Effect of Different Strategies of Management of Elephantgrass on Pasture Availability and Milk Yield of Crossbred Holstein X Zebu Cows

The trial was done to study different strategies of pasture management on milk production of cows grazing Elephantgrass (Pennisetum purpureum, Schum.). The treatments were: Elephantgrass with 30 days of resting and fertilized monthly (30MF), fertilized every two months (30BF). Elephantgrass with 45 days of resting and a stubble height of 90-100 cm (45HS) or a stubble height of 40-50 cm (45LS). The stubble height for treatments 30MF and 30BF was 90-100 cm. The study was done using six crossbred Holstein x Zebu cows/treatment, with 100 days of lactation, on average. The experimental design was a completely randomized block design with two replication. The stocking rate was 4.5 cows/ha and no concentrate was fed. The pasture was fertilized with 200 kg/ha/year of N and K2O. It was also applied 40 kg/ha/year of P2O5 and 1,000 kg/ha/year of dolomitic limestone. The average fat corrected (4%) milk yield was 10.3, 10.5, 9.3 and 9.2 kg/cow/day for treatments 30MF, 30BF, 45HS and 45LS, respectively. There were no effects (P\u3e 0.05) of stubble height or fertilization frequency, but the treatments with 30-day resting produced more (P\u3c 0.05) milk than those grazing at 45-day resting (10.4 versus 9.3). The overall average dry matter availability during the period was 1,652, 1,465, 1,821 and 1,707 kg/ha/cycle for the treatments 30MF, 30BF, 45HS and 45LS, respectively, and there was no treatment difference (P\u3e 0.05)

Effect of Concentrate Supplementation on Milk Yield of Crossbred Holstein X Zebu Cows Grazing Elephantgrass

The study was carried out using 12 ha of Elephantgrass (Pennisetum purpureum Schum.) pasture, fertilized with 660 kg/ha/year of 20.05.20 formula, during the rainy season of 1999. It was used eight cows per treatment/site in a completely randomized block design. Blocks were based on milk yield and date of calving. Pasture was managed with 30 days of resting period using a stocking rate of five cows/ha. The objective of the study was to evaluate the effects of feeding concentrate for the first 60 (T60) or 120 days (T120) post-partum on milk yield, in relation to the control-group (T0), fed no concentrate. Concentrate was fed at a rate of 1 kg per each 2 kg of milk above the basal level of 10 kg (rainy season) or 12 kg/cow/day (dry-season). It was planned to have half of the cows calving on the beginning of the dry season and half on the beginning of the rainy season. The study started in February in site one and in site two in March. Corn silage supplementation started on April 15 (site one) and May 14 (site two) and was halted on November 23 in both sites. After the afternoon milking, the cows had access to paddocks. The data were analyzed separately for the two seasons. There was no treatment effect on milk yield (P\u3e 0.05) for any season and the average dry season milk yield was 12.2, 12.8, 13.3, for the T0, T60 and T120 treatments, respectively

Within Resting Period Seasonal Soluble Carbohydrate Profiles of Rotationally Grazed Elephant Grass

Recent evidence indicates that carbohydrate-rich grazed herbage is effective for improving milk production (Trevaskis et al., 2004). However, the dynamics of water-soluble carbohydrate (WSC) seasonal accumulation as related to forage availability remains unknown, especially during the growth stage of tropical forage grazing systems. The objective of the work was to verify the seasonal WSC profiles of rotationally grazed elephantgrass (Pennisetum purpureum Schum.), by making measurements within each 30-day resting period

Flutuação populacional de cigarrinhas-das-pastagens em braquiária e capim-elefante

The objective of this work was to evaluate the fluctuation of spittlebug population in Brachiaria brizantha, Brachiaria decumbens and Pennisetum purpureum. The evaluations were conducted in field conditions, between September 2005 and March 2007. Spittlebug nymphs and adults were counted on B. brizantha cultivars Marandu, Xaraés and Arapoti, subjected to alternating grazing; on B. decumbens in a silvipastoral system and on 78 genotypes of P. purpureum. The Deois schach population density was greater on the Arapoti cultivar than on the Xaraés and Marandu cultivars. On B. decumbens, the number of spittlebugs was four times greater than on B. brizantha. No significant differences were observed in the number of spittlebugs infesting the different genotypes of P. purpureum.O objetivo deste trabalho foi avaliar a flutuação populacional de cigarrinhas-das-pastagens em Brachiaria brizantha, Brachiaria decumbens e Pennisetum purpureum. As avaliações foram realizadas em campo, entre setembro de 2005 e março de 2007. Ninfas e adultos de cigarrinhas-das-pastagens foram contabilizados em: B. brizantha cultivares Marandu, Xaraés e Arapoti, submetidas a rodízios de carga animal; em B. decumbens, em sistema silvipastoril; e em 78 genótipos de P. purpureum. A densidade populacional de Deois schach, na cultivar Arapoti, foi superior à de Xaraés e de Marandu. Em B. decumbens, o número de cigarrinhas-das-pastagens foi quatro vezes maior que em B. brizantha. Não foram observadas diferenças significativas no número de cigarrinhas-das-pastagens nos diferentes genótipos de P. purpureum

