Management strategies for increasing ruminant legume consumption and mitigating methane emissions from tropical livestock production systems require further study. The aim of this work was to evaluate the herbage intake, animal performance and enteric methane emissions of cattle grazing dwarf elephant grass (DEG) ( Pennisetum purpureum cv. BRS Kurumi) alone or DEG with peanut (Arachis pintoi cv. Amarillo). The experimental treatments were the following: DEG pastures receiving nitrogen fertilization (150 kg N/ha as ammonium nitrate) and DEG intercropped with peanut plus an adjacent area of peanut that was accessible to grazing animals for 5 h/day (from 0700 to 1200 h). The animals grazing legume pastures showed greater average daily gain and herbage intake, and shorter morning and total grazing times. Daily methane emissions were greater from the animals grazing legume pastures, whereas methane emissions per unit of herbage intake did not differ between treatments. Allowing animals access to an exclusive area of legumes in a tropical grass-pasture-based system can improve animal performance without increasing methane production per kg of dry matter intake.

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Condensed tannins can reduce protein degradation in the rumen by increasing the duodenal flow of metabolizable proteins and consequently improving animal performance. The objective of this study was to evaluate the effect of the tannin extract of Acacia mearnsii on lactating ewes receiving a total mixed ration (TMR) containing two concentrations of crude protein. The experimental treatments consisted of a TMR containing 16.4% or 22.3% of crude protein in dry matter either with or without the tannin extract of Acacia mearnsii at 20 g kg-1 dry matter. The extract concentration that guaranteed the daily intake of approximately 15 g of the extract per animal was determined. Eight lactating ewes of the Texel × Lacaune breed in the second third of lactation were distributed in a 4 × 4 Latin square experimental design, with four periods of 19 days, including 14 days of adaptation and 5 days of sample collection. Urinary nitrogen excretion was increased in the animals fed a diet containing a relatively higher protein concentration compared to those receiving a diet with a lower protein concentration. However, milk production and the concentration of milk solids did not vary significantly among treatments. The tannin extract of Acacia mearnsii decreased urinary nitrogen excretion, and consequently reduced the environmental impact of the production system, but did not significantly improve animal performance.

RESUMO A grama missioneira gigante (Axonopus catharinensis Valls) é uma espécie forrageira que merece ser melhor investigada tanto pura como recebendo a inclusão de leguminosas. Objetivou-se avaliar o consumo de MS por ovinos pastejando grama missioneira gigante com ou sem acesso a pastos de amendoim forrageiro (Arachis pintoi cv. Amarillo). Para isso, foi conduzido um experimento prévio com cordeiros alojados em gaiolas metabólicas, gerando-se uma equação para a estimativa do consumo tomando como base a excreção fecal de proteína bruta (PBf), que apresentou R2= 0,91. Em um segundo experimento, foi avaliado o consumo de forragem por ovinos em pastos de grama missioneira gigante com duas alturas de entrada (25 ou 35cm), com ou sem acesso a áreas de amendoim forrageiro por duas horas diárias. A altura de entrada na grama missioneira gigante não alterou o consumo total de MS, mas o acesso aos piquetes da leguminosa aumentou o consumo em aproximadamente 20%. Em conclusão, a grama missioneira gigante pode ser manejada com alturas de entrada entre 25 e 35cm, enquanto o acesso a áreas de amendoim forrageiro por duas horas diárias aumenta o consumo de MO por cordeiros pastejando a missioneira.

Food intake is determinant in the production process and can be modified when more than one type of forage is supplied in the diet. The aim of this study was to evaluate the effects of supplementation with corn silage + soybean meal (9:1 based on DM) in the proportion of 10 g DM kg?1 live weight (LW) for lambs receiving pre-dried ryegrass (Lolium multiflorum Lam) in two forage supply levels: ad libitum or restricted (60% of the consumption ad libitum). Eight castrated male sheep crosses Texel × Criollo (average of 31.5 ± 2.2 kg LW) were used in an experimental design of 4 × 4 Latin square. Each experimental period was performed for 19 days, with 14 days for adaptation and 5 days for collections. Animals were fed three times a day (08h00, 11h30, and 16h30). Supplemented animals received corn silage at 08h00 and ryegrass silage at 11h30 and 16h30. The substitution rates (kg DM consumed forage per kg DM consumed silage) were 0.93 for animals with a supply of ryegrass ad libitum and zero for those receiving the same in a restricted amount. The digestible OM (DOM) intake and nitrogen retention did not vary with supplementation in animals that received ryegrass ad libitum but increased in those with restricted supply. However, animals with restricted supply and supplemented had a less digestible OM intake and nitrogen retention than the average of those that received ryegrass ad libitum. Organic matter digestibility and efficiency of microbial protein synthesis were not affected by treatments, but the digestibility of NDF and ADF was lower in supplemented animals when compared to those non-supplemented and in restricted supply when compared to consumption ad libitum. Even with supplementation, feed restriction of base forage can limit the daily intake of digestible OM and the daily retention of N in sheep.