Elephantgrass Pasture Research Articles

Can N2 fixation by forage legumes build soil organic matter to rival fertilizer N in a tropical forest biome?

Fertilization of pastures with nitrogen (N) can increase animal productivity and may also increase the stocks of soil carbon (C). Recently stoloniferous forage legumes have been used to develop productive sustainable mixed pastures in the Atlantic forest biome. The objective of this study was to compare the impact over 24 years on soil C and N stocks of a productive N-fertilized pasture of Urochloa brizantha cv. Marandu with a mixed forage peanut (Arachis pintoi)-Marandu grass pasture introduced 8 years after an N-fertilized elephantgrass (Pennisetum purpureum) pasture. The pastures were rotationally stocked by Nellore cattle a green-forage allowance equivalent to 4% of body weight and animal performance was continuously monitored. Soil samples were taken at the start of the study and after 8 and 24 years of grazing and analyzed for total C and N and 13C abundance. In 8 years, the stocks of soil organic matter (SOM – 0-30 cm) increased by 4.4 Mg C and 0.58 Mg N ha−1 under the elephantgrass pasture and by 10.4 Mg C and 1.23 Mg N ha−1 under the Marandu grass pasture, both fertilized with 160 kg N ha−1 yr−1. Over the subsequent 16 years, SOM stocks under the Marandu grass fertilized with 120 kg N ha−1 and the mixed forage peanut-Marandu pasture which replaced elephantgrass attained similar stocks of soil C of 51.8 and 52.5 Mg C ha−1 respectively, approximately 12 Mg C greater than under the native vegetation. The 13C abundance of the soil samples indicated that the C4 grass roots made an insignificant contribution to soil C below 30 cm depth. The results show that the N2-fixing forage peanut was just as effective in accumulating SOM as an annual application of 120 kg N fertilizer ha−1 and indicated that after 24 years of these pastures there was little further SOM accumulation.

Performance of crossbred Holstein x Gyr dairy cows, with and without energy supplementation, in BRS Kurumi elephant grass pastures

This study evaluated the effect of energy supplementation with ground corn on the performance of crossbred dairy cows in BRS Kurumi elephant grass pastures managed under rotational stocking during the rainy season. Six Holstein × Gyr cows were used, with average milk production, body weight, body condition score, and days in milk of 18.0±2.89 kg day−1, 560±66 kg, 2.50±0.21, and 99±12, respectively. The experimental design used was the complete reversion (switchback), and the evaluations were conducted over three grazing cycles, with adaptation periods of 14 days and six days of sample collection. The concentrate supplement (ground corn) was supplied twice a day, at a rate of 2 kg cow−1 day−1 in the morning and 1 kg cow−1 day−1 in the afternoon (as-fed basis). A reduction of 23.4% was observed in the pasture dry matter (DM) intake (PDMI) in cows that received energy supplementation, which corresponds to 2.96 kg day-1 less of PDMI when compared to the group without supplementation. This corresponds to a substitution rate of 1.1 kg of pasture per kg of concentrate consumed (DM basis), which reduced the intake (kg cow−1 day−1) of neutral detergent fiber and crude protein by 18.9% and 13.9% in the cows that received ground corn. There were increases of 11.8%, 9.0%, and 10.1%, respectively, in the milk yield, the 3.5% fat-corrected milk yield, and the energy-corrected milk yield of the cows that received ground corn. The response to supplementation in kg of milk per kg of DM of concentrate consumed was 0.57, and the milk contents of fat, protein, and lactose did not differ between treatments. The energy supplementation with 3 kg cow−1 day−1 of ground corn resulted in an increase of 11.8% in the milk yield of Holstein × Gyr dairy cows grazed on BRS Kurumi elephant grass, as well as promoted increases in the daily protein, lactose, and total solids yields. In addition, the provision of 3 kg day−1 of ground corn for lactating cows grazing on BRS Kurumi increased the efficiency in the use of dietary nitrogen.

