Jamir Luis da Silva

Managing grazing animals to achieve nutrient cycling and soil improvement in no-till integrated systems

Crop-livestock systems are regaining their importance as an alternative to unsustainable intensive farming systems. Loss of biodiversity, nutrient pollution and habitat fragmentation are a few of many concerns recently reported with modern agriculture. Integrating crops and pastures in no-till systems can result in better environmental services, since conservation agriculture is improved by system diversity, paths of nutrient flux, and other processes common in nature. The presence of large herbivores can positively modify nutrient pathways and soil aggregation, increasing soil quality. Despite the low diversity involved, the integration of crops and pastures enhances nature’s biomimicry and allows attainment of a higher system organization level. This paper illustrates these benefits focusing on the use of grazing animals integrated with crops under no-tillage systems characteristic of southern Brazil.

Padrões de deslocamento e captura de forragem por novilhos em pastagem de azevém-anual e aveia-preta manejada sob diferentes alturas em sistema de integração lavoura-pecuária

Neste estudo avaliaram-se estrategias alimentares de novilhos em pastagem de azevem-anual (Lolium multiflorum Lam.) e aveia-preta (Avena strigosa Schreb.) em quatro alturas de manejo (10, 20, 30 e 40 cm) para investigar se as alturas do pasto podem influenciar os padroes de deslocamento e captura da forragem por animais em pastejo e seus impactos em sistemas de integracao lavoura-pecuaria. As alturas de manejo foram avaliadas em delineamento de blocos completos casualisados com tres repeticoes. Procedeu-se a tres avaliacoes diurnas, por observacao visual direta: duas avaliacoes de acordo com o estadio vegetativo e a terceira com o estadio reprodutivo. A reducao da altura de manejo do pasto esteve relacionada a maior carga animal e resultou em menor massa de forragem e massa de lâminas foliares. Nessa condicao de limitacao, os animais aumentaram a taxa de bocados, o numero de bocado por estacao alimentar, o numero total de bocados, o numero de estacao alimentar visitada e reduziram o tempo de permanencia na estacao alimentar. Esse padrao de resposta resultou em menor deslocamento entre estacoes alimentares, no entanto, a quantidade de deslocamento total foi maior. Os animais modificam seus padroes de deslocamento e captura de forragem em resposta a altura de manejo do pasto. A limitacao de forragem pode ter impacto no sistema de integracao lavoura-pecuaria.

Padrões de uso do tempo por novilhos em pastagem consorciada de azevém anual e aveia-preta

Aiming to assess the steer grazing behavior, an experiment was carried out with pastures composed by italian ryegrass (Lolium multiflorum Lam.) and black oat (Avena Strigosa Schreb) submitted to different sward heights (10, 20, 30, and 40 cm). The sward heights were distributed in an experimental randomized block design with three replicates. Data was recorded by visual assessment, from sunrise until sundown, in three evaluation dates, two in the vegetative stage and one in the reproductive stage. The evaluated variables were grazing time, rumination time, idling time, number and length of meals, and number and length of meals intervals. Results indicated that with increasing sward height the animals reduced grazing time and the meal length as well, however, the ruminating time increased. The variables such as idling time, number of meals and number/length of intervals were not influenced by the sward surface height. The results showed changes in the animal grazing behavior due to the variations in sward height management.

Produção animal em pastagem nativa submetida ao controle de plantas indesejáveis e a intensidades de pastejo

The aim of this experiment was to study different methods of controlling undesirable plants in native pastures, associated with two levels of herbage allowance, and their effects on animal production. The treatments were no control (T), spring slashing (P), spring+autumn slashing (P+O) and spring slashing +chemical control (P+Q), under two levels of herbage allowance (8 and 14kg of dry matter 100kg -1 of liveweight per day). The experimental design was a randomized complete block with two replicates. Not have block effects neither interaction between methods of control and herbage allowances (P>0.05). The higher herbage allowance resulted in more liveweight gain per area (P 0.05). The results showed that it’s possible to keep the live body weight of bovine in native pasture in Serra do Sudeste of Rio Grande do Sul/ Brazil, during the winter ’s period, utilizing management practices that secured a minimals levels of herbage allowance. These results showed also that the management of native pasture with slashing in spring, with or without chemical’s controlling, it’s provide a better individual development and less weight’s lose in winter’s period.

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.

Ganho de peso de novilhas em pastagem nativa da Serra do Sudeste do RS submetida ao controle de plantas indesejáveis e intensidades de pastejo

This work aimed to evaluate the effect of different undesirable plants controlling methods and grazing intensities on animal production in native pastures. The treatments were no control (T), spring clipping (P), autumn clipping (O) and chemical control (Q), under two levels of forage allowance, medium (8%) and high (14%), expressed in kg of dry matter offered daily per each 100kg of liveweight. The experimental design was a completely randomized block arranged in a factorial with two repetitions. Statistical analysis showed no interaction among treatments nor differences among control methods for variables concerning primary and secondary production (P>0.1). Animal performance in both forage allowances was not different (P>0.1). High forage allowances increased animal performance per unit area (P<0.1).

Desempenho e características das carcaças de novilhos superprecoces em pastos hibernais submetidos a intensidades de pastejo

The objective of this work was to assess the grazing intensity effects on the finishing of yearling bulls, in winter pastures in succession to soybean crop. Sward pre-grazing different heights of mixed pasture between ryegrass and oat were evaluated: 10, 20, 30 and 40 cm. A randomized complete block design was utilized with three replicates. Ten-month-old beef crossbred bulls were used, with initial live weight of 192±12 kg. The following variables were evaluated: forage mass and allowance, sward height, forage daily accumulation rate and forage total accumulation, average daily weight gain (ADG), stocking rate and weight gain per unit area (GA), as well as the qualitative characteristics of the carcasses. The yearling bulls were slaughtered at 14 months of age. ADG fitted a quadratic model, with maximum performance between 20 and 25-cm sward height, while GA fitted a negative linear model. Yearling bulls showed a satisfactory carcass quality when pastures were managed with pre-grazing heights higher than 10 cm. It is possible to finish yearling bulls in the pasture phase of integrated production systems, during winter, in succession to soybean crop. The management of ryegrass and oat mixed pastures at sward pre-grazing heights of 20 and 25 cm optimize individual animal performance and per area unit.

Silvopastoral systems in the cold zone of Brazil.

The cold zone of Brazil occupies approximately 6 % of the national territory and is located between latitudes 24° S and 33° S. In this area, extensive cattle and sheep farming systems and conventional cropping and forestry are predominant. With the end of government subsidies by the decade of 1980s, an increase in farming production costs, a decrease of native forest covering, an increase of degraded areas in agriculture and livestock farming systems and a mismatch between timber national supply and demand after 1990s, an opportunity arises for integrate forestry with livestock and agriculture activities in Brazil, particularly in the southern. This chapter initially reports key events over the last three decades that have supported the increasing interest of farmers and enterprises on agroforestry activities, with focus on silvopastoral systems in the cold area of Brazil. Then, relevant advances on silvopastoral systems from research and extension services were reported, highlighting the screening of shaded adapted forage plants and management, trees species screening for silvipastoral systems and animal performance and behaviour under trees. Finally, the chapter analyses the existent opportunities to increase silvopastoral areas in southern Brazil and future challenges for research, development and technology transfer.