A comparison of the effects of two low‐calcium diets on egg production in the domestic fowl

1. Hens fed on a diet containing 0–05% calcium virtually ceased egg laying (production <4%) whereas those fed on a diet containing 0–5% Ca maintained production at between 20 and 30%.

2. After a return to a normal diet (3% Ca) egg weight, shell weight, ovarian characteristics and oviduct size were of a similar nature in the two groups, though the differences in egg weight, shell weight and shell calcium were significant at the 1 % level.

3. Bone weight and bone ash did not differ significantly between the groups but after a return to normal rations, bone weight and bone ash became higher in the group that had received the 0.05% Ca diet.

4. There were no clinical signs of bone demineralisation during the experiments.     

Pulsed-field gel electrophoresis patterns and antimicrobial susceptibility phenotypes for coagulase-positive staphylococcal isolates from pustules and carriage sites in dogs with superficial bacterial folliculitis

OBJECTIVE: To determine whether coagulase-positive staphylococcal isolates that are genotypically the same strain obtained from pustules and carriage sites of individual dogs with superficial bacterial folliculitis have the same antimicrobial susceptibility phenotype. ANIMALS: 40 dogs with superficial bacterial folliculitis. PROCEDURES: Samples were obtained from 3 pustules and 3 carriage sites (ie, anus, nonlesional axillary skin, and nasal mucosa) for bacterial culture, morphologic identification, Gram staining, catalase and coagulase testing, antimicrobial susceptibility testing, speciation, and pulsed-field gel electrophoresis (PFGE). RESULTS: 223 isolates from pustules and carriage sites were included. Seventeen susceptibility phenotypes were found among isolates. One hundred twenty-eight (100%) isolates from pustules and 95 (100%) isolates from carriage sites were susceptible to cephalothin; 128 (100%) isolates from pustules and 94 (98.9%) isolates from carriage sites were susceptible to amoxicillin-clavulanic acid; 114 (89.1%) isolates from pustules and 82 (86.3%) isolates from carriage sites were susceptible to erythromycin and lincomycin hydrochloride; and 103 (80.5%) isolates from pustules and 70 (73.7%) isolates from carriage sites were susceptible to trimethoprim-sulfamethoxazole. In 37 of 39 (94.9%) dogs, isolates with the same PFGE pattern from multiple pustules had the same susceptibility phenotype. In 21 of 33 (63.6%) dogs, isolates from multiple carriage sites with the same PFGE pattern had the same susceptibility phenotype. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs with superficial bacterial folliculitis, most coagulase-positive staphylococcal isolates from pustules that are genotypically the same strain will have the same susceptibility phenotype and treatment may be based on empiric antimicrobial selection or susceptibility testing of 1 lesional isolate.     

Detection of cattle infected with bovine viral diarrhea virus using nucleic acid hybridization.

A ribonucleic acid (RNA) hybridization assay to identify cattle infected by bovine viral diarrhea virus (BVDV) is described. The RNA probe was derived from the coding region at the 3' end of the genome of the NADL strain of BVDV. Total RNA from infected cell cultures or peripheral blood leukocytes from suspect animals was extracted and applied to nylon membranes with a slot blot apparatus. Peripheral blood leukocytes were tested concurrently for BVDV by virus isolation. The results of hybridization and virus isolation were in agreement for 92% of the cases. When compared with virus isolation, hybridization had a sensitivity of detection of 59.5% and a specificity of 95%. Cross-reactivity to RNA extracts of border disease virus-infected cells was noted. No cross-reactivity was detected to other common bovine viruses (bovine herpesvirus-1, bovine respiratory syncytial virus, parainfluenza-3 virus, and bluetongue virus), to viruses classified in related families (equine arteritis virus and Venezuelan equine encephalitis virus), or to viruses having similar genomic organization (dengue virus type 2 and Japanese encephalitis virus).     

Enzyme studies with the livers of chicks fed semi‐synthetic diets containing crystalline amino acids and diammonium citrate

The levels of glutamate dehydrogenase [NAD(P)], (GDH), aspartate trans‐aminase (AspT) and alanine transaminase (AlT) were measured in livers from chicks fed on a semi‐synthetic diet containing crystalline essential amino acids as the sole nitrogen source (diet A). The effects of a supplement of 12.0% glutamic acid (diet H) or 11.07% diammonium citrate (DAC) (diet B) or 12.0% glutamic acid plus 1.0% proline with an additional 0.6% glycine (diet C) on these enzymes were studied and the results compared with the levels found for control chicks given a typical diet based on cereal protein (diet J). The abilities of livers from chicks given diets A, B and C to synthesise [14C] glutamic acid from [14C]2‐oxoglutaric acid and diammonium citrate (DAC) were assessed.

The levels of GDH, AspT and AlT found in the livers of chicks given the control diet were 54.1, 966 and 123.7 units/mg protein respectively. Non‐essential nitrogen added as glutamic acid or as DAC did not cause induction of the enzymes studied above control levels. Glutamic acid (diets H and B) caused a depression of GDH levels (37.4 and 38.9 units/mg protein respectively) but had no effect on AspT and AlT compared with the controls, whereas DAC caused a decrease in AlT (43.9 units/mg protein) but had no effect on AspT and GDH; diet A depressed AlT and AspT levels (64.4 and 735 units/mg protein respectively).

