Hyparrhenia Rufa Research Articles

PARTICIPATORY EVALUATION OF IMPROVED GRASSES AND FORAGE LEGUMES FOR SMALLHOLDER LIVESTOCK PRODUCTION IN CENTRAL AMERICA

SUMMARYSmallholder livestock systems in Central America are typically based on pastures with traditional grasses and associated management practices, such as pasture burning and extensive grazing. With the rise of the global population and a corresponding increase in demand for meat and milk production, research efforts have focused on the development of improved grasses and the incorporation of legume species that can increase productivity and sustainability of Central American livestock systems. However, farmer adoption remains very limited, in part due to the lack of site-specific evaluation and recommendations by local institutions. Using a multi-site participatory approach, this study examined the potential of five improved grasses and five species of forage legumes as alternatives to the broadly disseminated grass Hyparrhenia rufa (cv. Jaragua) in pasture-based cattle systems in western Honduras and northern El Salvador. Improved grasses (four Brachiaria sp. and Megathyrsus maximus) produced significantly more biomass than H. rufa; also four of the five legume varieties evaluated (Canavalia ensiformis, Canavalia brasiliensis, Vigna unguiculata, and Vigna radiata) demonstrated high adaptability to diverse environmental conditions across sites. Farmer participatory evaluation offers a valuable means to assess performance of forages and will likely contribute to their improved utilization. Future research is needed on more refined management recommendations, pasture system design, costs and environmental benefits associated with the adoption of these forages in local livestock production systems.

Hongos patógenos de Hyparrhenia rufa, una maleza invasiva en Puerto Rico, y su potencial como agentes de control biológico

Hyparrhenia rufa (Nees) Stapf., conocida comúnmente como pasto jaragüa, faragüa o yaragüa, es una maleza agresiva que ha invadido terrenos cultivables en Puerto Rico. Para disminuir la aplicación de herbicidas, se ha propuesto el uso de hongos fitopatógenos para su control. Se identificaron cuatro aislados de hongos asociados a lesiones foliares de H. rufa: Curvularia sp., Fusarium sp., Phoma sorghina y Sphaeropsis sp. Se evaluó su patogenicidad en condiciones de laboratorio, invernadero y campo. Todas las especies de hongos fueron patogénicas al tejido foliar (con herida) en condiciones de laboratorio mientras que P. sorghina y Sphaeropsis sp. fueron las especies más virulentas en el ensayo de invernadero. Fusarium sp. fue la especie más virulenta en el ensayo de campo. Se observaron bajos niveles de infección (nivel 1) en el campo para todos los aislados de hongos evaluados. La severidad de la enfermedad fue estimada en un 25% del área de la parcela experimental. Para completar los postulados de Koch, todos los hongos inoculados fueron re-aislados en agar de papa y dextrosa luego de concluir las pruebas de patogenicidad conducidas en condiciones de laboratorio, invernadero y campo. Este es el primer reporte de Curvularia sp., Fusarium sp., P. sorghina and Sphaeropsis sp. como patógenos foliares de H. rufa.

Sediment trapping with indigenous grass species showing differences in plant traits in northwest Ethiopia