Beef Production on Rotationally Grazed F1 Pennisetum Hybrid and Elephant Grass (Pennisetum Purpureum Schum.) Pastures

COMPARATIVE studies of elephant and the F1 hybrids between the ‘maiwa’ Cultivar of millet (Pennisetum americanum) elephant grass (P. purpureum) indicated a superiority in quality of the hybrids. To ascertain this potential superiority animal performance was measured by exciting beef production on F1 Pennisetum hybrid and elephant grass pastures consisting of random mixture of genotype which were grazed from July 28 to December 6. 1972 (132 days) by 18 to 24 months old White Falani (Bunaji) Zebu heifers. Each pasture was divided into Six 0.07- ha paddocks which were grazed in rotation by two heifers for 5 to 7 days with intervening rest periods of 30 to 35 days. Total liveweight gains per hectare, of animals grazing F1 Pennisetum hybrid and elephant grass pastures were 246.71 and 171.77kg respectively. Mean daily liveweight gain per 100 Kg body weight of animals on the F1 Pennisetum hybrid nature was 0.18 kg which was significantly higher than the 0.13 kg of animals grazing elephant grass. Dry matter (DM) utilisation and average daily intake of the F1 hybrids and elephant grass were respectively, 46 and 35% and 2.2 an 2.0% of body weight while 11.71 kg and 15.85 kg of F1 Pennisetum hybrids and elephant grass, respectively, were consumed per kg of liveweight gain. The superior performance of animals grazing F1 hybrid Pennisetum, was attributed to the higher intake and more efficient conversion of the hybrids. Stand mortality of F1 Pennisetum hybrids and elephant grass at the end of the study were 25 and 15%, respectively. Greater animal output can be expected from F1 Pennisetum hybrids selected for improved DM production quality and plant persistence.

Beef Production on Rotationally Grazed F1 Pennisetum Hybrid and Elephant Grass (Pennisetum Purpureum Schum.) Pastures

Comparative studies of elephant grass and the F1 hybrids between the 'maiwa' cultivar of millet ( Pennisetum americanum ) and elephant grass ( P. purpureum ) indicated a superiority in quality of the hybrids. To ascertain this potential superiority animal performance was measured by estimating beef production on F1 Pennisetum hybrid and elephant grass pastures consisting of random mixtures of genotypes which were grazed from July 28 to December 6, 1972 (132 days) by 18 to 24 months old White Fulani (Bunaji) Zebu heifers. Each pasture was divided into six 0.07-ha paddocks which were grazed in intervening rest periods of 30 to 35 days. Total liveweight gains per hectare, of animals grazing F1 Pennisetum hybrid and elephant grass pastures were 246.71 and 171.77 kg respetively. Mean daily liveweight gain per 100 kg body weight of animals on the F1 Pennisetum hybrid pasture was 0.18 kg of animals grazing elephant grass. Dry matter (DM) utilisation and average daily intake of the F1 hybrids and elephant grass were respectively, 46 and 35% and 2.2 and 2.0% of body weight while 11.71 kg and 15.85 kg of F1 Pennisetum hybrids and elephant grass, respectively, were consumed per kg of liveweight gain. The superior performance of animals grazing F1 Pennisetum hybrids was attributed to the higher intake and more efficient conversion of the hybrids. Stand mortality of F1 Pennisetum hybrids and elephant grass at the end of the study were 25 and 15%, respectively. greater animal output can be expected from F1 Pennisetum hybrids selected for improved DM production quality and plant persistence.

Soil and Root Attributes in Pastures Managed under Different Stocking Rates and Nitrogen Fertilization Levels

Core Ideas Grassland is a widespread agroecosystem in the globe; however, not enough attention has been given to link grazing management to soil health. Grazing management practices greatly impact soil quality. Moderate stocking rate are more adequate to keep grassland stability. Pasture management affects soil physical–chemical properties and root depth distribution. Adjusting grazing pressure and N fertilization are key management tools affecting these responses. This study evaluated the effect of N fertilization and stocking rate (SR) on soil physical and chemical attributes and root depth distribution in grazed elephantgrass (Pennisetum purpureum Schum. cv. 381) pastures (2009 and 2010). Treatments consisted of three SR (2.0, 3.9, and 5.8 AU ha−1; 1 AU = animal unit = 450 kg body weight) and three N doses (0, 150, and 300 kg N ha−1 yr−1) on elephantgrass pastures. Response variables included soil bulk density (BD), particle density (PD), total porosity (TP), aggregate stability (AS), water infiltration rate (WIR), light fraction of soil organic matter (LF‐SOM), soil fertility, root length density (RLD), and root biomass. Increased SR resulted in greater BD. Soil bulk density ranged from 1.42 to 1.58 g cm−3 for SR ranging from 2.0 to 5.8 AU ha−1, respectively. The C concentration of the LF‐SOM decreased with increasing SR, ranging from 383 to 174 mg C kg−1 soil. Soil fertility, RLD, and the stock of C and N in the root system varied among soil layers. At the end of 2 yr, SR and N fertilization did not affect TP, WIR, and AS nor influenced soil fertility and root system distribution. Overgrazing led to soil compaction and reduced LF‐SOM, indicating a trend of pasture degradation. Moderate SR resulted in greater LF‐SOM, indicating a positive trend for C accumulation in the long term.

