Hormonal responses to acute exercise, training and overtraining. A review with emphasis on the horse

Overtraining is an imbalance between training and recovery leading to symptoms associated with a neuroendocrine dysbalance called the overtraining syndrome, a disease characterized by behavioral, emotional and physical symptoms similar with depression. Although the prevalence of overtraining is high in human and equine athletes, at present no sensitive and specific test is available to prevent or diagnose overtraining. Nowadays, it is believed that combination of different (hormonal) parameters appear to be the best indicators of overtraining. Therefore, this review provides a summary of previous literature examining the response of the hypothalamic-pituitary-adrenal (HPA) axis and the growth hormone-insulin-like growth factor-I (GH-IGF-I) axis to acute and chronic exercise as well as overtraining in humans and horses. The exercise induced hormonal responses seem to be equal for the equine as well as the human athlete, which makes comparisons possible. Repeated bouts of exercise are suggested to provide a way to detect subtle changes in hormonal responses in the individual athlete, which may make them an important tool in detecting early overtraining. This should be combined with corticotropin releasing hormone (CRH) stimulation tests and basal ACTH and GH pulsatility determination. Further research is needed to establish the correct training intensity and rest period for the exercise test in equines.     

Comparison of two automated spectrophotometric methods for ceruloplasmin measurement in pigs

Ceruloplasmin (Cp) determination could provide an objective measure of the health status of an animal and could be used as marker of animal health and welfare (Skinner, 2001) (Skinner, J. G., 2001. Special report. International standardization of acute phase proteins. Veterinary Clinical Pathology 30, 2-7.) but only manual methods have been reported to determine Cp concentrations in pigs (McCosker, 1961; Toussaint et al., 1995; Eckersall et al., 1996) (McCosker, P. J., 1961. Paraphenylenediamine oxidase activity and copper-levels in mammalian plasmas. Nature. 190, 887-889; Toussaint, M. J. M., Van Ederen, A. M., Gruys, E., 1995. Implication of clinical pathology in assessment of animal health and in animal production and meat inspection. Comparative Haematology International 5, 149-157; Eckersall, P. D., Saini, P. K., McComb, C., 1996. The acute phase response of acid soluble glycoprotein, alpha(1)-acid glycoprotein, ceruloplasmin, haptoglobin and C-reactive protein, in the pig. Veterinary Immunology and Immunopathology 51, 377-385). In the present study two automated methods based on the use of two different substrates for the determination of serum ceruloplasmin in pigs were developed, evaluated and compared. Both methods showed a good precision and detection limits, with no signs of inaccuracy and could be applied to biochemical autoanalyzers usually found in clinical laboratories using only minimal amounts of serum. Additionally the behaviour of Cp in experimental and clinical situations was studied showing an increase of around two fold after turpentine administration and significantly higher values in cases of pigs with inflammatory conditions when compared with healthy pigs.     

Evaluation of dirlotapide for sustained weight loss in overweight Labrador retrievers

The effects of dirlotapide on body weight (BW) reduction were investigated in overweight Labradors in two parallel-design studies. Study A involved 42 dogs randomized to 0.0, 0.025, 0.05, 0.1, 0.2 or 0.4 mg dirlotapide/kg/day orally for 4 weeks. Study B involved 72 dogs randomized to nine treatments: placebo (24 weeks); dirlotapide (24 weeks) followed by placebo (28 weeks); or dirlotapide (52 weeks); on diets containing 5%, 10% or 15% fat. Dirlotapide dose (initially 0.1 mg/kg) was adjusted monthly during 24-week weight-loss and subsequent 28-week weight-stabilization phases. Food was offered above maintenance energy requirements (MER× 1.1–1.2) based on initial BW. Body composition (body fat, lean tissue and bone mineral content) was monitored using dual-energy X-ray absorptiometry. After treatment, dogs that had received dirlotapide for 52 weeks were fed 90% of quantity consumed at week 52. In study A, BW and food intake decreased asymptotically with dose: mean weekly weight loss exceeded 1% at 0.1–0.4 mg/kg. In study B, dirlotapide resulted in significant mean weekly weight loss (>0.8%) and decreased food intake over 24 weeks compared with placebo ( P  = 0.0001) for all diets. Food restriction minimized post-treatment weight rebound. Dirlotapide administered daily to dogs for up to 52 weeks was clinically safe and resulted in sustained weight reduction.     

