Review: Environmental enrichment builds functional capacity and improves resilience as an aspect of positive welfare in production animals.

The success of the animal in coping with challenges, and in harnessing opportunities to thrive, is central to its welfare. Functional capacity describes the capacity of molecules, cells, organs, body systems, the whole animal, and its community to buffer against the impacts of environmental perturbations. This buffering capacity determines the ability of the animal to maintain or regain functions in the face of environmental perturbations, which is recognised as resilience. The accuracy of physiological regulation and the maintenance of homeostatic balance underwrite the dynamic stability of outcomes such as biorhythms, feed intake, growth, milk yield, and egg production justifying their assessment as indicators of resilience. This narrative review examines the influence of environmental enrichments, especially during developmental stages in young animals, in building functional capacity and in its subsequent expression as resilience. Experience of enriched environments can build skills and competencies across multiple functional domains including but not limited to behaviour, immunity, and metabolism thereby increasing functional capacity and facilitating resilience within the context of challenges such as husbandry practices, social change, and infection. A quantitative method for measuring the distributed property of functional capacity may improve its assessment. Methods for analysing embedded energy (emergy) in ecosystems may have utility for this goal. We suggest functional capacity provides the common thread that links environmental enrichments with an ability to express resilience and may provide a novel and useful framework for measuring and reporting resilience. We conclude that the development of functional capacity and its subsequent expression as resilience is an aspect of positive animal welfare. The emergence of resilience from system dynamics highlights a need to shift from the study of physical and mental states to the study of physical and mental dynamics to describe the positive dimension of animal welfare.

Targeting improved resilience in Merino sheep - Correlations between immune competence and health and fitness traits.

Resilience can be defined as the ability of an animal to remain productive in the face of diverse environmental challenges. Several factors contribute to an animal's resilience including its ability to resist disease, cope with climatic extremes and respond to stressors. Immune competence, a proxy trait for general disease resistance, is expected to contribute to an animal's resilience. This research aimed to develop a practical method to assess immune competence in Merino sheep which would not restrict the future sale of tested animals, and to estimate genetic parameters associated with the novel trait. We also aimed to explore associations between immune competence and other industry-relevant disease resistance and fitness-related traits and to assess the ability of immune competence phenotypes to predict health outcomes. Here, the ability of Merino wethers (n = 1 339) to mount both an antibody-mediated and cell-mediated immune response was used to define their immune competence phenotype. For that purpose, antigens in a commercial vaccine were administered at the commencement of weaning and their responses were assessed. Univariate sire models were used to estimate variance components and heritabilities for immune competence and its component traits. Bivariate sire models were used to estimate genetic correlations between immune competence and a range of disease resistance and fitness-related traits. The heritability of immune competence and its component traits, antibody-mediated immune response and cell-mediated immune response were estimated at 0.49 ±â€¯0.14, 0.52 ±â€¯0.14 and 0.36 ±â€¯0.11, respectively. Immune competence was favourably genetically correlated with breech flystrike incidence (-0.44 ±â€¯0.39), worm egg count (-0.19 ±â€¯0.23), dag score (-0.26 ±â€¯0.31) and fitness compromise (-0.35 ±â€¯0.24) but not fleece rot (0.17 ±â€¯0.23). Results suggest that selection for immune competence has the potential to improve the resilience of Merino sheep; however, due to the large standard errors associated with correlation estimates reported here, further studies will be required in larger populations to validate associations between immune competence and disease resistance and fitness traits in Australian Merino sheep.

Efficacy of meloxicam in a pain model in sheep.

