The present work aims to evaluate the morphological and structural characteristics of Brachiaria brizantha cultivars in the system of grazing in the intermittent stocking. The experiment was conducted at EMBRAPA -Beef Cattle. The experimental delineation used was a randomized block with three treatments and three repetitions. The treatments were constituted by grasses of the same species (Brachiaria brizantha) composed by cv. Xaraé s, BRS Paiaguá s, and the ecotype B4. On the heights of post-grazing, it was observed an interaction between seasons of the year and cultivars. It was observed that the leaf appearance rate (LAR) was higher in the cv. BRS Paiaguá s, in relation to the other pastures. The leaf elongation rate (LER) was higher in perforations of the ecotype B4. In the winter, it was registered the lowest values of leaf area index (LAI), LAR, and LER, and, as a consequence, impact in a higher leaf life duration. Although there were some structural variations between tropical climate pastures, it was possible to verify that the phenotypic plasticity of these pastures presented the same behavior, once it suffered a higher influence of abiotic factors. Therefore, all the pastures of B. brizantha converged to the same LAI indicating high phenotypic plasticity.

The use of silage has been an efficient alternative to feed supply during the shortage of roughage in dry periods, providing quality feed that is widely used in ruminant feeding. Thus, the objective of this study was to evaluate the fermentative characteristics and nutritive value of corn silage with Tamani guinea grass (Panicum maximum BRS cv. Tamani) through chemical composition, in vitro dry matter digestibility and protein fractionation. The experiment was conducted in a completely randomized design with four replications. The treatments consisted of five silages: corn; corn with 10% Tamani guinea grass; corn with 20% Tamani guinea grass; corn with 30% Tamani guinea grass; and corn with 40% Tamani guinea grass, totalling 20 experimental silos. The addition of tamani grass to silages was determined based on fresh matter. For ensiling, corn was harvested with 320 g kg-1 DM (dry matter) and Tamani guinea grass in a 30-day development cycle with 286 g kg-1 DM. After 50 days of silage, the silos were opened to analyse the fermentative characteristics, chemical composition and protein fractionation of the silage. The results showed that the addition of Tamani guinea grass in corn silage increased the pH and buffering capacity and reduced the dry matter and lactic acid concentration but did not compromise the fermentative characteristics of silages. The addition of 40% Tamani guinea grass in corn silage provided increased levels of crude protein, in vitro dry matter digestibility, protein A, B1 and C, and decreased the fractions B3 and C, which makes Tamani guinea grass an alternative to improve the quality of exclusive corn silage, resulting in better quality silage.

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The hypothesis tested was that pastures of the genus Brachiaria, but with variations in forage canopy architecture (canopy height, leaf area index and tiller population density), would not present oscillations in the variables related to primary production and to nutritive value, under similar soil and climate conditions, and under the same management system. Thus, the present work intends to evaluate the different cultivars of Brachiaria brizantha, observing the dissimilarity of the variables related to forage biomass and nutritive value. The experiment was conducted by Embrapa beef cattle. The design was completely randomized blocks with three replicates. The treatments were three ecotypes of Brachiaria brizantha, B4, BRS Paiaguás and Xaraés. The grazing method used was the intermittent variable stocking rate. The data of forage canopy height (FCH), tiller population density (TPD) and leaf area index (LAI) were submitted to analysis of variance. Estimates of the first and second canonical variables, as well as standardized canonical coefficients were performed. It was noticed oscillations at the FCH between the grasses, in which, pastures of ecotype B4 present the highest height in relation to the other B. brizantha. BRS Paiaguás presents the highest TPD. The standard canonical coefficients of the first canonical variable showed that neutral detergent fiber (NDF) and lignin are the variables that most affect the first canonical variable, positively and negatively. This indicates that these are the variables that most interfere in the differentiation of characteristics related to the nutritive value of B. brizantha grasses. The first canonical variable explains 80.5% of the B. brizantha pasture variation, in addition, it is possible to observe a differentiated distribution among the pastures studied. The B. brizantha pastures present variations in forage canopy architecture, which end up impacted by the canopy lignin concentration.

This study aimed to determine possible differences between populations of Africanized bees in the coastal area and of the sertão of Piauí, as a technique using geometric morphometry. The material analyzed consisted of adult workers of Africanized bees from the coastal region and of the sertão of Piauí. It was used as a comparative reference breeds digital images of the wings of 50 individual's subspecies of European, African, and 45 individuals of Africanized bees coming from Ribeirao Preto in morphometric analyzes. In total we analyzed 645 images of wings. In the morphometric