Soil loss from an 8% sloping Teff field in north-western Ethiopia is significant (~70tha−1yr−1), and thus found to be an important source of sediment. Grass barriers showing sediment trapping efficacy (STE) are important measures in trapping sediment inside Teff fields and protecting downstream reservoirs and lakes from sedimentation. There are many indigenous grass species available that have the potential to act as sediment trapping measure when used in strips downstream of sloping crop fields. However, their STE and their key functional traits that determine their STE are not yet known. This negatively influence agricultural extension agents in disseminating conservation technology to farmers at larger scales. The indigenous grass species Desho (Pennisetum pedicellatum), Senbelet (Hyparrhenia rufa), Sebez (Pennisetum schimpri) and Akirma (Eleusine floccifolia) and one exotic species, Vetiver (Vetiveria zizanioides) were tested for two years (2013 and 2014) in 1.5m wide strips below Teff fields at 8% slope in the Debre Mewi watershed, northwest Ethiopia. The average runoff during the study was 79, 64, 69, 71, 74 and 75lm−2, with 7.0, 1.7, 2.9, 3.6, 4.5 and 5.6kgm−2yr−1 of sediment from the Control, Desho, Vetiver, Senbelet, Akirma and Sebez treatments, respectively. Differences in key functional traits affected the STE of the different grass barriers. Desho with the highest tiller number and density, and the second highest root length (depth) showed better STE (76%) than the other grass species, Vetiver (59%), Senbelet (49%), Akirma (36%) and Sebez (20%). This indicates that grass barriers can be used as a soil conservation measure replacing the costly and more maintenance demanding physical structures like trenches and ridges. As a co-benefit, grass barriers provided important fresh biomass for livestock, thereby helping to reduce the feed shortage. Thus we conclude that indigenous grass species provided a practical means to reduce soil loss from Teff fields (up to 8% slope) in the northwest Ethiopia and can be easily adopted by farmers due to their combined soil conservation and feed value.

Behavioural response of pure Ankole and crossbred (Ankole × Holstein) cows to seasonal pasture variations in south-western Uganda

This study evaluated the effects of season and pasture species on variations in sward composition, pasture quantity (plant-height and biomass) and quality [crude protein (CP), neutral detergent fibre (NDF) and in vitro organic matter digestibility (IVOMD)]. Behavioural responses of a group of 10 pure Ankole and another of 10 crossbred (Ankole×Holstein) cows to the seasonal variations in pasture quantity and quality were also examined. Irrespective of season, the dominant pasture species was Brachiaria decumbens, with scanty presence of Hyparrhenia rufa, Themeda triandra, Sporobolus pyramidalis and Cymbopogon afronardus. The sward height, biomass, CP, NDF and IVOMD were dependent on both season and species (P<0.001). Whereas the sward-height and biomass of B. decumbens, H. rufa, and T. triandra peaked during the rainy season, that of C. afronardus and S. pyramidalis peaked in the dry season. During the grazing cycle, a minimum plant-height of 31cm and forage biomass of 118g/m2, an equivalent of 1180kg/ha, was recorded for most of the pasture species. The CP content of the pasture species were below 7%, irrespective of season, except for B. decumbens which had 8.7% CP in the rainy season. Minimum NDF content for all the pasture species was 67% and 50% during the dry and rainy seasons, respectively. Consequently, IVOMD ranged between 29–61% and 51–65% during the dry and rainy seasons, respectively. Ankole and the crossbred cows increased the number of feeding stations, bites and residence time in patches of species, which were scantly grazed in the rainy season. They also increased standing (P<0.01) at the expense of walking (P<0.001) and social activities (P<0.001). Irrespective of season, more than 40% of grazing occurred in B. decumbens patches and both genotypes grazed for ¾ of the time on pasture. However, the crossbred cows required extended grazing duration, resulting into less lying and rumination (P<0.05) on pasture than the Ankole cows. Ankole and the crossbred cows grazed locales with high pasture groundcover and biomass. However, locales with high CP but low forage quantity were also grazed. This study revealed that at an appropriate stocking rate, sufficient forage supply was possible in both seasons. However, the low CP content and less preference for majority of the dominant species compelled the Ankole and the crossbred cows to graze for a long time. Thus, the crossbred cows were constrained by time in both the dry and rainy seasons.

