A prototype national cattle evaluation for sustained reproductive success in Hereford cattle

The objective of this research was to develop a prototype system for national cattle evaluation that would facilitate selection for improved fertility of daughters from Hereford sires. Raw data for this analysis were the birth dates of calves as reported by breeders to the American Hereford Association. Records from females entered this analysis with the reporting of a birth date for their first calf. At that time, females were required to be in contemporary groups of at least 3 animals and to have at least 2 additional paternal half-sibs also represented in the data. To explicitly define "sustained reproductive success," the philosophy taken was that a female that maintained a calving interval of 425 d or less would be considered successful. Females failing to meet this criterion were considered to be at the end of their successful lifetime. Data were analyzed using methodology for survival analysis with grouped data. Fixed contemporary groups were modeled as being time dependent, reflecting the females exposed for breeding in the same herd-year-season. Sire effects were time independent and considered random. Also included in the analysis were time-independent covariates for maternal weaning weight and total maternal calving ease from the national cattle evaluation of the American Hereford Association. Records from females still successfully in production at the time of this analysis, those that were transferred, those with calving intervals less than 280 d, and those that were successful until becoming donor dams for embryo transfer were considered censored. A total of 36,866 females contributed to this analysis, with 14,143 of these having censored records. The median number of females in a contemporary group was 6. A total of 3,323 sires had daughters with records. The median number of daughters per sire was 7. Heritability of sustained reproductive success on the underlying scale estimated from these data was approximately 0.05. Additional data accumulated over time will improve this genetic evaluation. Sustained reproductive success is important to the commercial beef industry, and results from this evaluation are expected to enhance the assessment of economic value of Hereford seedstock.     

低水平球虫病和其他疾病的交互作用

人们曾普遍认为,现场常见的亚临床球虫病(或叫作低水平球虫病)没有显著的经济意义。然而,近几年来,日益增多的证据使得人们对这一结论作了重新评价。多次精心设计的现场研究证明,低水平球虫病对生产参数有着显著的不利影响。     

Clinical and hematologic effects of experimental infection of dogs with recently identified Babesia gibsoni-like isolates from Oklahoma

OBJECTIVE: To characterize clinical and hematologic responses in dogs following experimental inoculation with Babesia gibsoni-like isolates from infected dogs in Oklahoma. DESIGN: Prospective study. ANIMALS: 6 mixed-breed dogs. PROCEDURE: 2 dogs were inoculated with organisms from a naturally infected dog, and 3 were inoculated with organisms from a second naturally infected dog (1 of these 3 dogs was splenectomized 1 week prior to inoculation). One dog was not inoculated. Complete blood counts were performed weekly. RESULTS: In the 5 dogs inoculated with organisms, parasites were initially detected 1 to 5 weeks after inoculation, and severity of parasitemia peaked with 1.9 to 6.0% of RBC infected by 4 to 6 weeks after inoculation. Parasitemia was easily detectable (> 0.1% of RBC infected) for 3 to 4 weeks. Clinical abnormalities included lethargy, fever, and pale mucous membranes but were mild to nearly inapparent in 2 dogs. All dogs developed regenerative anemia and marked thrombocytopenia. Thrombocytopenia developed before and lasted longer than the parasitemia. Profound but transient neutropenia was detected in some dogs. The splenectomized dog developed more severe parasitemia and anemia and more pronounced clinical abnormalities. Three dogs with intact spleens recovered without treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that 2 or more genotypically distinct, but morphologically identical, small Babesia parasites can infect dogs in the United States. Compared with infection with small Babesia parasites from California, infection with these isolates resulted in less severe parasitemia and clinical abnormalities. Parasitemia was transient, indicating that identification of organisms in blood smears may be difficult in some dogs.     

Clinicopathologic findings and outcome in dogs with infective endocarditis: 71 cases (1992-2005)

OBJECTIVES: To evaluate clinical, laboratory, and necropsy findings in dogs with infective endocarditis (IE). DESIGN: Retrospective case series. ANIMALS: 71 dogs with possible or definite IE. PROCEDURES: Medical records were reviewed for signalment, clinical features, and results of clinicopathologic testing and diagnostic imaging. Yearly incidence and the effect of variables on survival were determined by use of survival curve analysis. RESULTS: The overall incidence of IE was 0.05%. Most affected dogs were of large breeds, and > 75% were older than 5 years. The aortic valve was affected in 36 of the 71 (51%) dogs, and the mitral valve was affected in 59%. Lameness caused by immune-mediated polyarthritis, septic arthritis, or peripheral arterial thromboembolism was observed in 53% of the dogs. Neurologic complications were diagnosed in 17 of 71 (24%) dogs. Thromboembolic disease was suspected in 31 of 71 (44%) of dogs. The mortality rate associated with IE was 56%, and median survival time was 54 days. Factors negatively associated with survival included thrombocytopenia, high serum creatinine concentration, renal complications, and thromboembolic complications. CONCLUSIONS AND CLINICAL RELEVANCE: A diagnosis of IE should be suspected in dogs with fever, systolic or diastolic murmur, and locomotor problems. Dogs with thrombocytopenia, high serum creatinine concentration, thromboembolism, or renal complications may have a shorter survival time.     

