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Diets for feedlot cattle must be a higher energy density, entailing high fermentable carbohydrate content. Feed additives are needed to reduce possible metabolic disorders. This study aimed to analyze the post-rumen effects of different levels of starch (25%, 35%, and 45%) and additives (monensin or a blend of essential oils and exogenous α-amylase) in diets for Nellore feedlot cattle. The cecum tissue proteome was analyzed via two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and then differentially expressed protein spots were identified with liquid chromatography–tandem mass spectrometry (LC–MS/MS). The use of blends of essential oils associated with α-amylase as a feed additive promoted the upregulation of enzymes such as triosephosphate isomerase, phosphoglycerate mutase, alpha-enolase, beta-enolase, fructose-bisphosphate aldolase, pyruvate kinase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), l-lactate dehydrogenase B, l-lactate dehydrogenase A chain, l-lactate dehydrogenase, and ATP synthase subunit beta, which promote the degradation of carbohydrates in the glycolysis and gluconeogenesis pathways and oxidative phosphorylation, support pyruvate metabolism through the synthesis of lactate from pyruvate, and participate in the electron transport chain, producing ATP from ADP in the presence of a proton gradient across the membrane. The absence of proteins related to inflammation processes (leukocyte elastase inhibitors) in the cecum tissues of animals fed essential oils and amylase may be because feed enzymes can remain active in the intestine and aid in the digestion of nutrients that escape rumen fermentation; conversely, the effect of monensin is more evident in the rumen and less than 10% results in post-ruminal action, corroborating the hypothesis that ionophore antibiotics have a limited effect on the microbiota and intestinal fermentation of ruminants. However, the increase in starch in these diets promoted a downregulation of enzymes linked to carbohydrate degradation, probably caused by damage to the cecum epithelium due to increased responses linked to inflammatory injuries.

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.

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