ABSTRACT Tifton 85 bermudagrass has been widely used in tropical and subtropical regions. Owing to its high forage yield, the fertilizer requirement of Tifton 85 is also high. Inoculation with Azospirillum brasilense is an alternative to reduce the use of nitrogen fertilizers and decrease their environmental impact. However, the effects of inoculation in tropical grasses remain poorly understood. This study aimed to evaluate the productivity, pasture characteristics, and nutritive value of Tifton 85 bermudagrass inoculated with A. brasilense in association with nitrogen fertilization. The study evaluated four nitrogen levels (0, 100, 200, and 300 kg ha-1 ), inoculated and uninoculated, under cutting conditions. The experimental design was completely randomized, in a factorial arrangement, with two qualitative (inoculated with A. brasilense or uninoculated) and four quantitative levels (nitrogen doses) with three replications (24 plots). Botanical composition and morphological characteristics, leaf blade/stem+sheath ratio, nutritive value, and forage yield were evaluated. The inoculation increased the leaf blade/stem+sheath ratio and forage yield of Tifton 85, but did not affect crude protein concentration, neutral detergent fiber content, and total digestible nutrient content of the forage constituted by Tifton 85 leaf blades. The protein concentration and forage production corresponded linearly to the nitrogen dose increase.

ABSTRACT Forage-legume systems are a sustainable and competitive alternative for improving pasture yield and quality because of the symbiotic nitrogen fixation capacity and high nutritional value of legumes. This study aimed to evaluate the forage mass, nutritional value, and nutrient export rate in three forage systems (FS): FS1, with elephant grass (Pennisetum purpureum) (EG), annual ryegrass (Lolium multiflorum) (AR), and spontaneous growth species (SGS); FS2, with EG + AR + SGS + arrowleaf clover (Trifolum vesiculosum); and FS3, with EG + AR + SGS + forage peanut (Arachis pintoi ). The experiment was arranged in a completely randomized design, with three replicates, and repeated measures over time. Results of pre-grazing forage mass were 3.5, 3.8, and 3.9 t/ha, and crude protein export were 1.4, 2.1, and 2.3 t/ha, for the treatments FS1, FS2 and FS3, respectively. Highest crude protein, in situ dry matter digestibility and total digestible nutrients, and lowest neutral detergent fiber were found in the intercropping system with forage peanut, especially in winter. Nutritional values were also better in legume-systems than the non-legume system.

RESUMO Sistemas forrageiros constituídos pelo consórcio gramínea-leguminosa equilibram a oferta de forragem e minimizam impactos ambientais, pela redução da fertilização nitrogenada. O amendoim forrageiro tem várias características que são adequadas aos consórcios forrageiros, mas ainda não foram adequadamente explorados. O objetivo deste trabalho foi avaliar o consórcio constituído por capim bermuda, cv. Tifton 85, e o amendoim forrageiro quanto à produção de forragem, proteína bruta e taxa de lotação. Em dois anos agrícolas, foram avaliados três sistemas forrageiros assim constituídos: (a) Tifton 85 (T) + 100 kg de N ha-1 ano-1 + amendoim forrageiro (T + AF + 100); (b) T + 100 kg de N ha-1 ano-1 (T + 100; controle, somente gramínea); e (c) T + 200 kg de N ha-1 ano-1 (T + 200; controle positivo, somente gramínea). Neste estudo foram avaliados o rendimento de forragem, características da pastagem e respostas das vacas em lactação. O delineamento experimental foi o inteiramente casualizado com três tratamentos (sistemas forrageiros) e três repetições (piquetes) e medidas repetidas (ciclos de pastejo dentro das estações do ano). O acúmulo de forragem, a concentração de proteína e a taxa de lotação foram de 15,1; 11,3 e 14,1 t de MS ha-1 ano-1; 17%, 16% e 17%; e 5,3; 4,9 e 6,1 UA ha-1 dia-1, respectivamente. Melhores resultados foram obtidos no consórcio forrageiro.

ABSTRACT Mixed pasture grass-legume systems balance forage supply and minimize environmental impacts by reducing the need for nitrogen fertilization. Pinto peanut (Arachis pintoi Krap. and Greg. “Amarillo”) has several traits that are suitable for mixed pastures but have not yet been adequately explored. The aim of this study was to evaluate a mixture of Tifton 85 bermudagrass (Cynodon dactylon) and pinto peanut and evaluate forage yield, crude protein, and stocking density. A two-year study of three grazing systems was used with the following treatment combinations: (a) Tifton 85 (T) + 100 kg N ha-1 yr-1 + pinto peanut (T + PP+100); (b) T + 100 kg N ha-1 yr-1 (T + 100; control, pure grass); and (c) T + 200 kg N ha-1 yr-1 (T + 200; positive control, pure grass). In this study, forage yield, pasture characteristics and responses of lactating cows were evaluated. The experimental design was completely randomized with three treatments (grazing systems), three replicates (paddocks), and repeated measures (grazing cycles within seasons). Forage accumulation, crude protein concentration, and stocking rate were 15.1; 11.3 and 14.1 t DM ha-1 yr-1; 17%, 16%, and 17%; and 5.3; 4.9 and 6.1 AU ha-1 day-1, respectively. The grass-legume system yielded the best results.