English

Kiang'ombe hilltop forest is overexploited for fuel wood, charcoal, timber and non-wood forest products, thus threatening its biodiversity conservation role. The extent of forest degradation is not yet quantified and this impedes rehabilitation interventions. This study was conducted to evaluate the status of Kiang'ombe forest resources to initiate rehabilitation interventions and to support sustainable forest management. Remote sensing and geographic information systems (GIS) were used to determine trends of spatial and temporal vegetation changes over 25 years. Image analysis revealed high, moderate and low categories of forest degradation over the assessment period. Thirty two nested sample plots were used for vegetation inventory in the three degradation gradient clusters. Additional data was obtained from local informants through focused discussions and field observations. A total of 155 plant species belonging to 58 families were identified. Shannon Weiner diversity index of seedling and sapling were higher in low and moderate than in high degraded areas. Based on species importance values, the candidate trees for rehabilitation of degraded areas were Croton macrostachyus, Acacia hockii, Combretum molle and Faurea saligna whereas Enteropogon macrostachys, Cymbopogon sp., Eragrostis superba and Hyparrhenia rufa were the most suitable grass species for reseeding expansive glades. The recommended rehabilitation techniques are enrichment tree planting in water catchments areas, enhancing natural regeneration through protection and grazing management, gully healing at the hill slopes and establishment of woodlots plantations and boundary planting in the surrounding farmlands. Key words: Hilltop forest, geographic information systems (GIS), vegetation inventory, rehabilitation techniques.

Consumo y digestibilidad de una dieta para corderos basada en henos de gramíneas tropicales y de Hyparrhenia rufa con un probiótico aportador de Bacillus subtilis y Bacillus licheniformi

Se realizó un experimento en dos periodos (P1 y P2) para determinar el efecto de la inclusión de un probiótico aportador de las bacterias Bacillus subtilis y B. licheniformis en una dieta basada en henos de gramíneas de baja calidad sobre el consumo voluntario (CV) y digestibilidad utilizando 10 corderos criollos. Los corderos se asignaron aleatoriamente a uno de dos tratamientos: sin (control) o con el probiótico dietético. La dieta basal constó de un ofrecimiento diario de forraje igual al 4% del peso vivo (PV) en la materia seca (MS). El forraje consistió de 50% de heno de gramíneas tropicales naturalizadas [71.7% Fibra Detergente Neutra (FDN), 4.9% Proteína Bruta (PB) en P1; y 71.2% FDN, 5.4% PB en P2] y 50% de heno de Hyparrhenia rufa (78.8% FDN, 3.5% PB en P1; y 75.6% FDN, 5.5% PB en P2). Se suplió también 225 g diarios de concentrado comercial (CC). El aditivo se mezcló con el CC para suplir 1.33 X 10 ufe/animal diariamente durante 49 días en P1. Del día 50 al 84 (P2) se suspendió el ofrecimiento del aditivo para determinar posibles efectos residuales de este. Se pesaron los corderos semanalmente. El CV y digestibilidad de la MS, FDN y PB se determinaron del día 42 al 49 en P1. y del día 77 al 84 en P2. Las variables indicativas de parasitismo y anemia: conteo de huevos en las heces (CHH), valor FAMACHA® y hematocrito, se determinaron cada 21 días. Los datos por periodo experimental se analizaron según un diseño completamente aleatorizado con cinco repeticiones por tratamiento. Durante el P1, la ganancia en PV de los ovinos fue de 23 vs. 20 g/día para los tratamientos control y con probiótico, respectivamente. La adición dietética del probiótico aumentó (p &amp;lt; 0.05) el consumo total de MS (445 vs. 484 g/d), dicho consumo como porcentaje del PV (2.04 vs. 2.37), además del consumo de MS de forraje como porcentaje del consumo de MS total (54.77 vs. 59.42). La digestibilidad porcentual de MS (59.98 vs. 62.62) y de PB (59.35 vs. 61.76) no difirió entre tratamientos, pero hubo tendencia (p = 0.09) a mejorar la digestibilidad de FDN con el probiótico (58.71 vs. 62.48). El CHH de los respectivos grupos testigo y con probiótico fue 820 vs. 1,380 huevos/g ¡nlclalmente y aumentó más (p &amp;lt; 0.05) en el testigo a 2,390 vs. 2,780 huevos/g al día 21 y luego bajó a 1,830 vs. 1,480 huevos/g al día 42. Entre los días 0 y 42, el hematocrlto cambió significativamente (p &gt; 0.05) de 24.4 a 17.9 en el testigo y de 20.6 a 22.6 en el grupo con problótlco. El nivel de anemia estimado por FAMACHA® difirió mínimamente entre ambos tratamientos y no pasó de un valor máximo de 2.6. Durante el P2, la ganancia en PV de los ovinos de ambos grupos (testigo y previamente con el problótlco) fue 48 g/ día. Al comparar estos dos respectivos grupos, el consumo de MS fue 587 vs. 562 g/día y las dlgestlbllldades fueron: MS (58.46 vs. 57.59%), FDN (57.50 vs. 56.85%) y PB (60.78 vs. 62.11%), sin diferencias (p &gt; 0.05). El CHH bajó progresivamente a respectivos valores finales de 1,230 y 440 huevos/g a los 84 días, mientras el hematocrlto subió a valores de 23.4 y 25.1% a los 84 días, sin diferencias (p &gt; 0.05). El valor máximo de FAMACHA® fue de 2.8 y 2.2 en los dos respectivos tratamientos. En resumen, la adición dietética del probiótico incentivó el CV y tendió a aumentar la digestibilidad de FDN, pero no afectó el crecimiento, aunque dio ciertos indicios de favorecer la salud animal. Después de suspender el aditivo, no se observó ningún efecto residual del mismo sobre las variables evaluadas.