Productivity and nutritive value of elephant grass pastures under organic and conventional production systems.

Elephant grass (EG) (Pennisetum purpureum Schum.) have great importance in tropical and subtropical climates, especially on dairy farms. Normally, EG is established alone under high fertilization levels. EG in organic production system can improve low production costs and environmental issues, are still little known. The aim of this research was to evaluate the performance of herbage yield, nutritive value, extraction/ export nutrient and forage yield and animal responses. Three production systems of EG were analyzed: (i) EG mixed spontaneous-growing species (SGE) in warm-season and ryegrass (R) in cool-season under organic production; (ii) EG mixed SGE + R under conventional system (positive control); and (iii) EG based under conventional production (control). Holstein cows were used in a rotational stocking. Forage samples were collected to evaluate the pasture and animal responses. Seven grazing cycles were performed during the experimental period (312 days). Herbage yield, forage intake, and stocking rate were 12548; 10270; 19168 kg ha-1 and 2.5; 2.6; 2.7% and 3.3; 2.1; 4.5 AU ha-1 day-1, respectively. Crude protein of EG was 17.9; 15.4; 16.4%, respectively. Mixed pastures, in conventional and organic production, had a better forage distribution throughout the seasons. Highest forage yield and extraction/ export nutrient was reported in pure EG within the conventional system.

Longitudinal model for categorical data applied in an agriculture experiment about elephant grass

Experiments where the response is a categorical variable are usually carried out in many fields such as agriculture. In addition, in some situations this response has three or more levels without an order between them characterizing a multinomial (nominal) response. Statistical models for scenarios where the observations of a nominal response can be considered independent have an extensive literature, such as the baseline-category logit models. However, situations where this assumption is violated (as in longitudinal studies) require specific models that take into consideration the dependence between observations. In this paper, a fairly new extension of the generalized estimating equations is applied to analyze an experiment carried out to investigate the type of vegetation observed in an elephant grass pasture, according to some management conditions over time. This extension uses local odds ratios to explain the dependence among the categories of the outcome over the repeated measurements. Two different structures were compared to describe this dependence, and the Wald test was used to select the significant variables. Further, we built confidence intervals for the predicted probabilities of occurrence of each category and assessed the results comparing observed/predicted values and using the diagnostic analysis. The results allowed to conclude that there are various significant effects for treatments and for time. The structure of local odds ratio also proved as a good way to describe the dependence between categorical responses over time.

Preemergence herbicides on weed control in elephant grass pasture

ABSTRACT Elephant grass (Pennisetum purpureum Schum.) is an important forage crop that has been proposed as a potential feedstock for bioenergy production. However, weed interference is a major factor limiting elephant grass production. Field experiments were conducted in 2014 and 2015 to evaluate preemergence herbicides for selective weed control in an elephant grass pasture. Herbicide treatments included atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, diuron + hexazinone, sulfentrazone, imazethapyr, and atrazine at label use rates. Weedy and weed-free treatments were included. Atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine did not cause phytotoxicity on elephantgrass 35 days after treatment (DAT). However, diuron + hexazinone and imazethapyr were the most phytotoxic on elephantgrass, resulting in 81 and 70% phytotoxicity in 2014, and 7 and 6% phytotoxicity in 2015 respectively 35 DAT. All treatments provided effective weed control (>81%) with the exception of ethoxysulfuron (0 and 11% in 2014 and 2015, respectively), and atrazine (59% in 2014). These results show that atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine were selectives when applied in preemergence in elephant grass pasture.

