Doses response of dietary viscosity on digestibility and faecal characteristics of striped catfish (Pangasionodon hypophthalmus)     

L. C. Tu-Tran  Thanh‐Cong Nguyen  Johan A. J. Verreth  Johan W. Schrama 《Aquaculture Research》2020,51(2):595-604

The study analysed the dose–response relationship between dietary viscosity and nutrient digestibility, faecal waste characteristics in striped catfish and the long‐term impacts of viscosity on performance of striped catfish. This was done in two experiments: Exp.1 lasted 29 days, in which six dietary viscosity levels were created by including different amount of guar gum (GG; 0, 0.25, 0.5, 1.0, 2.0 or 3.0 g/kg) and Exp.2 lasted 60 days and assessed the long‐term effects of three dietary GG levels (0, 0.5 and 3.0 g/kg) were checked. In Exp.1, digestibility of nutrients (except crude fat) decreased linearly with dietary viscosity. With increasing viscosity, removal efficiency of faeces from the water reduced linearly, whereas the total amount of faeces produced and the fraction of big‐sized faecal particles (>2 mm). increased linearly. In Exp.1, viscosity did not affect performance. However, in Exp.2, the GG inclusion level of 3.0 g/kg (1.72 cP for the viscosity) affected fish performance. In conclusion, the best strategy for faecal waste management in striped catfish by dietary viscosity is to keep it as low as possible in the diet.  相似文献   

Effect of rainfall and atmospheric temperature on the prevalence of the whitespot syndrome virus in pond‐cultured Penaeus monodon     

Eleonor A Tendencia  Roel H Bosma  Roselyn C Usero  Johan A J Verreth 《Aquaculture Research》2010,41(4):594-597

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Mussel (Mytilus edulis L.) and ragworm (Nereis virens,Sars) both alleviate anaemia in common sole (Solea solea L.)          下载免费PDF全文

Jeroen Kals  Robbert J W Blonk  Henk W van der Mheen  Johan W Schrama  Johan A J Verreth 《Aquaculture Research》2017,48(3):1338-1341

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Willingness of Iowa agricultural landowners to allow fee hunting associated with in-field shelterbelts   总被引：1，自引：1，他引：0  

Robert K. Grala  Joe P. Colletti  Carl W. Mize 《Agroforestry Systems》2009,76(1):207-218

In 2004, four focus groups consisting of agricultural landowners were organized in Northcentral Iowa to assess opportunities for hunting along in-field shelterbelts and on adjacent lands. A majority of respondents (95%) allowed/practiced some hunting on their lands. About 55% of respondents indicated that the potential existed for developing a fee hunting market associated with in-field shelterbelts. Intangible features of hunting, such as recreation/enjoyment and better land stewardship, were ranked higher than tangible ones—additional income and provision of economic opportunities for local communities. Respondents were highly concerned with negative consequences of hunting—trespassing and hunter misconduct. On average, agricultural landowners were willing to accept (WTA) US$30 per visit per party of four hunters to allow hunting of ring-necked pheasants (Phasianus colchicus) on their land. About 33% would grant access to hunters free of charge. Those who lived in urban areas would require five times the monetary compensation (US$50) as those who lived in rural areas (US$10).  相似文献   

Regeneration of mahogany and Spanish cedar in gaps created by railroad tie extraction in Quintana Roo,Mexico     

Patricia Negreros-Castillo  Carl W. Mize 《Forest Ecology and Management》2008

Seeds of mahogany and Spanish cedar were planted in gaps created by harvesting railroad ties at two locations in the Yucatan Peninsula. Gaps averaged 40 m² in area. Germination after 2 months was very low (2%) for Spanish cedar and moderately low (29%) for mahogany at the one location where it was measured, probably due to predation and fungal damage. Annual seedling mortality was 25–40%, and height growth was moderate to normal, with average height equal to 45 cm after 3 or 4 years, depending upon the location. We conclude that gaps from railroad tie harvesting are not adequate for the establishment of either species from seed. If, however, gaps created by harvesting could be concentrated into at least moderately open areas 400 m² in area or larger, they may be useful as sites for regenerating both species.  相似文献   

Simple sequence repeat (SSR)-based marker variation in Brassica nigra genebank accessions and weed populations   总被引：3，自引：0，他引：3  

Anne L. Westman  Stephen Kresovich 《Euphytica》1999,109(2):85-92

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EFFECTS OF DIET AND AGING ON RENAL MEASUREMENTS IN UNINEPHRECTOMIZED GERIATRIC BITCHES     

Julie A.  Churchill  DVM  Daniel A.  Feeney  DVM  MS  Thomas F.  Fletcher  DVM  PhD  Carl A.  Osborne  DVM  PhD  David J.  Polzin  DVM  PhD 《Veterinary radiology & ultrasound》1999,40(3):233-240