Scale up and efficient bioethanol production involving recombinant cellulase (Glycoside hydrolase family 5) from Clostridium thermocellum

Abstract Background Lignocellulose degrading fungal enzymes have been in use at industrial level for more than three decades. However, the main drawback is the high cost of the commercially available Trichoderma reesei cellulolytic enzymes. Results The hydrolytic performance of a novel Clostridium thermocellum cellulolytic recombinant cellulase expressed in Escherichia coli cells was compared with the naturally isolated cellulases in different modes of fermentation trials using steam explosion pretreated thatch grass and Zymomonas mobilis. Fourier transform infrared (FT-IR) spectroscopic analysis confirmed the efficiency of steam explosion pretreatment in significant release of free glucose moiety from complex lignocellulosic thatch grass. The recombinant GH5 cellulase with 1% (w v-1) substrate and Z. mobilis in shake flask separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) trials demonstrated highest ethanol titre (0.99 g L-1, 1.2 g L-1) as compared to Bacillus subtilis (0.51 g L-1, 0.72 g L-1) and Trichoderma reesei (0.67 g L-1, 0.94 g L-1). A 5% (w v-1) substrate with recombinant enzyme in shake flask SSF resulted in a 7 fold increment of ethanol titre (8.8 g L-1). The subsequent scale up in a 2 L bioreactor with 1 L working volume yielded 16.13 g L-1 ethanol titre implying a 2 fold upturn. The rotary evaporator based product recovery from bioreactor contributed 94.4 (%, v v-1) pure ethanol with purification process efficiency of 22.2%. Conclusions The saccharification of steam exploded thatch grass (Hyparrhenia rufa) by recombinant cellulase (GH5) along with Z. mobilis in bioethanol production was studied for the first time. The effective pretreatment released substantial hexose sugars from cellulose as confirmed by FT-IR studies. In contrast to two modes of fermentation, SSF processes utilizing recombinant C. thermocellum enzymes have the capability of yielding a value-added product, bioethanol with the curtailment of the production costs in industry.

Pasture use and management strategies in the Ankole pastoral system in Uganda

AbstractThe Bahima ethnic group have been crossbreeding autochthonous Ankole with Holstein‐Friesian cattle. Separate herds (pure Ankole and crossbreds) are common. A survey was conducted to characterize pasture utilization and management in the Ankole region to gain a better understanding of current and emerging practices. Herds are largely grazed by continuous stocking although there are efforts to establish paddocks. Factors considered for pasture allocation to cattle genotypes were high‐quality feed, limited shrubs/weeds and close proximity to homestead for 80, 80 and 30% of farmers, respectively. Cross‐bred cattle were kept on medium/high‐quality, and Ankole cattle on medium/low‐quality pastures. Pastures for cross‐bred cattle yielded 0·17 t ha−1 more dry matter than pastures allocated to Ankole cattle. Crude protein (CP) content of Ankole pasture was significantly (P &lt; 0·05) lower than CP of cross‐bred pasture (6·3% compared with 7·3%). Neutral detergent fibre content was similar (72·8% vs. 69·8%) for both pasture types. Farmers’ perceptions of indicator plant species were important for allocation of pasture. Hyparrhenia rufa, Brachiaria spp., Themeda triandra and Chloris gayana were identified as the preferred pasture species. Sporobolus pyramidalis and Cymbopogon afronardus were the most undesirable pasture species. Brachiaria spp. offers an opportunity for utilization as hay for dry season supplementation.