Produção de leite com vacas mestiças em capim-elefante

A trial was carried out with objective of identifying economical sources of alimentary supplementation for cows milk in exclusive feeding regime of elephant-grass pasture (Pennisetum purpureum cv. Napier), submitted to the fertilization and irrigation. The experimental design was completely randomized with three treatments: T1 = cows grazing exclusively in elephant-grass pasture; T2 = T1 + bank of leucena protein and T3 = T1 + concentrated ration, supplied in the amount of 1 kg for each 3 kg of milk produced above 5 kg. The largest production milk was obtained of the animals of T3 (11.11 kg of milk/cow/day and 3,594.08 kg of milk/cow/lactation), followed by T2 (9.19 kg of milk/cow/day and 2,740.15 kg of milk/cow/lactation) and T1 (8.54 milk/cow/day kg and 2,520.36 milk/cow/lactation kg). The lower profitability was obtained with cows grazing elephant-grass supplemented with concentrates.

Dinâmica e valor nutritivo da forragem de sistemas forrageiros submetidos à produção orgânica e convencional

ResumoObjetivou-se com esta pesquisa, avaliar o valor nutritivo de pastagens de capim elefante submetidas aos sistemas de produção orgânico e convencional. No sistema convencional, o capim elefante foi plantado em linhas afastadas a cada 1,2m. No sistema orgânico, o capim elefante foi plantado em linhas afastadas a cada 3m; no espaço entre as linhas, no período hibernal, foi semeado o azevém anual e, no período estival, permitiu-se o desenvolvimento de espécies de crescimento espontâneo. Foram utilizados 100kg de N/hacom fertilizantes químico e orgânico (esterco de bovino e chorume de suínos) para os respectivos sistemas de produção. O método de pastejo adotado foi o de lotação rotacionada, com tempo de ocupação de um ou dois dias, utilizando vacas em lactação que receberam complementação alimentar com concentrado à razão de 0,9% do peso corporal. Para a determinação da composição química (matéria mineral, matéria orgânica, proteína bruta e fibra em detergente neutro) e digestibilidade da forragem, foram retiradas amostras simulando o pastejo. O delineamento experimental foi o inteiramente casualizado com dois tratamentos (sistemas forrageiros), com três repetições (piquetes) e com medidas repetidas no tempo (estações do ano). Durante o período experimental, foram conduzidos oito e sete pastejos para os respectivos sistemas. Valores similares foram observados quanto à composição química e digestibilidade do capim elefante em ambos os sistemas. Tanto no sistema orgânico quanto no convencional, o valor nutritivo foi elevado, considerando-se a adubação, manejo e tempo de utilização da pastagem.

Root development and soil carbon stocks of tropical pastures managed under different grazing intensities

Grasslands may act as a carbon (C) sink or C source depending on how they are managed. Soil C stocks, root biomass, root length, root length density and soil organic C concentrations were assessed on pastures of elephant grass ( Pennisetum purpureum ) managed under different post-grazing stubble heights and signal grass ( Brachiaria decumbens ) managed under different stocking rates. Soil samples were collected in 20-cm layers down to 1-m soil depth. Neither stubble height nor stocking rate had any significant effects on root parameters. Both the root system and C stocks declined in both pastures with increasing soil depth. Root biomass in the 0–20 cm layer contained 2.84 and 2.04 t C/ha, declining to 0.39 and 0.64 t C/ha at 80–100 cm for elephant grass and signal grass, respectively. Signal grass had greater root development deeper in the soil than elephant grass pastures, possibly due to its greater tolerance of Al toxicity and acidity. Total soil C stocks were greater for signal grass than for elephant grass (358 vs. 214 t C/ha, respectively). Keywords: Carbon sequestration, nutrient cycling, soil nutrients, stocking rate, tropical grass. DOI: 10.17138/TGFT(2)254-261

Steers performance in dwarf elephant grass pastures alone or mixed with Arachis pintoi