OBJECTIVE: To evaluate the efficacy of the non-steroidal anti-inflammatory drug, meloxicam, in alleviating pain and inflammation and on production-related variables in a model of sterile acute inflammation in sheep. METHODS: Groups of 12 mature Merino ewes received 0, 0.5, 1.0 or 1.5 mg/kg meloxicam subcutaneously 90 min before injection of 0.1 mL turpentine subcutaneously on the anterior aspect of the proximal phalanx of a forelimb. Pain- and inflammation-related variables were assessed at -18, 3, 6, 9, 12, 24, 48 and 72 h relative to meloxicam administration. Daily feed intake and body weight change 7 days later were also assessed. Pain-related variables measured were weight borne on each forelimb, lameness score, time each forelimb was raised in a 20-s interval and tolerance to a noxious mechanical stimulus. Inflammation-related variables measured were skin temperature, limb circumference, body temperature, plasma haptoglobin concentration and peripheral blood leucocyte parameters. RESULTS: Meloxicam was effective in improving all pain-related variables. A dose-dependent response was seen between 0 and 1.0 mg/kg, with no additional benefit provided by 1.5 mg/kg. At a dose rate of 1.0 mg/kg, meloxicam improved weight borne on the turpentine-treated limb by 14%, reduced the time the treated limb was held in a non-weight-bearing posture by 46%, reduced the lameness score by 58% and improved tolerance to pressure by 52%. No significant effects of meloxicam on inflammatory variables or appetite were observed. CONCLUSIONS: Using a validated pain model, the data suggested that 1.0 mg/kg meloxicam provided significant analgesic benefits to sheep.

Randomised trial of the bioavailability and efficacy of orally administered flunixin, carprofen and ketoprofen in a pain model in sheep.

OBJECTIVE: To determine the efficacy and bioavailability of non-steroidal anti-inflammatory drugs (NSAIDs) when administered orally to sheep. DESIGN: Randomised experimental design with four treatment groups: three NSAID groups and one control group (n = 10/group). The study animals were 40 18-month-old Merino ewes with an average weight of 31.4 ± 0.5 kg. METHODS: Treatment was given orally at 24 h intervals for 6 days at dose rates expected to achieve therapeutic levels in sheep: carprofen (8.0 mg/kg), ketoprofen (8.0 mg/kg) and flunixin (4.0 mg/kg). Oil of turpentine (0.1 mL) was injected into a forelimb of each sheep to induce inflammation and pain; responses (force plate pressure, skin temperature, limb circumference, haematology and plasma cortisol) were measured at 0, 3, 6, 9, 12, 24, 36, 48, 72 and 96 h post-injection. NSAID concentrations were determined by ultra-high-pressure liquid chromatography. RESULTS: The NSAIDs were detectable in ovine plasma 2 h after oral administration, with average concentrations of 4.5-8.4 µg/mL for ketoprofen, 2.6-4.1 µg/mL for flunixin and 30-80 µg/mL for carprofen. NSAID concentrations dropped 24 h after administration. Pain response to an oil of turpentine injection was assessed using the measures applied but no effect of the NSAIDs was observed. Although this pain model has been previously validated, the responses observed in this study differed from those in the previous study. CONCLUSIONS AND CLINICAL RELEVANCE: The three NSAIDs reached inferred therapeutic concentrations in blood at 2 h after oral administration. The oil of turpentine lameness model may need further validation.

Effect of local infusion of NSAID analgesics administered alone or in combination on the pain associated with band castration in calves.

OBJECTIVE: To evaluate the analgesic efficacy of flunixin alone or in combination with diclofenac administered locally to the scrotum at the time of band castration of calves. METHODS: Angus bull calves (n = 40; ≈7-9 weeks old) were allocated to four treatment groups (n = 10 per group) to examine the effects of two non-steroidal anti-inflammatory analgesics (NSAIDs) administered locally at the time of band castration: sham control; castration + flunixin; castration + flunixin + diclofenac; castration + saline. The NSAIDs and saline were administered subcutaneously into the scrotum under the band. Blood was sampled at -0.5, 0.5, 1.5, 3, 12, 24, 48 and 72 h relative to castration. Haematology parameters and plasma cortisol levels were determined in samples at all time points and plasma haptoglobin levels determined in samples collected at -0.5, 24, 48 and 72 h. Pain avoidance and postural behaviours were measured for 2 and 12 h, respectively, after castration. RESULTS: Band-castrated calves exhibited significantly higher peak cortisol and higher integrated cortisol responses during the first 6 h post-castration relative to sham controls. Individual active pain avoidance behaviours observed for 1 h post-castration were not significantly different between treatment groups; however; the sum of the total behaviours was significantly increased by castration (P = 0.023). Postural changes included increased abnormal ventral lying for all castrated groups and decreased normal standing and increased combined abnormal postures for the flunixin- and saline-treated groups. Growth rates of calves were not affected by treatments during weeks 1 and 2 post-castration; however, growth rates of castrated calves were significantly lower than those of sham-treated calves in week 3 post-castration (1.41 vs 0.84, 0.75 and 0.56±0.19 kg/day for sham, flunixin-, flunixin + diclofenac- and saline-treated groups, respectively). CONCLUSIONS: The administration of flunixin or flunixin + diclofenac intrascrotally at several sites at the time of banding did not improve the welfare of young Angus bull calves undergoing this method of castration when assessed by both physiological and behavioural parameters. In this study, band castration at 7-9 weeks of age had less effect compared with results for older calves reported previously. Further research is required to develop effective analgesic treatments that can be administered at the time of castration to large numbers of animals.

