Role of leptin in farm animals: a review

The discovery of hormone leptin has led to better understanding of the energy balance control. In addition to its effects on food intake and energy expenditure, leptin has now been implicated as a mediator of diverse physiological functions. Recently, leptin has been cloned in several domestic species. The sequence similarity suggests a common function or mechanism of this peptide hormone across species. Leptin receptors are expressed in most of tissues, which is consistent with the multiplicity of leptin functions. The main goal of this review was to summarize knowledge about effect of leptin on physiology of farm animals. Experiments point to a stimulatory action of leptin on growth hormone (GH) secretion, normal growth and development of the brain. Surprisingly, leptin is synthesized at a high rate in placenta and may function as a growth factor for fetus, signalling the nutritional status from the mother to her offspring. Maturation of reproductive system can be stimulated by leptin administration. Morphological and hormonal changes, consistent with a major role of leptin in the reproductive system, have also been described, including the stimulation of the release of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin. Leptin has a substantial effect on food intake and feeding behaviour in animals. Administration of leptin reduces food intake. Its level decrease within hours after initiation of fasting. Leptin also serves as a mediator of the adaptation to fasting, and this role may be the primary function for which was the molecule evolved.     

Evaluation of assays for perinuclear antineutrophilic cytoplasmic antibodies and antibodies to Saccharomyces cerevisiae in dogs with inflammatory bowel disease

OBJECTIVE: To evaluate the use of immunofluorescence asssays for perinuclear antineutrophilic cytoplasmic antibodies (pANCAs) and antibodies to Saccharomyces cerevisiae (ASCAs) in dogs with inflammatory bowel disease (IBD) and assess the clinical value of these serologic markers of the disease. ANIMALS: 39 dogs with IBD, 18 dogs with acute diarrhea, 19 dogs with chronic non-IBD-associated diarrhea, 26 healthy dogs of various breeds and age, and 22 healthy young working dogs. PROCEDURE: Sera obtained from the dogs in each group were added to canine granulocyte- and Saccharomyces cerevisiae-mounted slides for detection of pANCAs and ASCAs via immunofluorescence techniques. Sensitivity and specificity (with 95% confidence intervals [CIs]) were calculated for the group of dogs with IBD versus each of the 2 groups of healthy dogs, the group of dogs with acute diarrhea, and the group of dogs with chronic non-IBD-associated diarrhea. RESULTS: Among the 39 dogs with IBD, 20 yielded positive results via the pANCA assay (sensitivity, 0.51 [95% CI, 0.35 to 0.67]) and 17 yielded positive results via the ASCA assay (sensitivity, 0.44 [95% CI, 0.22 to 0.69]). The specificity of the pANCA assay in the 4 groups of non-IBD-affected dogs ranged from 0.83 (95% CI, 0.85 to 0.96) to 0.95 (95% CI, 0.72 to 1.00). CONCLUSIONS AND CLINICAL RELEVANCE: Immunofluorescence assays for pANCA and ASCA appear to be useful for the detection of IBD in dogs. The pANCA immunofluorescence assay had high specificity for canine IBD, and pANCAs appear to be accurate markers of intestinal inflammation.     

Feeding value of pastures for ruminants

Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seedhead development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements. The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions. The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability. Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.     

A computer program for calculation of doses and prices of injectable medications based on body weight or body surface area

A computer program (CalcAnesth) was developed with Visual Basic for the purpose of calculating the doses and prices of injectable medications on the basis of body weight or body surface area. The drug names, concentrations, and prices are loaded from a drug database. This database is a simple text file, that the user can easily create or modify. The animal names and body weights can be loaded from a similar database. After typing the dose and the units into the user interface, the results will be automatically displayed. The program is able to open and save anesthetic protocols, and export or print the results. This CalcAnesth program can be useful in clinical veterinary anesthesiology and research. The rationale for dosing on the basis of body surface area is also discussed in this article.     

Behavioural analysis of the efficacy of treatments for injuries to the spinal cord in animals

There have been very few clinical trials evaluating therapies for naturally occurring spinal cord injury in dogs and cats. This review describes the methods suitable for evaluating the behavioural recovery of animals with spinal cord injuries, in either a clinical or a laboratory setting. A list of commonly used methods for evaluating behavioural recovery in animals is provided, both in the clinical and laboratory setting; the tests, their limitations and benefits and specific recommendations for their use are also discussed in more depth.     

