Veterinary legal issues: 2006 in review     

Settles EL  Babcock SL 《Journal of the American Veterinary Medical Association》2007,230(3):350-352

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Effect of crabgrass (Digitaria ciliaris) hay harvest interval on forage quality and performance of growing calves fed mixed diets     

Beck PA  Hutchison S  Stewart CB  Shockey JD  Gunter SA 《Journal of animal science》2007,85(2):527-535

Twelve 0.81-ha crabgrass (Digitaria ciliaris [Retz.] Koel.) hay fields were harvested at 21, 35, and 49 d of regrowth (average phonological growth stage of 30, 51, and 56, respectively). Increased harvest interval exhibited a linear decrease (P < 0.01) in CP (14.1, 13.7, and 10.6% of DM, respectively) and increase (P < 0.01) in NDF (65.3, 70.6, and 70.2% of DM, respectively) and ADF (35.7, 38.9, and 42.7% of DM, respectively). Hays were incorporated into 3 diets that contained 20% (DM basis) crabgrass hay, ground corn (33%), and soybean hulls (32%). Diets contained 14.4, 14.4, and 13.6% CP; 1.83, 1.72, and 1.81 Mcal of NE(m)/kg; and 1.21, 1.10, and 1.17 Mcal of NE(g)/kg; respectively. Diets were fed to beef calves in 12 pens at a rate of 2.3% (DM basis) of BW in 1 experiment (n = 120, initial BW 210 +/- 4.4 kg) and ad libitum in another experiment (n = 60, initial BW 207 +/- 4.4 kg). To measure passage rate of the hay and concentrate portions of the diets, 12 heifer calves (BW = 145 +/- 4.5 kg) were individually fed at 2.3% of BW for 14 d and dosed with Dy-labeled soybean hulls and Yb-labeled hay. In situ DM digestibility of the hays and diets were determined using 3 ruminally cannulated steers (BW = 584 +/- 10.4 kg). Harvest interval did not affect (P > or = 0.11) ADG of limit-fed calves during the diet acclimation or growing phases (average 0.32 and 0.80 kg, respectively) or ADG of calves fed ad libitum (average 1.21 kg). Dry matter intake of calves fed ad libitum averaged 7.9 kg/d (3.28% of BW) and was not affected (P > or = 0.22) by harvest interval. Gain:feed was not affected (P > or = 0.20) by harvest interval (0.13 and 0.15 for limit-fed and ad libitum-fed calves, respectively). Increased harvest interval linearly increased (P < 0.01) ruminal retention time of the hay and tended (P = 0.06) to linearly increase ruminal retention time of the concentrate portions of the diet. Harvest interval linearly decreased (P < or = 0.05) the extent of degradability and effective degradability of DM and NDF of hays, but DM disappearance of the total diet did not differ (P > or = 0.35). In the conditions of this study, increasing harvest interval of crabgrass hay from 21 to 49 d had no deleterious impact on animal performance or efficiency of gain when fed to growing calves in a high-concentrate mixture.  相似文献   

Why landscape ecologists should contribute to life cycle sustainability approaches     

Ian M. S. Eddy  Sarah E. Gergel 《Landscape Ecology》2015,30(2):215-228

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Staining of heterochromatin bands and the determination of rye chromosomes in triticale (wheat × rye hybrid)     

Val T. Sapra  Moira D. Stewart 《Euphytica》1980,29(2):497-509

Summary Fifteen lines of triticale were studied using the C-banding staining method. A typical, complete chromosomal complement was found in 11 lines, while the remaining lines demonstrated some variations. A slight modification in the technique is discussed.Supported in part by CSRS/USDA Grant No. 801-15-03A.  相似文献   

Biodiversity of mannose-specific lectins within Narcissus species     

Lopez S  Codina C  Bastida J  Viladomat F  Davidson E  Stewart D 《Journal of agricultural and food chemistry》2002,50(9):2507-2513

Mannose-specific lectins (MSLs) were isolated from the bulbs of 27 species of wild Spanish Narcissi and compared to the commercially available MSL from daffodil (Narcissus pseudonarcissus, NPA). Molecular weight analysis showed the monomers of all the MSLs were at, or around, 12.5 kD. Haemagglutination assays showed that the MSLs exhibited activities at up to four times greater than that displayed by NPA and other MSLs derived from other species such as Galanthus nivalus (snowdrop) and Allium ursinum (ramson). Elution profiles from ion exchange chromatography exhibited similarities for species within the same taxonomic section suggesting that this method could aid in species classification. Further analysis by isoelectric focusing showed many isolectins are present in vivo and that even within a single peak from ion exchange chromatography there are numerous isolectins present. The basis of the isolectin heterogeneity is suggested to reside in the tetraploidy (sometime triploidy) nature of Narcissus genes.  相似文献   

Human activities modify soil properties in urban parks: a case study of Tel Aviv-Jaffa     

Pariente Sarah  Helena M. Zhevelev  Atar Oz 《Journal of Soils and Sediments》2016,16(11):2538-2547