The livers of chicks given diets A, C and B varied in their ability to synthesise glutamic acid, 39.3%, 31.9% and 24.0% respectively of the radioactivity being recovered as glutamic acid.     

Use of thermokeratoplasty for treatment of ulcerative keratitis and bullous keratopathy secondary to corneal endothelial disease in dogs: 13 cases (1994-2001)

OBJECTIVE: To evaluate the outcome of thermokeratoplasty for treatment of ulcerative keratitis and bullous keratopathy secondary to corneal endothelial disease in dogs. DESIGN: Retrospective study. ANIMALS: 13 dogs. PROCEDURES: Medical records from 1994 to 2001 for dogs evaluated because of ulcerative keratitis and bullous keratopathy and treated with thermokeratoplasty were reviewed. RESULTS: There were 7 spayed females, 5 castrated males, and 1 sexually intact male, ranging from 6 to 16 years of age. Ten dogs had endothelial degeneration, and 3 dogs had breed-related endothelial dystrophy. All dogs had bullous keratopathy, characterized by microbullae formation that was detected via biomicroscopy. Recurrent or nonhealing corneal ulcers were detected unilaterally in 5 dogs and bilaterally in 8 dogs. Mean +/- SD duration from thermokeratoplasty until ulcerations were healed for all dogs was 2.2 +/- 1.1 weeks. All dogs that underwent thermokeratoplasty for nonhealing corneal ulceration secondary to endothelial disease and corneal edema had epithelial wound healing and resolution of corneal ulceration. Mean duration of treatment (ie, topical treatment required until resolution of ulceration) was significantly less after thermokeratoplasty than duration of treatment (with multiple treatments) prior to referral. CONCLUSIONS AND CLINICAL RELEVANCE: It may be necessary to perform thermokeratoplasty of the entire cornea to prevent recurrence of ulcerations in areas that have not been treated with thermokeratoplasty.     

Chondrodysplasia of Texel sheep - a new disease of suspected genetic aetiology (abstract)

A chondrodysplasia characterised by dwarfism and varus deformity of the forelimbs has been recognised over four seasons in Texel and Texel-cross lambs on three related properties. Affected lambs appear normal at birth, but by 2 weeks of age have reduced growth rate, shortened neck and legs, varus forelimb deformities and a progressive reluctance to walk. Most die within the first 4 months of life. Some affected lambs have had normal co-twins. Post mortem examination of two severely affected 3-month-old lambs revealed extensive loss of articular cartilage and exposure of subchondral bone on the weight-bearing surfaces of the proximal humeri and femurs. Articular and physeal cartilages were thicker than normal, suggesting delayed or impaired endochondral ossification. Histopathologically, there was disorganisation of chondrocytes in articular and physeal cartilage of all bones examined. In addition, there were multiple foci of chondrolysis, which coalesced in some areas to form large clefts. The chondroid matrix surrounding chondrocytes had an abnormal fibrillar appearance. One lamb that exhibited early signs of the disease died of an unrelated cause at 3 weeks of age, and although there was no erosion of articular cartilage, characteristic microscopic lesions were present in articular and physeal cartilage. Although most of the affected lambs were born on a commercial property with a mix of different sheep breeds, all had Texel genes on both sire and dam sides of the pedigree. The farmer had been purchasing his Texel rams from the same flock for several seasons. Circumstantial evidence favours a genetic aetiology, characterised by either autosomal recessive inheritance or over dominance. Studies on the genetic and biochemical basis of the disease are continuing.     

Factors Associated with Grassland Bird Species Richness: The Relative Roles of Grassland Area, Landscape Structure, and Prey

The factors responsible for widespread declines of grassland birds in the United States are not well understood. This study, conducted in the short-grass prairie of eastern Wyoming, was designed to investigate the relationship between variation in habitat amount, landscape heterogeneity, prey resources, and spatial variation in grassland bird species richness. We estimated bird richness over a 5-year period (1994–1998) from 29 Breeding Bird Survey locations. Estimated bird richness was modeled as a function of landscape structure surrounding survey routes using satellite-based imagery (1996) and grasshopper density and richness, a potentially important prey of grassland birds. Model specification progressed from simple to complex explanations for spatial variation in bird richness. An information-theoretic approach was used to rank and select candidate models. Our best model included measurements of habitat amount, habitat arrangement, landscape matrix, and prey diversity. Grassland bird richness was positively associated with grassland habitat; was negatively associated with habitat dispersion; positively associated with edge habitats; negatively associated with landscape matrix attributes that may restrict movement of grassland bird; and positively related to grasshopper richness. Collectively, 62% of the spatial variation in grassland bird richness was accounted for by the model (adj-R² = 0.514). These results suggest that the distribution of grassland bird species is influenced by a complex mixture of factors that include habitat area affects, landscape pattern and composition, and the availability of prey.