Dietary crude protein concentration does not affect the leucine requirement of growing dogs

The objective of the present study was to examine the interaction between graded levels of leucine and dietary crude protein. Dose–response curves were generated using four 3 × 3 Latin squares (two dogs/square). Each square represented one of two concentrations of crude protein (140 or 280 g/kg diet) and one of two combinations of three concentrations of leucine (5.0, 7.0 and 9.0 g/kg diet or 9.0, 11 and 13 g/kg diet). An additional experiment was performed by feeding crude protein at 210 g/kg diet with either 7.0 or 11 g leucine/kg diet. Weight gain, food intake, nitrogen retention, plasma albumin and plasma amino acids were measured. The requirement was determined to be the minimum leucine concentration required to maximize weight gain and nitrogen retention. For 8–14-week-old male Beagle dogs, 140 g crude protein/kg diet in a diet containing 18 kJ metabolizable energy/g does not appear to support maximal growth. The leucine requirement was not affected by doubling the dietary crude protein level from 140 to 280 g/kg diet. From these results, the leucine requirement of 8–14-week-old Beagle dogs appears to be 11 g leucine/kg diet independent of the level of dietary crude protein, whereas dogs over 14 weeks require only 7 g leucine/kg diet for maximal nitrogen retention.     

Effects of glutamine supplementation of an amino acid-based purified diet on intestinal mucosal integrity in cats with methotrexate-induced enteritis.

OBJECTIVE: To determine effects of glutamine-supplemented and glutamine-free amino acid-based purified diets, compared with a dry expanded diet, on intestinal structure and function in a model that used cats with methotrexate-induced enteritis. ANIMALS: 18 adult specific-pathogen-free cats. PROCEDURE: 12 cats were given intragastric feedings of an amino acid-based purified diet supplemented with glutamine (7% [wt:wt]) or an isonitrogenous amount of glycine and alanine; 6 cats consumed a dry expanded diet. After 21 days, cats received methotrexate (MTX; 11 mg/kg of body weight, IV). Intestinal permeability testing was performed immediately before and 66 hours after MTX administration. Celiotomy was performed 72 hours after MTX administration for aseptic removal of mesenteric lymph nodes, collection of full-thickness intestinal biopsy specimens, determination of intestinal cellular proliferation, and collection of aortic and portal venous blood samples for determination of arteriovenous amino acid concentrations across the intestine. RESULTS: Administration of MTX was associated with severe enterotoxicosis manifested as diarrhea (8/12 cats), vomiting (12/12), and positive results for bacterial culture of mesenteric lymph nodes (12/12) in cats receiving the purified diets, independent of glutamine supplementation. Diet did not affect villus tip length and villus surface area in the small intestine or cellular proliferation. Administration of MTX was associated with significantly increased intestinal permeability, which was not attenuated by glutamine supplementation. CONCLUSIONS: Feeding of a glutamine-supplemented amino acid-based purified diet was unable to preserve intestinal function in cats with MTX-induced enteritis. CLINICAL RELEVANCE: Intestinal morphologic alterations correlate poorly with intestinal function as measured by means of bacterial translocation and intestinal permeability.     

Fecal pH and Microbial Populations in Thoroughbred Horses During Transition from Pasture to Concentrate Feeding

Abrupt dietary transitions and feeding of rapidly fermentable diets are common practices in the horse industry and have been associated with digestive and metabolic disorders that can impair the performance of horses. The present study investigated the effect of dietary transition from pasture grazing to confinement with concentrate feeding, and back, on fecal pH and bacterial populations of Streptococcus spp and Lactobacillus spp. Six Thoroughbred fillies, previously grazing perennial ryegrass and white clover-based pasture, were housed in individual stalls and fed an increasing ratio of concentrate to conserved forages for 13 days (days 1-13), followed by an abrupt transition back to only pasture-grazing for 3 days (days 14-16). The concentrate was initially offered at 0.83 kg dry matter (DM)/d and increased to 5 kg DM/d, whereas ensiled alfalfa was initially offered at 0.61 kg DM/d, increasing to 1.22 kg DM/d. Meadow hay was initially offered at 6.73 kg DM/d, decreasing to 1.6 kg DM/d. Fecal specimens were collected daily for determination of pH, and every 2 days for quantitative analysis of Streptococcus spp and Lactobacillus spp. Mean fecal pH increased significantly from pasture baseline values (pH 6.18) during the initial confinement and supplementation on day 1 (6.37), day 2 (6.52), day 3 (6.58), and day 4 (6.43) (standard error of mean [SEM]: 0.056; P < .001). By day 5, mean fecal pH values had decreased to, and remained at, baseline values until the horses returned to pasture, when another increase occurred at day 15 (6.45). Fecal colony forming units (cfu) of Streptococcus spp and Lactobacillus spp increased linearly (r = 0.94; P < .001) from 6.0 and 6.1 log₁₀ cfu/g on day -4, to 7.8 log₁₀ cfu/g on day 14 (SEM: 0.2 P < .001), respectively. Fecal cfu decreased on return to a pasture-only diet (P < .001). In this study, the increment of bacterial populations was associated with a relatively stable fecal pH and highlights the difficulty in identifying the effects of dietary transition on the equine hindgut health, without microbial culture.     