Trial of human laser epilation technology for permanent wool removal in Merino sheep.

OBJECTIVE: To assess whether human laser epilation technology can permanently prevent wool growth in sheep. DESIGN: An observational study. METHODS: Two commercial human epilation lasers (Sharplan alexandrite 755 nm laser, and Lumenis LightSheer 800 nm diode laser) were tested at energies between 10 and 100 J/cm2 and pulse widths from 2 to 400 ms. Wool was clipped from flank, breech, pizzle and around the eyes of superfine Merino sheep with Oster clippers. After initial laser removal of residual wool to reveal bare skin, individual skin sites were treated with up to 15 cycles of laser irradiation. Behavioural responses during treatment, skin temperature immediately after treatment and skin and wool responses for 3 months after treatment were monitored. RESULTS: A clear transudate was evident on the skin surface within minutes. A dry superficial scab developed by 24 h and remained adherent for at least 6 weeks. When scabs were shed, there was evidence of scarring at sites receiving multiple treatment cycles and normal wool growth in unscarred skin. There was no evidence of laser energy level or pulse width affecting the response of skin and wool to treatment and no evidence of permanent inhibition of wool growth by laser treatment. Laser treatment was well tolerated by the sheep. CONCLUSIONS: Treatment of woolled skin with laser parameters that induce epilation by selective photothermolysis in humans failed to induce permanent inhibition of wool growth in sheep. Absence of melanin in wool may have contributed to the result.

Efficacy of a buccal meloxicam formulation for pain relief in Merino lambs undergoing knife castration and tail docking in a randomised field trial.

OBJECTIVE: To assess the efficacy of oral transmucosal meloxicam for pain relief in lambs at marking. DESIGN: A blinded, placebo-controlled, randomised, block design field study of 60 Merino lambs aged 7-10 weeks allocated to placebo and meloxicam treatments and studied in two cohorts of 30. Placebo-treated lambs received 1 mL/10 kg of drug vehicle and meloxicam-treated lambs received 1 mg/kg meloxicam at 10 mg/mL. Treatments were administered into the buccal cavity immediately before knife castration and hot-iron tail docking. Lambs were then released into a grassed paddock (0.34 ha). Time to mother-up was recorded and behaviours were observed every 15 min for 8 h and again for 45 min at 24 h. The sequence in which lambs exited the paddock with their mothers was then recorded. Weight change and wound scores were recorded 4 and 7 days after marking. RESULTS: Meloxicam did not affect mothering-up. In the 8 h following marking, meloxicam led to a 7-fold reduction (P < 0.001) in combined abnormal behaviours (hunched standing, standing with a stretched posture, walking stiffly). The meloxicam group spent significantly less time in standing postures and tended to spend more time grazing, suckling and in normal lying postures. At 24 h, the meloxicam group spent more time lying and less time standing. There was no effect of treatments on the sequence in which lambs moved into a fresh paddock or on weight change. CONCLUSIONS: The buccal meloxicam formulation provided substantial analgesia to lambs on the day of marking. Slight benefits were evident the following morning.