Femoral bone adaptation to unstable long-term cemented total hip arthroplasty in dogs

OBJECTIVE: To evaluate femoral adaptation after unstable long-term cemented total hip arthroplasty (cTHA) in dogs. STUDY DESIGN: Clinical study. ANIMALS: Four dogs. METHODS: Paired femurs were examined from client-owned dogs that were donated to a retrieval program after death from causes unrelated to their cTHA. Mean (+/-SEM) dog age was 10.0+/-1.5 years and implant duration was 6.0+/-1.4 years. Implanted femurs had radiographic changes associated with implant loosening and gross mechanical instability at femur retrieval. Femurs were evaluated at 3 levels relative to implant length. Cortical area and medullary area were measured at each level, and cortical porosity was assessed at each level in 4 quadrants and in 3 regions. Implanted femurs were compared with the contralateral non-implanted femurs. RESULTS: Cortical area and cortical porosity were increased at all levels in femurs with unstable implants. Implanted femurs had increased porosity in all quadrants and regions at the proximal 2 levels, and increased porosity in only the cranial quadrant and mid-cortical area at the distal level, when compared with contralateral non-implanted femurs. Corresponding medullary areas were not different. CONCLUSIONS: Significant histomorphometric changes occur in femurs after unstable cTHA. The patterns of periosteal bone formation and endosteal bone resorption support mechanisms of stress shielding and wear debris-mediated osteolysis as factors that may contribute to femoral adaptation and implant loosening. CLINICAL RELEVANCE: Despite popularity and excellent return to function with cTHA, aseptic loosening remains a serious long-term complication. Substantial net bone loss and unfavorable environment with unstable cTHA may make revision surgery less successful.     

Recombinant bovine interferon-gamma enhances expression of class I and class II bovine lymphocyte antigens

Recombinant bovine interferon-gamma augments expression of class I and class II histocompatibility antigens on the surface membrane of bovine lymphocytes. Immunofluorescence techniques using a series of monoclonal anti-HLA antibodies demonstrate that this enhancement is detectable as early as 24 h after incubation with rBoIFN, while maximum surface expression is obtained within 3-5 days. A concentration as low as 10 units of rBoIFN is effective. Such results may be useful for characterizing the BoLA gene products.     

Antibody to alcelaphine herpesvirus-1 (AHV-1) in hamsters experimentally infected with AHV-1 and the 'sheep-associated' agent of malignant catarrhal fever

Malignant catarrhal fever was induced in four groups of hamsters by the inoculation of cells infected with either the C/500 isolate of alcelaphine herpes-virus-1 (AHV-1) or the sheep-associated agent derived from cattle, red deer or Père David's deer. Using an indirect immunofluorescence assay, antibody to AHV-1 was detected in sera of clinically affected animals of all four groups. The reaction of sera from hamsters affected with malignant catarrhal fever induced by AHV-1 caused diffuse cytoplasmic staining while that from sera of hamsters with the sheep-associated form of the disease stained particulate nuclear antigens. Tests employing three other bovid herpesviruses were negative and no reaction was found with sera from normal hamsters. These studies provide convincing evidence that a virus antigenically related to AHV-1 is the cause of sheep-associated malignant catarrhal fever and that the same virus probably causes this form of the disease in both cattle and deer.     

The relationship of insulin-like growth factor-I with postweaning performance in Angus beef cattle

This study was designed to evaluate the ontogeny of serum IGF-I (SI) concentrations and its relationship to animal performance in a 140-d postweaning feeding trial. Ninety-eight progeny representing six sires (three high and three low feed conversion) and two sexes (43 bulls and 55 heifers) with ad libitum access to feed were allocated by sire and sex to monitor individual weights and pen feed consumption. Blood serum samples were obtained at the beginning of test (average age of 230 d) and every 28 d thereafter until each animal reached a fat thickness (estimated by sonoray) of 8.9 mm. Individual serum samples were acid-ethanol extracted and measured for IGF-I peptide by heterologous RIA. Serum IGF-I concentrations differed (P less than .10) between high (H) and low (L) feed conversion progeny groups at the end of the first 28-d period (125.12 vs 89.52 ng/ml) and tended to differ at the conclusion of the second 28-d period (P less than .15). Weight gains of H and L groups tended to differ in the second and third 28-d periods (P = .11 and .10, respectively). Serum IGF-I concentrations differed (P less than .05) between bulls and heifers for the first through fourth 28-d periods (P less than .01, P less than .05, P less than .10 and P less than .01, respectively). Phenotypic correlations indicated that pens with higher mean SI concentrations at the beginning of the test consumed less feed and had lower cumulative feed:gain ratios.(ABSTRACT TRUNCATED AT 250 WORDS)