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 ± 0.14, 0.52 ± 0.14 and 0.36 ± 0.11, respectively. Immune competence was favourably genetically correlated with breech flystrike incidence (-0.44 ± 0.39), worm egg count (-0.19 ± 0.23), dag score (-0.26 ± 0.31) and fitness compromise (-0.35 ± 0.24) but not fleece rot (0.17 ± 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.

The innate immune stimulant Amplimune® is safe to administer to young feedlot cattle

BACKGROUND

Infectious disease has a significant impact on livestock production. Availability of alternatives to antibiotics to prevent and treat disease is required to reduce reliance on antibiotics while not impacting animal welfare. Innate immune stimulants, such as mycobacterium cell wall fractions (MCWF), are used as alternatives to antibiotics for the treatment and prevention of infectious disease in a number of species including cattle, horses and dogs. This study aimed to evaluate the safety of Amplimune®, an MCWF-based immune stimulant, for weaner Angus cattle.

METHODS

On day -1 and 0, sixty mixed-sex Angus weaner cattle were transported for 6 h before being inducted and housed in a large single pen, simulating feedlot induction conditions. The cattle were assigned to one of six treatment groups (n = 10 per group): 2 mL Amplimune intramuscularly (2IM); 2 mL Amplimune subcutaneously (2SC); 5 mL Amplimune intramuscularly (5IM); 5 mL Amplimune subcutaneously (5SC); 5 mL saline intramuscularly (SalIM) and 5 mL saline subcutaneously (SalSC) on day 0 following transportation. Body temperature, body weight, concentrations of circulating pro-inflammatory cytokines (TNFα, IL-1β, IL-6 and IL-12) and haematology parameters were measured at various times up to 96 h post-treatment.

RESULTS

No adverse effects from Amplimune treatment were observed. Amplimune induced an increase in circulating cytokine TNFα concentrations, total white blood cell count and lymphocyte counts indicative of activation of the innate immune system without causing an excessive inflammatory response.

CONCLUSIONS

Results confirm that Amplimune can be safely administered to beef cattle at the dose rates and via the routes of administration investigated here.

Molecular cloning and characterisation of ovine dual oxidase 2

The dual oxidases (DUOX1 and DUOX2) are NADPH-dependent hydrogen peroxide-producing enzymes that are reported to function in a physiological capacity and as a component of the mucosal immune response. We have previously reported increased expression of the DUOX2 gene in the gut mucosa of sheep in response to gastrointestinal nematode (GIN) challenge. In this paper, we report the cloning of the full-length ovine DUOX2 transcript, using a PCR based strategy. The ovine DUOX2 transcript includes an ORF of 4644 bases, and encodes a protein with 97% identity to the bovine sequence. We also cloned a fragment of DUOX1 (encompassing nucleotides 2692-2829), and the proximal promoter sequence of DUOX2. Through analysis of sequence data we have confirmed that DUOX1 and DUOX2 are co-located in a head to tail arrangement conserved across many species. Alignment of the sequences to the ovine genome predicts a location of this gene cluster on ovine chromosome 7. We quantified the expression of ovine DUOX1 and DUOX2 transcripts in 24 different sheep tissues, and discovered tissue specific expression signatures. DUOX2 was found to be most highly expressed in tissues of the gastrointestinal tract, while expression of DUOX1 predominated in the bladder. Rapid amplification of cDNA ends (RACE) analysis identified the existence of multiple 5' UTR variants in DUOX2, ranging in size from 32 to 242 nucleotides, with 3 distinct transcribed regions. Real time PCR quantification of the DUOX2 UTR variants revealed that these were differentially expressed between tissues, and at various stages of the response to GIN parasite infection. The collective evidence suggested a complex regulation of DUOX2, prompting a bioinformatic analysis of the proximal promoter regions of ovine DUOX2 to identify potential transcription factor binding sites (TFBS) that may explain the differences in the observed expression of the transcript variants of DUOX2. Possible transcription factor families that may regulate this process were identified as Kruppel-like factors (KLF), ETS-factors, erythroid growth receptor factors (EGRF) and myogenic differentiation factors (MYOD).

A versatile system for the expression of nonmodified bacteriocins in Escherichia coli

AIMS

To develop a method and plasmid vectors suitable for expression of class II bacteriocins from Escherichia coli.

METHODS AND RESULTS

The expression vector pSuV1 was constructed by inserting the PelB secretion signal coding sequence and a number of restriction endonuclease sites for cloning, into pTYB1. Codon optimized genes encoding the active mature region of each bacteriocin were constructed and inserted into pSuV1. Transfer of these constructs to a host expressing T7 RNA polymerase allowed for expression of secreted mature or fusion forms of the bacteriocins. Generation of the fusion, to the adjacent intein-chitin-binding domain gene, was achieved by removal of a small intervening BseRI fragment. The bacteriocins BacR1, divercin V41, enterocin P, pediocin PA-1 and piscicolin 126 were expressed from this system. For piscicolin 126, expression levels of 200 microg l(-1) in the mature form and 1100 microg l(-1) when cleaved from the fusion partner were achieved. All expressed bacteriocins displayed antimicrobial activity.

CONCLUSIONS

Several class II bacteriocins have been expressed in E. coli using purpose designed plasmid vectors described here.

SIGNIFICANCE AND IMPACT OF THE STUDY

This method provides a common expression system capable of producing a range of different class II bacteriocins. It allows researchers to study class II bacteriocins without access to the original producer strain, the native bacteriocin gene, or highly specific heterologous producing strains. Resulting expression levels are as high or higher than those previously reported for related bacteriocins.

A lipase of Aeromonas hydrophila showing nonhemolytic phospholipase C activity

Extracellular lipase activity detected on tributyrin agar has been identified in a cosmid clone, JM3084, constructed from the chromosome of Aeromonas hydrophila and vector pHC79. This lipase, named apl-1, also exhibits nonhemolytic phospholipase C activity on lecithin and p-nitrophenylphosphorylcholine. Subcloning of the cosmid JMP3084 with partial Sau3a1 digestion localized the lipase gene to a 3.4-kb DNA fragment. Southern blot analysis shows the gene apl-1 to exist in single copy on the A. hydrophila chromosome. Expression of apl-1 in the pT7 system identified a single protein of molecular weight 70 kDa. Nucleotide sequencing of apl-1 has identified an open reading frame of 2055 bases predicting a protein of 73 kDa. The presence of an amino terminal signal sequence of 18 amino acids accounts for this molecular weight disparity. Further analysis of the lipase amino acid sequence revealed the presence of a classical serine active lipase site (Gly-X-Ser-X-Gly) located between residues 561 and 570. The A. hydrophila chromosomal copy of apl-1 has been inactivated by use of the mutagenesis vector pJP5603, resulting in the complete removal of phospholipase C activity and lowered levels of lipase activity detected on tributyrin agar.