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21.
The radial pattern of both maximum ring density and ring area of 36 black spruce trees were used to determine the transition age from juvenile wood to mature wood. The data were obtained by X-ray densitometry and both segmented linear and polynomial regressions were used to point out the age of the juvenile wood boundary. Three stand densities (1,790, 2,700 and 3,400 stems/ha) and three sampling heights (2.4, 5.1 and 7.8 m) were studied. Although maximum ring density and ring area presented similar radial patterns, they gave two significantly different results of transition ages. The maximum ring density over-estimated the transition age (17.6 years) in contrast to ring area (14 years). The results show that the transition from juvenile wood to mature wood occurred after 12 years at 7.8 m (versus 13.1 years at a height of 5.1 m, and 17.6 years at 2.4 m). Although transition age occurred later in the high stand density group (21 years), the difference was not significant between the three stand density groups. Nevertheless, transition age remains difficult to determine since no standard definition exists. The transition occurs over years, and most probably a transition wood exists between juvenile wood and mature wood. Estimation of the juvenile wood proportion in volume shows that it remains constant along the stem and it increases with stand density. 相似文献
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Felipe Nogueira Soares Maria Emilia Franco Oliveira Luciana Cristina Padilha-Nakaghi Luís Guilherme de Oliveira Marcus Antônio Rossi Feliciano Felipe Brener Bezerra de Oliveira Pedro Paulo Maia Teixeira Wilter Ricardo Russiano Vicente Cristian Faturi Luiz Fernando de Souza Rodrigues 《Tropical animal health and production》2015,47(8):1465-1471
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Denise R. Freitas Leorges M. Fonseca Fernando N. Souza Cristiane V. G. Ladeira Soraia A. Diniz João Paulo A. Haddad Diêgo S. Ferreira Mônica M. O. P. Cerqueira 《Animal Science Journal》2015,86(5):553-556
Casein (CN) micelles are colloidal aggregates of protein dispersed in milk, the importance of which in the dairy industry is related to functionality and yield in dairy products. The objective of this work was to investigate the correlation of milk CN micelles diameter from Holstein and Zebu crossbreds with milk composition (protein, fat, lactose, total and nonfat solids and milk urea nitrogen), somatic cell count (SCC), age, lactation stage and production. Average casein micelles diameters of milk samples obtained from 200 cows were measured using photon correlation spectroscopy and multiple regression analysis was used to find relationship between variables. CN micelle diameter, SCC and nonfat solids were different between animals with different Holstein crossbreed ratios, which suggests influence of genetic factors, mammary gland health and milk composition. Overall, results indicate the potential use of CN micelle diameter as a tool to select animals to produce milk more suitable to cheese production. 相似文献
26.
Diversity of insecticide resistance mechanisms and spectrum in European populations of the codling moth, Cydia pomonella 总被引:1,自引:0,他引:1
Reyes M Franck P Charmillot PJ Ioriatti C Olivares J Pasqualini E Sauphanor B 《Pest management science》2007,63(9):890-902
Only a few of the registered insecticides against Cydia pomonella L. are still effective in areas where insecticide resistance has emerged in this pest. Resistance mechanisms are multiple, and their lone or cumulative effects in a single population are not completely understood. A detailed estimation of resistance spectrum is still required to define the suitable insecticides to use against a given population. The efficacy of ten insecticides was therefore investigated together with the resistance mechanisms expressed in four laboratory strains and 47 field populations of C. pomonella from five countries. Bioassays were performed using topical applications of diagnostic concentrations on diapausing larvae, and resistance mechanisms were analysed on adults emerging from control insects. All populations exhibited a reduced susceptibility to at least one insecticide when compared with the susceptible laboratory strain. Cross-resistances were observed between azinphos-methyl or phosalone and more recent compounds such as spinosad and thiacloprid. Resistances to azinphos-methyl, diflubenzuron, spinosad, tebufenozide and thiacloprid were significantly correlated with mixed-function oxidase activity, while increased glutathione-S-transferase and reduced non-specific esterase activities were correlated with resistance to azinphos-methyl and emamectin, respectively. Conversely, resistances to azinphos-methyl, tebufenozide and thiacloprid were negatively correlated with increased esterase activity. None of the observed mechanisms explained the loss of susceptibility of populations to chlorpyrifos-ethyl, and no significant correlation was detected between resistance to deltamethrin and the presence of the kdr mutation. The suitability of such non-target instars to monitor insecticide resistance in field populations is discussed. 相似文献
27.
