Modelling the effects of reserve size and fishing mortality for Caribbean queen conch Strombus gigas

相似文献   

Evaluation of crossbreeding systems for small beef herds: II. Two-sire systems

Stochastic computer models were used to evaluate nine crossbreeding systems in beef herds consisting of two bulls, 50 cows and 15 replacements. Systems examined were: 1) purebred (PB), 2) two- and three-breed rotations using natural service (2R and 3R) or artificial insemination (2RAI and 3RAI), 3) two-breed roto-terminals not exploiting complementarity using natural service (2RT) or AI (2RTAI) and 4) two-breed roto-terminals exploiting complementarity using natural service (2RTC) or AI (2RTCAI). Average heterosis estimates were taken from literature sources. Replacement females were produced within the herd; sires were purchased. Estimates of calf and dam heterosis were used to calculate performance of calf weight weaned and sold, cow and total weights sold and gross calf, cow and total incomes. All crossbred systems were superior to PB for weights sold and income. The natural-service systems (2R, 3R, 2RT and 2RTC) utilized 90 to 98% of the heterosis available in their AI counterparts (2RAI, 3RAI, 2RTAI and 2RTCAI). No differences were found between corresponding natural-service and AI systems for weights sold and incomes. Increasing the complexity of the system did not provide important improvements in traits measured.     

Effects of feeding polyclonal antibody preparations on rumen fermentation patterns, performance, and carcass characteristics of feedlot steers

In a previous study, preparations of polyclonal antibodies (PAP) against Fusobacterium necrophorum (PAP-Fn) or Streptococcus bovis (PAP-Sb) were successful in decreasing ruminal counts of target bacteria and increasing ruminal pH in steers fed high-grain diets. The objective of this study was to evaluate the effects of feeding PAP-Fn or PAP-Sb on performance, carcass characteristics, and ruminal fermentation variables of feedlot steers. In Exp. 1, during 2 consecutive years, 226 or 192 Angus and Angus crossbred steers were fed a high-grain diet containing either PAP-Sb or PAP-Fn, or both. When measured on a BW basis, steers fed only PAP-Sb had a greater G:F (P < 0.05) than those fed no PAP. Nevertheless, when both PAP were fed, feed efficiency was similar (P > 0.10) to steers fed no PAP or only PAP-Sb. Steers receiving PAP-Fn (alone or in combination with PAP-Sb) had a decreased (P < 0.05) dressing percentage. Steers receiving PAP-Fn (alone or in combination with PAP-Sb) had a decreased severity of liver abscess (P < 0.05). No differences (P > 0.10) were observed in any other carcass characteristics. In Exp. 2, sixteen ruminally cannulated Angus crossbred steers (BW = 665 +/- 86 kg) were fed a high-grain diet containing either PAP-Sb or PAP-Fn, or both. Feeding only PAP-Fn or PAP-Sb for 19 d decreased (P < 0.05) ruminal counts of S. bovis when compared with steers fed both or no PAP. The ruminal counts of F. necrophorum in steers fed PAP-Fn alone or in combination with PAP-Sb were decreased by 98% (P < 0.05) after 19 d, when compared with the counts in control steers. Mean daily ruminal pH was greater (P < 0.05) in steers fed both PAP when compared with feeding either or no PAP. Ruminal pH in the first 4 h after feeding was greater (P < 0.05) for steers receiving PAP-Fn alone or in combination with PAP-Sb. Steers receiving either PAP alone or in combination had less (P < 0.05) ruminal NH(3)-N concentrations in the first 4 h after feeding when compared with those of control steers. Polyclonal antibody preparations against S. bovis were effective in enhancing G:F of steers fed high-grain diets, but dressing percentage was decreased. Mechanisms of enhancement of G:F remain unknown but may be related to changes in ruminal counts of target bacteria and associated effects on ruminal fermentation products.     

Advanced imaging: use and misuse

SUMMARY: The primary purpose of diagnostic imaging is to enable clinicians to make correct decisions about a patient's diagnosis and severity of its condition and, thereby, to contribute to effective and efficient treatment. Advanced imaging modalities are inherently better detectors of morphological lesions than radiography; hence, they offer the possibility of more accurate diagnosis and staging, with correspondingly better patient outcomes. However, there is a lack of evidence that better outcomes are being realised for veterinary patients. Furthermore, increased use of advanced imaging carries the possibility of increased misuse, primarily through unnecessary studies that contribute little to patient management other than increased costs. SCOPE: This article is intended to be relevant to all veterinary species. Advanced imaging of cats is not sufficiently developed as a specific discipline that a balanced review could be based purely on feline examples or references.     