Under controlled, but varied dietary conditions among geriatric, uninephrectomized Beagle bitches (dogs) observed for 4 years, renal size increase as assessed radiographically and ultrasonographically occurred at variable rates, but on a seemingly continuous basis. The maximum observed mean renal linear parameter increase found was approximately 15%. However, a 10 and 15% increase is a more representative expectation among the 4 parameters (sonographic length, radiographic length, sonographic width, radiographic width) under consideration. The rate of renal size increase was rapid during the first 2 to 3 months following uninephrectomy. Thereafter, the rate of increase was slow, but occurred to varying degrees in both the length and width as assessed radiographically or ultrasonographically. The mechanism creating the size change was hypertrophy, not hyperplasia. Within limits of the 3 diets used in the study, no significant diet effect was found on the rate or degree of long term compensatory hypertrophy. Radiographically and ultrasonographically measured renal length had the greatest correlation with each other as well as with post mortem measurements and are, therefore, the recommended parameter for imaging assessment of compensatory hypertrophy. When the prenephrectomy, radiographic renal lengths and widths were normalized as a ratio of the second lumbar vertebral body length (L2) measured from ventrodorsal radiographs, the diet group means across dogs (approximately three L2 lengths for renal length; two L2 lengths for renal width) were in the middle of the respective previously published normal radiographic ranges for mature dogs (e.g. 2.5 L2 < or = length < or = 3.5 L2; 1.58 L2 < or = width < or = 2.38 L2 lengths). Even after the hypertrophic changes occurred, the radiographic group mean lengths and widths across dogs were still within the specified normal ranges, although toward the upper end of the respective range. This information provides background for clinical interpretation of potential compensatory hypertrophy that may be encountered following uninephrectomy for spontaneous disease in aged dogs. In addition, it appears that available radiographic renal linear ranges for normal mature dogs are applicable to geriatric dogs as well.  相似文献   

Chloroacetanilides,oxyacetamides, tetrazolinones: mode of action. 1. Cross resistance and oleic acid incorporation in algal model systems     

Carl Fedtke  Jochen Schmalfuß  Michel Couderchet 《Pest management science》1999,55(5):580-582

Results presented suggest that chloroacetamides, oxyacetamides, tetrazolinones, and possibly cafenstrole, act at the same site, although the precise molecular mode of action is still unknown, despite much research effort.  相似文献   

impact of high aluminium loading on a small catchment area (thuringia slate mining area) – geochemical transformations and hydrological transport     

Peiffer  Stefan  Beierkuhnlein  Carl  Sandhage-Hofmann  Alexandra  Kaupenjohann  Martin  Bär  Silke 《Water, air, and soil pollution》1997,94(3-4):401-416

A field study was performed on the effects of acid mine leachate from slate mine tailings seeping into a small river passing through the tailings. Before entering the tailings the river water has high alkalinity which neutralizes acidity upon mixing with leachate within the tailings. Donwstreams of the tailings the pH of the river water ranges about pH = 8, the water contains high concentrations of sulfate (≈1500 μmol/1 and particulate bound aluminium (≈80 μmol/I), but low concentrations of dissolved aluminium (≈3 μmol/1). It is therefore assumed that AI(OH)₃ colloids are precipitated during the neutralisation process and transported out of the tailings. The concentration of particulate bound aluminium along the river shows a strong correlation with the concentration of sulfate, which indicates that particulate bound aluminium is conservative. It therefore seems that under dry weather conditions (under most of the sampling was performed) no chemical retention mechanism exists which confines the distribution of aluminium to a restricted part of the catchment area. In contrast, the white river sediment is rich in both aluminium and sulfate, which suggests the temporary formation of aluminium hydroxosulfate minerals. Favorable (i.e. acidic) conditions may prevail at high discharges where the acidity accumulated in the tailings is flushed into the river with its subsequent acidification.  相似文献   

Maize root development and grain production as affected by soil and water management on a sandy soil in a semi-arid region of southern Mozambique     

Emílio Magaia  Johan Arvidsson  Rui Brito  Abraham Joel 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2016,66(3):247-258

Average yield of maize (Zea mays L.) in Mozambique is low, mainly due to low use of inputs in agriculture, high seasonal rainfall variability and inadequate soil preparation. A study conducted in two summer crop seasons (November–March 2012/2013 and 2013/2014) examined the impact of three tillage methods (hand hoeing, strip tillage and conventional tillage), two fertiliser levels (0 and 40% N) and two water supply regimes (rainfed and irrigated) on maize root development and grain yield on a sandy soil in a semi-arid region of Mozambique. Tillage had a major effect on soil penetration resistance, but little effect on root growth and limited effect on yield. Thus, there appears to be little need for loosening on this soil. There was also no interaction between tillage and the other experimental factors, meaning that tillage system can be chosen irrespective of fertiliser and water supply. Irrigation had the largest impact on root and shoot growth and crop yield, increasing yield in season 2 from 670 to 4780?kg ha^–1.There was a very strong interaction between fertiliser and water supply, with no yield increase for fertiliser in the rainfed treatment, while combined with irrigation it increased yield by 1590?kg ha^–1 in season 1 and 1840?kg ha^–1 in season 2. Thus, for the conditions studied here, it was rational to add fertiliser only in combination with irrigation and not in a rainfed system.  相似文献