Academic literature on the topic 'Digitaria decumbens Stent (Pangola)'

A widespread disease of pangola grass (Digitaria decumbens) and summer grass (D. ciliaris) in south-eastern Queensland was characterized by a bunched and stunted growth habit, yellow or red discolouration of the foliage, seed heads with crimped, distorted racemes, and sometimes premature plant death. Virus-like particles present in extracts of diseased plants were unstable, 50-70 nm in diameter, had a core and outer coat and were morphologically similar to particles of viruses in the genus Fijivirus, family Reoviridae. The particles were shown by immune electron microscopy to be serologically closely related to pangola stunt and maize rough dwarf viruses, but unrelated to oat sterile dwarf virus. Similar virus-like particles were observed in crystalline arrays in ultrathin sections of cells in vein enations of D. ciliaris. Extracts of diseased pangola grass and summer grass contained 10 double-stranded RNA species, which were somewhat similar in size to those reported for pangola stunt virus. A planthopper, Sogatella kolophon, which is related to the South American vector of pangola stunt virus, S. furcifera, was associated with diseased pangola grass and summer grass in the field, and was shown to be a vector. However, efforts to infect maize, a major host of maize rough dwarf virus, were unsuccessful. On the basis of these properties the Australian virus is considered to be pangola stunt virus.

Two groups of Angora wether goats were grazed over 1 year on replicated areas (0.4 ha each) of either pure N-fertilized Pangola grass (Digitaria decumbens Stent.) pasture or native pastures containing Acacia, Eucalyptus and groundsel (Baccharis halimfolia L.) regrowth. Half of the goats in each group were given a cobalt bullet and their health, liveweight change and fleece growth were monitored. When adequate levels of native pasture were available (>800 kg green matter/ha) performance of goats on the different pastures was similar over the spring and summer grazing periods. In the winter period, fleece growth rate and yield were significantly (P<0.05) lower and liveweight loss (11 g/day) occurred in goats grazing native pastures. In the same period, goats on Pangola grass pastures supplemented with cobalt continued to grow (39 g/day) and maintained high fleece yields while unsupplemented goats on the same area lost weight rapidly (84 g/day), indicating the onset of cobalt deficiency. Over a 9-month period, the population of regrowth acacias and eucalypts less than 1.5 m high were markedly reduced, and groundsel was completely eliminated from the area. In this period, the palatable native grasses were selected in preference to blady grass (Imperata cylindrica (L.) Beauv.), which increased as a proportion of declining total grass yield.

O objetivo deste experimento foi estudar os efeitos da densidade populacional sobre o desempenho produtivo de coelhos para corte na fase de recria. Foram utilizados 108 coelhos da raça Nova Zelândia Branco, de ambos os sexos, desmamados aos 28 dias e alojados aos 35 dias de idade por um período experimental de 6 semanas, em gaiolas de arame galvanizado, de dimensões 0,6 x 0,6 x 0,375 m, equipadas com comedouro automático e bebedouro tipo "nipple", instaladas em galpões semi-abertos. Os animais foram alimentados à vontade com ração peletizada comercial contendo 16% de proteína bruta (PB), 11,84% de fibra em detergente ácido (FDA), 17,49% de fibra em detergente neutro (FDN), 1,20% de cálcio (Ca), 0,60% de fósforo (P) e 2500 kcal de energia digestível (ED)/kg, ad libitum, em todo período experimental, e suplementados a partir dos 56 dias de idade com feno de capim Pangola (Digitaria decumbens, STENT) contendo 4,04% PB; 37,31% FDA; 52,04%FDN; 0,61% Ca; 0,10% P; e 1180 kcal ED/kg, oferecido na quantidade de 50 gramas por animal/dia. As densidades populacionais testadas foram de 1200, 900, 720 e 600 cm²/animal, equivalentes às lotações de 3, 4, 5 e 6 animais por gaiola, respectivamente. O aumento da densidade populacional acarretou diminuição significativa do ganho de peso diário e do consumo diário de ração por animal alojado, sem influir na conversão alimentar e no rendimento de carcaça. Não houve efeito de sexo nas variáveis estudadas. A mortalidade ocorrida no período experimental não apresentou associação com a densidade populacional.

The liveweight change and fleece growth Of Australian cashmere goats were studied in a 14 week grazing experiment (Mar.-June) in south-eastern Queensland. Weaner goats grazed nitro-fertilised Pangola grass (Digitavia decumbens Stent.) pastures and were supplemented every second day with a range of protein meals (60 g crude protein/goat.day), i.itht.1. untreated or fomialdehyde treated. Following high growth rates (> 90 g 1iveweight.day) by all kids early in the experiment, control animals experienced severe weight loss (-40 g/day). Goats given protein supplements performed significantly (P<0.05) better, though they only maintained weight. There were no differences (P> 0.05) in liveweight change between the untreated and formaldehyde treated protein groups. The poor growth of goats in this study was associated with declining feed availability under the high stocking rates used (80 goats/ha) and possibly with a seasonal depression in appetite. Total fleece growth was significantly (P<0.05) increased by protein supplementation, except for sunflower meal. However, cashmere growth (mean � s.e., 16.3 � 2.1 g) was largely unaffected by supplementation, with greater hair growth (64 v. 54 g) being responsible for the improved fleece weight in those goats receiving protein supplements. Kids supplemented with formaldehyde treated protein tended to grow more fleece than did kids given untreated protein meals but the differences were not significant.

