Cristina Maria Pacheco Barbosa

Variáveis morfogênicas e estruturais de azevém anual (Lolium multiflorum Lam.) manejado sob diferentes intensidades e métodos de pastejo

Um experimento foi conduzido com o objetivo de avaliar a influencia de intensidades e metodos de pastejo nas caracteristicas morfogenicas (taxa de elongacao de folhas, taxa de surgimento de folhas, tempo de vida da folha) e estruturais (numero de folhas verdes, comprimento de folhas e densidade populacional de perfilhos) de azevem em dois ciclos de avaliacao. Os tratamentos experimentais consistiram de duas intensidades e dois metodos de pastejo (continuo e rotacionado), em um delineamento em blocos completamente casualizados, em arranjo fatorial com quatro repeticoes. Foram marcados 30 perfilhos por unidade experimental. As intensidades de pastejo foram responsaveis pelas diferencas encontradas na taxa de elongacao de folhas (intensidade baixa resultou em maior taxa de elongacao) e nas caracteristicas estruturais (intensidade baixa resultou em menor densidade populacional de perfilhos, maior comprimento e maior numero de folhas vivas por perfilho). Os metodos de pastejo influenciaram as caracteristicas morfogenicas (o pastejo continuo resultou em maior taxa de elongacao de folhas, mais alta taxa de surgimento e maior tempo de vida das folhas no primeiro ciclo de observacao) e estruturais (o pastejo continuo resultou em maior densidade populacional de perfilhos). Observou-se interacao intensidades de pastejo x ciclos de avaliacao. A forma de conducao do processo de desfolhacao, por meio do controle de intensidades e metodos de pastejo, afeta as caracteristicas morfogenicas e estruturais da pastagem.

Terminação de cordeiros em pastagens de azevém anual manejadas em diferentes intensidades e métodos de pastejo

This work measured lamb performance in a ryegrass pasture (Lolium multiflorum Lam.) under different grazing intensities and methods. The pasture was used from July 12th to November 1st of 2003 (total of 113 days). The treatments were two grazing intensities (moderate and low) in rotational and continuous stocking. The moderate and low grazing intensities were represented, respectively, by forage allowance of 2.5 and 5 fold the intake potential. It was used a factorial arrangement (2 intensities × 2 methods × 4 replicates) in a complete randomized block design. There was no interaction among grazing methods and grazing intensities and they were analyzed separately. The moderate grazing intensity provided the lower forage allowance, lower herbage mass and lower pasture height. This intensity affected positively the qualitative characteristics of pasture as well. Regarding the grazing methods, the height and the herbage mass were larger under rotational stocking, while the forage quality was higher under continuous stocking. There was no difference of forage allowance between methods, and the necessary conditions to compare all the variables measured were reached. There were significant differences between average daily gain and stocking rates on both, grazing methods and intensities. The gain/hectare was better under moderate grazing intensity, but no difference was identified under grazing methods for this intensity. The amount of forage available for the animal is the central key for the productivity, despite the grazing method used. Low grazing intensity was considered more appropriate for pasture management because it allows better gain per animal.

Comparação de métodos de medida indireta de massa de forragem em pasto de azevém anual (Lolium multiflorum Lam.)

This work was conducted between May and October of 2003 at the Experimental Station of the Universidade Federal do Rio Grande do Sul (EEA-UFRGS) and was aimed at studing and comparing the efficiency of the rising plate meter, sward-stick and capacitance meter to predict the herbage mass in an italian ryegrass pasture. The work had two experiments: the experiment 1 where the three methods were evaluated when the pasture had free growth (establishment phase) in a completely randomized with 32 replicates and three treatments; the experiment 2 where pre and post grazing herbage mass was evaluated by the sward-stick and rising plate meter in paddocks under rotational grazing. The experimental design of experiment 2 was a completely randomized block with four replicates; the experimental treatments were two grazing intensities (low and moderate) defined by herbage allowances representing 2,5 and 5,0 times the potential intake of the lambs. In the experiment 1 the sward-stick showed the best determination coefficient (r2=0,65). In the experiment 2 the best determination coefficients were obtained when the pasture under rotational stocking was evaluated using the sward-stick.

Fluxo de biomassa aérea em azevém anual manejado sob duas intensidades e dois métodos de pastejo

The trial was conducted to evaluate the influence of two grazing intensities (moderate and low) and two stocking methods (continuous and rotational stocking) in the aerial biomass fluxes of an Italian ryegrass measured by the fluxes of growth, senescence, and intake, using the marked tillers technique. It was used a factorial arrangement in a complete randomized block design with four replicates per treatment. Treatments and their interactions affected the fluxes of growth and senescence. Rotational stocking at low intensity favored the growth flux of the pasture. Senescence flux was greater at continuous stocking and low intensity and the intake flux was not affected by the treatments.

Componentes do processo de pastejo de cordeiros em azevém sob diferentes intensidades e métodos

The aim of this study was to evaluate the components of lamb grazing process in ryegrass pastures (Lolium multiflorum Lam.). The treatments were two grazing intensities: moderate and low (forage suply: 2.5 and 5-fold the animal intake potential, respectively) in rotational and continuous stocking. The experimental design was a randomized complete block arranged in a factorial with three replicates (2 intensities x 2 methods x 3 replicates). There was no interaction among grazing intensities and methods, and its effects were analyzed separately. There was no difference of herbage allowance between grazing methods (p= 0.3393), and so, the basic conditions to compare all treatments were reached. Herbage mass during the experiment were: 3159 and 2327 kg of DM/ha for rotational and continuous stocking; and 1971 and 3514 kg of DM/ha for moderate and low grazing intensities, respectively. There was no significant differences for number of meals (M), meal duration (MD), inter meals intervals (IMI), duration of intervals (DI), grazing time (GT), ruminating time (RT) and idling time (IT) (p>0.1) for grazing methods. There was no statistical difference for RT, M, MD and IMI (p>0.1) regarding grazing intensities. DI, GT, IT, bite rate (BR) and time for feeding station (TFS) were affected by grazing intensity (p<0.1). Grazing methods affected just BR and TFS (p<0.1) due to the higher herbage mass under rotational stocking. The use of correct grazing intensities for the animals, more than the choice between grazing methods, is capital to built sustainable grazing environments aiming the production of high quality lambs.