Hyparrhenia grass white leaf disease, associated with a 16SrXI phytoplasma, newly reported in Kenya

Hyparrhenia rufa is a thatching grass commonly found throughout the tropics where it also serves as valuable cattle fodder and border grass to prevent soil erosion (Skerman & Riveros, 1990). In June 2010, we observed some H. rufa …

Characterization of tropical forage grass development pattern through the morphogenetic and structural characteristics

An experiment was carried out with the objective to evaluate growth pattern of tropical forage grass under free growth by using morphogenetic and structural characteristics with the expectation of using this study for forage grass evaluation protocol. The experimental area was established with two cultivars of Panicum maximum Jacq. (Mombaca and Aruana), a hybrid cultivar of P. maximum Jacq. and P. Infestum BRA-7102 (Massai), two cultivars of Brachiaria brizantha (A. Rich.) Stapf (Marandu and Xaraes) and Molasses grass (Melinis minutiflora Beauv.) and jaragua grass (Hyparrhenia rufa (Nees) Stapf.). The grasses were planted in 1.0-m² experimental units with 24 plants arranged in a completely randomized block design with three replications. Growth pattern of the grasses was evaluated through mass development, tiller mortality, development stage and leaf longevity. Development patterns differed significantly among groups of grasses, indicating that the same available resources can be used in different manners by grasses from the same genus and/or species.

Restoring abandoned pasture land with native tree species in Costa Rica: Effects of exotic grass competition and light

Understanding the early establishment requirements and performance of tropical tree seedlings is essential to ensuring the success of restoration plantings. This study was designed to characterize growth and light requirements of six common neotropical tree species Pseudosamanea guachapele (Fabaceae), Tabebuia impetiginosa (Bignoniaceae), Ceiba pentandra (Bombacaceae), Pachira quinata (Bombacaceae), Dalbergia retusa (Fabaceae), and Tabebuia rosea (Bignoniaceae) in an abandoned pasture under contrasting light environments and grass competition. Field studies were conducted in the pastures of the Santa Ana Conservation Center in Costa Rica. Two differing grass competition sites were selected, one dominated by a tall grass, Hyparrhenia rufa and another dominated by a short grass, Cynodon mlenfluensis. Three light treatments were created (2, 37 and 100% light) using either neutral shade cloth (2 and 37%) or no shade cloth (100%). Growth characteristics and biomass partitioning of the seedlings were measured. Species differed in their relative growth rates (RGRs). The light × species interaction was significant at both sites. While all species had similar performance under 100% light on both short grass and tall grass sites, species growth differences were evident under 37 and 2% light levels. For example, at the short grass site, T. rosea had higher RGR than D. retusa and P. quinata under 2% light whereas both Tabebuia species performed better than other species at the tall grass site. The general trend was to increase root mass ratio and decrease leaf mass ratio with increasing levels of light. As an initial step for restoring abandoned pasture lands we recommend using all these species in direct and moderate light conditions. Incorporating all species will create a more heterogeneous environment. Choosing light demanding species that can tolerate grass competition may help ensure success in the early stage of restoration.

Estabilidade da sílica biogênica extraída de capim Jaraguá (Hyparrhenia rufa) em solução de NaOH

Biogenic silica is used to describe compounds of hydrated silica (SiO2.nH2O), with specific shapes and sizes, deposited in plants. The chemical composition of biogenic silica and its stability in Jaragua grass was studied in increasing concentration of NaOH. The analytical results demonstrated high concentration of Si, Al, Fe, Mg, P and low of Cu, Cd and Zn in the phytoliths composition. The silica bodies stability in NaOH solution with increasing concentration was different among the shapes and sizes. Silicified stomata and silicified plant tissues were dissolved along with the dumbbells because they are the less stable forms of biogenic silica.