Clinical outcome of collateral ligament injuries of the tarsus

The significance of collateral ligament desmitis of the tarsocrural joint is often clinically underestimated, because it is an uncommon injury with a guarded prognosis for athletic soundness. The objective of this study was to describe the clinical presentation, treatment, and outcome of 12 horses with collateral ligament desmitis, along with tarsocrural joint synovitis secondary to hemarthrosis. Criteria for inclusion in this study included clinical signs of tarsocrural joint synovitis and sonographic evidence of collateral ligament desmitis. This retrospective study evaluated horses over an 8-year period. Median follow-up after treatment was 5.5 years. Four horses in the study returned to their previous level of performance, 6 horses remained lame due to pain in the tarsus, 1 was euthanized, and 1 is in convalescence. This study highlights the importance of collateral ligament desmitis, and emphasizes the need for early, aggressive treatment to prevent the development of osteoarthritis.     

Lack of associations between ultrasonographic appearance of parenchymal lesions of the canine liver and histological diagnosis

Objective: To assess if there are any ultrasonographic features that may enable tentative diagnosis of hepatic parenchymal disease. Methods: Records of 371 dogs that had abdominal ultrasonography and abnormal liver on biopsy or necropsy were reviewed. Results: Histological diagnoses were hepatitis (n=77), nodular hyperplasia (n=47), vacuolar change (n=45), fibrosis (n=32), primary hepatic carcinoma (n=30), lymphoma (n=28), metastatic neoplasia (n=27), necrosis (n=21), lipidosis (n=17), haemangiosarcoma (n=13), round cell tumour (n=9), hepatocellular adenoma (n=8), degenerative change (n=6), steroid hepatopathy (n=7) and extramedullary haematopoiesis (n=4). The most prevalent ultrasonographic features were multifocal lesions (63% livers with haemangiosarcoma and 43% livers with hepatocellular carcinoma), diffuse lesions (71% livers with steroid hepatopathy, 44% livers with fibrosis and 40% livers with vacuolar hepatopathy), hyperechoic lesions (71% livers with steroid hepatopathy, 41% livers with lipidosis and 38% livers with fibrosis), heterogeneous lesions (62% livers with haemangiosarcoma), hepatomegaly (43% livers with steroid hepatopathy) and peritoneal fluid (62% livers with haemangiosarcoma). Target lesions were associated with malignancy in 67% instances. Marked variability in ultrasonographic appearance of lesions was observed for all diagnoses, and no statistically significant associations between ultrasonographic appearance and diagnosis were found. Clinical Significance: Histological examination remains essential for diagnosis of canine hepatic disease.     

The Connectivity Map: using gene-expression signatures to connect small molecules, genes, and disease

To pursue a systematic approach to the discovery of functional connections among diseases, genetic perturbation, and drug action, we have created the first installment of a reference collection of gene-expression profiles from cultured human cells treated with bioactive small molecules, together with pattern-matching software to mine these data. We demonstrate that this "Connectivity Map" resource can be used to find connections among small molecules sharing a mechanism of action, chemicals and physiological processes, and diseases and drugs. These results indicate the feasibility of the approach and suggest the value of a large-scale community Connectivity Map project.     

Synchronization of estrus and artificial insemination in replacement beef heifers using gonadotropin-releasing hormone, prostaglandin F2alpha, and progesterone

