Isolation rearing does not constrain social plasticity in a family-living lizard

Financial support for this research was provided by the Australian Research Council (ARC DP130102998, grant to MJW and RWB), Natural Sciences and Engineering Research Council of Canada (scholarship to JLR), the Australasian Society for the Study of Animal Behavior, the Australian Museum, and Macquarie University (scholarship to JLR). DWAN was supported by an ARC Discovery Early Career Research Award (DE150101774) and University of New South Wales Vice Chancellors Fellowship.An animal’s social environment can be both dynamic and complex. Thus, social species often garner fitness benefits through being plastic in their social behavior. Yet, social plasticity can be constrained by an individual’s experience. We examined the influence of early social environment on social behavior in the tree skink (Egernia striolata), a family-living lizard. In the first phase of this study, we reared juveniles in 2 different social environments for 1.5 years: either in isolation or in unrelated pairs. We quantified each lizard’s sociability at 4-month intervals using a standardized laboratory assay and found that isolated lizards were more sociable, spending the assay closer to an adult female, than socially-reared lizards. In the second phase of this study (at the end of 1.5 years), we released all lizards into a semi-natural environment, observed their associations, and used social network analysis to quantify social behavior. During the initial 6 weeks post-release, we detected no differences in social behavior between rearing treatments. However, during the following 6 months differences emerged. Isolated lizards were more homogeneous in the strength of their associations than socially-reared lizards. Also, at first, isolated lizards associated more strongly than socially-reared lizards. Over time, isolated lizard associations became weaker and involved fewer lizards. In contrast, the level and number of associations of socially-reared lizards were stable over time. Our findings suggest that early experience influences tree skink social behavior but does not constrain social plasticity: isolation rearing did not limit their ability to respond to a novel social environment.PostprintPeer reviewe

Antibacterial and anticoccidial activities of black soldier fly extract

International audienceTo improve the protein autonomy and enrichment for animal welfare, the production of insects for animal feed is growing. Black soldier fly (Hermetia illucens) larvae (BSFL) are easily raised and can valorise co-products and food wastes. Besides a high nutrient content, BSFL contain compounds (chitin, lauric acid, antimicrobial peptides) of interest for gut microbiota and animal health. A wide variety of bacteria can cause diseases in poultry and foodborne illness in human. Avian coccidiosis is another highly prevalent disease, caused by Eimeria protozoan. Disease severity extends from morbidity to mortality. Its economic impact was recently reassessed to 13 billion $/year worldwide. The occurrence of antibacterial and coccidiostat drugs residues in animal-food products may promote (i) risk of allergic reactions by hypersensitive individuals, (ii) bad impact on the dynamics of gastrointestinal flora and (iii) the antibiotic resistance in gut bacteria. The steady increase of occurrence of bacteria resistant to multiple antibiotics has become a global public health threat that is driving the prudent use of antimicrobial in animals and the development of new alternatives. The aim of this study was to evaluate antimicrobial activities of BSFL extracts, comparing protein extracts solubilized in water and lipid extracts solubilized in methanol. We screened a library of bacterial strains that threaten livestock production (poultry, cattle, pigs) and against Eimeria tenella, responsible for avian cecal coccidiosis. Although protein extracts had no antibacterial activity, an inhibition of Eimeria development was observed at [0.001 - 0.01 g/L] of dry matter. The lipid extracts were efficient (0.7 - 5.66 g/L dry matter) against some strains of Pasteurella multocida, Corynebacterium bovis, Streptococcus suis, Riemerella anatipestifer and Trueperella pyogenes. They also inhibited Eimeria development at 0.6 mg/L dry matter. More research is needed to confirm those results in vivo: the antimicrobial effects of BSFL could improve the health and immune response of birds, when facing sanitary or environmental challenges

Black soldier fly products inclusion in broiler diets: effects on animal performance, meat quality, health, and welfare

International audienc

Use of black soldier fly larvae to improve the welfare and behavior of broilers

International audienc

Utilisation de larves de mouches soldat noires pour améliorer le bien-être et le comportement des poulets de chair

National audienc

Utilisation de larves de mouches soldat noires pour améliorer le bien être des poulets de chair

National audienc

Effects of provisioning black soldier fly whole larvae or larvae meal on carcass and meat quality traits in fast-growing broilers