Morphogenesis and leaf biomass accumulation in elephantgrass sward evaluated at diferent period of the year

O objetivo deste trabalho foi avaliar o efeito da época do ano nas características morfogênicas e estruturais e no acúmulo de biomassa foliar de uma pastagem de capim-elefante (Pennisetum purpureum Schum.). Vacas mestiças Holandês x Zebu foram manejadas segundo o método de pastejo com lotação rotacionada com três dias de ocupação e 30 dias de descanso. Foi usado delineamento em blocos casualizados com seis repetições. As avaliações foram realizadas em fevereiro/março, abril/maio, julho/agosto e outubro de 2001. As maiores taxas de alongamento e aparecimento de folhas ocorreram durante fevereiro/março. Os perfilhos aéreos superaram os basilares em quantidade, mas apresentaram menores taxas de alongamento (5,1 versus 9,8 cm/dia/perfilho), aparecimento (0,13 versus 0,16 folhas/dia/perfilho) e senescência (0,9 versus 1,3 cm/dia/perfilho) foliares. As produções e taxas de acúmulo de biomassa foliar foram maiores durante fevereiro/março e apresentaram estreita relação com as variáveis morfogênicas. Os perfilhos aéreos contribuíram, em média, com 63% da biomassa foliar do capim-elefante.The objective of this work was to evaluate the effect of the time of the year on morphogenetic and structural traits and leaf biomass accumulation of elephantgrass (Pennisetum purpureum Schum.). The sward was managed in a rotational stocking method with lactacting cows with 30 days of resting period and three days of paddock occupation. A randomized block and six replicates were used. Evaluations were carried out at February/March, April/May, July/August and October of 2001. Higher values of leaf appearance and expansion rates were observed during the February/March period. Although the aerial tiller density was greater than the basal one, they showed lower leaf expansion (5.1 versus 9.8 cm/day/tiller), appearance (0.13 versus 0.16 leaves/day/tiller) and senescence (0.9 versus 1.3 cm/day/tiller) rates. The forage mass production and accumulation rates of leaf biomass were higher during February/March period and showed strong relationship with pasture morphogenetic traits. The aerial tillers contributed, in average, with 63% of total elephantgrass leaf biomass

Tiller classes on leaf area index composition in elephant grass swards

O trabalho foi conduzido de outubro de 2002 a abril de 2003, em Coronel Pacheco, MG, com o objetivo de avaliar os efeitos da altura do resíduo pós-pastejo (50 e 100 cm) sobre a radiação fotossinteticamente ativa (RFA) interceptada pelo dossel e o coeficiente de extinção luminosa; a contribuição relativa de classes de perfilhos (basais e aéreos) sobre o índice de área foliar (IAF) e o acúmulo de forragem (AF), em pastos de capim-elefante (Pennisetum purpureum Schum.) cv. Napier manejados com intervalos de 30 dias entre pastejos. Foi usado o delineamento blocos completos ao acaso e um arranjo de parcelas subdivididas com quatro repetições, com alturas de resíduo alocadas nas parcelas e as classes de perfilhos nas subparcelas. O IAF, a interceptação da RFA e o coeficiente de extinção luminosa foram influenciados pela altura do resíduo pós-pastejo. As interceptações da RFA foram maiores no verão do que na primavera, em pastos manejados com resíduo de 100 cm. As variações do IAF e da interceptação da RFA não estiveram associados, durante todos os ciclos de pastejo. O IAF e o AF apresentaram variações sazonais, relacionadas à participação de perfilhos basais e aéreos, na população de perfilhos do pasto.The work was carried out at Coronel Pacheco, MG, Brazil, from October 2002 to April 2003 with the objective of evaluating the effects of two post-grazing residues (50 and 100 cm) on the interception of photosynthetically active radiation (PAR) and light extinction coefficient; relative contribution of tiller classes (basal and aerial) to leaf area index (LAI) and herbage accumulation of elephant grass swards (Pennisetum purpureum Schum.) cv. Napier subjected to grazing intervals of 30 days. The experimental design was a complete randomized block, and treatments were allocated to experimental units using a split plot arrangement, with four replicates. Post-grazing residues were allocated to plots and tiller classes to sub plots. Sward LAI, PAR interception and light extinction coefficient were affected by heigth of post-grazing residue. The intercepted PAR was higher in the summer than in the spring, with higher values recorded for the 100 cm residues. Variations in LAI and intercepted PAR were not consistently associated throughout the experimental period. LAI and herbage accumulation showed seasonal variations related to the varying contribution of aerial and basal tillers to sward tiller population