The inclusion of legumes in pasture reduces the need for mineral nitrogen applications and the pollution of groundwater; however, the agronomic and animal husbandry advantages with tropical legumes are still little known. The objective of this study was to quantify the effect of the use of forage peanut (Arachis pintoi cv. Amarillo) in dwarf elephant grass pastures (Pennisetum purpureum cv. BRS Kurumi) on forage intake and animal performance. The experimental treatments were dwarf elephant grass fertilized with 200 kg N/ha, and dwarf elephant grass mixed with forage peanut without mineral fertilizers. The animals used for the experiment were 12 Charolais steers (body weight (BW) = 288 ± 5.2 kg) divided into four lots (two per treatment). Pastures were managed under intermittent stocking with an herbage allowance of 5.4 kg dry matter of green leaves/100 kg BW. Dry matter intake (mean = 2.44 % BW), the average daily gain (mean = 0.76 kg), and the stocking rate (mean = 3.8 AU/ha) were similar between the studied pastures, but decreased drastically in last grazing cycle with the same herbage allowance. The presence of peanut in dwarf elephant grass pastures was enough to sustain the stocking rate, but did not allow increasing forage intake and animal performance.

Milk production as a function of supplementation levels with concentrate for dairy cows on an elephant-grass pasture

This study aimed to evaluate the effects of supplement amount on milk production and composition. Eight crossbred Holstein-Zebu cows (517±40 kg) were allotted in two 4 x 4 Latin squares, in four periods of 14 days. The experiment was conducted on pasture of Elephant grass (Pennisetum purpureum, Schum) in the rainy Pimentel et al., Revista Brasileira de Higiene e Sanidade Animal (v.7, n.1) p. 61 78 (2013) 62 season, and the treatments included a control (mineral mixture) and supplement with 24% CP in dry matter at levels of 1.25, 2.5, and 5.0 kg/animal/day, based on corn meal, soybean meal, urea and mineral mixture. The experiment was analyzed as Latin square design including effects of treatment, Latin square, animal within Latin square and period. There was no treatment effect (P>0.05) for the evaluated variables, due to large animal per animal variation. However, by evaluating the mean of milk production as a function of supplementation, there was a trend for curvilinear response, following a Michaelis-Menten relationship of enzymatic systems and was explained by the following equation of Lineweaver-Burk: 1/Milk = 0.0125*(1/Suppl) + 0.0826; r 2 = 1.00. The theoretical maximum milk production (1/a) was 12.1 kg/animal/day, and the amount of concentrate to cause half maximum milk production (b/a) was verified with 5.2% of that necessary to reach 95% maximum response. It can be concluded that the marginal increase in milk production reduces with increasing supplementation, in which the adequate level of supplementation is between 1.25 and 2.5 kg of concentrate/cow/day.

Evaluation of the Cornell Net Carbohydrate and Protein System model on the prediction of dry matter intake and milk production of grazing crossbred cows

The Cornel Net Carbohydrate and Protein System model version 5.0 was assessed as for its prediction of dry matter intake and milk production of grazing lactating Holstein × Zebu cows. Eight lactating cows grazing elephant grass (Pennisetum purpureum, Schum., cv. Napier) were used in two experiments of 30 days each. The experimental design was of randomized blocks (subplots). Dry matter intake was estimated using the chromium oxide and in vitro dry matter digestibility techniques. The estimated dry matter intake was compared with the values predicted by the model. Extrusa samples of the elephant grass pasture were obtained from a cow with esophageal fistula during nine days in each experimental period. Carbohydrate and nitrogenous fractions were analyzed and the degradation rate of carbohydrate was estimated by the gas production technique. The inputs referring to the animals (body weight, age, milk production, milk composition and breed type), to the environment (temperature, relative humidity of air and management condition) and to feeds chemical composition in each experimental period were inserted in the model. The model was accurate on the prediction of dry matter intake, considering that the mean values obtained by the chromium oxide technique and predicted by model (2.45 and 2.46% of body weight, respectively) did not differ significantly from each other. However, the model underestimated the observed milk production in 62.4%, where the metabolizable energy was the first limiting. These results demonstrate the need for studies that provide the development of a database for tropical foods (chemical composition and dynamics of rumen fermentation) and fitting of the model to the tropical conditions, for its appropriate application in formulation of diets and supplements in these regions.