Evaluating longevity of composite beef females using survival analysis techniques

Objectives were to 1) identify risk factors affecting the longevity of beef females, 2) evaluate the utility of measures collected early in life in predicting longevity, and 3) estimate the heritability of longevity when females were culled primarily for not being pregnant following a 45-d breeding season. Data were from 1,379 Composite Gene Combination (CGC; 1/2 Red Angus, 1/4 Charolais, 1/4 Tarentaise) cows born from 1982 through 1999 at the USDA-ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, MT, and first calving at approximately 2 yr of age. The length of productive life was modeled using Cox regression to identify factors affecting the longevity of beef females. Age at first calving and calf birth weight did not influence longevity. Cows that experienced dystocia were at greater risk of being culled than those that calved without assistance (P < 0.01). On average, as breeding value for cow weight increased, the risk of being culled decreased (P < 0.01), whereas the risk of being culled increased with increasing maternal breeding values for preweaning gain (P < 0.05). Traits measured before 1 yr of age were not useful in predicting the subsequent longevity of cows. The heritability of functional longevity was estimated to be 0.14. Relatively low heritability and the lack of indicators of longevity expressed early in life suggest that genetic improvement of longevity will be difficult. Matching the genetic potential of cows for size and milk production to the production environment such that rebreeding performance is not compromised by concurrent lactation seems to be a consideration in retaining beef females when open cows are culled.     

In situ hybridization for the detection and localization of swine Chlamydia trachomatis

Gnotobiotic piglets were inoculated intralaryngeally with swine Chlamydia trachomatis strain R33 or orally with swine C. trachmatis strain R27. Archived formalin-fixed, paraffin-embedded tissues from piglets euthanatized 4-7 days postinoculation were examined by in situ hybridization for C. trachomatis nucleic acid using a nonradioactive digoxigenin-labeled DNA probes that targeted specific ribosomal RNA or omp1 mRNA molecules of the swine C. trachomatis strains. Positive hybridization signals were detected in bronchial epithelial cells, bronchiolar epithelial cells, pneumocytes, alveolar and interstitial macrophages, and jejunal and ileal enterocytes. Chlamydia-infected cells had a strong signal that was confined to the intracytoplasmic inclusions. Positive hybridization signals were not detected in tissue sections from an uninfected control piglet or in C. psittaci-infected sheep placenta. The morphology of host cells was preserved despite the relatively high temperature required in parts of the incubation procedure. The data indicate that in situ hybridization can be used to detect swine C. trachomatis in formalin-fixed, paraffin-embedded tissue specimens.     

Development and evaluation of a high-fidelity canine patient simulator for veterinary clinical training

High-fidelity human patient simulators have been used for decades in medical education to provide opportunities for students to practice technical skills, diagnostic and therapeutic planning, and communication skills in a safe environment. A high-fidelity canine patient simulator (CPS) was developed using components from a human patient simulator and a low-fidelity foam core canine mannequin. Ninety-six veterinary students participated in cardiopulmonary arrest scenarios in groups of three to five students. Afterwards, participants were asked to complete an anonymous online survey describing their experiences. A total of 70 students (73%) completed the survey. All of the students (100%) felt that the simulator session expanded their cardiopulmonary resuscitation (CPR) knowledge base, and 97% responded that their skills and abilities had improved. Students also expressed positive opinions about the CPS, with 89% agreeing or strongly agreeing that the CPS was realistic and 73% agreeing or strongly agreeing that the scenarios generated emotions similar to real clinical situations. Most participants (98.5%) agreed or strongly agreed that the simulator was an engaging learning experience. Students commonly commented that the simulations allowed them to practice communication and teamwork skills and were more effective than paper-based, problem-oriented learning opportunities and lecture. Students also commented that they wanted more opportunities to participate in simulation exercises. These results suggest that high-fidelity veterinary simulation is an engaging educational methodology that addresses some limitations of other forms of problem-based learning. More studies are needed to quantitatively determine the effectiveness of this novel veterinary educational technology in comparison with more traditional approaches.     