Secuestro de carbono y uso de agua en sistemas silvopastoriles con especies maderables nativas en el trópico seco de Costa Rica

Se estimó el secuestro de carbono y uso de agua en seis sistemas silvopastoriles basados en la combinación de Brachiaria brizantha e Hyparrhenia rufa con especies maderables nativas en el trópico seco. Se empleó un diseño experimental de bloques completos al azar con parcelas divididas, donde las pasturas (B. brizantha e H. rufa) fueron las parcelas principales y los maderables (Dalbergia retusa, Dyphisa robinioides y Pithecellobium saman) las subparcelas. Se evaluó el carbono total en la biomasa aérea (árbol y pastura) y debajo del suelo (suelo y raíces), y la transpiración arbórea mediante el método de “flujo de savia” usando 18 individuos (3 repeticiones por especie arbórea por pastura). El mayor almacenamiento de carbono en la biomasa aérea la realizó D. robinoides (4,4 t C/ha), y en la pastura, B. brizantha con P. saman (5,8 t C/ ha). La mayor acumulación de C en raíces finas (d &lt; 2 mm) se encontró en los primeros 20 cm del suelo. La mayor cantidad de carbono en raíces se encontró en árboles que crecieron con B. brizantha (1,1 t C/ha) y en pasturas que crecen con la asociación B. brizantha y D. robinioides (1,5 t C/ha). El 55% de C en el suelo se encontró en los primeros 20 cm. La mayor transpiración se encontró en D. robinioides (1,5 mm/día) y la menor, en P. saman (0,3 mm/día). Los sistemas silvopastoriles evaluados resultaron promisorios gracias a su alto secuestro de carbono y su uso de especies maderables con alta eficiencia de uso de agua. &#x0D; &#x0D;

Changes in the Herbaceous Communities on the Landslide of the Casita Volcano, Nicaragua, during Early Succession

This study examined the main changes in the herbaceous communities during the first four years of succession in a large landslide on Casita Volcano, Nicaragua, located in a densely populated area that has a tropical dry climate. Our main objective was to determine the major pathways of change in community features, such as richness, biovolume, species composition, and abundances of plant traits and to verify if they varied between the different landslide areas based on abiotic heterogeneity and landscape context. Number, percent cover, mean height and traits of herbaceous species, and several abiotic factors related to fertility and geomorphological stability of substrates were sampled in 28 permanent plots. Environmental heterogeneity strongly influenced early successional changes in the herbaceous communities during the four years of the study. Biovolume increased in the unstable and infertile areas and decreased in the stable and fertile landslide areas. In most zones, species richness decreased significantly because of the expansion of a few dominant species that developed a large cover and excluded other species. Those dominant species were mainly responsible for changes in species composition and included annual forbs, e.g., Calopogonium mucunoides and Stizolobium pruriens, graminoids that have rhizomes or stolons, e.g., Hyparrhenia rufa, and perennial nitrogen-fixing forbs, e.g., Clitoria ternatea. They might be important in determining future successional patterns on the Casita Volcano landslide.

Supplementations of Hyparrhenia rufa -dominated hay with groundnut cake- wheat bran mix: effects on feed intake, digestibility and nitrogen balance of Somali goats

A digestibility and nitrogen (N) balance experiment was conducted using twenty yearling male Somali goats weighing 23.4 +/- 2.02 (mean+/-SD). The objectives of the study were to evaluate the effects of supplementation with graded levels of mixture of groundnut cake and wheat bran at a ratio of 3:1 on DM basis on feed intake, apparent digestibility and N balance in Somali goats. The experimental design was a completely randomized design consisting of five animals in each treatment. The dietary treatments included ad libitum feeding of hay (T1, control), and daily supplementation with 200 (T2, low) 300 (T3, medium) and 400 g DM (T4, high) of the concentrate mix. Increased level of supplementation reduced (P < 0.001) daily hay DM intake. Digestibility of crude protein (CP) was higher (P < 0.001) for the supplemented goats. Urinary nitrogen, total nitrogen excretion and retention increased (P < 0.01) with the level of supplementation. It was concluded that supplementation with groundnut -wheat bran mixture promoted feed intake and digestibility of DM, CP, and N retention in Somali goats fed hay. However, supplementation at the medium level appeared to be more effective since it promoted similar N balance with the high level of supplementation.