A method for determining the concentration of haptoglobin in cattle blood following haemolysis caused at collection.

This study aimed to develop an in-house assay for haptoglobin determination in bovine blood samples, assess the effect of haemolysis on the reported haptoglobin concentration and develop a method to correct for haemolysis interference. The assay developed is highly repeatable (92.3% across plates and 94.8% between assays). A correction equation (Hp(corrected)=Hp(raw)-Hp(endogenous activity)-Hp(due to Hb); where Hp(due to Hb)=0.118×Hb(free)+0.015) was developed based around the linear relationship of haptoglobin and haemoglobin (by-product of haemolysis) and endogenous interference, tested and validated for use with haemolysed samples. The method described in this paper allows samples inadvertently haemolysed at collection to be analysed, with the reported haptoglobin concentration being an accurate reflection of the physiological levels in the animal's blood at the time of collection.

Development of a lameness model in sheep for assessing efficacy of analgesics.

OBJECTIVE: To develop a lameness model to assess the efficacy of analgesics for alleviating pain, swelling and systemic signs of inflammation in sheep. PROCEDURES: The response to subcutaneous injection of 0.1 or 0.2 mL turpentine in a forelimb pastern (n = 4 ewes per dose) was examined at 0, 3, 6, 24, 48 and 72 h. In a second experiment, responses were measured at 0, 2, 4, 6, 8, 10, 12 and 24 h in ewes receiving 0.1 mL turpentine ± meloxicam 1 mg/kg IV at 0 h (n = 6 per group). Responses measured included forceplate pressure, skin temperature, limb circumference, nociception, leucocyte count, neutrophil : lymphocyte ratio, haptoglobin and daily feed intake. RESULTS: Turpentine injection caused a decrease in weight borne on the treated limb, increased skin temperature, increased sensitivity at the injection site and leucocytosis by 2 h and increased limb circumference by 4 h. Weight borne and sensitivity of the injected limb returned to control levels after around 24 h, whereas tissue swelling, elevated skin temperature and elevated haptoglobin levels persisted for at least 72 h. Treatment with meloxicam improved weight borne by and tolerance to pressure exerted on the turpentine-injected limb. CONCLUSIONS: The local and systemic signs of inflammation and pain, temporary reduction in function of the affected limb and partial amelioration of some of these changes by the dose of meloxicam used here suggest that injection of turpentine in the lower forelimb provides a suitable model for examining the efficacy of analgesics for alleviation of pain and inflammation in sheep.

Physiological and behavioural effects of intradermal injection of sodium lauryl sulfate as an alternative to mulesing in lambs.

OBJECTIVE: To assess the effects on physiology and behaviour of intradermal injection of sodium lauryl sulfate (SLS) as an alternative to mulesing. PROCEDURES: Three groups of Merino lambs were studied: Control (n = 10), SLS (n = 11) and Mulesed (n = 11). The SLS group received SLS (7% w/v) and benzyl alcohol (20 mg/mL) in phosphate buffer, and the Mulesed group received 6 mL topical local anaesthetic as a wound dressing. Haematology, cortisol, beta-endorphin and haptoglobin concentrations, rectal temperatures, body weight and behaviours were monitored for up to 42 days post treatments. RESULTS: SLS treatment induced mild swelling followed by thin scab formation. Fever (>40°C) was observed at 12 and 24 h, cortisol concentration was elevated on days 1 and 2, haptoglobin concentration was highly elevated on days 2-7, white blood cell count was elevated on days 2 and 4 post treatment, but average daily gain was not affected. Fever at 12 h was significantly higher in the SLS than in the Mulesed group, whereas maximum temperature, temperature area under the curve (AUC), occurrence of fever, cortisol profile, cortisol AUC, white blood cell counts and haptoglobin concentrations until day 7 were comparable. The behaviours of normal standing, total standing and total lying were modified for 2 days by SLS treatment, but changes were less marked and of shorter duration than in the Mulesed group. On day 1, the SLS group spent <5% of time in total abnormal behaviours compared with 18% in the Mulesed group. The SLS group tended to spend more time in abnormal behaviours on day 1 than the Controls. CONCLUSIONS: The behaviour of the SLS group was similar to that of the unmulesed Controls and their physiological responses were intermediate between the Mulesed lambs receiving post-surgical analgesia and the Controls.