Collaria oleosa (Hemiptera: Miridae) on Brachiaria ruziziensis and Penissetum purpureum (Poaceae): Characterization of injury and biological aspects

Injuries caused by Collaria oleosa have often been observed in signal grass and elephant grass pastures. Therefore, the aim of this study was to diagnose and delineate the sites of the injuries caused by C. oleosa and to evaluate some biological aspects of this insect on forage. The duration and survival of the instars and nymph phase of the pest were analyzed. The epidermises were evaluated to identify the sites where the style of the pest entered and to characterize the anatomy of the injured site. The stoma was the entry place of the style and the main injuries were caused to the chlorenchyma of both grasses, and to the parenchymatic sheath of the signal grass. The lignified sheath remained intact, so this appears to be a feeding barrier for the insect. The duration was shorter from second to fifth instars and the nymphal phase when fed with the elephant grass. The way the food sources were hydrated did not alter the development of the nymphs. The survival was greater for the specimens maintained on elephant grass and the nymphs of the first instar were less sensitive when the grass blades were maintained on agar. This hydration method was also better for the survival of the mirid’s nymph phase.

Repetibilidade e respostas de características morfofisiológicas e produtivas de capim-elefante de porte baixo sob pastejo

O objetivo deste trabalho foi estimar os coeficientes de repetibilidade, de determinação (R²) e o número mínimo de medições necessárias para predizer o valor real de variáveis morfofisiológicas e produtivas, bem como as respostas do capim-elefante de porte baixo ao pastejo com ovinos. O experimento foi realizadoem blocos ao acaso, com cinco tratamentos - Taiwan A-146 2.27, Taiwan A-146 2.37, Taiwan A-146 2.114, Merker México MX 6.31 e Mott - e quatro repetições, ao longo de cinco ciclos de pastejo entre setembro de2008 e abril de 2009. Foram avaliados a altura média de plantas, o índice de área foliar (IAF), a interceptação luminosa (IL), os ângulos foliares médios (AFM), o acúmulo de forragem (AF) e a taxa de acúmulo de forragem(TAF). Para as variáveis IAF, IL e altura média de plantas, nos ciclos longos, foi necessária apenas uma medição (R² = 80%) para classificá-las como de mais fácil predição em clones de capim-elefante. Avaliações de AF e de TAF necessitam de períodos experimentais mais longos, para maior confiabilidade na estimativa dessas variáveis resposta. Dosséis de capim-elefante de porte baixo interceptam maior quantidade de radiação incidente, quanto maior for a altura média das plantas e o IAF.

Estrutura do pasto disponível e do resíduo pós-pastejo em pastagens de capim-cameroon e capim-marandu

Avaliaram-se, em dois experimentos, as características estruturais e o teor de proteína bruta das forrageiras Pennisetum purpureum cv. Cameroon e Brachiaria brizantha cv. Marandu em pastagens submetidas a quatro taxas de lotação rotacionadas. No período das águas, as taxas de lotação impostas a ambas as pastagens foram de 3, 4, 5 e 6 novilhos/ha e, no período seco, de 2, 3, 4 e 5 novilhos/ha. Nos dois experimentos, o capim-cameroon apresentou maior massa de forragem total e massa de forragem verde, que decresceram com o aumento da desfolha imposta pelas taxas de lotação, principalmente no período seco. Nessa forrageira, o aumento da taxa de lotação comprometeu em maior intensidade a fração de matéria seca de lâmina foliar verde. No período das águas, as taxas de lotação que propiciaram maior oferta de massa seca de forragem total, forragem verde e fração de lâmina foliar foram as de 5 e 4 novilhos/ha, respectivamente, para os capins cameroon e marandu. No período seco, no entanto, os maiores valores obtidos para essas variáveis foram, respectivamente, de 4 e 3 novilhos/ha. As taxas de lotação não influenciaram o teor de proteína bruta das gramíneas, que foi maior no componente lâmina foliar verde da planta.