Growth, production and carbon sequestration of silvopastoral systems with native timber species in the dry lowlands of Costa Rica

The multiple environmental issues of loss of forest cover due to cattle farming combined with pasture degradation leading to low levels of production, consequent extensification and therefore to more deforestation, are serious concerns in Costa Rica. To test the feasibility of countering these by combining a more productive pasture system with indigenous tree species, a silvopastoral experiment was established on a farm in the seasonally dry lowlands of Canas, Guanacaste Province. A rapidly growing pasture species (Brachiaria brizantha) was tested against a traditional pasture dominated by Hyparrhenia rufa. Three indigenous tree species were established: Pithecellobium saman, Diphysa robinioides and Dalbergia retusa. Plots were grazed by cattle for 4 or 5 days with one to 2 month intervals between grazing episodes. After 51 months, D. robinioides was the fastest growing species, and P. saman the slowest, while B. brizantha produced three times the above ground and twice the below ground biomass as H. rufa, and trees had no effect upon grass yield. Contrary to competition theory, there was no effect of pasture species upon the two faster growing tree species. The carbon in above and below ground phytomass varied between 3.5 and 12.5 Mg C ha−1 in treeless pasture controls and silvopastoral systems, respectively, and total soil organic carbon (TSOC) in the upper 0.6 m averaged 110 Mg ha−1. B. brizantha appeared to stimulate tree root production, which in turn was highly correlated with TSOC, resulting in annual increments in TSOC of up to 9.9 Mg ha−1 year−1. These early results indicate the promising potential of this silvopastoral system for combining cattle production, and increasing tree cover and carbon sequestration.

Respuesta de seis gramíneas tropicales a la quema prescrita en la costa oeste de México

A three year study was conducted in Nayarit, Mexico with the objective of evaluating the effect of fire on yield, forage quality, and height of six tropical grasses. Panicum maximum and Hyparrhenia rufa were studied at El Verdineno Experimental Station. Cenchrus ciliaris, P. maximum var. Trichoglume, Cynodon plectostachyus, and C. dactylon were studied at El Macho Experimental Station. Treatments applied were prescribed burn and an unburned control. Two, 150-m2 field plots were used per treatment during three consecutive years. Each year in late May and early June, experimental areas were burned and environmental conditions recorded including temperature, relative humidity, wind speed, and soil moisture. When regrowth initiated, grasses were sampled at 15-day intervals until maturation. Analysis of variance and mean separation (LSD) tests were conducted. The response of grasses to fire varied with species. Yield of P. maximum, H. rufa, C. plectostachyus, and C. dactylon were not improved (P>0.05) by fire. In contrast, C. ciliaris and P. maximum var. Trichoglume showed a positive response (P<0.05) to prescribed burning. Forage quality was improved by fire in all forage species. Height of C. ciliaris was positively (P<0.05) influenced by fire. Prescribed burning only increased yield in two grasses, but forage quality was improved for all species. Fire is ordinarily used in tropical areas to eliminate old growth, to maintain pastures free of weeds, and to reduce certain insect pests. In this case results obtained are of great value for pasture management and animal production implications.