International audienceBlack soldier fly larvae (BSFL) represent a promising protein source for poultry. The aim of this study was to assess in Ross 308 male broilers, the effects on carcass and meat quality traits of feeding strategies using products derived from BSFL. Birds were reared from D1 in floor pens (402 birds; 6 pens). Six strategies were tested: a control (C) vs. the inclusion of 10% defatted BSFL meal in the feed (M) vs. the provision of live (L) or dry (D) BSFL either in starter phase (1-13d; LLS vs. DLS) or during the entire trial (LL vs. DL). For strategies with BSFL, a pelleted diet with adjusted composition was provided ad libitum and larvae were distributed twice a day to represent 15% of daily DM intake. The growth performances were registered. At D36, 34 birds per strategy were slaughtered. Abdominal fat pad percentage and meat yields were measured, as well as, the ultimate pH and color of breast and leg meat. For breast meat, structural defects (white striping, wooden breast and spaghetti meat), drip loss, and tenderness were also evaluated. Finally, the sensory traits of roasted leg meat from C, M, and LL strategies were assessed with a trained jury. At D36, DL birds were lighter than C ones (2056 vs. 2272 g; P<0.001). Abdominal fat pad percentage was higher in DL and M compared to C (2.0 and 1.6%, resp. vs. 1.4% BW; P<0.001). Comparatively to C, breast meat yield was increased in LL and lowered in DL (LL: +1.1 % pts; DL: -2.6 % pts; P<0.001). The ultimate pH of breast meat in DL was lower compared to C (5.64 vs. 5.79; P<0.001). This difference could explain the significantly lighter meat (L*; P<0.001) and the higher drip loss (5.1% vs. 3.3% of initial breast weight; P<0.001) observed in DL comparatively to C. In DL, compared to C, the proportion of breasts without any defect was higher both for white striping (91 vs. 56%; P<0.05) and wooden breast (91 vs. 50%; P<0.01), probably because of smaller breast muscles. Yellowness of leg meat was found to be lower in LL compared to C (b*; P<0.05), probably because of a lower feed (and therefore maize) intake. Finally, no effect on sensory traits for leg meat was found, except for meat tenderness which was found slightly lower in LL compared to C (P<0.01). These results suggest that feeding broilers with BSFL meal or live larvae are two relevant strategies to improve protein self-sufficiency in Europe without significant detrimental effect on the quality of chicken meat

Data from: Isolation rearing does not constrain social plasticity in a family-living lizard

An animal’s social environment can be both dynamic and complex. Thus, social species often garner fitness benefits through being plastic in their social behavior. Yet, social plasticity can be constrained by an individual’s experience. We examined the influence of early social environment on social behavior in the tree skink (Egernia striolata), a family-living lizard. In the first phase of this study, we reared juveniles in two different social environments for 1.5 years: either in isolation or in unrelated pairs. We quantified each lizard’s sociability at four-month intervals using a standardized laboratory assay, and found that isolated lizards were more sociable, spending the assay closer to an adult female, than socially-reared lizards. In the second phase of this study (at the end of 1.5 years), we released all lizards into a semi-natural environment, observed their associations, and used social network analysis to quantify social behavior. During the initial six weeks post-release, we detected no differences in social behavior between rearing treatments. However, during the following six months differences emerged. Isolated lizards were more homogeneous in the strength of their associations than socially-reared lizards. Also, at first, isolated lizards associated more strongly than socially-reared lizards. Over time, isolated lizard associations became weaker and involved fewer lizards. In contrast, the level and number of associations of socially-reared lizards were stable over time. Our findings suggest that early experience influences tree skink social behavior but does not constrain social plasticity: isolation rearing did not limit their ability to respond to a novel social environment

Evaluation of the Microbial Quality of <i>Hermetia illucens</i> Larvae for Animal Feed and Human Consumption: Study of Different Type of Rearing Substrates

In the context of climate change and depletion of natural resources, meeting the growing demand for animal feed and human food through sufficient, nutritious, safe, and affordable sources of protein is becoming a priority. The use of Hermetia illucens, the black soldier fly (BSF), has emerged as a strategy to enhance the circularity of the agri-food chain, but its microbiological safety remains a concern. The aim of the present study was to systematically review available data on the microbiological quality of BSF and to investigate the impact of using four different rearing substrates including classic options allowed by the EU regulation (cereals, fruits, vegetables) and options not allowed by EU regulations regarding vegetable agri-food (co-products, food at shelf life, and meat). A total of 13 studies were collected and synthesized, including 910 sample results, while 102 new sample results were collected from the present experiments in three farms. Both datasets combined revealed a high level of contamination of larvae, potentially transmitted through the substrate. The main pathogenic bacteria identified were Bacillus cereus, Clostridium perfringens, Cronobacter spp., Escherichia coli, Salmonella spp., and Staphylococcus aureus coagulase-positive, while Campylobacter spp. and Listeria monocytogenes were not detected. Any of these four substrates were excluded for their use in insect rearing; however, safety concerns were confirmed and must be managed by the operators of the sector using microbial inactivation treatment after the harvest of the larvae in order to propose safe products for the market. The results obtained will guide the definition of the control criteria and optimize the following manufacturing steps