Needle-free vaccination in sheep.

Multi-dose vaccinators have been in use for many years to vaccinate livestock. A number of needle-free vaccinators that use compressed gas to drive the vaccine through intact skin have been recently introduced to the market. We recently examined the efficacy of a needle-free vaccinator to induce antibodies to tetanus toxoid in sheep. The result indicates that needle-free vaccination can stimulate antibody responses comparable to conventional needle vaccination.

Selective transport of IgE into ovine mammary secretions.

Immunoglobulin (Ig) E is actively transported into ovine colostrum. Here we examine the degree of selectivity and the mechanism by which this transfer occurs in sheep. Results indicate that during colostrogenesis in sheep, transfer of immunoglobulins was most selective for IgG1 and IgA followed by IgE, IgM and IgG2. In milk, selectivity was greatest for IgA, followed by IgM, IgE, IgG1 and IgG2. The neonatal Fc receptor (FcRn) and poly immunoglobulin receptor (pIgR) mediate the transport of IgG1 and IgA across the ovine mammary epithelium respectively. In primates and rodents, the low-affinity IgE receptor, Fc epsilonRII, functions to transport IgE across the intestinal epithelium. We therefore investigated the expression of the low-affinity IgE receptor (CD23), pIgR and FcRn transcripts in the ovine mammary gland. The expression profiles of FcRn, pIgR and CD23 mRNA reflected concentrations of their Ig ligands in mammary secretions. These findings suggest a role for CD23 in transport of IgE across the mammary epithelium of sheep.

Effects of a topical anaesthetic formulation and systemic carprofen, given singly or in combination, on the cortisol and behavioural responses of Merino lambs to castration.

OBJECTIVE: To determine the effectiveness of a topical anaesthetic formulation (Tri-Solfen) with or without the administration of a non-steroidal anti-inflammatory drug (carprofen) on the pain and distress response associated with ring or surgical castration of ram lambs. PROCEDURES: Merino ram lambs (n = 78) were allocated to 10 treatment groups: 4 groups of knife-castrated lambs and 4 groups of ring-castrated lambs received carprofen (4 mg/kg SC) and Tri-Solfen; 2 control groups (sham) received carprofen at 0 or 4 mg/kg SC. Measurements included plasma cortisol and haptoglobin concentrations, haematology, and behaviour, including posture. RESULTS: Knife-castrated lambs had higher peak cortisol and integrated cortisol responses for the first 6 h after treatment and greater concentration s of circulating acute phase proteins than ring-castrated lambs, both of which were significantly different from the sham controls. Tri-Solfen applied to the knife castration wound significantly reduced both the peak plasma cortisol concentration and the integrated cortisol response for the first 6 h and improved lying behaviour in the first 12 h. Carprofen reduced the cortisol response to knife castration at 30 min, but elevated the cortisol responses at 24 and 48 h. Carprofen nearly halved the number of acute pain behaviours associated with ring castration. There were no significant additive or synergistic effects from combining the analgesic treatments. Tri-Solfen applied to the tail wound provided no detectible benefits during ring castration + tail docking. CONCLUSIONS: The physiological and behavioural responses suggest that ring castration has less impact on the lamb than knife castration. The specific analgesic treatments can provide modest amelioration of the pain and discomfort associated with castration. Alternative doses or application methods may enhance their efficacy.

Assessment of welfare of suckling lambs following intradermal injection of cetrimide as a non-surgical alternative to conventional mulesing.

