with absence or at lower levels (8.85 and 9.57 ml/kg seed) of growth regulators. This was not observed for conventional seeds, the higher doses (15.5 and 18.1 ml/kg) presented higher development for the same characteristics. In second experiment, rates of photoassimilate were increased by soil fertilization and use of PGRs. No influence of foliar fertilization was observed when used exclusively, but N‐fertilization multiple and soil promotes an increase in chlorophyll content and mass yield, respectively. The use of exogenous hormonal compounds acts on the organogenesis of plant tissues and increases the formation of plant tissues and acts in the promotion of germination and development of structures, making it a key tool in pasture establishment.

This review aimed to approach the dynamics of pasture degradation, relating its causes and forms of recovery and/or renewal. Despite being based on extensive systems, Brazilian agriculture faces serious problems related to pasture degradation. The reduction in forage productivity directly affects the production system, having negative impacts on the economy and the ecosystem. Factors such as the choice of forage species, grazing management and the use of fire are the main factors responsible for the degradation of pastures in Brazil, causing an environmental and productive imbalance. However, it is possible to stop the progress of degradation and resume system productivity using pre-defined techniques in accordance with the objective of the production system. Furthermore, pasture recovery techniques are efficient for the resumption of productivity, and environmental protection, by helping to reduce greenhouse gases. Nevertheless, more research is needed to prove and consolidate pasture recovery techniques in the environmental, economic, and social scope.

The objective was to evaluate the rumen degradability of dry matter, crude protein and fiber fraction of some oilseed byproducts. Oilseed byproducts evaluated were: Sunflower Meal, Cotton Cake and Castor Bean Cake. The rumen degradability test was performed following a split plot randomized complete block design with three treatments (plots) and seven incubation times (subplots) and six blocks (animals). The readily soluble fraction of the dry matter of sunflower meal was 35.0% higher than the same fraction of cotton cake and castor bean cake (mean 24.46%, P < 0.01). The highest potential degradability of crude protein (P < 0.01) was verified in castor bean cake (96.90%, 5% rate of passage). Sunflower meal had the lowest insoluble fraction of the fiber fraction, 34.4%, compared to cotton cake and castor bean cake, with 64.4% and 39.4%, respectively (P < 0.01). Sunflower meal had the highest fiber effective degradability (25.2%). Sunflower meal presented better values of ruminal parameters of dry matter, crude protein and neutral detergent fiber in relation to the other byproducts.

This review addressed the existing energy flows in the pasture ecosystem, as well as the use of organic reserves by forage grasses. The radiant energy is absorbed by the leaves and transformed into chemical energy by which the assimilated carbon is fixed. During the process of assimilation and fixation of C, photochemical, and biochemical processes are carried out, which are influenced by light. Several environmental factors can influence the ability of plants to respond to stimuli. In this sense, energy flows within the pasture system are in constant movement to maintain the forage plant. The direction of energy flow varies with the growth environment of the forage plant, since in addition to affecting the structural characteristics, the environmental factors exert control over the root system. In theory, organic reserves located in roots and stems play a crucial role in the growth of grazed plants, especially in the first days after defoliation. Therefore, it is important to encourage research involving the reserve organs and their accumulation patterns so that the results can assist in the development of sustainable grazing systems.