RESUMO -Este estudo visou avaliar o efeito da amonização do feno de capim-Annoni 2 (Eragrostis plana Nees) com 4% de uréia, em base de matéria seca, sobre os teores de proteína bruta (PB), fibra detergente neutro (FDN), fibra detergente ácido (FDA), hemicelulose (HEM), celulose (CEL) e lignina (LIG) e o coeficiente da digestibilidade in vitro da matéria orgânica (DIVMO), em cinco épocas de corte (30, 60, 90, 120, 150 dias). O delineamento experimental foi o de blocos completos casualisados, em número de quatro, num arranjo fatorial (2x5) com dois fatores: tratamento dos fenos (2) e épocas de corte (5). A comparação entre os dois grupos de fenos (amonizados ou não) demonstrou que a amonização propiciou aumento altamente significativo dos teores de PB. Por outro lado, a fração de FDA decresceu significantemente, juntamente com os teores de CEL, em função do tratamento com uréia. Não foram detectadas diferenças entre os tratamentos, relativamente aos teores de FDN, HEM, LIG e ao coeficiente da DIVMO. Inferiu-se que: 1. a amonização do feno de capimAnnoni 2 não afetou os teores de FDN , HEM, LIG e os coeficientes da DIVMO; 2. tratamento do feno de capim-Annoni 2 com uréia propiciou aumento nos teores de PB e decréscimo nos teores de FDA e CEL; 3. o capim-Annoni 2 pode ser fenado até os 90 dias de crescimento, sem que ocorram modificações expressivas dos parâmetros de qualidade, desde que o feno seja amonizado.Palavras-chave: celulose, fibra detergente ácido, fibra detergente neutro, hemicelulose, lignina, proteína bruta Effect of Urea-Ammonia Treatment on the Quality Parameters of Annonigrass 2 (Eragrostis plana Nees) HayABSTRACT -This study aimed to evaluate the ammoniation effect on the crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HEM), cellulose (CEL) and lignin (LIG) levels and the in vitro organic matter digestibility (IVOMD) coefficient of urea-ammonia treated (4%; dry matter basis) Annonigrass 2 (Eragrostis plana Nees) hay, at five cutting ages (30, 60, 90, 120, 150 days). A randomized complete block design was used, with four replicates in a factorial arrangement (2x5), with two factors: hay treatments (2) and cutting ages (5). The comparison among hay groups (ammoniated or not) showed a highly significant increase on the CP contents of ammoniated hay. On the other hand, FDA and CEL fraction significantly decreased as a function of urea-ammonia treatment. No differences were found for NDF, HEM, LIG contents and the IVOMD coefficients among hay groups. It was concluded that: 1. ammoniation does not affect NDF, HEM, LIG levels and IVOMD coefficients; 2. urea-ammonia treatment of Annonigrass 2 hay promotes an increase on the CP contents and a decrease on the ADF and CEL contents of this grass; 3. Annonigrass 2 hay is feasible up to 90 days of growth without prejudice to the quality parameters, since urea-ammonia is treated.Key Words: acid detergent fiber, cellulose, crude protein, hemicellulose, lignin, neutral detergent fiber R. Bras. Zootec., v.31, n.2, p.842-8...

The aim was to evaluate how the fodder pre-dehydration time and its phenological stages influence on ruminal degradability and digestibility of ryegrass silage. The evaluated samples consisted of treatments: Vegetative: Cut and ensiled; cut + 4 hours pre-drying and ensiled and; cut + 7 hours pre-drying and ensiled; Pre-flowering: Silage cutting and ensiled and 4 hours pre-drying and ensiled; Flowering: cut and ensiled, no pre-drying, with four replications each treatment. Silage was storage for four months. It was carried out three in situ digestibility assays to determine the curve of ruminal degradability at different times (3, 6, 9, 12, 24, 48 and 72 hours), like in situ digestibility and other three assays of 24 hours and 48 hours to determinate in vitro digestibility of silage. The digestibility of ryegrass silage was influenced by both the pre-dehydration times and phenological stage, and the dehydration time of cut and silage had a high proportion of degradable components, with higher degradation rate by 24 hours of incubation. The in vitro digestibility of the ryegrass silage was greater than that in situ for up to 48 hours. The digestibility of the ensiled ryegrass biomass was influenced by the dehydration times, as well as the plant growth stage, regardless of the methodology used, being higher values for the treatment without previous drying of the vegetative stage.

Um estudo foi realizado para determinar a correlação do P no sistema solo-planta-animal com características da paisagem e qualidade da forragem em três tipos de solo não perturbados, localizados na região da Campanha-RS. Efetuou-se a amostragem em áreas sobre os solos Neossolo Regolítico eutrófico (RLe), Argissolo Bruno-Acinzentado (ABA) e Planossolo Háplico eutrófico (PHe) durante um ano. A correlação linear entre P no solo x P na planta apresentou significância no outono (p

We aimed to evaluate the dynamics of magnesium (Mg) in the soil - plant – animal chain. It was conducted in two natural rangeland areas on two types of undisturbed (virgin) soils (medium/clayey texture) in the Serra do Sudeste (Rio Grande do Sul State, Brazil). In each of these areas, 12 animals (heifers) were kept under continuous extensive grazing for twelve months without mineral supplementation. Every month, samples of soil and vegetation were collected at 16 fixed points (radius: 25 m) as well as blood serum from each of the animals in each area for the determination of Mg and other minerals levels. The data were analyzed using the analysis of variance, decomposition of the annual variation of the response variables and periodic regression (harmonic analysis) for adjustment of function to express this variation. The relationship of Mg with other variables within the links of the soil-plant-animal chain is influenced by some factors such as physicochemical and biological soil reactions, floristic composition and environmental conditions. In natural non perturbed rangeland areas the organic matter is the main colloid of the soil for the availability of magnesium to plants and, consequently, to the animals.

We aimed to evaluate the seasonal dynamics of magnesium (Mg) in the system soil - plant - animal. It was conducted in two natural rangeland areas on two types of undisturbed soils (medium-clayey texture) in the Serra do Sudeste region (Rio Grande do Sul State, Brazil). In each area, 12 heifers were kept under continuous extensive grazing for twelve months without mineral supplementation. Samples of soil and vegetation were collected monthly from 16 fixed points and blood serum from each of the animals in each area monthly for the determination of Mg levels. The data were analyzed by analysis of variance, decomposition of the annual variation of the response variables and regression (harmonic analysis) for adjustment of function to express this variation. The Mg content in the soils of the two areas was high (1.86 ± 0.045 cmolc.dm-3). Mg levels in the vegetation (0.23 ± 0.0025 % DM) are sufficient to meet the needs of all categories of ruminants. The Mg contents in the blood serum (3.05 ± 0.0025) of grazing animals are considered medium to high and in normal levels. Mg supplementation is suggested in the cold season months for the most demanding animal categories (gestating and lactating females).

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