Identification of polymorphisms and association analysis with meat quality traits in the porcine KIAA1717 and HUMMLC2B genes

Skeletal muscle genes are potential candidates for production and meat quality. Screening a subtracted cDNA library constructed with mRNA obtained from longissimus dorsi muscles of F1 hybrids Landrace × Yorkshire and their female parents Yorkshire, we isolated two partial sequences coding for the H3-K4-specific methyltransferase (KIAA1717) and skeletal muscle myosin regulatory light chain (HUMMLC2B) genes. Database search revealed KIAA1717 and HUMMLC2B encoded proteins with SET domain and EF-hand calcium binding motif, respectively. In the present work we identified their partial polymorphisms and two SNPs, one (C1354T) at the 3′ untranslated region (UTR) of KIAA1717 and one (A345G) at the SINE (PRE-1) element of HUMMLC2B, both created/disrupted a restriction site for endonuclease Msp I. The selected pigs were genotyped at the KIAA1717 C1354T and HUMMLC2B A345G sites by means of a PCR-RFLP protocol. Significant associations were observed for the KIAA1717 C1354T polymorphic site with meat marbling (longissimus doris (p < 0.05), biceps femoris (p < 0.01)) and intramuscular fat (p < 0.01). HUMMLC2B A345G were significantly associated with meat pH (longissimus doris (p < 0.05), biceps femoris (p < 0.01)), drip loss (p < 0.01), water holding capacity (p < 0.01) and meat color value (longissimus doris (p < 0.01), biceps femoris (p < 0.05)). Further studies are needed to confirm these preliminary results.     

Feeding corn milling byproducts to feedlot cattle.

Corn milling byproducts are expected to increase dramatically in supply as the ethanol industry expands. Distillers grains, corn gluten feed, or a combination of both byproducts offer many feeding options when included in feedlot rations. These byproduct feeds may effectively improve cattle performance and operation profitability. When these byproducts are fed in feedlot diets, adjustments to grain processing method and roughage level may improve cattle performance. Innovative storage methods for wet byproducts and the use of dried byproducts offer small operations flexibility when using byproducts. As new byproducts are developed by ethanol plants, they should be evaluated with performance data to determine their product-specific feeding values.     

Disseminated Aspergillus flavus infection in broiler breeder pullets

Increased morbidity and mortality occurred in a 5-wk-old broiler breeder replacement pullet flock. The affected broiler pullet flock was housed on the first floor of a two-story confinement building. Mortality increased to 0.1%/day compared to the flock on the second floor, which had mortality levels of less than 0.01%/day. Clinical signs in the affected chickens included inactivity, decreased response to stimuli, and anorexia. No respiratory or neurologic signs were observed. On necropsy, affected pullets were dehydrated and emaciated and had disseminated variably sized single or multiple heterophilic granulomas that contained intralesional septate and branching fungal hyphae. Lesions were extensive around the base of the heart in the thoracic inlet and in the kidneys. Other affected organs included eyelid, muscle, proventriculus, ventriculus, intestine, liver, spleen, lung, and heart. Aspergillus flavus was cultured from the visceral granulomas. The source of flock exposure to the organism was not determined.     

Doramectin concentration profiles in the gastrointestinal tract of topically-treated calves: Influence of animal licking restriction

