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Context ​Defoliation management targets applied to forages under the full sun have not yet been properly evaluated for shaded environments such as occur in integrated crop–livestock systems with the presence of trees. Aims This study aimed to determine defoliation targets under full sun and shaded environments for the shade-tolerant perennial summer grass hybrid Axonopus catharinensis (giant missionary grass), widely used in pasture systems of South Brazil and Argentina. Methods Four pre-defoliation canopy heights (15, 25, 35 and 45 cm) and four defoliation severities (20%, 40%, 60% and 80% reduction in pre-defoliation canopy height) were evaluated. Plants were grown in 0.15 m3 wooden boxes filled with sand/vermiculite substrate (1:1 v/v) and irrigated with a complete nutrient solution. An artificial shade structure was made with wooden slats, reducing light intensity by 50% for shaded plants. Key results Herbage accumulation decreased by 54% in shaded plants compared with those under full sun. Regardless of the light environment, the lowest crude protein content (650 g/kg dry matter) were observed when the defoliation target height was >35 cm. Both shaded and full sun environments showed decreases in tiller density when defoliation severity was >60% of pre-defoliation canopy heights. Conclusions Pre-defoliation canopy heights >35 cm and defoliation severity >60% of pre-defoliation canopy height should be avoided when managing A. catharinensis, regardless of the light environment. Implications Recommended targets may be easily implemented by livestock producers and are similar for full sun and shade environments.

Na região sul do Brasil, é frequente a ocorrência de geadas no inverno. Este evento climático pode provocar a morte das plantas, ou de suas partes. Portanto, o objetivo com este trabalho foi avaliar os danos por geada em cinco espécies/cultivares de forrageiras perenes estivais (Capim Áries, Convert HD364, Capim Tangola, Jiggs e Missioneira-gigante), bem como a recuperação das plantas na estação subsequente após a remoção ou não da massa de forragem previamente a ocorrência das geadas. O trabalho foi conduzido na Universidade do Oeste de Santa Catarina. No experimento de campo, ocorreram duas geadas, a primeira com moderada intensidade (-2°C) e a segunda com baixa intensidade (-0,5°C). Plantas em vasos foram submetidas a geadas artificiais em câmara BOD, com intensidade de -2°C e -4°C. Previamente ao período de ocorrência de baixas temperaturas, perfilhos de cada cultivar foram marcados. Os danos nas folhas de cada perfilho foram avaliados sete dias após cada geada. O percentual de dano foi composto pelo dano médio das folhas de cada perfilho, avaliado de forma visual, sempre pelo mesmo avaliador. A espécie missioneira-gigante tem alta tolerância a geadas. Cultivares do gênero Brachiaria (Urochloa) apresentam reduzida tolerância a danos por geadas. Dentre as cultivares com boa tolerância a geadas estão a Jiggs e Áries, com ressalva a cultivares com hábito de crescimento cespitoso ereto, que podem apresentar dificuldades na cobertura de solo após a morte de plantas posterior a geadas severas. O manejo de remoção ou não da massa previamente a geada não impactou na população de perfilhos na estação subsequente. Mais trabalhos devem ser realizados em locais com maior frequência e intensidade de geadas para validar esta informação. A avaliação de danos por geadas em plantas forrageiras em ambiente controlado apresenta-se como alternativa viável para a definição de níveis de tolerância a este evento climático.

This work was carried out to evaluate the fermentation characteristics and aerobic stability, regarding the conventional high moisture corn grain silage (Fortuna variety), the high moisture sweet corn grain silage and the high moisture rehydrated corn silage. Data were statistically analyzed as a 3x3 factorial arrangement in a completely randomized design, and the factors were three types of corn (Fortuna, sweet and rehydrated) and three inoculation treatments (without inoculum, bacterial inoculum and bacterial inoculum plus enzymes). The aerobic stability values were assessed, collecting the temperatures from the room dry bulb and from the silage thermometers, and the pH values, at 0, 24, 48, 72, 96, 168, 192, 216, 240 and 296 hours after aerobic exposition. Additionally, different mathematical models to estimate the mean pH values after opening were tested. Interactions were observed (P The sweet corn silage presented lowest pH values at 48 hours after opening. The pH values at 168 hours of rehydrated corn silage treated with bacterial inoculum plus enzymes was more acid. Richard’s Equation (1959) was the best tool for the pH estimation when either types of inoculants or rehydrated corn silage were considered. On the other hand, the model proposed by Morgan et al. (1975) was the best equation model to fit the data regarding either Fortuna or sweet corn silages. Normal 0 21 false false false PT-BR X-NONE X-NONE

Foram conduzidos tres ensaios de digestibilidade para determinar o valor nutricional, os coeficientes de digestibilidade aparente e os teores de energia do trigo de duplo proposito (cultivar BRS Taruma), produzido em sistema agroecologico ou convencional, para suinos em diferentes fases da criacao (15, 45 e 75 kg de peso vivo-PV). Foram utilizados 15 suinos machos castrados, hibridos comerciais de alto desempenho para cada fase, divididos em tres grupos experimentais, o primeiro recebeu uma racao especifica para a fase, denominada de racao referencia (RR), os demais grupos receberam uma racao experimental com 70% de RR e 30% de trigo de duplo proposito dos sistemas agroecologico (Grupo 2) ou convencional (Grupo 3). Foram testadas diferencas entre os coeficientes para cada fase do estudo. Para as diferencas entre as fases foram realizadas analises descritivas das medias. Os sistemas de producao (convencional ou agroecologico) nao alteraram os coeficientes de digestibilidade do trigo. As medias dos coeficientes de digestibilidade aos 45 e 75 kg foram maiores. Os valores de energia digestivel foram de 3,25; 3,56 e 3,59 Mcal/kg para o trigo convencional e 3,14; 3,45 e 3,57 Mcal/kg para o trigo agroecologico, para as fases de 15, 45 e 75 kg de PV, respectivamente. A utilizacao do trigo a partir da fase de 45 kg apresentou melhores valores de digestibilidade, independente do sistema de producao.

A study was conducted to evaluate the use of macro ingredients as markers of the quality of mixed feeds. Were used: popcorn grain, sorghum, millet, rice colored and purple corn grinded (0.5% added to the diet, substituting grind corn) and coarse limestone sieved through sieve no 10 ABNT with 2 mm (added in 0.5% in the diet, substituting finely ground limestone). Microtracer F-Red was used as a method of reference. It was used a Y-type mixer (capacity of 5,000 cm3), and produced 1 kg of feed per repetition. It was adopted six mixing times (10 seconds, 1, 6, 11, 16 and 21 minutes) and five particle size of corn (386, 513, 610, 731 and 839 ?m), amounting 30 treatments with three repetitions for each treatment. Where collected 12 samples, for each replicate, to measurement of the markers and determination of the coefficient of variation (CV). A quadratic effect with minimum point for the CV was observed for all markers with the increasing of the mixing time. There was no effect of the particle size of corn for the coefficients of variation of coarse limestone and millet. There was a quadratic response of the particle size of corn for the coefficients of variation of purple corn and popcorn grain and linear effect for the colored rice, sorghum and reference method. The particle size of corn changed the time needed to reduce the CV of the markers: colored rice, milled purple corn, popcorn, sorghum and microtracer . The use of alternative markers has shown that it is a promising tool for the determination of the optimum mixing time, especially millet and limestone, that showed the highest correlations with the reference method.