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Effects of past and current crop management on soil microbial biomass and activity     

Christine Stark  Leo M. Condron  Alison Stewart  Hong J. Di  Maureen O’Callaghan 《Biology and Fertility of Soils》2007,43(5):531-540

Because soil biota is influenced by a number of factors, including land use and management techniques, changing management practices could have significant effects on the soil microbial properties and processes. An experiment was conducted to investigate differences in soil microbiological properties caused by long- and short-term management practices. Intact monolith lysimeters (0.2 m² surface area) were taken from two sites of the same soil type that had been under long-term organic or conventional crop management and were then subjected to the same 2.5-year crop rotation [winter barley (Hordeum vulgare L.), maize (Zea mais L.), lupin (Lupinus angustifolius L.), and rape (Brassica napus L. ssp. oleifera)] and two fertilizer regimes (following common organic and conventional practices). Soil samples were taken after crop harvest and analyzed for microbial biomass C and N, microbial activity (fluorescein diacetate hydrolysis, arginine deaminase activity, and dehydrogenase activity), and total C and N. The incorporation of the green manure stimulated growth and activity of the microbial communities in soils of both management histories. Soil microbial properties did not show any differences between organically and conventionally fertilized soils, indicating that crop rotation and plant type had a larger influence on the microbial biomass and enzyme activities than fertilization. Initial differences in microbial biomass declined, while the effects of farm management history were still evident in enzyme activities and total C and N. Links between enzyme activities and microbial biomass C varied depending on treatment, indicating differences in microbial community composition.  相似文献   

Classification of Ilex species based on metabolomic fingerprinting using nuclear magnetic resonance and multivariate data analysis     

Choi YH  Sertic S  Kim HK  Wilson EG  Michopoulos F  Lefeber AW  Erkelens C  Prat Kricun SD  Verpoorte R 《Journal of agricultural and food chemistry》2005,53(4):1237-1245

The metabolomic analysis of 11 Ilex species, I. argentina, I. brasiliensis, I. brevicuspis, I. dumosavar. dumosa, I. dumosa var. guaranina, I. integerrima, I. microdonta, I. paraguariensis var. paraguariensis, I. pseudobuxus, I. taubertiana, and I. theezans, was carried out by NMR spectroscopy and multivariate data analysis. The analysis using principal component analysis and classification of the (1)H NMR spectra showed a clear discrimination of those samples based on the metabolites present in the organic and aqueous fractions. The major metabolites that contribute to the discrimination are arbutin, caffeine, phenylpropanoids, and theobromine. Among those metabolites, arbutin, which has not been reported yet as a constituent of Ilex species, was found to be a biomarker for I. argentina,I. brasiliensis, I. brevicuspis, I. integerrima, I. microdonta, I. pseudobuxus, I. taubertiana, and I. theezans. This reliable method based on the determination of a large number of metabolites makes the chemotaxonomical analysis of Ilex species possible.  相似文献   

The buffer effect of non-breeding birds and the timing of farmland bird declines     

Sarah E.A.Le V.dit Durell  Ralph T Clarke 《Biological conservation》2004,120(3):375-382

Breeding territoriality in birds means that a certain proportion of the adult population may breed in suboptimal habitats or not breed at all. Non-breeding birds, or floaters, can have a `buffer effect' on breeding population size. Farmland bird declines in Britain are measured and analysed in terms of numbers of territory-holding birds. We use a population dynamics model to illustrate how, because of the buffer effect of floaters, there can be a time lag between the start of total population decline and detectable breeding population decline. Differences in the timing of declines of closely related farmland birds could therefore be due to slight differences in their population dynamics, rather than differences in their response to agricultural change.  相似文献   

Comparisons of Mayan forest management, restoration, and conservation   总被引：1，自引：0，他引：1  

Stewart A.W. Diemont  Jessica L. BohnDonald D. Rayome  Sarah J. KelsenKaity Cheng 《Forest Ecology and Management》2011,261(10):1696-1705

Numerous communities associated with at least five distinct ethnic Mayan groups in southern Mexico and Central America continue to rely upon forested areas as integral components of their agricultural systems. They carefully manage these areas so that forests provide food, raw materials, and animals. Management practices include removing and planting of woody and herbaceous species, apiculture, and seed harvest. Mayan agroforestry systems in geographically and ecologically distinct areas of Mesoamerica were evaluated to better understand traditional agroforestry system components and how indigenous Mayan agroforestry could be a part of regional forest conservation and restoration. Systems were within Mexican land grant areas (ejidos) or on contested land. Although these systems rely upon different woody species and management techniques, common among them are: (1) the use of multi-stage and successional pathways with forest as a part of the larger system, (2) species that are believed by traditional ecological knowledge (TEK) to accelerate forest regeneration - more than 30 tree species are recognized and managed as potential facilitators of forest regeneration and (3) direct human consumption of forest products at all stages of regeneration.  相似文献