The research was carried out at the animal experimental station of the National Agricultural Research Institute of the French West Indies (Guadeloupe) in 1999. Effects on intake and digestion by sheep of addition of Gliricidia leaves to a diet of 35-day-old Digitaria decumbens (pangola) hay, have been studied. In a first trial (a 4×4 Latin Square design), four rams were fed four diets: hay (G0); hay plus 1300 g of Gliricidia (G0·25), hay plus 2600 g of Gliricidia (G0·50), hay plus 3900 g of Gliricidia (G0·75). Total dry matter intake (DM), hay and Gliricidia intake, total tract and rumen digestibility of DM and its components, microbial and total nitrogen flows were estimated. In a second trial (a 2×2 Latin Square design), the same animals received hay (G0) or Gliricidia (G1·00) ad libitum to estimate the rumen turnover of pangola and Gliricidia fibrous particle. Neutral detergent fibre and crude protein content of the Digitaria decumbens hay and Gliricidia were 746 and 51, 458 and 198 g/kg dry matter respectively. Total dry matter intake (DM) varied from 42·7 to 76 g DM/kg LW0·75 from G0 to G0·75. The rate of substitution of pangola by Gliricidia (decrease of pangola intake for one unit Gliricidia consumed) was 233 g/kg. The digestibility of cell-wall linearly decreased with increasing level of Gliricidia in the diet. No digestive interaction was registered in the mixed diets. The total nitrogen and microbial nitrogen duodenal flows increased with the level of Gliricidia in the diet. The rumen turnover of fibrous particles of Gliricidia was double that of pangola. The incorporation of Gliricidia in diets increases their nutritive value by higher intake and intestinal nitrogen duodenal flows, but no positive digestive interaction was observed between pangola hay and Gliricidia leaves.

We compare the voluntary intake and digestibility of 6 genotypes selected from 3 F1 families of Digitaria milanjiana for high or low leaf digestibility, and D. decumbens (pangola grass). Swards were harvested on 6 occasions (4 by 4-week regrowths, 1 by 10-week and 1 by 14-week regrowth) and fed to sheep in metabolism cages. Averaged over families and regrowths, high digestibility selections were significantly superior to low digestibility selections in digestibility, voluntary dry matter intake and intake of metabolisable energy. There was a large range in leafiness of the genotypes. Correlations between leafiness and in vivo digestibility, dry matter (DM) intake and intake of metabolisable energy were positive and statistically significant. Comparison of full-sibs at the same percentage stem (80 and 100%) suggested a higher DM intake, digestibility and intake of metabolisable energy of stem from genotypes selected for high leaf digestibility. Averaged over harvests, none of the selected genotypes was significantly superior to pangola grass in digestibility but all were superior in DM intake and 5 in intake of metabolisable energy. The best selected genotype was 35% better than pangola grass in terms of intake of metabolisable energy. Differences in in vitro digestibility of young leaves from vegetative tillers of full sibs, the characteristic on which the genotypes had been selected, were maintained under sward conditions, although differences were reduced.

An elite genotype of Digitaria milanjiana, which had been selected on the basis of improved leaf digestibility, was compared with pangola grass (Digitaria eriantha ssp. pentzii, formerly Digitaria decumbens) in terms of milk production, at Mutdapilly in south-eastem Queensland. Unsupplemented Holstein-Friesian cows grazed nitrogen-fertilised, irrigated swards of 2 grasses using a switch-back experimental design. Pasture management and stocking rate were adjusted to provide the animals with 15 kg of green leaf (on a dry matter basis) per cow per day, so that any differences in milk yield could be attributed to differences in leaf quality rather than to total dry matter yield. Cows grazing the selected genotype produced 0.9 kg more milk, 0.07 kg more butterfat and 0.05 kg more protein per cow per day (5.8, 13.0 and 10.9%, respectively) than those grazing pangola grass. These increases were associated with a small increase in leaf digestibility, a faster rate of breakdown of leaf (in an artificial masticator) and a higher proportion of leaf in the diet chosen by the cows grazing the selected genotype. The results of this experiment demonstrate that a tropical grass selected on the basis of digestibility increased milk production of grazing cows. However, factors other than higher digestibility (such as leafiness) contributed to the improvement in production over that from pangola grass.

