RESUMO
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 affected (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 affected 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 effect, 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.
Assuntos
Fabaceae , Valor Nutritivo , Proantocianidinas , Árvores , Proantocianidinas/análise , Fabaceae/química , Fabaceae/metabolismo , Folhas de Planta/química , Estações do Ano , Mimosa/química , Animais , Brasil , Ração Animal/análise , Nitrogênio/análiseRESUMO
The objective of this study was to evaluate the exclusive supply of dwarf or tall elephant grass silages, harvested at 60 days of growth, without wilting or the use of additives, on intake, apparent digestibility, nitrogen balance, rumen parameters, and ingestive behavior of sheep. Eight castrated male crossbred sheep (57.6 ± 5.25 kg body weight), fistulated in the rumen, were distributed in two 4 × 4 Latin squares with four treatments and eight animals per treatment and four periods. The treatments consisted of four elephant grass genotype silages (Mott, Taiwan A-146 2.37, IRI-381, or Elephant B). There was no effect of silages (P > 0.05) on dry matter, neutral detergent fiber, and total digestible nutrient intake. The dwarf-sized elephant grass silages provided higher crude protein intake (P = 0.047) and N intake (P = 0.047), while the IRI-381 genotype silage provided higher non-fibrous carbohydrate intake compared to Mott (P = 0.042), without differing from Taiwan A-146 2.37 and Elephant B silages. There were no differences (P > 0.05) among the digestibility coefficients of the evaluated silages. It was observed that silages produced with Mott and IRI-381 genotypes caused a slight decrease in ruminal pH (P = 0.013), and the propionic acid concentration was higher in the rumen fluid of the animals fed with Mott silage (P = 0.021). Therefore, dwarf or tall elephant grass silages, produced with cut genotypes at 60 days of growth and without the use of additives or wilting process, can be used in sheep feeding.
Assuntos
Dieta , Silagem , Masculino , Animais , Ovinos , Silagem/análise , Dieta/veterinária , Fermentação , Rúmen/metabolismo , Digestão , Fibras na Dieta/metabolismo , Ingestão de Alimentos , Nitrogênio/metabolismo , Poaceae/metabolismoRESUMO
This study evaluated the nutritive value of signalgrass (Urochloa decumbens Stapf R. D. Webster) and sabiá (Mimosa caesalpiniifolia Benth.), and animal performance in grass monoculture pastures and in silvopastoral system (SPS) in the early development stage, in the Agreste of Pernambuco. Four treatments were evaluated in a randomized block design with three replications: signalgrass + Eucalyptus spp.; signalgrass + sabiá; signalgrass monoculture and sabiá monoculture. Holstein × Zebu crossbred calves (170 ± 15 kg BW) were managed under continuous stocking with variable stocking rate (SR). The dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), and in vitro dry matter digestibility (IVDMD) of signalgrass and sabiá were assessed, as well as forage allowance (FA), stocking rate (SR), average daily weight gain (ADG) and weight gain per area (WGA) over eleven evaluation cycles (March 2019 to January 2020). Signalgrass had the highest DM contents in March 2019 and January 2020 (456 and 507 g kg-1, respectively), while for IVDMD the highest values ranged from 436 to 547 g kg-1 (April to August 2019). Sabiá presented the highest's IVDMD (311 and 381 g kg-1 DM) and DM content (385 and 416 g kg-1) and lowest CP (110 and 82 g kg-1 DM) and NDF (568 and 500 g kg-1 DM) in November 2019 and January 2020, respectively. FA and SR decreased throughout the evaluation cycles. ADG (0.38 kg animal-1 day-1) and WGA (17.89 kg ha-1 28 days-1) did not differ among treatments, with weight loss in the period of low water availability. In the early development stage of the trees, SPS does not affect the nutritive value of signalgrass, nor the animal performance.
Assuntos
Ração Animal , Mimosa , Ração Animal/análise , Animais , Bovinos , Dieta/veterinária , Fibras na Dieta/metabolismo , Valor Nutritivo , Poaceae/metabolismo , Aumento de PesoRESUMO
Tall- and dwarf-sized elephant grass cultivars have been developed for cut-and-carry system. Dwarf clones have better digestibility; on the other hand, tall-sized cultivars are more productive. The aim was to verify which grass would be most recommended for cut-and-carry: tall-sized (Elephant B and IRI-381) or dwarf (Taiwan A-146 2.37 and Mott) elephant grass cultivars to feed 24 male sheep, aged between 4 and 5 months, uncastrated, weighing approximately 24.08 ± 1.76 kg body weight which were sampled on intake, digestibility, performance, ingestive behavior, nitrogen balance, microbial protein synthesis, metabolic parameters, and ruminal degradability. This research was divided into two experiments: experiment 1 lasted 38 days, seven for adaptation and 31 for data collection. Elephant grass cultivars were supplied with a mineral mixture. Data collected were intake, digestibility, ingestive behavior, metabolic parameters, microbial protein synthesis, and performance submitted to a completely randomized design. For experiment 2, three rumen fistulae animals were sampled, lasting 20 days. In this case, a randomized block in split-plot design was applied. Both designs were with P < 0.05 and analyzed through SAS statistical software. Mott and Taiwan A-146 2.37 cultivars provided greater intake, digestibility, weight gain, feeding time, nitrogen retention, production and efficiency of microbial protein synthesis, dry matter (DM) and neutral detergent fiber (NDF) degradability, and DM, crude protein, and NDF, but shorter rumination time rather than Elephant B and IRI-381. There was also a significant difference for glucose, triglycerides, plasma urea, total serum protein, urinary urea (mg/L), and urea excretion in urine (mg/day). Dwarf elephant grass cultivars as Mott and Taiwan A-146 2.37 have greater nutritional value than tall-sized Elephant B and IRI-381. Dwarf elephant grass is recommended for cut-and-carry system.