Evidence for a ubiquitous seismic discontinuity at the base of the mantle     

Sidorin I  Gurnis M  Helmberger DV 《Science (New York, N.Y.)》1999,286(5443):1326-1331

A sharp discontinuity at the base of Earth's mantle has been suggested from seismic waveform studies; the observed travel time and amplitude variations have been interpreted as changes in the depth of a spatially intermittent discontinuity. Most of the observed variations in travel times and the spatial intermittance of the seismic triplication can be reproduced by a ubiquitous first-order discontinuity superimposed on global seismic velocity structure derived from tomography. The observations can be modeled by a solid-solid phase transition that has a 200-kilometer elevation above the core-mantle boundary under adiabatic temperatures and a Clapeyron slope of about 6 megapascal per kelvin.  相似文献   

Determination of saleable product in finished cattle and beef carcasses utilizing bioelectrical impedance technology     

Marchello MJ  McLennan JE  Dhuyvetter DV  Slanger WD 《Journal of animal science》1999,77(11):2965-2970

Two experiments were performed to develop prediction equations of saleable beef and to validate the prediction equations. In Exp. 1, 50 beef cattle were finished to typical slaughter weights, and multiple linear regression equations were developed to predict kilograms of trimmed boneless, retail product of live cattle, and hot and cold carcasses. A four-terminal bioelectrical impedance analyzer (BIA) was used to measure resistance (Rs) and reactance (Xc) on each animal and processed carcass. The IMPS cuts plus trim were weighed and recorded. Distance between detector terminals (Lg) and carcass temperature (Tp) at time of BIA readings were recorded. Other variables included live weight (BW), hot carcass weight (HCW), cold carcass weight (CCW), and volume (Lg2/Rs). Regression equations for predicting kilograms of saleable product were [11.87 + (.409 x BW) - (.335 x Lg) + (.0518 x volume)] for live (R2 = .80); [-58.83 + (.589 x HCW) - (.846 x Rs) + (1.152 x Xc) + (.142 x Lg) + (2.608 x Tp)] for hot carcass (R2 = .95); and [32.15 + (.633 x CCW) + (.33 x Xc) - (.83 x Lg) + (.677 x volume)] for cold carcass (R2 = .93). In Exp. 2, 27 beef cattle were finished in a manner similar to Exp. 1, and the prediction equations from Exp. 1 were used to predict the saleable product of these animals. The Pearson correlations between actual saleable product and the predictions based on live and cold carcass data were .91 and .95, respectively. The Spearman and Kendall rank correlations were .95 and .83, respectively, for the cold carcass data. These results provide a practical application of bioelectrical impedance for market-based pricing. They complement previous studies that assessed fat-free mass.  相似文献   

Presence of naturally occurring Campylobacter and Salmonella in the mature and immature ovarian follicles of late-life broiler breeder hens     

Cox NA  Bailey JS  Richardson LJ  Buhr RJ  Cosby DE  Wilson JL  Hiett KL  Siragusa GR  Bourassa DV 《Avian diseases》2005,49(2):285-287

Campylobacter and Salmonella are known to cause acute bacterial gastroenteritis in humans. Raw poultry products have been implicated as a significant source of these infections. Five trials were conducted to determine whether Campylobacter and Salmonella spp. exist naturally in the mature and immature ovarian follicles of late-life broiler breeder hens. Broiler breeder hens ranging from 60 to 66 wk of age were obtained from four different commercial breeder operations. For each trial, the hens were removed from the commercial operation and held overnight at the University of Georgia processing facility. The hens were euthanized, defeathered, and aseptically opened. To reduce the possibility of cross-contamination between samples, first the mature and immature ovarian follicles, then the ceca, were aseptically removed. Individual samples were placed in sterile bags, packed on ice, and transported to the laboratory for evaluation. Overall, Campylobacter was found in 7 of 55 immature follicles, 12 of 47 mature follicles, and 41 of 55 ceca. Campylobacter was found in at least one of each sample of mature follicles and in ceca in each of the five trials. Salmonella was found in 0 of 55 immature follicles, 1 of 47 mature follicles, and 8 of 55 ceca. In this study, the recovery rate of Salmonella from late-life broiler breeder hen ovarian follicles was relatively low. However, the recovery rate of Campylobacter from the hen ovarian follicles was reasonably high, suggesting that these breeder hens could be infecting fertile hatching eggs. Determining how Campylobacter contaminated these ovarian follicles and how many chicks could be colonized from this source are the next steps in helping to elucidate a better understanding of this ecology and the control of Campylobacter in poultry production.  相似文献   

Presence of Campylobacter jejuni in various organs one hour, one day, and one week following oral or intracloacal inoculations of broiler chicks     

Cox NA  Hofacre CL  Bailey JS  Buhr RJ  Wilson JL  Hiett KL  Richardson LJ  Musgrove MT  Cosby DE  Tankson JD  Vizzier YL  Cray PF  Vaughn LE  Holt PS  Bourassaa DV 《Avian diseases》2005,49(1):155-158

