Nutritive value and condensed tannins of tree legumes in silvopasture systems

Introducing legumes into C4-dominated tropical pastures, may enhance their sustainability but has some pasture management constraints. One potential alternative is using arboreal legumes, but several of these species have relatively high condensed tannin (CT) concentrations, which negatively impact forage quality. There is limited knowledge, however, on how arboreal legume leaf CT content varies over the year and how this might impact forage quality. The objective of this 2 year study was to assess the seasonal variation of CT and nutritive value for ruminants of the tropical tree legumes gliricidia [Gliricidia sepium (Jacq.) Kunth ex. Walp.] and mimosa (Mimosa caesalpiniifolia Benth). The research was carried out in the sub-humid tropical region of Brazil on well-established pastures in which either legume was present with signalgrass (Urochloa decumbens Stapf.). We determined CT and nitrogen concentrations, in vitro digestible organic matter (IVDOM), and leaf δ13C and δ15N from January to October of 2017 and 2018. All parameters were afected (P< 0.05) by the interaction between legume species and sampling time, with generally higher leaf CT content for mimosa than gliricidia, and both were reduced at the start of the dry season, although much more drastically for mimosa. The IVDOM was strongly afected by CT content and increased at the start of the dry season, coincidentally when C4 grass forage quality typically decreased. There is a marked species efect, with CT from gliricidia impacting IVDOM more than the same CT content from mimosa. While N concentration from mimosa also increased at the start of the dry season, that for gliricidia did not vary over the year. We conclude that although these arboreal legumes have relatively high CT contents, these reduce during the dry season when CT concentrations coinciding with a reduced forage quality as the protein content for C4 grasses is usually inadequate in this season.Coordination of Superior Level Staff Improvement - CAPES; National Council for Scientifc and Technological Development - CNPq; Pernambuco Research Foundation - FACEPEinfo:eu-repo/semantics/publishedVersio

Potential of elephant grass genotypes silages as exclusive roughage on tissue composition and meat quality of lambs: a preliminary study

ABSTRACT This study aimed to evaluate the effects of diets containing elephant grass genotypes silages as exclusive roughage on leg tissue composition, and physicochemical characteristics of meat of lambs. Twenty-four crossbred male lambs with an average initial body weight of 20.29±2.66kg were distributed in a complete randomized design with three treatments and eight replicates. The treatments consisted of three silages of elephant grass genotypes (IRI-381, Elephant B or Mott), without additives or wilting, as the only roughage. The diets did not affect (P>0.05) the dry matter (898.70±60.10 g/day), crude protein (128.93±6.91g/day), total digestible nutrients (690.20±91.82g/day) intakes, body weight at slaughter (24.83±2.79kg), and carcass yields (P>0.05). The tissue composition of the leg did not differ significantly between silages of elephant grass genotypes (P>0.05). No difference (P>0.05) for the physicochemical characteristics of meat from lambs fed diets tested was observed. Therefore, our results indicate that diets containing 50% elephant grass genotypes silages (IRI-381, Elephant B or Mott), harvested at 60 days of growth, have potential for use in lambs feeding

Biomass accumulation in mombasa guineagrass plants under different levels of nitrogen supply and plant densities

The objective of this study was to evaluate the effect of different levels of nitrogen supply and plants densities in the productivity of mombasa guineagrass (Panicum maximum) in the period of establishment. The design was of completely randomized blocks, with 12 treatments and three repetitions, with four nitrogen supplies (absence of application, 80, 160 and 320 kg/ha.year) and three plant densities (9, 25 and 49 plants/m²). The plot was cut at 30 cm from the ground when the sward high intercepted 95% of light. The following items were evaluated: sward height at 95% light interception, interval and number of cuts, dry mass production, total dry mass of leaves, stems and dead material and the morphologic composition. Nitrogen increased the dry mass production and the dry mass of stem in winter and summer, and decreased in the fall. The total dry mass of leaf presented decrease of 19% in the summer between the smallest and biggest densities in the 320 kg/ha. The dry mass of dead material had negative effect of the density in the fall. The leaf percentage increased 88% between the smallest and largest nitrogen level at the plant density of 49 plants/m². Only density influenced the sward height in the condition of 95% of light interception. The number of cuts increased with nitrogen levels in the fall, spring and summer, while the interval of cuts decreased with fertilization in the spring and summer. Nitrogen increases the production of mombasa guineagrass in each cycle