Daily intake of lactating crossbred cows grazing elephant grass rotationally

O objetivo deste trabalho foi o de estimar o consumo total e o diário de matéria seca do pasto, de vacas mestiças Holandês – Zebu, em piquetes de capim-elefante (Pennisetum purpureum Schum.). Três grupos de 24 vacas foram usados em piquetes (4,5 vacas/ha), pastejados por três dias e submetidos a diferentes períodos de descanso durante dois anos. Os tratamentos consistiram de descansos de 30 dias sem concentrado e 30, 37,5 e 45 dias com a suplementação de 2 kg de concentrado (20,6% de proteína bruta). De julho a outubro, as vacas receberam, como suplementação, cana-de-açúcar mais 1% de uréia. O consumo total de matéria seca foi estimado a partir da digestibilidade in vitro da matéria seca da extrusa e da produção fecal obtida com óxido crômico. Independentemente do tratamento, o consumo total foi 2,7; 2,9 e 2.9±0,03%, e o consumo de matéria seca do pasto foi de 1,9; 2,1 e 2,1±0,03% do peso vivo (p < 0,05), respectivamente, no primeiro, segundo e terceiro dia de ocupação do piquete. Somente no verão, o consumo do pasto foi semelhante nos três dias de pastejo. A mistura cana-de-açúcar e uréia substituiu o pasto, principalmente no primeiro dia de pastejo, ocasião em que o consumo do pasto era mais baixo.The goal of this trial was to estimate the total dry matter (TDMI) and daily pasture dry matter intakes (PDMI) by lactating crossbred Holstein – Zebu cows grazing elephant grass (Pennisetum purpureum Schum.) paddocks submitted to different rest periods. Three groups of 24 cows were used during two years. The paddocks were grazed during three days at the stocking rate of 4.5 cows/ha. Treatments consisted of resting periods of 30 days without concentrate and resting periods of 30, 37.5 and 45 days with 2 kg/cow/day of 20.6% crude protein concentrate. From July to October, pasture was supplemented with chopped sugarcane plus 1% urea. Total daily dry matter intake was estimated using the extrusa in vitro dry matter digestibility and the fecal output with chromium oxide. Regardless of the treatment the estimated average TDMI was 2.7, 2.9 and 2.9±0.03% and the mean PDMI was 1.9, 2.1 and 2.1±0.03% of body weight in the first, second and third grazing day, respectively (P < 0.05). Only during the summer pasture quality was the same whichever the grazing day. Sugarcane effectively replaced grazing pasture, mainly in the first day when pasture dry matter intake was lowest

Métodos para estimar a forragem consumível em pastagem de capim-elefante

The objective of this work was to evaluate the efficiency and reliability of methods to estimate edible forage dry matter on an elephant grass pasture (Pennisetum purpureum Schumach.). Visual comparative yield method (VCYM) and hand plucking (HP) were used. Two samplings, one in March 20, and another in April 5, 2001, with one and four observers for HP and VCYM, respectively, were done. Estimates of edible forage dry matter were analysed by linear regression and the average estimates were compared by using F test with a probability level of 1%. There was no difference between the two sampling methods. Both, VCYM and HP were efficient to estimate potentially edible forage in the elephant grass pasture. The observers training is decisive, especially when VCYM is used.O objetivo deste trabalho foi avaliar a eficiência e a confiabilidade de métodos para estimar a forragem consumível em pastagem de capim-elefante (Pennisetum purpureum Schumach.). Foram usados o método do rendimento visual comparativo (MRVC) e o método do pastejo simulado (PSIM). Foram realizadas amostragens em 20 de março e 5 de abril de 2001, com um e quatro observadores para PSIM e MRVC, respectivamente. As estimativas obtidas foram analisadas por meio de regressão linear da produção de matéria seca em razão dos padrões estimados e as médias comparadas pelo teste F, a 1% de probabilidade. Não houve diferença entre os métodos. Tanto o MRVC como o PSIM podem ser recomendados para estimar a forragem potencialmente consumível em pastagem de capim-elefante. O treinamento dos avaliadores torna-se decisivo, especialmente quando o MRVC estiver sendo utilizado