RESUMO -Cinco híbridos de milho foram avaliados quanto à produtividade de matéria seca, ao valor nutritivo da silagem e à produtividade de leite. Os híbridos avaliados foram AS 32, AG 9090, CD 308, DKB 747 e P 30F87, colhidos em três alturas de corte: 15, 35 e 55 cm. O delineamento experimental foi em blocos casualizados com parcelas subdivididas e três repetições.Para confecção das silagens, utilizaram-se silos experimentais de PVC com 20 cm de diâmetro e 40 cm de altura. A produtividade de leite, por tonelada de silagem (eficiência alimentar) e por hectare, foi estimada pelo modelo Milk2006. A produtividade de forragem ensilável reduziu com o aumento da altura de colheita, com resultados de 14,6; 13,0 e 12,6 t/ha MS para as alturas de colheita de 15 cm, 35 cm e 55 cm, respectivamente. O híbrido de milho e a altura de colheita influenciaram a composição bromatológica das silagens, com exceção do teor de extrato etéreo (EE), que não foi influenciado pela altura de colheita. Ocorreu interação híbrido × altura de colheita para o teor de amido, a digestibilidade in vitro da MS e da fibra em detergente neutro (FDN) e o teor de nutrientes digestíveis totais (NDT). Houve efeito da altura de colheita sobre a eficiência alimentar, cujos valores médios foram de 1.226, 1.291 e 1.393 kg leite/t silagem nas alturas de colheita de 15, 35 e 55 cm, respectivamente. Observou-se também efeito do tipo de híbrido sobre a produtividade de leite e a eficiência alimentar, com melhores valores verificados para o híbrido DKB 747 colhido na altura de 55 cm. Ao elevar a altura de colheita, melhora-se o valor nutritivo da silagem sem prejudicar a produtividade de leite por hectare. O manejo da altura de corte não substitui a escolha de melhores híbridos para produção de silagem de alta qualidade e produtividade. Palavras-chave: digestibilidade, eficiência alimentar, produtividade de leite Productivity and nutritional value of silage of corn hybrids with different heights of harvestABSTRACT -Five corn hybrids were evaluated to the productivity of dry matter, nutritive value of silage and milk yield.The hybrids evaluated were AS 32, AG 9090, CD 308, DKB 747 and P 30F87, harvested at three cutting heights: 15, 35 and 55 cm. The experimental design was a randomized block with split plots and three replicates. Experimental silos of PVC with 20 cm of diameter and 40 cm of height were used. Milk yield per ton of silage (feed efficiency) and milk production per hectare were estimated by using the model Milk2006. The productivity of ensilable forage decreased with increase in height of harvest, with results of 14.6, 13.0 and 12.6 t/ha DM for the cut heights of 15 cm, 35 cm and 55 cm, respectively. Corn hybrid and cut height influenced chemical composition of silage, except for EE, which was not influenced by cut height. There was an interaction hybrid × cut height for the content of starch, in vitro digestibility of DM and of neutral detergent fiber (NDF), and content of total digestible nutrients (TDN). Cut height affected feed efficiency whose a...

Limpograss [Hemarthria altissima (Poir.) Stapf & C.E. Hubb.] is commonly used as stockpiled forage. Variation in forage characteristics during the stockpiling period may affect supplementation strategies. Our objective was to characterize herbage mass (HM) and nutritive value of different canopy layers of stockpiled limpograss under continuous stocking from January to March in 2014 and 2015. Treatments were two limpograss cultivars (Floralta or Gibtuck) and three canopy layers (below 25 cm [CL0], 25–50 cm [CL25], or above 50 cm [CL50]) sampled biweekly. Gibtuck had greater HM (6.1 vs. 5.5 Mg ha−1) and in vitro digestible organic matter (IVDOM, 490 vs. 440 g kg−1) than Floralta. Herbage mass was 4.2, 3.3, and 1.0 Mg ha−1 in January, 2.5, 3.2, and 0 Mg ha−1 in February, and 3.4, 0.3, and 0 Mg ha−1 in March for CL0, CL25, and CL50, respectively. The IVDOM concentrations were 380, 470, and 570 g kg−1 in January for CL0, CL25, and CL50, and 390 and 450 g kg−1 in February and 390 and 400 g kg−1 in March for CL0 and CL25, respectively. Leaf proportion in the canopy decreased from CL50 to CL0. To meet the nutritional requirements of beef cattle grazing stockpiled limpograss pastures, it is necessary to adjust the supplementation quantity and composition during the stockpiling period due to the variation in HM, plant‐part proportion, and nutritive value of the canopy.