OBJECTIVE: To assess in suckling lambs the impact of intradermal injection of cetrimide, a quaternary ammonium compound formulated to induce non-surgical mulesing, on some physiological and behavioural indicators of welfare. PROCEDURES: We allocated 32 suckling lambs (9-11 weeks old) to three groups: (1) control (n = 10), (2) conventional surgical mules (n = 11) and (3) non-surgical mules (n = 11). Non-surgical mulesing was induced by intradermal injection of 4% (w/w) cetrimide + 3% (w/w) polyvinylpyrrolidone in water. Lambs were run in pens of four together with their dams. Haematology, cortisol, beta-endorphin and haptoglobin levels, and rectal temperature were monitored at least daily for the first 7 days after treatment, then weekly until day 28. Body weight was measured weekly and behaviour was measured every 15 min for 12 h on the day of treatment, then on days 1, 2, 4, 6, 12, 21 and 28 following treatment. RESULTS: The intradermal treatment induced local tissue swelling, systemic signs of severe inflammation, including high fever (> 41.0 degrees C) and elevated blood cortisol levels, by 12 h. Rectal temperatures were significantly elevated until 6 days after treatment, cortisol levels were elevated until 4 days after treatment, haptoglobin levels for at least 7 days after treatment and the neutrophil to lymphocyte ratio until 5 days after treatment. Peak cortisol values were comparable in mulesed lambs and lambs receiving the intradermal treatment, whereas the areas under the curves for cortisol and temperature were greater in lambs receiving the intradermal treatment than in mulesed lambs. Beta-endorphin levels were significantly elevated in mulesed sheep at 12 h. There was no effect of intradermal treatment on average daily gain, fibre diameter or beta-endorphin concentration. Mulesed lambs spent 44% of the time in abnormal behaviours (hunched standing, stiff walking, pawing, lateral lying and lying intention) on the day of treatment. On the day after treatment, lambs receiving the intradermal treatment spent 11% of the time (comparable to mulesed lambs) in abnormal behaviours. In comparison, control lambs spent 0.4% of their time in abnormal behaviours on the same day. CONCLUSIONS: The welfare of suckling lambs that were non-surgically mulesed by intradermal injection of cetrimide was measurably poorer than control lambs.

Effect of the non-steroidal anti-inflammatory drug, carprofen, on weaned sheep following non-surgical mulesing by intradermal injection of cetrimide.

OBJECTIVE: To assess in weaned lambs the palliative effects of the non-steroidal anti-inflammatory drug, carprofen, following intradermal injection of cetrimide to induce non-surgical mulesing. PROCEDURES: We allocated 40 weaned lambs (20-22 weeks old) to four groups of 10 animals: (1) control, 2) conventional surgical mules, (3) intradermal treatment and (4) intradermal treatment + carprofen. Non-surgical mulesing was induced by intradermal injection of 4% (w/w) cetrimide + 3% (w/w) polyvinylpyrrolidone in water. In group 4, carprofen (4 mg/kg, SC) was administered 1 h before intradermal treatment. Five weaners, including an animal from each treatment, were run in each pen. Neutrophil to lymphocyte ratio, cortisol, beta-endorphin and haptoglobin levels and rectal temperature were monitored at least daily for the first 7 days after treatment, then weekly until day 28. Body weight was measured weekly and behaviour was measured every 15 min for 12 h on the day of treatment, then on days 1, 2, 4, 6, 12, 21 and 28 following treatment. RESULTS: The intradermal treatment resulted in high fever and elevated blood cortisol by 12 h. Rectal temperatures were significantly elevated until 5 days after treatment, cortisol was elevated until 3 days after treatment, haptoglobin for at least 7 days after treatment and the neutrophil to lymphocyte ratio until 4 days after treatment. Average daily gain was depressed in the week following treatment. Abnormal behaviours (hunched standing, stiff walking, pawing, lateral lying and lying intention) were increased on the day of treatment and for 6 days post treatment. Carprofen reduced the time spent in abnormal behaviours by approximately two-thirds but did not ameliorate the physiological responses to the intradermal treatment. CONCLUSIONS: In weaner sheep, carprofen ameliorated the behavioural responses, but was unable to provide relief from the intense and sustained physiological responses to non-surgical mulesing by intradermal injection of cetrimide. Systemic side-effects may be unavoidable with formulations based on quaternary ammonium compounds that are designed to reduce the risk of fly strike in sheep by remodelling breech tissue through induction of tissue necrosis.