Metabolizable protein supply according to the nrc (2001) for dairy cows grazing elephant grass

Tropical pastures fertilized with nitrogen may have high crude protein (CP) contents with high rumen degradability. High crude protein concentrates offered to cows grazing these pastures may increase feed costs without positive effects on their performance. The objectives of this trial were to evaluate the effects of increasing metabolizable protein (MP) supply beyond the NRC (2001) recommendations for mid lactating dairy cows grazing elephant grass pasture (Pennisetum purpureum Schum. cv. Napier) managed with high stocking rates. Three concentrates (6.3 kg DM-1 cow-1 day-1) were evaluated: control (17%CP) was adjusted in relation to MP according to the NRC (2001); the other two contained extra soybean meal, to increase the CP content to 21.2% (CP) and 25.0% (CP). Twelve multiparous Holstein cows, averaging 150 days of milk production at a rate of 19.5 kg of milk day-1, were used in a 3 × 3 latin square design, replicated four times. Forage consumption was 11,270 kg DM ha-1 with 34% of green leaves and 12% CP. Milk production, corrected to 3.5% fat, milk fat, protein, lactose and total solids contents were not affected by treatments (P > 0.05). Milk urea nitrogen and plasma urea nitrogen increased linearly (P < 0.05) as the MP supply increased. Treatments did not affect (P > 0.05) body weight gain, body condition score, grazing time, ruminating time, resting time, rectal temperature and respiratory rate. Crude protein content in the concentrate formulated according to NRC (2001) is adequate for mid lactating cows grazing tropical pastures.

Grazing characteristics in the dwarf Elephantgrass (Pennisetum purpureum Schumach) pasture by breeding beef cows at the first and second years after establishment

In order to determine grazing characteristics in the dwarf Elephantgrass pasture under the rotational grazing system, 5 a of pasture established by rooted tillers of dwarf variety of late-heading type (DL) was grazed by 3 head of breeding beef cows in the following 2 years after establishment in 2003 and 2004. Grazing system was conducted at 4 and 5 times for about 1-week grazing with 3-weeks and 1-month rest period in 2003 and 2004, respectively. Tiller number increased seasonally from the first through the fourth or fifth grazing, and herbage dry matter weight reached the peak at the fourth grazing both years, while some characters such as plant height, mean tiller dry matter weight and percentage of leaf blade tended to decrease with the grazing. From the stratified clipping method, percentage leaf blades in the top two, third and in the fourth strata were consumed perfectly and almost perfectly, respectively both years. Herbage consumption increased with the grazing up to the third and fourth grazing and dropped at the last grazing due to the poor regrowth under the decreasing air temperature both years. Dry matter intake per head averaged 4.3–13.4 kg DM head -1 day -1 in 2003 and 6.7-11.4 kg DM head -1 day -1 (15.5-28.6 g DM/kg LW -1 day -1 ) in 2004. Grazing time on DL elephantgrass was stable at 50–60% in daytime at the first grazing day both years, while that at the last grazing day tended to increase with the grazing both years. Thus, live weights of 3 head of beef cows were maintained in the grazing from the second to the fourth time without concentrate feeding in 2004, when dry matter intake was above 20 g DM LW -1 day -1 . Key Words : Dwarf-Elephantgrass, Grazing Characteristics, Beef Cows, Percentage Leaf of Blade

Massas de lâminas foliares nas características produtivas e qualitativas da pastagem de capim-elefante "Pennisetum purpureum, Schum" (cv. "Taiwan") e desempenho animal

O experimento foi conduzido no Departamento de Zootecnia da Universidade Federal de Santa Maria, para avaliar produtiva e qualitativamente a pastagem de capim elefante e o desempenho animal sob pastejo. A área experimental foi composta de oito piquetes de 0,443ha cada de capim-elefante (Pennisetun purpureum, Schum. cv. "Tawian"), onde pastejaram 36 novilhos das raças Charolês, Nelore e suas cruzas, com três animais "testers" por piquete, em duas repetições. Foram estudadas as variáveis relacionadas à produtividade e à qualidade da pastagem e ao desempenho animal. As massas reais de lâminas foliares (MLF) de capim-elefante foram: 1.167; 1.543; 1.926 e 2.248kg MS LF/ha, o que constitui os tratamentos. A carga animal suportada pela pastagem, pode ser descrita pela equação y=2.243,14 - 0,32MLF (R2=0,4). O peso vivo final em kg apresentou resposta quadrática (PF=103,41 + 0,114x - 0,00003x², R2=0,5) com o acréscimo da MLF. O ganho de peso diário médio apresentou comportamento linear positivo (GMD = 0,25 + 0,0002MLF, R2=0,2). O aumento na massa de lâminas foliares de capim-elefante acarreta diminuição na carga animal suportada pela pastagem e aumenta o ganho de peso médio diário.