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排序方式: 共有693条查询结果,搜索用时 93 毫秒
21.
Loneragan GH Morley PS Wagner JJ Mason GL Yost GS Thoren MA Triantis J 《American journal of veterinary research》2002,63(4):591-597
OBJECTIVE: To describe time-dependent changes in plasma concentrations of 3-methylindole (3MI) and blood concentrations of 3-methyleneindolenine (3MEIN)-adduct in feedlot cattle. ANIMALS: 64 yearling steers. PROCEDURES: Steers were assigned to 2 groups (32 steers/group). During the first 8 weeks, blood samples were collected from group 1 before the morning ration was fed, whereas samples from group 2 were collected 2 to 3 hours after the ration was fed. Blood samples were collected from all steers approximately 4 times/wk for 3 weeks and 3 times/wk for the subsequent 5 weeks. Samples were collected at the same time for all steers for an additional 10 weeks. Plasma samples were analyzed for 3MI concentrations. Blood samples collected from cattle in group 2 during the first 8 weeks were analyzed for 3MEIN-adduct concentrations. RESULTS: Mean blood concentration of 3MEIN-adduct increased to a maximum value on day 33 (0.80 U/microg of protein) and then decreased to a minimum on day 54 0.40 U/microg of protein). Plasma 3MI concentrations initially decreased and remained low until after day 54. Group-1 cattle had lower plasma 3MI concentrations, compared with concentrations for group-2 cattle. Blood 3MEIN-adduct concentrations and plasma 3MI concentrations were not associated with deleterious effects on weight gains. CONCLUSIONS AND CLINICAL RELEVANCE: Blood 3MEIN-adduct concentrations peaked during the period of greatest risk for development of bovine respiratory disease complex. Conversely, plasma 3MI concentrations decreased during the same period. Animal-to-animal variation in metabolic capacity to convert 3MI to 3MEIN may be of more importance than differences in plasma 3MI concentration. 相似文献
22.
"Kennel cough" in dogs in animal shelters is readily transmissible, reduces adoption rates, and commonly leads to the euthanasia of affected dogs. In cats, tracheobronchitis, conjunctivitis, and pneumonia have been associated with Bordetella bronchiseptica infection-but most cases of upper-respiratory infection (URI) probably are caused by herpesvirus and calicivirus, and many B. bronchiseptica culture-positive cats are clinically normal. Our prospective observational study was undertaken to document the contribution of B. bronchiseptica to disease in cats and dogs from two animal shelters undergoing outbreaks of canine kennel cough, to evaluate whether cross-species transmission might have occurred, and to determine if the presence of infected cats represented a risk to dogs. Clinically defined cases of kennel cough in dogs and URI in cats were investigated in two shelters by calculating clinical-disease incidence, alveolar-lavage cytological examination, bacterial and viral cultures, antibiotic-susceptibility testing, and molecular fingerprinting by pulsed-field gel electrophoresis.In a 40-cat and 40-dog "no-kill" shelter, the prevalences of culture positivity were 47% for B. bronchiseptica and 36% for calicivirus at the same time as two resident dogs demonstrated clinical cough. When no dogs had kennel cough 3 months later, 10% of cats were B. bronchiseptica-culture-positive and 63% calicivirus positive. In a large traditional shelter, the incidence of kennel cough in dogs increased over 12 weeks to a maximum of 19 cases/week/120 dogs, during which time the culture prevalence was 23% for B. bronchiseptica in dogs and 47% in cats. Three to 6 months before the kennel-cough epidemic, no dogs or cats were B. bronchiseptica positive. Very little genetic variability was detected in isolates from these shelters; all isolates except one corresponded to a single strain type which was identical to the pattern in a vaccine used in these shelters. Isolates from other cats, a horse, a llama, and a sea otter were genetically distinct from the shelter isolates. There was widespread resistance to cephalosporins and ampicillin, but low or no resistance to amoxicillin/clavulanate, trimethoprim-sulfamethoxazole, tetracycline, and enrofloxacin. Greater percent resistance was observed in the traditional shelter than in the no-kill shelter and feline isolates were more likely to be resistant than canine isolates. 相似文献
23.
1 前言一个成功的仔猪营养方案的基本准则是: (1)开饲体重尽可能高: (2)尽可能饲喂简单的日粮; (3)着重于幼畜的饲养管理。我们不能忽视猪的初生体重、年龄、饲养管理质量对于整个饲养过程影响的重要性。 相似文献
24.
Comparison of the Sensitivity of Landscape-fire-succession Models to Variation in Terrain, Fuel Pattern, Climate and Weather 总被引:1,自引:0,他引:1
Geoffrey J. Cary Robert E. Keane Robert H. Gardner Sandra Lavorel Mike D. Flannigan Ian D. Davies Chao Li James M. Lenihan T. Scott Rupp Florent Mouillot 《Landscape Ecology》2006,21(1):121-137
The purpose of this study was to compare the sensitivity of modelled area burned to environmental factors across a range of
independently-developed landscape-fire-succession models. The sensitivity of area burned to variation in four factors, namely
terrain (flat, undulating and mountainous), fuel pattern (finely and coarsely clumped), climate (observed, warmer & wetter,
and warmer & drier) and weather (year-to-year variability) was determined for four existing landscape-fire-succession models
(EMBYR, FIRESCAPE, LANDSUM and SEM-LAND) and a new model implemented in the LAMOS modelling shell (LAMOS(DS)). Sensitivity
was measured as the variance in area burned explained by each of the four factors, and all of the interactions amongst them,
in a standard generalised linear modelling analysis. Modelled area burned was most sensitive to climate and variation in weather,
with four models sensitive to each of these factors and three models sensitive to their interaction. Models generally exhibited
a trend of increasing area burned from observed, through warmer and wetter, to warmer and drier climates with a 23-fold increase
in area burned, on average, from the observed to the warmer, drier climate. Area burned was sensitive to terrain for FIRESCAPE
and fuel pattern for EMBYR. These results demonstrate that the models are generally more sensitive to variation in climate
and weather as compared with terrain complexity and fuel pattern, although the sensitivity to these latter factors in a small
number of models demonstrates the importance of representing key processes. The models that represented fire ignition and
spread in a relatively complex fashion were more sensitive to changes in all four factors because they explicitly simulate
the processes that link these factors to area burned.