Different methods of selecting animals for genotyping to maximize the amount of genetic information known in the population

It is possible to predict genotypes of some individuals based on genotypes of relatives. Different methods of sampling individuals to be genotyped from populations were evaluated using simulation. Simulated pedigrees included 5,000 animals and were assigned genotypes based on assumed allelic frequencies for a SNP (favorable/unfavorable) of 0.3/0.7, 0.5/0.5, and 0.8/0.2. A field data pedigree (29,101 animals) and a research pedigree (8,688 animals) were used to test selected methods using simulated genotypes with allelic frequencies of 0.3/0.7 and 0.5/0.5. For the simulated pedigrees, known and unknown allelic frequencies were assumed. The methods used included random sampling, selection of males, and selection of both sexes based on the diagonal element of the inverse of the relationship matrix (A(-1)) and absorption of either the A or A(-1) matrix. For random sampling, scenarios included selection of 5 and 15% of the animals, and all other methods presented concentrated on the selection of 5% of the animals for genotyping. The methods were evaluated based on the percentage of alleles correctly assigned after peeling (AK(P)), the probability of assigning true alleles (AK(G)), and the average probability of correctly assigning the true genotype. As expected, random sampling was the least desirable method. The most desirable method in the simulated pedigrees was selecting both males and females based on their diagonal element of A(-1). Increases in AK(P) and AK(G) ranged from 26.58 to 29.11% and 2.76 to 6.08%, respectively, when males and females (equal to 5% of all animals) were selected based on their diagonal element of A(-1) compared with selecting 15% of the animals at random. In the case of a real beef cattle pedigree, selection of males only or males and females yielded similar results and both selection methods were superior to random selection.     

Ex vivo investigation of the use of hydrothermal energy to induce chondrocyte necrosis in articular cartilage of the metacarpophalangeal and metatarsophalangeal joints of horses

OBJECTIVE: To evaluate the use of hydrothermal ablation of articular cartilage for arthrodesis in horses through investigation of the effects of joint lavage with physiologic saline (0.9% NaCI) solution (80 degrees C) for various treatment times on chondrocyte viability in the articular cartilage of the metacarpophalangeal and metatarsophalangeal joints of cadaveric horse limbs. Sample Population-7 pairs of metacarpophalangeal and 8 pairs of metatarsophalangeal joints from 8 Thoroughbreds. PROCEDURE: The horses were euthanatized for reasons unrelated to musculoskeletal disease. On a random basis, 1 joint of each pair underwent intra-articular lavage for 5, 10, or 15 minutes with heated saline solution (80 degrees C); the other joint underwent sham treatment of similar duration with saline solution at 22 degrees C (control). Cartilage samples from the distal articular surface of metacarpus III (or metatarsus III), the proximal surface of the proximal phalanx, and the lateral and medial proximal sesamoid bones were assessed for chondrocyte viability via confocal microscopy and viability staining following enzymatic digestion. RESULTS: Compared with the control joints, findings of both viability assays indicated that the percentage of sites containing viable chondrocytes in heat-treated joints was decreased.Treatment hazard ratios of 0.048 (confocal microscopy) and 0.2 (digestion assay) were estimated. Histologically, periarticular soft tissues had minimal detrimental effects after heat treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Ex vivo intra-articular lavage with saline solution at 80 degrees C resulted in the death of almost all articular chondrocytes in the joint. This technique may be a satisfactory method for extensive cartilage ablation when performing arthrodesis by minimally invasive techniques.     

Molecular typing of Mycoplasma agalactiae: tracing European-wide genetic diversity and an endemic clonal population

Mycoplasma agalactiae causes chronic infections in small ruminants and remains endemic in many regions of the world, despite intensive and costly eradication programs. In this study, the innate genomic plasticity of M. agalactiae was exploited to design and assess a combination of molecular epidemiological tools to trace the pathogen in different geographic locations and to understand its emergence or re-emergence after eradication campaigns. For this purpose, two collections of M. agalactiae isolates, representing European outbreaks or localized endemic disease in a single region of France, were subjected to RFLP (Restriction Fragment Length Polymorphism) analyses using two sets of DNA probes (distributed across the genome and specific for the vpma gene locus), and a previously described VNTR (Variable Number Tandem Repeats) analysis. A combination of four genome-specific DNA probes and two VNTRs gave the highest discriminative power. Molecular typing revealed that, while isolates from diverse geographical origins fell into clearly different groups, the endemic disease repeatedly observed in the Western Pyrenees region over the past 30 years has been caused by a unique subtype of M. agalactiae. This indicates that the re-emergence of the pathogen after seemingly successful eradication programs is not due to the importation of exotic strains, but to the persistence of local reservoirs of infection.