RESUMO. O objetivo nesta pesquisa foi avaliar a produtividade, a taxa de lotação e o valor nutritivo de três sistemas forrageiros: capim elefante (CE) + azevém (AZ) + espécies de crescimento espontâneo (ECE), sem leguminosa; CE + AZ + ECE + amendoim forrageiro (AM), consórcio com AM; e CE + AZ + ECE + trevo vermelho (TV), consórcio com TV, em pastejo com lotação rotacionada utilizando vacas em lactação. Possibilitou-se o desenvolvimento do AZ entre as touceiras de CE. O AM foi preservado na área e o TV foi semeado, respectivamente para os sistemas forrageiros. O delineamento experimental foi inteiramente casualizado, com três tratamentos, duas repetições e parcelas subdividas no tempo. Os valores médios de produção e das taxas de lotação foram de 10,6; 11,6 e 14,4 t ha-1; 3,0; 2,8; e 3,1 unidades animal ha-1 dia-1, para os respectivos sistemas. Os teores de proteína bruta e de nutrientes digestíveis totais foram de 17,77; 18,70 e 17,45%; 66,47; 66,77 e 64,76% para os respectivos sistemas. O consórcio com TV resulta em melhor e maior produção de forragem, enquanto o consórcio com AM resulta em melhor controle de ECE. A inclusão de leguminosas forrageiras implica em melhor valor nutritivo do pasto.

ABSTRACT. Current research evaluates productivity, stocking and nutritional rates of three forage systems with Elephant Grass (EG) + Italian Ryegrass (IR) + Spontaneous Growth Species (SGS), without forage legumes; EG + IR + SGS + Forage Peanut (FP), mixed with FP; and EG + IR + SGS + Red Clover (RC), mixed with RC, in rotational grazing method by lactating cows. IR developed between rows of EG. FP was maintained, whilst RC was sow to respective forage systems. The experimental design was completely randomized, with three treatments and two replication, subdivided into parcels over time. Mean rate for forage yield and average stocking rate were 10.6, 11.6 and 14.4 t ha-1; 3.0, 2.8 and 3.1 animal unit ha-1 day-1, for the respective systems. Levels of crude protein and total digestible nutrients were 17.8, 18.7 and 17.5%; 66.5, 66.8 and 64.8%, for the respective forage systems. The presence of RC results in better and higher forage yield in the mixture, whilst FP results in greater control of SGS. The inclusion of forage legumes in pasture systems provides better nutritional rates.

RESUMO Este trabalho foi realizado para avaliar três sistemas forrageiros constituídos por capim bermuda, cv. Coastcross-1 (CC) + 100 kg N ha -1 ano-1 + ervilhaca comum; CC + 100 kg N ha -1 ano-1 + trevo vesiculoso e CC + 200 kg N ha -1 ano-1. Foram realizados 13 ciclos de pastejo durante o período experimental (313 dias), dois, cinco, quatro e dois ciclos, no inverno, primavera, verão e outono, respectivamente. Para avaliação experimental foram utilizadas vacas em lactação da raça Holandesa. Foram avaliados a taxa de acúmulo diário, a produção de forragem, a taxa de desaparecimento, o consumo agronômico, a eficiência de pastejo, a oferta de forragem e a taxa de lotação. Os valores médios da produção de forragem e taxa de lotação foram 20,8; 17,6 e 19,7 t MS ha-1 e 7,0; 6,8 e 6,8 unidade animal ha-1 dia-1 para os respectivos sistemas de forrageiras. O consórcio constituído por Coastcross-1 + ervilhaca, adubado com 100 kg N ha -1 ano-1 e a pastagem de Coastcross-1 adubada com 200 kg N ha -1 ano-1 proporcionaram maior produtividade e melhor distribuição da forragem ao longo das estações.

ABSTRACT Three grazing systems with Coastcross-1 bermuda grass (CC) + 100 kg N ha-1 year-1 + common vetch; CC + 100 kg N ha-1 year-1 + arrowleaf clover; and CC + 200 kg N ha-1 year-1 were evaluated. Thirteen grazing cycles were performed during the experimental period (313 days), with two, five, four and two cycles respectively in winter, spring, summer and fall. Lactating Holstein cows were used in the evaluation. Daily accumulation rate, forage production, rate of forage disappearance, agronomic intake, grazing efficiency, herbage allowance and stocking rate were evaluated. Mean rates of forage yield and stocking rate were 20.8; 17.6 and 19.7 t DM ha-1 and 7.0; 6.8 to 6.8 animal units ha-1 day-1 for the respective forage systems. The mixture Coastcross-1 plus common vetch, fertilized with 100 kg N ha-1 year-1 and Coastcross-1 fertilized with 200 kg N ha-1 year-1 provided greater productivity and better distribution of forage throughout the seasons.