We evaluated whether a fixed-time AI (TAI) protocol could yield pregnancy rates similar to a protocol requiring detection of estrus, or detection of estrus and AI plus a clean-up TAI for heifers not detected in estrus, and whether adding an injection of GnRH at controlled internal drug release (CIDR) insertion would enhance fertility in CIDR-based protocols. Estrus in 2,075 replacement beef heifers at 12 locations was synchronized, and AI was preceded by 1 of 4 treatments arranged as a 2 x 2 factorial design: 1) Estrus detection + TAI (ETAI) (n = 516): CIDR for 7 d plus 25 mg of prostaglandin F2alpha (PG) at CIDR insert removal, followed by detection of estrus for 72 h and AI for 84 h after PG (heifers not detected in estrus by 84 h received 100 microg of GnRH and TAI); 2) G+ETAI (n = 503): ETAI plus 100 microg GnRH at CIDR insertion; 3) Fixed-time AI (FTAI) (n = 525): CIDR for 7 d plus 25 mg of PG at CIDR removal, followed in 60 h by a second injection of GnRH and TAI; 4) G+FTAI (n = 531): FTAI plus 100 microg of GnRH at CIDR insertion. Blood samples were collected (d -17 and -7, relative to PG) to determine ovarian status. For heifers in ETAI and G+ETAI treatments, a minimum of twice daily observations for estrus began on d 0 and continued for at least 72 h. Inseminations were performed according to the a.m.-p.m. rule. Pregnancy was diagnosed by transrectal ultrasonography. The percentage of heifers exhibiting ovarian cyclic activity at the initiation of treatments was 89%. Pregnancy rates among locations across treatments ranged from 38 to 74%. Pregnancy rates were 54.7, 57.5, 49.3, and 53.1% for ETAI, G+ETAI, FTAI, and G+FTAI treatments, respectively. Although pregnancy rates were similar among treatments, a tendency (P = 0.065) occurred for pregnancy rates in the G+ETAI treatment to be greater than in the FTAI treatment. We concluded that the G+FTAI protocol yielded pregnancy rates similar to protocols that combine estrus detection and TAI. Further, the G+FTAI protocol produced the most consistent pregnancy rates among locations and eliminated the necessity for detection of estrus when inseminating replacement beef heifers.     

Association of portovenographic findings with outcome in dogs receiving surgical treatment for single congenital portosystemic shunts: 45 cases (2000-2004)

OBJECTIVE: To determine whether hepatic portal vascularity, as assessed by intraoperative mesenteric portovenography (IMP), is related to outcome in dogs undergoing attenuation of single congenital portosystemic shunts (CPSSs). DESIGN: Retrospective case series. ANIMALS: 45 dogs, each with a single CPSS, in which IMP was performed before and after temporary complete occlusion of the shunting vessel and that underwent complete (17 dogs) or partial (28 dogs) CPSS attenuation (surgery 1). PROCEDURES: Medical records were reviewed for signalment, clinical history, and bile acids stimulation test results. Intrahepatic portal vessel (IPV) opacification in pre- and postocclusion portovenograms was graded to determine whether the degree of opacification was correlated with the degree of shunt attenuation, clinical or biochemical factors, or long-term clinical outcome. In 17 of 28 dogs that had partial CPSS attenuation, these procedures were subsequently repeated (surgery 2) to achieve complete (14 dogs) or further partial (3 dogs) CPSS attenuation. RESULTS: Compared with preattenuation findings, IPV opacification increased significantly after partial or complete CPSS attenuation. The degree of IPV opacification before and after CPSS occlusion (surgery 1) was greater in dogs that tolerated complete versus partial CPSS attenuation and was correlated positively with age. The degree of IPV opacification following CPSS occlusion (surgery 1) was maximal in all dogs without encephalopathy and was correlated negatively with follow-up preprandial serum bile acids concentrations and positively with clinical improvement. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggest that IMP can be used to assess changes in IPV blood flow and help predict outcome following attenuation of single CPSSs in dogs.     

Brain and spinal cord haemorrhages associated with Angiostrongylus vasorum infection in four dogs

Multifocal haemorrhages associated with Angiostrongylus vasorum infection were observed in the central nervous system of four dogs with neurological signs including depression, seizures, spinal pain and paresis. In magnetic resonance images the majority of the lesions were isointense or slightly hyperintense in T1-weighted images, hyperintense in T2-weighted images and hypointense in T2*-weighted (gradient echo) images, compatible with haemorrhages more than seven days old. Lesions were found in the brain of three of the dogs and in the spinal cord of two. The cerebrospinal fluid contained high concentrations of protein and evidence of erythrophagia. All the dogs had coagulopathy and pulmonary haemorrhage of varying severity. A vasorum larvae were detected in the faeces of each of the dogs. Neural A vasorum was confirmed at postmortem examination in two dogs.