Some determinants of the spatio-temporal fire cycle in a mediterranean landscape (Corsica,France)     

Mouillot  Florent  Ratte  Jean-Pierre  Joffre  Richard  Moreno  Jose Manuel  Rambal  Serge 《Landscape Ecology》2003,18(7):665-674

Based on recent needs to accurately understand fire regimes and post-fire vegetation resilience at a supra-level for carbon cycle studies, this article focusses on the coupled history of fire and vegetation pattern for 40 years on a fire-prone area in central Corsica (France). This area has been submitted since the beginning of the 20^th century to land abandonment and the remaining land management has been largely controlled by frequent fires. Our objectives were to rebuild vegetation and fire maps in order to determine the factors which have driven the spatial and temporal distribution of fires on the area, what were the feed backs on the vegetation dynamics, and the long-term consequences of this inter-relationship. The results show a stable but high frequency of small fires, coupled with forest expansion over the study period. The results particularly illustrate the spatial distribution of fires according to topography and vegetation, leading to a strong contrast between areas never burnt and areas which have been burnt up to 7 times. Fires, when occuring, affect on average 9 to 12% of the S, SE and SW facing slopes (compared to only 2 to 5% for the N facing slopes), spread recurrently over ridge tops, affect all the vegetation types but reburn preferentially shrublands and grasslands. As these fire-proning parameters have also been shown to decrease the regeneration capacity of forests, this study highlights the needs in spatial studies (both in terms of fire spread and vegetation dynamic) to accurately apprehend vegetation dynamic and functionning in fire-prone areas.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

Induction of an antioxidant enzyme system and other oxidative stress markers associated with compatible and incompatible interactions between chickpea (Cicer arietinum L.) and Fusarium oxysporum f. sp.ciceris   总被引：1，自引：0，他引：1  

Carmen García-Limones  Ana Hervs  Juan A. Navas-Corts  Rafael M. Jimnez-Díaz  Manuel Tena 《Physiological and Molecular Plant Pathology》2002,61(6):325

To ascertain if active oxygen species play a role in fusarium wilt of chickpea caused by Fusarium oxysporum f. sp. ciceris, the degree of lipid peroxidation (malondialdehyde formation) and the activity levels of diamine oxidase (DAO), an apoplastic H₂O₂-forming oxidase, and several antioxidant enzymes, namely ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), guaiacol-dependent peroxidase (GPX) and superoxide dismutase (SOD), were determined spectrophotometrically in roots and stems of ‘WR315’ (resistant) and ‘JG62’ (susceptible) chickpea cultivars inoculated with the highly virulent race 5 of the pathogen. Moreover, APX, CAT, GPX and SOD were also analysed in roots and stems by gel electrophoresis and activity staining; and the protein levels of APX and SOD in roots were determined by Western blotting. In roots, infection by the pathogen increased lipid peroxidation and CAT and SOD activities, although such responses occurred earlier in the incompatible compared with the compatible interactions. APX, GPX and GR activities were also increased in infected roots, but only in the compatible interaction. In stems, infection by the pathogen increased lipid peroxidation and APX, CAT, SOD and GPX activities only in the compatible interaction, and DAO activity only in the incompatible one. In general, electrophoregrams agreed with the activity levels determined spectrophotometrically and did not reveal any differences in isoenzyme patterns between cultivars or between infected and non-infected plants. Further, Western blots revealed an increase in the root protein levels of APX in the compatible interaction and in those of SOD in both compatible and incompatible interactions. In conclusion, whereas enhanced DAO activity in stems, and earlier increases in lipid peroxidation and CAT and SOD activities in roots, can be associated with resistance to fusarium wilt in chickpea, the induction of the latter three parameters in roots and stems along with that of APX, GR (only in roots) and GPX (only in stems) activities are rather more associated with the establishment of the compatible interaction.  相似文献   