Scorza Júnior RP Jarvis NJ Boesten JJ van der Zee SE Roulier S 《Pest management science》2007,63(10):1011-1025
Testing of pesticide leaching models against comprehensive field-scale measurements is necessary to increase confidence in their predictive ability when used as regulatory tools. Version 5.1 of the MACRO model was tested against measurements of water flow and the behaviour of bromide, bentazone [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide] and imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] in a cracked clay soil. In keeping with EU (FOCUS) procedures, the model was first calibrated against the measured moisture profiles and bromide concentrations in soil and in drain water. Uncalibrated pesticide simulations based on laboratory measurements of sorption and degradation were then compared with field data on the leaching of bentazone and imidacloprid. Calibrated parameter values indicated that a high degree of physical non-equilibrium (i.e. strong macropore flow) was necessary to describe solute transport in this soil. Comparison of measured and simulated bentazone concentration profiles revealed that the bulk of the bentazone movement in this soil was underestimated by MACRO. Nevertheless, the model simulated the dynamics of the bentazone breakthrough in drain water rather well and, in particular, accurately simulated the timing and the concentration level of the early bentazone breakthrough in drain water. The imidacloprid concentration profiles and its persistence in soil were simulated well. Moreover, the timing of the early imidacloprid breakthrough in the drain water was simulated well, although the simulated concentrations were about 2-3 times larger than measured. Deep groundwater concentrations for all substances were underestimated by MACRO, although it simulated concentrations in the shallow groundwater reasonably well. It is concluded that, in the context of ecotoxicological risk assessments for surface water, MACRO can give reasonably good simulations of pesticide concentrations in water draining from cracking clay soils, but that prior calibration against hydrologic and tracer data is desirable to reduce uncertainty and improve accuracy. 相似文献
28.
Bienvenu Kambashi Christelle Boudry Pascale Picron Honoré Kiatoko Jérôme Bindelle 《Tropical animal health and production》2014,46(8):1497-1502
The effects of four tropical forage legume hays (Vigna unguiculata, Psophocarpus scandens, Pueraria phaseoloides and Stylosanthes guianensis) on voluntary feed intake (VFI) and their nutritive value were studied in growing pigs using a corn-soybean meal-based diet containing varying proportions of forage legume hays (0, 10, 20 and 40 % or 0, 12.5 and 25 % for VFI and nutritive value determination, respectively). There was no difference in VFI between species (P?>?0.20), but a linear response to forage inclusion level (P?0.05) was observed decreasing from 126 for 0 % to approximately 84 g/kg of body weight for the 40 % forage diets, except for V. unguiculata, where the response was quadratic (P?=?0.01). All four forage species linearly decreased the total tract apparent digestibility (TTAD) from 0.76 to 0.61, 0.80 to 0.68, 0.54 to 0.40 and 0.58 to 0.31 except for S. guianensis (0.44) for DM, N, NDF and N retention, respectively. Differences in digestibility (P?0.05) between species were also observed. Due to their negative influence on the overall digestibility, the contribution of hays should not exceed 12.5 %, except for S. guianensis, in which N retention remained quite high (0.44) at the highest inclusion level (25 %). P. phaseoloides hay should be avoided in pigs as it combines the lowest VFI with the lowest nutrient digestibility. 相似文献
29.
João Borges Guimarães Éder Clementino dos Santos Eustáquio Souza Dias Antônio Gilberto Bertechini Carla Luiza da Silva Ávila Francesca Silva Dias 《Tropical animal health and production》2014,46(8):1509-1514
This trial was performed to study the use of the mushroom Agaricus brasiliensis as an alternative additive to antimicrobial growth promoters in broiler chicken diets and to assess the quality of the broiler chicken breast meat of birds that are fed diets containing this fungus. Thus, 595 1-day-old chicks were reared in reused poultry litter without anticoccidial and antimicrobial additives. The results showed that a concentration of 1.6 g mushrooms/kg diet was ideal for these birds because it provided better bird performance. When the birds’ immune system organs were analyzed, it was found that the addition of both mushrooms influenced the immune system organs of these broiler chickens. Adding A. brasiliensis to broiler chicken diets did not compromise breast meat quality. 相似文献
30.
V. M. P. Bernardino P. B. Rodrigues L. de Paula Naves P. V. Rosa M. G. Zangerônimo E. M. Gomide M. M. Saldanha R. R. Alvarenga 《Journal of animal physiology and animal nutrition》2014,98(2):328-337
The objective of this study was to evaluate the effect of three sources of glycerine (crude glycerine from soya bean oil – CGSO, mixed crude glycerine from frying oil and lard – MCG, and a semipurified glycerine from soya bean oil – SPGSO) in four concentrations in the diet (17.5, 35.0, 52.5 and 70.0 g of each type of glycerine per kg of feed) on the levels of plasmatic glycerol and the activity of the hepatic enzyme glycerol kinase in broilers of 22–35 days old (experiment I) and 33–42 days old (experiment II). The highest (p < 0.05) plasmatic glycerol level was detected in broilers fed diet containing CGSO. Independent of the source, increasing the concentration of glycerine led to a linear increase (p < 0.05) in the plasmatic glycerol concentration. In experiment I, all the diets containing glycerine resulted in increased concentrations of plasmatic glycerol, in relation to the control diet without glycerine. However, in experiment II, only the diet containing 17.5 g of CGSO per kg of feed and the diets formulated with any of the three types of glycerine in the inclusion concentrations of 35, 52.5 and 70 g/kg of feed resulted in higher plasmatic glycerol levels than those observed in the control broilers. The source of glycerine influenced the glycerol kinase activity only in experiment II, where the use of CGSO in the diet increased the enzyme activity. For both experiments, the glycerol kinase activity increased with the inclusion of glycerine in the diet. In conclusion, based on the absence of saturation of the glycerol kinase activity for the three glycerine sources and for both rearing periods evaluated, the broilers can metabolize the glycerol (at the level of the phosphorylation of the glycerol to glycerol‐3‐phosphate in the liver) present in the glycerine when the diet is supplemented with up to 70 g of glycerine per kg of feed. 相似文献