Day-old broiler chicks (n=30) were obtained from a commercial hatchery and inoculated, either orally or intracloacally, with a characterized strain of Campylobacter jejuni. At 1 hr, 1 day, and 1 wk after inoculation, broilers (n = 5) from the orally and intracloacally inoculated groups along with control birds (n=4) were humanely killed by cervical dislocation. The broilers from the control and treatment groups were aseptically opened, and the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca were aseptically removed and individually analyzed for C. jejuni. Overall, C. jejuni was isolated after oral inoculation from 13% (10/ 75), 17% (13/75), and 28% (14/50) of the 1-hr, 1-day, and 1-wk samples, respectively. Campylobacter jejuni was isolated from 10% (4/ 40), 8% (3/40), 10% (4/40), 25% (10/40), and 40% (16/40) of the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca samples, respectively. Following the intracloacal route of inoculation, C. jejuni was recovered from 32% (24/75), 8% (6/75), and 16% (8/50) of the 1-hr, 1-day, and 1-wk samples, respectively. Campylobacter jejuni was isolated from 5% (2/40), 5% (2/40), 5% (2/40), 45% (18/40), and 40% (16/40) of the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca samples, respectively, for all sampling periods. Campylobacter spp. were not recovered from sample sites examined from the control broilers from trial one, trial two, or trial three samples examined after 1 hr and 1 day. However, one control sample was positive from the 1-wk sampling from repetition three; therefore, those data were omitted. The rapid movement of Campylobacter to internal organs following both oral and intracloacal inoculation may be significant, particularly if it persists in these organs as reservoirs throughout the 65-wk life cycle of breeding birds.  相似文献   

Effect of Scavenging and Supplementation of Lysine and Methionine on the Feed Intake,Performance and Carcase Quality of Improved Dual-Purpose Growing Chickens   总被引：1，自引：0，他引：1  

Minh DV  Ogle B 《Tropical animal health and production》2005,37(7):573-587

An experiment was conducted with 192 improved dual-purpose chickens from 4 to 12 weeks of age to evaluate the effects of management system (confinement and scavenging) and amino acid supplementation (with and without lysine and methionine) of a low-protein diet on the feed and nutrient intake, performance and carcase quality of improved chickens. Mean daily dry matter (DM), crude protein and metabolizable energy intakes were higher for the confined birds (65 g, 13.3 g and 966 kJ, respectively) than for the scavenging birds (58 g, 12.0 g and 868 kJ, respectively) (p < 0.001) and higher for the unsupplemented (63.3 g, 13.0 g and 945 kJ, respectively) than for the supplemented birds (59.5 g, 12.2 g and 889 kJ, respectively) (p < 0.001). Mean DM intake was 68.0 and 54.9 g/day for the males and females (p < 0.001), respectively. Average daily weight gains (ADG) were higher for scavenging (26.9 g) than for confined birds (23.9 g) (p < 0.001), higher for supplemented (27.6 g) than for unsupplemented birds (23.2 g) (p < 0.001) and higher for males (27.5 g) than for females (23.3 g) (p < 0.001). Carcase, breast and thigh percentages were higher for supplemented than for unsupplemented birds (p < 0.001) and higher for scavenging than for confined birds (p < 0.001). Abdominal fat percentage was significantly lower for the scavenging treatments compared to the corresponding confined treatments (p < 0.001). Feed conversion ratios (kg feed/kg gain) and feed costs/kg gain were lower for the scavenging than for the confinement treatments, and lower for the supplemented than for the unsupplemented birds (p < 0.001). Supplementation of lysine and methionine in diets that were suboptimal in terms of protein and essential amino acids improved performance and carcase quality and reduced feed costs, in particular of the confined growers.  相似文献   

Fracture, luxation, and chronic septic arthritis of the temporomandibular joint in a juvenile horse     

Devine DV  Moll HD  Bahr RJ 《Journal of veterinary dentistry》2005,22(2):96-99

This case report describes chronic sepsis of the right temporomandibular joint in a juvenile horse. Diagnostic work-up included physical examination, radiography, and computed tomography. Humane euthanasia was indicated due to the chronicity of the condition, prognosis, and financial constraints.  相似文献   

Factors affecting ascorbic acid (AsA) biosynthesis in chickens. II. Effect of dietary AsA and strain of chicken     

Hooper CL  Maurice DV  Lightsey SF  Toler JE 《Journal of animal physiology and animal nutrition》2002,86(9-10):326-332