Challenges to the development of new tests for diagnosis of infection and prediction of resistance of sheep to gastrointestinal nematodes.

Strategies for control of gastrointestinal nematode (GIN) infections in sheep require information on the severity of infection and species (or genus) of parasite present. Tests for diagnosis of GIN fall into 3 classes. Current tests measure either: 1) the presence of eggs, worm antigens or worms themselves; 2) components of host immunity (e.g. antibodies, eosinophils, other immune mediators); or 3) components of host pathology (e.g. wool growth, body growth, appetite, blood loss, digestive enzymes, anaemia, hypoproteinaemia, odours). To offer advantages over current diagnostic methods, new tests need to be more informative, more accurate, more timely, cheaper, technically easier, or suitable for use in the field. To improve sheep management, a new test needs to determine severity or predict the onset and severity of infection. This is a technically more difficult challenge than qualitative diagnosis of the presence of infection and creates a substantial obstacle to the development of new diagnostic methods. Estimation of the performance characteristics of a test including its sensitivity, specificity and predictive value is important before widespread adoption. This paper reviews current diagnostic tests for GIN, and opportunities for new tests that aid management of infections or that inform the estimated breeding value of animals for use in programs that breed sheep for resistance to GIN. Gene marker and biomarker tests for resistance to GIN infection or disease will require validation in the population in which they are to be used and may require revalidation as the genetic background of the population changes over time. Estimation of the specificity, sensitivity, and predictive value of gene markers and biomarkers for GIN infection may help inform the value of these markers as selection criteria for use in breeding programs.

Six costs of immunity to gastrointestinal nematode infections.

The strength of the immune response and the outcome of the interaction of a host with a parasite are influenced by genetic and phenotypic characteristics of both parties, and by environmental variables. Allocation of host resources to immune defence reduces resources available for other life-history traits. This review identifies six potential costs to the host from immune activation. The costs are likely to be broadly applicable to other immune responses in vertebrate species. Five phenotypic costs arise from: (i) increased metabolic activity; (ii) reduced nutrient availability due to anorexia; (iii) altered priorities for nutrient utilization; (iv) change in size and turnover of pools of immune cells and proteins; and (v) immunopathology from inappropriate or excessive immune activation. Subsumed by these costs is the cost of altered efficiency of nutrient use. A sixth cost is the genetic cost which arises from a change in the capacity of offspring to express production and life-history traits following selection for parasite resistance. The sensitivity of immune responses to the phenotypic status of the host, and the role the immune system shares with the neuroendocrine system in controlling use of resources underpin the importance of immunocompetence to the life-history of the host.

Fleece rot and dermatophilosis in sheep.

Fleece rot and dermatophilosis reduce health and production of sheep and predispose them to blow fly strike. This paper reviews aetiology, prevalence, pathogenesis, resistance, attempts to develop vaccines and prospects for new control strategies to these important skin diseases. Although the severity of fleece rot is associated with the abundance of Pseudomonas aeruginosa on skin, microbial ecology studies are providing new insights into the contribution of other bacteria to the disease. Wool traits and body conformation traits that predispose sheep to fleece rot and dermatophilosis are heritable and have been used as indirect selection criteria for resistance for many years. Selection against BoLA-DRB3-DQB class II haplotype in cattle can substantially reduce the prevalence of dermatophilosis and holds promise for identification of gene markers for resistance to these bacterial diseases in sheep. Immune responses in skin and systemic antibody responses to bacterial antigens are acquired through natural infection and contribute to resistance; however, prototype antibacterial vaccines have to date failed to provide protection against the diversity of isolates of Dermatophilus congolensis and Pseudomonas species present in the field. Opportunities for future control through breeding for resistance, vaccines and non-vaccine strategies for controlling the microbial ecology of fleece are discussed. In combination, control strategies need to reduce the risk of transmission, minimise exposure of animals to stressors that enhance the risk of infection, and enhance resistance though genetics or vaccines.