The US Government's and the Canadian Government's right to retain a non-exclusive, royalty-free license is acknowledged 相似文献
25.
26.
Ke Dong Steven M. Valles Mike E. Scharf Brian Zeichner Gary W. Bennett 《Pesticide biochemistry and physiology》1998,60(3):195
A point mutation in thepara-homologous sodium channel gene has been shown to be associated with knockdown resistance (kdr) in several insect species including the German cockroach. In this study, we analyzed the genomic organization of the region where thekdrmutation resides and then performed polymerase chain reaction (PCR) and sequencing using genomic DNA as the template to detectkdrmutation in 24 pyrethroid-resistant German cockroach strains, most of which have been collected recently from the field. Thekdrmutation, G to C at nt 2979 resulting in a leucine to phenylalanine amino acid substitution, was detected in 20 strains including 2 strains from overseas (China and Germany). Our results clearly indicate that thekdrmutation is widespread in German cockroach populations. However, the super-kdrmutation detected in super-kdrhouse flies was not found in any of the 4 strains that showed higher levels of knockdown resistance. Little correlation was observed between the presence of thekdrmutation and the level of knockdown resistance, suggesting the existence of multiple resistance mechanisms in many of these strains. 相似文献
27.
肉种鸡的营养管理 总被引:1,自引:1,他引:0
Mike Wineland 《中国家禽》2009,31(16)
肉仔鸡对饲料的适应性比较强,原因之一就是肉仔鸡食欲极强,所以饲喂不同的日粮对胴体的影响不是太大. 而对肉种鸡的饲养来说,情况就完全不一样了,因为肉种鸡在管理中要限饲.要让肉种鸡的生产力达到最大,特别要关注营养成分的摄入量,对肉种鸡采用的限饲,这本身就是个很大的应激,所以说,肉种鸡对疾病以及逆境也很敏感. 相似文献
28.
Mike Sissons 《Cereal Chemistry》2016,93(6):550-556
A rapid shear‐based test using a GlutoPeak instrument was compared with tests commonly used by durum wheat breeders to assess the potential of this instrument to discriminate between samples. Thirty‐two durum wheat semolina samples were analyzed by mixograph, SDS sedimentation (SDSS), gluten index (GI), and GlutoPeak testing. A subset was also tested for pasta quality. GlutoPeak peak maximum time (PMT) was the best indicator of gluten strength and correlated well with the other tests except SDSS. Samples with higher levels of SDS‐unextractable glutenin (insoluble protein [IP]) had stronger dough and longer PMT, but the GlutoPeak test only correlated with pasta stickiness using a smaller set of samples. The range in mixogram profiles encountered in breeding material was related to the IP content, and the pasta made from the different types was of similar quality, differing more because of protein content rather than mixogram type. The GlutoPeak test is faster than GI and uses less sample, requires little technical skill, and is suitable for evaluating large numbers of breeder's lines. The GlutoPeak test is best suited to discriminating weak from strong dough samples and allows for testing with small samples, thus facilitating quality evaluations at early stages of a breeding program. 相似文献
29.
30.
Harry X. Wu Mike B. Powell Junli L. Yang Milo Ivković Tony A. McRae 《Annals of Forest Science》2007,64(1):1-9
A total of 360 bark-to-bark-through-pith wood strips were sampled at breast height from 180 trees in 30 open-pollinated families from two rotation-aged genetic trials to study inheritance, age-age genetic correlation, and early selection efficiency for wood quality traits in radiata pine. Wood strips were evaluated by SilviScan® and annual pattern and genetic parameters for growth, wood density, microfibril angle (MFA), and stiffness (modulus of elasticity: MOE) for early to rotation ages were estimated. Annual ring growth was the largest between ages 2–5 years from pith, and decreased linearly to ages 9–10. Annual growth was similar and consistent at later ages. Wood density was the lowest near the pith, increased steadily to age 11–15 years, then was relatively stable after these ages. MFA was highest (35°) near the pith and reduced to about 10° at age 10–15 years. MFA was almost unchanged at later ages. MOE increased from about 2.5 GPa near the pith to about 20 GPa at ages 11–15 years. MOE was relatively unchanged at later ages. Wood density and MOE were inversely related to MFA. Heritability increased from zero near the pith and stabilised at ages 4 or 5 for all four growth and wood quality traits (DBH, density, MFA and MOE). Across age classes, heritability was the highest for area-weighted density and MFA, lowest for DBH, and intermediate for MOE. Age-age genetic correlations were high for the four traits studied. The genetic correlation reached 0.8 after age 7 for most traits. Early selection for density, MFA and MOE were very effective. Selection at age 7–8 has similar effectiveness as selection conducted at rotation age for MFA and MOE and at least 80% effective for wood density. 相似文献