Bermudagrass is the main warm-season grass species used for livestock production in the southeastern United States; however, when it is ensiled, the silage fermentation parameters are often less than desirable. The objective of this study was to investigate the effects of management practices on the nutritive value and fermentation characteristics of bermudagrass silage. In Exp. 1, treatments were the factorial combinations of 2 bermudagrass genotypes, 'Jiggs' () and 'Tifton 85' ( sp.), 4 additives, and 2 DM concentrations at ensiling. The additives were 1) untreated control (deionized water), 2) Ecosyl, 3) B500, or 4) sugarcane molasses. The 2 DM concentrations at ensiling were low DM (22% DM) or high DM (53% DM). Treatments were replicated 3 times in a completely randomized design. Silage treated with molasses had a lesser ( < 0.05) pH and greater ( < 0.01) lactate concentrations than the control, Ecosyl, and B500 in silage with low DM concentrations and greater ( < 0.01) in vitro true digestibility (IVTD) and lesser ( < 0.01) ADF concentrations than the other treatments at either DM concentration. Silage treated with B500 had the greatest ( < 0.01) aerobic stability, whereas that treated with molasses had the least aerobic stability. However, all treatments presented long aerobic stability (≥150 h). Jiggs had lesser ( < 0.01) ADF and NDF and NDF digestibility (NDFD) concentrations than Tifton 85 and Tifton 85 had greater ( < 0.01) IVTD than Jiggs in the silage with a high DM concentration. In Exp. 2, Jiggs silage treated with either molasses (20 g molasses [DM]/kg forage [as-fed basis]) or nothing (control, untreated silage) was fed to 16 beef heifers ( sp.) in individual drylot pens in a completely randomized design with 8 replicates for voluntary DMI, in vivo apparent DM digestibility, and NDFD evaluations. There were no differences ( = 0.36) among treatments in NDFD; however, there was a trend ( < 0.08) for greater in vivo apparent DM digestibility and DMI in heifers fed the molasses-treated silage. Microbial inoculants had decreased effects on Jiggs and Tifton 85 bermudagrass silage ensiled at a low DM concentration; however, adding molasses was an effective management practice to improve its nutritive value and fermentation characteristics.

Core Ideas Bahiagrass pastures on soils with low K concentration may not respond to K fertilization. Tissue K concentration in bahiagrass is variable and dependent on fertilization levels. Bahiagrass tissue K concentration of 17 g kg−1 was related to the greatest herbage accumulation in plants receiving greater levels of fertilization. Bahiagrass (Paspalum notatum Flügge) is the most utilized forage for beef cattle (Bos spp.) in Florida, but there is concern that bahiagrass pastures are declining due to insufficient K fertilization. Two studies determined the effects of K and N fertilization on bahiagrass herbage mass (HM) and nutritive value in field plots (Exp. 1), and greenhouse (Exp. 2). At two locations from May to December 2014 and 2015, Exp. 1 evaluated the combinations of three N fertilization levels (0, 50 kg N ha−1 in May, or 50 kg N ha−1 in May and August) and two levels of K fertilization (0 or 42 kg K ha−1). Potassium fertilization did not affect HM, crude protein (CP), or in vitro digestible organic matter (IVDOM); however, tissue K concentration increased from 10.6 to 11.2 g kg−1 with increasing K fertilization. Plots fertilized with N had greater HM than the control, but there was no difference between plots fertilized in May only vs. those fertilized in May and August. Experiment 2 was conducted in a greenhouse in 2014 and 2015 with a factorial combination of three levels of N fertilization (0, 50, and 100 kg N ha−1) and four levels of K fertilization (0, 16, 33, and 66 kg K ha−1). There was a quadratic relationship between tissue K concentration and herbage accumulation (HA) and maximum HA occurred with tissue K concentration of 17 g kg−1. Bahiagrass tissue K concentration and response to K fertilization are variable and can be related to fertilization levels.

O objetivo deste trabalho foi avaliar o ganho médio diário (GMD) de novilhos em pastejo de B.brizantha cv. Marandu, suplementados com três tipos de suplementos, no período de julho a dezembro, em dois níveis de fornecimento. Foram utilizados 54 novilhos Nelore (nove por tratamento) com idade aproximada de 20 meses e peso vivo inicial de 370 kg. Os suplementos utilizados foram: suplemento rico em amido (AMI), rico em óleo (OLE) e suplemento composto de amido+óleo (A+O). Os suplementos foram fornecidos em níveis de 0,7 e 1,4% do peso vivo. A disponibilidade de lâminas verdes do capim-braquiária foi de 5,12 kg de MS/100 kg de PV. Os suplementos e níveis influenciaram o ganho médio diário (GMD). Nos dois níveis de fornecimento, o suplemento A+O promoveu o melhor desempenho. No menor nível de fornecimento (0,7% PV), os suplementos com AMI e OLE não diferiram entre si, mas ambos diferiram do suplemento A+O. Para este nível de fornecimento, o GMD foi 0,46; 0,44 e 0,57 kg para os tratamentos AMI, OLE e A+O, respectivamente. Resultados semelhantes foram observados no nível de fornecimento de 1,4% do PV. Neste caso, o suplemento A+O foi superior ao AMI e OLE, que não diferiram entre si. O GMD foi 0,58 kg para AMI, 0,61 kg para OLE e 0,72 kg para A+O. A suplementação com concentrados compostos pela mistura de alimentos ricos em amido (milho) e óleo (caroço de algodão) proporcionou melhor desempenho dos animais em comparação aos suplementados separadamente com as respectivas fontes, independentemente do nível de suplementação. O maior nível de suplementação (1,4% do PV) apresentou eficiência econômica inferior, quando comparada à do menor nível (0,7% do PV).