The digestion of mature pangola grass (Digitaria decurnbens) by Hereford (Bos taurus) and Brahman (Bos indicus) steers was studied. There was no significant difference between breeds in the digestion of organic matter (OM) and cell wall constituents (CWC). The OM digestibility in the whole tract was 0.59 with 90% of the digestion occurring in the stomachs. There was a significantly (P < 0.05) greater nonammonia nitrogen flow through the abomasum in Herefords (66 g/day) than Brahmans (59 g/day). Likewise the ratio of crude protein digested in the intestines to digestible OM (DCPi:DOMI) was higher (P < 0.05) in Herefords (0.120) than in Brahmans (0.102). In both breeds 66% of the nitrogen associated with the CWC was digested in the whole tract, essentially all digestion occurring in the stomachs. These results for pangola grass, especially the DCPi:DOMI ratios, are compared with the digestion characteristics of other tropical grasses and are discussed in terms of the capacity of tropical grasses to meet the protein requirements of growing cattle.

Seven agroforestry (AF) systems namely Eucalyptus grandis Hill ex Maiden (flooded gum, E), Dendrocalamus latiflorus Munro (Ma bamboo, B) and Digitaria decumbens Stent (Pangola, P), and their mixed plantations (BE, BP, EP, BEP) were monitored during the initial two years of growth for their efficiency in effluent removal. The municipal effluent irrigated plantation trial was established on a 1.6 ha site in the Capricornia coastal region at Yeppoon, Queensland in June 2002. This site was monitored until June 2004 for changes in site hydrology, physical, chemical and microbial properties of soil, and for plant growth, biomass production and nutrient uptake. The residual maximum likelihood method (REML) and analysis of variance (ANOVA) were extensively used to statistically compare the changes.

The plantations were irrigated at a modelled conservative irrigation rate of 1.42 ML ha^-1yr^-1. The total water use of all the AF systems was four to six times of that provided via irrigation. The mixed AF systems used more water than monoculture AF systems. During the initial two years, all the AF systems were effective in utilising effluent (both water and nutrients) due to the presence of groundflora. Over time, the efficiency and total water use may decline with reduction in groundflora and photosynthetically active canopy.

The vegetation of these AF systems accumulated six to ten times the major nutrients supplied via effluent irrigation. However, the AF systems with the exception of the E system failed to take up the supplied sodium and sulphur. Progressive build up of sodium in the soil would introduce sodicity in the soil and this may restrict the long term use of effluent disposal site. The electrical conductivity (EC_1.5) increased significantly in upper two soil layers whereas exchangeable sodium, CEC and ESP significantly increased over time in all the soil layers. Although soil compaction, reduction in infiltration rate, and increase in electrical conductivity and exchangeable sodium were observed at the site, the current changes did not indicate any ecological degradation. A long term study may help determine the optional rotation age of the AF crops to avoid adverse impact to the site.

Although the build up of microbiota in the effluent irrigated site increased considerably in all the AF systems, it did not reveal any health hazard. A study in mortality rates of different enteric bacteria indicated that the pathogens died within 15 days in winter and in less than 27 days in summer upon cessation of irrigation. Restricting access to the effluent irrigated site for up to 30 days would reduce the probability of a human health hazard due to the effluent irrigation.

At the conservative rate of irrigation (1.42 ML ha^-1yr^-1), the plantations produced up to 72 tonne biomass ha^-1 (dry biomass) within 24 months. Largely, the biomass produced in the AF systems was non-woody, thus it would need non-conventional markets. Leaves were the major site of nutrient storage. Senescence of leaves and twigs may accelerate nutrient recycling and this may defeat the objective of effluent irrigation. Moreover, the plants were selective in nutrient sequestering. Not more than one kg ha^-1 of any micro-nutrients was accumulated by bamboo and groundflora. For sustainability of effluent irrigation, the plantations may have to be either harvested in short rotation or irrigation has to be regulated according to plant growth. The commercial viability of the biomass produced in the AF systems was assessed to determine local suitability of the plantation models.

Canonical variate analysis (CVA), a type of multiple variate analysis, based on the combined data of various parameters showed differences between AF systems. These differences are likely to diverge with age of the plantations. The CVA based on more than four parameters showed differences amongst the AF systems. Moreover, the CVA for the datasets of some parameters collected at different time also revealed divergence amongst the AF systems. The analysis showed that the AF systems may develop contrasting differences with maturity. Monoculture E plantation produced more biomass than other AF systems, and it also accumulated more nutrients, compared to mixed AF systems. In contrast mixed AF systems (e.g., BP and BE) used more water than the monoculture systems. Overall, at 24 months, the mixed AF systems prove to offer improved benefits for effluent irrigation in terms of technical feasibility, ecological safety, and commercial viability of the effluent irrigated plantations.