The present study examined the effect of supplemental ascorbic acid (AsA) and ascertained if genotype is a determinant of biosynthesis and the response of strains to dietary AsA. Slow- (Ottawa Meat Control; OMC) and fast-growing (Peterson Enhanced x Hubbard; PEH) chicks were fed 1000 mg/kg AsA from 1 to 10 weeks of age. The activity of l-gulonolactone oxidase (GLO) was used to measure biosynthesis and estimated synthetic capacity (ESC) computed. Body weight was not affected by diets and relative kidney weight decreased with age. In 1 week, dietary AsA increased plasma AsA and inhibited GLO activity with a greater reduction in OMC birds. At 10 weeks, GLO activity was depressed almost uniformly in both strains. Strain by age and diet by age interactions were detected for GLO activity and ESC with significantly greater decline in PEH birds and birds fed supplemental AsA. The results demonstrated that dietary AsA inhibited biosynthesis in meat type chickens and the response at 10 weeks was not influenced by growth rate; and the age dependent decline in biosynthesis was more pronounced in the commercial PEH birds. The result suggests that such strains may be compromised in some situations. Research using multiple dietary levels of AsA, commercial strains, and defined stressors is warranted.  相似文献   

Factors affecting ascorbic acid biosynthesis in chickens: III. Effect of dietary fluoride on L-gulonolactone oxidase activity and tissue ascorbic acid (AsA) concentration     

Maurice DV  Lightsey SF  Abudabos A  Toler JE 《Journal of animal physiology and animal nutrition》2002,86(11-12):383-388

The inconsistent beneficial responses to dietary ascorbic acid (AsA) may be due to dietary factors that alter biosynthesis or tissue turnover of AsA. It has been suggested on the basis of altered tissue AsA that dietary fluoride is a determinant of biosynthesis in chickens. Fluoride may enter the food chain of poultry via industrial contamination, feed ingredients and drinking water. The goal of this study was to ascertain whether dietary fluoride at 300 mg/kg influences l-gulonolactone oxidase (GLO) activity in commercial meat-type chickens. The experimental diet was fed from day-old to 3 weeks and responses measured. Growth and feed conversion were not affected by fluoride in the diet. Dietary fluoride neither inhibited nor enhanced GLO activity nor did it increase or decrease AsA concentration in plasma, liver, kidney, adrenal gland and muscle (pectoralis major). Tissue AsA concentration in ascending order was adrenal > liver > kidney > pectoralis major > plasma. The results are consistent with that reported for the rat and calculations based on the results eliminate fluorine contamination for the inconsistent responses of immature chickens to dietary AsA.  相似文献   

Phylogeography and Genotype-Symptom Associations in Early and Late Season Infections of Canola by Sclerotinia sclerotiorum     

Phillips DV  Carbone I  Gold SE  Kohn LM 《Phytopathology》2002,92(7):785-793

ABSTRACT Both typical late season stem infections and atypical early season rosette infections of canola, a relatively new crop in the southeastern United States, were caused by Sclerotinia sclerotiorum. The 51 DNA fingerprints (from 71 isolates) did not match any fingerprints from previous studies of canola or other crops. Single locus haplotypes from nuclear DNA sequences included 18 in the intergenic spacer (IGS) of the rRNA repeat, four in 44.11, six in translation elongation factor 1alpha, three in calmodulin (CAL), and two in chitin synthase 1. Contingency permutation testing for associations of infection type with DNA fingerprint, single- or multilocus haplotype, or hierarchically nested clades based on single locus haplotypes found significant association of haplotype with mycelial compatibility group and DNA fingerprint for all loci except CAL. Significant association of IGS haplotypes with symptom type was detected in one pathogen population. Southeastern U.S. canola was infected by both recently evolved, geographically dispersed pathogen genotypes and older, indigenous genotypes (Carbone and Kohn, 2001. Mol. Ecol. 10:947-964). Indigenous haplotypes are infection-type generalists, and the most frequently isolated from rosette infections. In contrast, haplotypes from the most recently evolved, dispersed population were associated one-to-one with infection type, with only the most recently evolved haplotypes infecting rosettes.  相似文献   

Analysis and management of resistance to chemotherapeutants in salmon lice,Lepeophtheirus salmonis (Copepoda: Caligidae)     

Denholm I  Devine GJ  Horsberg TE  Sevatdal S  Fallang A  Nolan DV  Powell R 《Pest management science》2002,58(6):528-536

In Northern Europe and Canada, the salmon louse, Lepeophtheirus salmonis (Kr?yer), seriously affects the marine phase of salmon production. Although the problem is long-standing, the development of sustainable methods of pest management has been unable to keep pace with the intensification of production, leading to large-scale reliance on very few chemotherapeutants. This runs the risk of selecting for genetically determined resistance in target organisms. There are many examples of similar evolutionary adaptations in arthropod pests of arable crops, livestock and human health. Several hundred pest species are now documented as being resistant to one or more chemical classes of insecticides and acaricides. Many of these compounds are identical or closely related to ones currently employed against salmon lice. It is, therefore, opportune to consider what lessons have been learnt from contending with resistance in terrestrial organisms, the implications for sustainable use of chemotherapeutants in aquaculture, and the potential for developing effective resistance management strategies. An EU-funded project named SEARCH (QLK2-CT-2000-00809) has been initiated to explore in more detail the diagnosis, incidence, dynamics and management of resistance to chemotherapeutants in L salmonis.  相似文献