Características anatômicas e valor nutritivo de quatro gramíneas predominantes em pastagem natural de Viçosa, MG

Avaliou-se a influência das características anatômicas e dos sítios de lignificação dos tecidos sobre o valor nutritivo de lâminas foliares de quatro gramíneas coletadas nas estações chuvosa e seca. Amostras frescas das duas últimas lâminas foliares recém-expandidas, correspondentes à última e à penúltima posição no perfilho de capim-gordura (Melinis minutiflora Pal. De Beauv), capim-braquiária (Brachiaria decumbens Staph.), capim-sapé (Imperata brasiliensis Trin.) e capim-jaraguá (Hyparrhenia rufa (Nees) Staph.) foram avaliadas quanto às características anatômicas, segundo técnicas de microscopia de luz e varredura. Nessas amostras analisou-se a proporção de tecidos e de sítios de lignificação. Também foram determinadas as concentrações de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), lignina e celulose da parede celular, assim como a digestibilidade in vitro da matéria seca (DIVMS). Os dados foram analisados segundo delineamento inteiramente casualizado, com os tratamentos no esquema fatorial, com três repetições. Determinaram-se as correlações entre DIVMS, componentes químicos da parede celular e proporção de tecidos. Observou-se o mesmo padrão de proporção de tecidos e DIVMS no capim-gordura e no capim-braquiária, assim como nos capins sapé e jaraguá. A digestibilidade in vitro da matéria seca e os componentes da parede celular sofreram influência da estação, enquanto as características anatômicas não foram significativamente influenciadas por esse fator. Os capins gordura e braquiária caracterizaram-se por maiores proporções de bainha parenquimática do feixe e os capins sapé e jaraguá por maiores proporções de xilema e esclerênquima. Altos coeficientes negativos de correlação foram estabelecidos entre os coeficientes de digestibilidade e as proporções de xilema e esclerênquima, assim como com os teores de FDN, FDA e lignina das lâminas foliares.

INFLUÊNCIA DOS MATERIAIS DE COBERTURA NA TEMPERATURA INTERNA DAS CONSTRUÇÕES

Temperature changes were observed in enclosed shelters covered with different roofing materia1s. The best thermis conditions occurred in the shelters covered with thatch (Hyparrhenia rufa). The second and third best temperatures were found, respectively, in the shelters covered with clay tile roofing and aluminum roofing. The least favorable temperatures were found in shelters covered with corrugated, asbestos—cement sheet roofing, with the shelters covered with gray—tinted sheets registering lower temperatures than the shelters covered with the red—tinted sheets.

HIPOFOSFOROSE EM BOVINOS NO MUNICÍPIO DE CONTAGEM – MINAS GERAIS HYPOPHOSPHOROSIS IN BOVINES IN THE CONTAGEM MUNICIPALITY - MINAS GERAIS, BRAZIL

Cases of hypophosphorose in dairy cattle were studied in Contagem County in the State of Minas Gerais - Brazil. The serum and calcium levels of six (6) sick animals, before and twenty-one (21) days after the treatment began, were determined. The treatment consisted of Phos-20 and bonemeal which were permanently available in the feeder. The levels of calcium and phosphorous in the soil and in the “jaragua” grass (Hyparrhenia rufa) of the pasture of the two ranches were also determined. In the first group, the parenteral treatment consisted of Phos-20, given in a daily dose of l0 ml per 100 kg of animal weight for 10 days and bonemeal permanently available, in the feeder with salt (NaCL) alongside. In the second group, 1 mg of cobalt sulphate, diluted in 20 ml of water, was administered by mouth to each animal daily for 10 days and salt was always available to each. Afterwards, because of the negative result of the cobalt treatment in this group, the treatment which had been administered the first group, was given to the second. Following this, the clinical picture of the cattle in the second group showed definite improvement. The third group was given no treatment for an equal period of time. After the bonemeal salt, and Fhos-20 treatment, the cattle recovered partially, but were left sterile, a side-effect of the treatment. In the cattle of the first group the symptoms disappeared after the first week of treatment with Phos-20 and bonemeal. In all of the animals treated with phosphorous sources the phosphostemia returned to normal levels, when the bonemeal and salt were furnished constantly in the feed. There was a close correlation between the phosphorous levels in the serum of the animals and the phosphorous levels in the soil and the “jaragua’ grass (Hyparrhenia rufa). The clinical diagnosis of hipophosphorous was based on the analysis of the following clinical data: symptoms, disease history, the level of phosphorous in the cattle serum the histopathological exam of bone tissue, and the phosphorus levels in the grazing grass and soil of the two ranches where the experiment was carried out.