In vitro evaluation of various quinolone antibacterial agents against veterinary mycoplasmas and porcine respiratory bacterial pathogens

The in vitro activities of 12 quinolones and four antibiotics were determined against 15 veterinary mycoplasmal species and four species of bacteria commonly involved in respiratory infections in pigs. The newer quinolones were markedly more active in vitro against a wide range of mycoplasmas than nalidixic acid and the earlier quinolones. Against Mycoplasma hyopneumoniae ciprofloxacin was the most active quinolone with a geometric mean minimal inhibitory concentration (MIC) against 16 strains of 0.01 microgram ml-1 compared with 0.04 microgram ml-1 for tiamulin, 0.06 microgram ml-1 for tylosin, 0.17 microgram ml-1 for oxytetracycline and 0.23 microgram ml-1 for gentamicin. M hyosynoviae was less sensitive to the quinolones with mean MICs of 0.6 microgram ml-1 for ofloxacin and 0.7 microgram ml-1 for ciprofloxacin compared with 0.034 microgram ml-1, or less, for tiamulin. Norfloxacin and its 6-chloro analogue were both mycoplasmacidal in vitro at five or 10 times their MICs against M hyopneumoniae UCD4. Tiamulin was mycoplasmastatic. The quinolones were also active against porcine Bordetella bronchiseptica and Pasteurella multocida strains and Haemophilus species. Ciprofloxacin was the most active quinolone with mean MICs of 0.58 microgram ml-1 against B bronchiseptica (nine strains), 0.026 microgram ml-1 against P multocida (five strains) and 0.01 microgram ml-1, or less, against Haemophilus pleuropneumoniae (nine strains) and H parasuis (two strains) compared with mean MICs of from 0.5 microgram ml-1 to 64 micrograms ml-1, or more, for the antibiotics. This combination of excellent mycoplasmacidal activity against M hyopneumoniae and good antibacterial activity, suggests that the quinolones have great potential for treating respiratory infections in pigs, including enzootic pneumonia.     

Evaluation of a new strategy to modulate skeletal development in Thoroughbred performance horses by imposing track-based exercise during growth

REASON FOR PERFORMING STUDY: No data exist on the intensity of exercise required or on possible harmful effects of increasing exercise in foals over the natural level when free at pasture. OBJECTIVES: To investigate whether an increase in workload over free pasture exercise in the period from directly after birth to the start of training is tolerated by Thoroughbred (TB) foals without increasing injury rate or producing other undesired side effects. METHODS: Thirty-three TB foals were allocated to one of 2 exercise groups directly after birth. One group (PASTEX) was raised on pasture and the other (CONDEX) kept under identical circumstances, but was additionally subjected to an exercise protocol of gradually increasing intensity. Foals were monitored periodically and scored for the presence of clinical signs related to the musculoskeletal system (joint effusion, pain at flexion, occurrence of physeal swelling), and radiographs taken at the end of the conditioning phase. Also, behavioural studies were performed to detect any changes in behaviour related to the exercise programme. Cortisol levels were measured in both groups, to assess the level of stress. RESULTS: Workload in the CONDEX group was significantly higher than in the PASTEX group (approximately 30%). Conditioning increased the likelihood for joint effusion in the antebrachiocarpal joint, but reduced tarsocrural effusion and physeal swelling at the lateral distal radius, the third metacarpal bone (medial aspect) and lateral and medial aspects of the third metatarsal bone. CONCLUSIONS: The 30% increase in workload did not affect the animals' welfare, effects of conditioning exercise on clinical musculoskeletal health were few and there were no adverse effects. POTENTIAL RELEVANCE: This study supports the feasibility of imposing early conditioning exercise in horses and is a benchmark for its effects on the development of equine musculoskeletal tissues.