Endectocide compounds are extensively used for broad-spectrum parasite control and their topical administration to cattle is widespread in clinical practice. Pour-on formulations of moxidectin, ivermectin, eprinomectin and doramectin (DRM) are marketed internationally for use in cattle. However, variability in antiparasitic efficacy and pharmacokinetic profiles has been observed. Although the tissue distribution pattern for different endectocide molecules given subcutaneously to cattle has been described, only limited information on drug concentration profiles in tissues of parasite location after topical treatment is available. Understanding the plasma and target tissue kinetics for topically-administered endectocide compounds is relevant to optimise their therapeutic potential. The current work was designed to measure the plasma and gastrointestinal (GI) concentration profiles of DRM following its pour-on administration to calves. The influence of natural licking behaviour of cattle on DRM concentration in mucosal tissue and luminal content of different GI sections was evaluated. The trial was conducted in two experimental phases. In Phase I, the DRM plasma kinetics was comparatively characterised in free-licking and in 2-day licking-restricted (non-licking) calves. The pattern of distribution of topical DRM to mucosal and luminal contents from abomasum, duodenum, ileum, caecum and spiral colon was assessed in free-licking and non-licking calves restricted over 10 days post-administration (Phase II). The prevention of licking caused marked changes on the plasma and GI kinetics of DRM administered pour-on. In 2-day licking restricted calves, DRM systemic availability was significantly lower (29%) than in free licking animals during the first 9 days post-treatment. Following a 10-day long licking restriction period, DRM concentrations profiles in both mucosal tissue and luminal contents of the GI tract were markedly higher in animals allowed to lick freely. This enhancement in drug concentrations in free-licking compared to non-licking calves, was particularly pronounced in the abomasal (38-fold higher) and duodenal (six-fold higher) luminal content. As shown earlier for ivermectin, licking behaviour may facilitate the oral ingestion of topically-administered DRM in cattle. This would be consistent with the marked lower drug concentration profiles measured in the bloodstream and GI tract of the animals prevented from licking. The work reported here provides relevant information on the pattern of DRM distribution to the GI tract after pour-on treatment, and contributes to understand the variability observed in the antiparasitic persistence of topically-administered endectocides in cattle. The implications of natural licking in topical treatments are required to be seriously assessed to achieve optimal parasite control and to design parasitological and pharmacological studies within the drug approval process.     

Biochemical analysis of the articular cartilage and subchondral and trabecular bone of the metacarpophalangeal joint of horses with early osteoarthritis

OBJECTIVE: To assess whether site-related changes in biochemical composition are present in the cartilage and subchondral and trabecular bone of the metacarpophalangeal joint of horses with early osteoarthritis. SAMPLE POPULATION: Right metacarpophalangeal joints from 59 mature warmblood horses. PROCEDURE: Biochemical data (cross-link, amino acid, DNA, and ash contents; denatured collagen and glycosaminoglycan [GAG] concentrations; bone mineral density; and mineral composition) were obtained from 2 differently loaded sites of phalanx I cartilage and subchondral and trabecular bone samples; data were compared with previously published values from nonosteoarthritic equine joints. RESULTS: Compared with findings in nonosteoarthritic joints, GAG concentration was lower in cartilage from osteoarthritic joints and there was a loss of site differences in cellularity and lysylpyridinoline (LP) cross-link content. In subchondral bone, LP cross-link content was decreased overall and there was a loss of site differences in osteoarthritic joints; ash content was higher in the osteoarthritic joints. Hydroxyproline content in trabecular bone from osteoarthritic joints was greater than that in nonosteoarthritic trabecular bone. In all 3 layers and at both sites, the linear increase of the pentosidine cross-link content with age had diminished or was not apparent in the horses with osteoarthritic joints. CONCLUSIONS AND CLINICAL RELEVANCE: In equine metacarpophalangeal joints with early osteoarthritis, distinct biochemical changes were detected in the cartilage and subchondral and trabecular bone. The dissimilarity in response of the different tissues and differences between the sites that are affected may be related to differences in biomechanical loading and transmission and dissipation of force.     

Activin A: from sometime reproductive factor to genuine cytokine

The growth factor, activin A, was initially characterized as a putative reproductive hormone but is now known to have many other divergent roles. One of these is during inflammation. Following intravenous injection of bacterial lipopolysaccharide (LPS) into sheep, activin A is released extremely rapidly into the circulation. The release of activin A appears to be independent of fever, prostaglandins or other key proinflammatory cytokines such as TNF-alpha or IL-1beta. While the precise roles and function of this factor in inflammation are yet to be elucidated, the activin response occurs in other mammalian species besides the sheep and elevated activin has been documented for a number of clinical inflammatory conditions. Activin A therefore seems to be part of the regulatory component of the innate immune response.