新一代植酸酶的经济效益     

Y．J．RU 《饲料广角》2004,(18):31-33

现已证明，在酵母中产生的一种新型的6-植酸酶比其他在市场上供应的植酸酶的效率至少高20％。因为6-植酸酶与其他商品化的植酸酶相比，可进一步减少无机磷源的使用，从而降低生产成本以及磷的污染。  相似文献   

Lactobacillus rhamnosus strain GG is a potential probiotic for calves   总被引：2，自引：0，他引：2       下载免费PDF全文

Julia B. Ewaschuk  Jonathan M. Naylor  Manuel Chirino-Trejo    Gordon A. Zello 《Canadian journal of veterinary research》2004,68(4):249-253

Diarrhea is a common occurrence in neonatal calves. Several veterinary probiotics claiming to prevent or treat calf diarrhea are available, but have not been well studied. This study assessed the capability of Lactobacillus rhamnosus strain GG (LGG) to maintain viability in the gastrointestinal tract of calves. We also determined whether LGG can be administered in an oral rehydration solution (ORS) without compromising the efficacy of the ORS or the viability of LGG, and whether LGG produces D-lactate or not. To investigate the intestinal survival of LGG, 15 calves were randomized into 3 groups and LGG was administered orally with their morning milk feeding on 3 consecutive days at a low (LD), medium (MD), or high (HD) dosage. Fecal samples were collected on days 0 (control), 1, 2, 3, 5, and 7 and incubated for 72 h on deMan, Rogosa, Sharpe agar. Twenty-four hours after the 1st feeding, LGG was recovered from 1 out of 5 calves in the LD group, 4 out of 5 calves in the MD group, and 5 out of 5 calves in the HD group. To determine if LGG caused the glucose levels in the ORS to drop below effective levels, 1.5 L of the ORS was incubated with LGG for 2 h at 37 degrees C and the glucose concentration was measured every 20 min using a glucose meter. This ORS was then further incubated for 10 h and aliquots analyzed by high performance liquid chromatography to determine if D-lactate was produced by LGG. Glucose concentrations did not change over the 2 h of incubation, and no D-lactate was produced after 48 h. The LGG maintained viability in ORS. Therefore, this study demonstrated that LGG survives intestinal transit in the young calf, produces no D-lactate, and can be administered in an ORS.  相似文献   

Distribution of alpha‐neoendorphin,ACTH (18–39) and beta‐endorphin (1–27) in the alpaca brainstem          下载免费PDF全文

Manuel L. Sánchez  Eliana de Souza  Luis A. Aguilar  Rafael Coveñas 《Anatomia, histologia, embryologia》2018,47(5):481-492

Using an immunocytochemical technique, we have studied in the alpaca brainstem the distribution of immunoreactive structures containing prodynorphin (alpha‐neoendorphin)‐ and pro‐opiomelanocortin (adrenocorticotrophin hormone (18–39) (ACTH), beta‐endorphin (1–27))‐derived peptides. No peptidergic‐immunoreactive cell body was observed. Immunoreactive fibres were widely distributed, although in most of the brainstem nuclei the density of the peptidergic fibres was low or very low. In general, the distribution of the immunoreactive fibres containing the peptides studied was very similar. A close anatomical relationship occurred among the fibres containing alpha‐neoendorphin, ACTH or beta‐endorphin (1–27), suggesting a functional interaction among the three peptides in many of the brainstem nuclei. The number of fibres belonging to the prodynorphin system was higher than that of the pro‐opiomelanocortin system. A moderate/low density of immunoreactive fibres was observed in 65.11% (for alpha‐neoendorphin (1–27)), 18.18% (for ACTH) and 13.95% (for beta‐endorphin) of the brainstem nuclei/tracts. In the alpaca brainstem, a high density of immunoreactive fibres was not observed. The neuroanatomical distribution of the immunoreactive fibres suggests that the peptides studied are involved in auditory, motor, gastric, feeding, vigilance, stress, respiratory and cardiovascular mechanisms, taste response, sleep‐waking cycle and the control of pain transmission.  相似文献   

Prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria     

Ogugua  Akwoba Joseph  Akinseye  Victor Oluwatoyin  Cadmus  Eniola O.  Jolaoluwa Awosanya  Emmanuel A.  Alabi  Peter Ibukun  Idowu  Olugbenga S.  Akinade  Samson A.  Dale  Emma J.  Perrett  Lorraine  Taylor  Andrew  Ignocio  Moriyon  Cadmus  Simeon I. B. 《Tropical animal health and production》2018,50(7):1573-1582

Using a cross-sectional survey, we determined the prevalence and risk factors associated with bovine brucellosis in herds under extensive production system in southwestern Nigeria. Antibodies to Brucella species in serum samples were tested using the Rose Bengal test (RBT) and competitive enzyme-linked immunosorbent assay (cELISA); for milk, the milk ring test (MRT) and indirect-ELISA (i-ELISA) were used. Questionnaire was administered to cattle herdsmen to determine factors predisposing the animals to bovine brucellosis. Data were analyzed using STATA 12. From 513 serum and 635 milk samples tested among 120 herds, overall animal-level prevalence of 10.1% (95% CI 7.5–12.7%) and 20.2% (95% CI 17.1–23.3%) were recorded by RBT and MRT, respectively; while 9.4% (95% CI 6.9–11.9%) and 17.8% (95% CI 14.8–20.8%) were obtained using cELISA and i-ELISA, respectively. In all, from the 120 herds tested, 29.2% and 43.3% were positive by RBT and MRT, respectively. Multivariable logistic regression revealed that herd location (OR?=?8.12, 95% CI 1.68–38.90) and improper disposal of placenta/fetus (OR?=?17.33, 95% CI 4.81–62.33) were predictors for a seropositive herd using RBT; while herd location (OR?=?5.13, 95% CI 1.27–20.28), large herd size (OR?=?2.62, 95% CI 1.15–5.85), and occurrence of abortion for a year or more (OR?=?4.62, 95% CI 1.53–13.71) were predictors of seropositivity to antibodies to Brucella spp. using MRT. We found high prevalence of brucellosis in cattle herds under extensive management system in southwestern Nigeria. Urgent and coordinated control strategies are required to mitigate this problem.

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Effects of brooding periods on performance of poults and grow-out small bronze turkeys in hot humid tropical environment     

Nwaodu  Chibuzo Hope  Okoro  Victor Mela Obinna  Uchegbu  Martins Chigozie  Mbajiorgu  Christian Anayochukwu 《Tropical animal health and production》2018,50(4):851-856

Tropical Animal Health and Production - A study was conducted to determine the effects of varied brooding regimes on the performance of small bronze turkey poults and their grow-outs. One hundred...  相似文献   

Laryngeal mask airway and transient hypercapnic hyperpnea for video‐endoscopic assessment of unilateral laryngeal paralysis in dogs          下载免费PDF全文

Daniel M. Sakai MV  DACVAA  Manuel Martin‐Flores MV  DACVAA  Amanda K. Jones PhD  Galina M. Hayes BVSc  PhD  DACVECC  DACVS‐SA  Marina J. McConkey DVM  DACVS‐SA  Jonathan Cheetham VetMB  PhD  DACVS‐LA 《Veterinary surgery : VS》2018,47(4):543-548

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<Emphasis Type="SmallCaps">d</Emphasis>-Cloprostenol enhances estrus synchronization in tropical hair sheep     

Alejandro Alavez Ramírez  Victor Manuel Meza Villalvazo  Emmanuel Sosa Arredondo  Hugo Alonso Ramírez Ramírez  Héctor Magaña Sevilla 《Tropical animal health and production》2018,50(5):991-996