The effect of a topical anaesthetic formulation, systemic flunixin and carprofen, singly or in combination, on cortisol and behavioural responses of Merino lambs to mulesing.

OBJECTIVE: To determine the pain responses of lambs to mulesing, and the effectiveness of potential analgesic treatments. PROCEDURES: Merino lambs (n=64) were allocated at 5 weeks of age to eight treatment groups: 1) sham mules; 2) conventional mules; 3) topical anaesthetic, incorporating lignocaine, bupivicaine, adrenaline and cetrimide, applied immediately after mulesing; 4) flunixin + topical anaesthetic, with flunixin administered 2.5 mg/kg s.c. 90 min before mulesing; 5) carprofen + topical anaesthetic, with carprofen administered 4 mg/kg s.c. 90 min before mulesing; 6) carprofen, administered as above; 7) flunixin, administered as above; and 8) carprofen + flunixin, administered as above. Plasma cortisol was measured at 0, 0.5, 6, 12 and 24 h relative to mulesing. Animal behaviour, including posture, was recorded for 12 h after mulesing. RESULTS: The conventional mules lambs exhibited large increases in plasma cortisol, reduced lying and increased standing with a hunched back compared with sham mules animals. Topical anaesthetic reduced the cortisol peak to mulesing and hunched standing, and increased lying compared with the conventional mules treatment, but generally did not result in values equivalent to sham mules animals. Carprofen, flunixin, and carprofen + flunixin treatments did not reduce the cortisol response to mulesing but substantially ameliorated some changes in behavioural postures. Flunixin + topical anaesthetic reduced the cortisol peak following mulesing and substantially ameliorated most changes in behavioural postures. Carprofen + topical anaesthetic abolished the cortisol peak following mulesing and substantially ameliorated most changes in behavioural postures. All mulesed animals lost weight in the week after mulesing regardless of analgesic administration, but there were no significant differences in growth rate between any of the eight treatments over the 3 weeks after mulesing. CONCLUSIONS: Analgesics can moderate the pain response of lambs to mulesing. The welfare outcome for lambs of mulesing could be improved by use of a combination of local anaesthetic and long acting non-steroidal anti-inflammatory drug.

Adjusting worm egg counts for faecal moisture in sheep.

The number of eggs from gastrointestinal nematodes per gram of faeces (worm egg count WEC) is commonly used to determine the need for anti-parasite treatments and the breeding value of animals when selecting for worm resistance. Diarrhoea increases faecal moisture and may dilute the number of worm eggs observed. To quantify this effect, egg counts in sheep at pasture were simulated by dosing 15 animals with chromic oxide particles. The simulated WEC diminished as faecal moisture increased. When faeces were dried, simulated WEC per unit dry matter was not influenced by the amount of faecal moisture present prior to drying. The results suggest that adjustment for faecal moisture may provide an improved estimate of FEC. Drying faeces to calculate the WEC per unit dry matter would provide such an adjustment but may not be practical for industry application. In the past, the CSIRO McMaster Laboratory has used an adjustment factor developed by Gordon based on the classification of faecal consistency derived from the morphology of faeces. To examine the utility of an adjustment factor based on faecal consistency score (FCS), the relationships between FCS and simulated WEC and dry matter were examined. Dry matter and simulated WEC exhibited an exponential decline as FCS increased. The relationship between FCS and dry matter was further examined in 368 samples collected over 12 months from sheep at pasture, where it was observed that dry matter showed a linear decline as FCS increased. Adjustment factors based on dry matter were similar to those proposed by Gordon however adjustment factors predicted from simulated WEC diverged from the remainder for FCS>4. As no samples scored FCS 5 in the study of simulated FEC, the adjustment factors based on the larger study that included samples with FCS 5 was therefore considered more robust. Adjustment factors were given by the equation: WEC(estimated)=(WEC(observed)/(34.21-5.15 FCS))x29.06. This equation estimates for samples with FCS>1 the WEC that would be expected if the samples were FCS 1, the faecal consistency score for normal faeces. The impact of adjustment of observed WEC for faecal moisture predicted by FCS on decision points for treatment and on estimated breeding values requires further examination.