To compare the effects of PGF2α (dinoprost tromethamine) and d-cloprostenol in a two-dose protocol for estrus synchronization in hair sheep during breeding season in Yucatán, México, two experiments were conducted. In experiment 1, 61 cyclic hair sheep were divided into two groups: G1 (control n?=?30), two doses of 50 μg of dinoprost tromethamine IM with 12 days between applications, and G2 (n?=?31), two doses of 50 μg of d-cloprostenol IM at the same time interval. For determination of progesterone levels, 16 ewes from each group were randomly selected. In experiment 2, 70 cyclic hair sheep were assigned at the same treatments (G1 and G2, n?=?35) and 48 h after the second application, the ewes in estrus were detected by two vasectomized rams. Sheep with detected estrus were inseminated, and 45 days after, pregnant animals were identified by ultrasonography. An exact Fisher’s test was performed for the analysis of ewes in estrus (experiments 1 and 2) and number of pregnant ewes (experiment 2); for the comparison of time between end of treatment-estrus presentation, a survival analysis was used. Duration of estrus in hours was analyzed using a generalized mixed model (GLM) ANOVA whereas plasma progesterone concentrations were analyzed by non-linear regression. There were significant differences (P?<?0.05) in the proportion of ewes in estrus upon treatments (G1, 57% vs G2, 87% and G1, 37.1% vs G2, 65.7% in experiments 1 and 2, respectively), and between the end of treatment-onset estrus interval (P?<?0.01), survival curves showed the highest number of sheep in estrus between 40 and 48 h (G1, 43.7?+?8.05 h vs G2, 42.9?+?6.7 h, experiment 1). There were no significant differences (P?>?0.05) in duration of estrus (G1, 42?+?6.1 h, vs G2, 41.1?+?11.2 h, experiment 1) and pregnancy in the ewes that presented estrus, and were inseminated (G1, 38.4% vs 52.1%, experiment 2). With regard to concentrations of progesterone, significant differences (P?<?0.01) were found between treatments, and progesterone levels before the second application of d-cloprostenol were higher. In consideration of the results, it can be concluded that in a two-dose protocol of a luteolytic agent, more ewes presented estrus in response to d-cloprostenol compared to dinoprost tromethamine with similar pregnancy rates.  相似文献   

Prevalence and risk factors of mycobacterial infections in farm and trade cattle in southwestern Nigeria     

Victor O. Akinseye  Muideen D. Adebayo  Oghenekaro O. Genesis  Olubukola D. Adelakun  Simeon I. B. Cadmus 《Tropical animal health and production》2018,50(4):761-772

We evaluated the prevalence of mycobacterial infections (i.e., Mycobacterium bovis and non-tuberculous mycobacteria [NTM]) and their associated risk factors among cattle herds and trade cattle in southwestern Nigeria. Through cross-sectional study design, cattle herds from three locations were screened using the single intradermal comparative cervical tuberculin test based on two diagnostic standards; more than 4 mm (? 4 mm) and more than 2 mm (? 2 mm) cut-off points. Abattoir study involved screening trade cattle for tuberculous lesions. Overall, 515 cattle from 45 herds were screened. Using >?4 mm, animal level and herd prevalence of 11.7 and 46.7% were recorded, respectively. Applying the ? 2 mm cut-off, animal level and herd prevalence increased to 31.1 and 60.0%, respectively. Significantly, using the ? 2 mm cut-off, cattle in medium size herds/extensive management system (OR?=?1.6; 95% CI 1.1–2.5) and Sokoto Gudali (OR?=?2.3; 95% CI 1.4–3.8) were more at risk of being positive reactors, while Rahaji (OR?=?0.3; 95% CI 0.1–0.7) breeds of cattle and cows in the peri-urban area (OR?=?0.4; 95% CI 0.2–0.9) were less at risk of being positive reactors. Again, M. avium reactor of 21.7% was observed. In the abattoir, 1797 cattle were examined with 126 lesions suggestive of tuberculosis (TB). Culture/molecular analyses confirmed 2.2% M. bovis and 0.9% NTM infections. Risk factors associated with bovine TB among trade cattle were sex (OR?=?4.0; 95% CI 1.2–13.5) and age (OR?=?0.3; 95% CI 0.1–0.9). We confirm 11.7% prevalence of mycobacterial infections among populations of cattle screened with breed and herd size being major risk factors.  相似文献