Would behavioral thermoregulation enable pregnant viviparous tropical lizards to cope with a warmer world?

Sceloporus lizards depend on external heat to achieve their preferred temperature (T_sel) for performing physiological processes. Evidence both in the field and laboratory indicates that pregnant females of this Genus select body temperatures (T_b) lower than 34 °C as higher temperatures may be lethal to embryos. Therefore, thermoregulation is crucial for successful embryo development. Given the increase in global air temperature, it is expected that the first compensatory response of species that inhabit tropical climates will be behavioral thermoregulation. We tested whether viviparous Sceloporus formosus group lizards in the wild exhibited differences in thermoregulatory behavior to achieve the known T_sel for developing embryos regardless of local thermal conditions. We quantified field active body temperature, thermoregulatory behavior mechanisms (time of sighting, microhabitat used and basking time) and available microhabitat thermal conditions (i.e. operative temperature) for 10 lizard species during gestation, distributed along an altitudinal gradient. We applied both conventional and phylogenic analyses to explore whether T_b or behavioral thermoregulation could be regulated in response to different thermal conditions. These species showed no significant differences in field T_b during gestation regardless of local thermal conditions. In contrast, they exhibited significant differences in their behavioral thermoregulation associated with local environmental conditions. Based on these observations, the differences in thermoregulatory behavior identified are interpreted as compensatory adjustments to local thermal conditions. We conclude that these species may deal with higher temperatures predicted for the tropics by modulating their thermoregulatory behavior.     

Prevalence of Ehrlichia canis infection in thrombocytopenic dogs from Rio de Janeiro, Brazil

BACKGROUND: Infection with Ehrlichia canis causes a highly variable, multisystemic disease in dogs. Nevertheless, many clinicians in Rio de Janeiro, Brazil, use the presence of only thrombocytopenia to make a presumptive diagnosis of E canis infection. OBJECTIVE: The objective of this study was to determine the prevalence of E canis in thrombocytopenic dogs from Rio de Janeiro, Brazil, using polymerase chain reaction (PCR). METHODS: Following DNA extraction of whole blood samples from 226 dogs, PCR assays were done using primers for rickettsial DNA (including Ehrlichia spp, Anaplasma platys and A phagocytophilum) and using E canis-specific primers (16S rRNA gene). Dogs were grouped as thrombocytopenic and nonthrombocytopenic based on platelet counts. The null hypothesis that there was no difference in the prevalence of E canis in these groups was rejected at P<.05. RESULTS: Thirty-six (32.1%) of the thrombocytopenic dogs and 4 (3.5%) of the nonthrombocytopenic dogs were positive for rickettsial gene sequences (P<.0001). Further, 30 (26.8%) of thrombocytopenic dogs and 4 (3.5%) nonthrombocytopenic dogs were positive for E canis-specific gene sequences (P<.0001). CONCLUSIONS: Although the prevalence of E canis infection was higher in thrombocytopenic dogs, less than one third of these dogs had demonstrable E canis infection. Thus, thrombocytopenia is not specific for the detection of E canis infection and should not be used solely to establish a diagnosis of canine ehrlichiosis, even in a geographic area with relatively high disease prevalence.     

Effect of dietary inclusion of Spirulina on production performance,nutrient digestibility and meat quality traits in post-weaning piglets

The effect of Spirulina (Arthrospira platensis), individually or in combination with two commercial carbohydrases, in piglet diets was assessed on growth performance, nutrient digestibility and meat quality traits. Forty post-weaned male piglets from Large White × Landrace sows crossed with Pietrain boars with an initial live weight of 12.0 ± 0.89 kg were used. Piglets were assigned to one of four dietary treatments (n = 10): cereal and soya bean meal base diet (control), base diet with 10% Spirulina (SP), SP diet supplemented with 0.005% Rovabio^® Excel AP (SP + R) and SP diet supplemented with 0.01% lysozyme (SP + L). Animals were slaughtered after a 4-week experimental period. Growth performance was negatively affected by the incorporation of Spirulina in the diets, with an average decrease of 9.1% on final weight, in comparison with control animals. Total tract apparent digestibility (TTAD) of crude protein was higher (p < .05) in the control group than in other groups. In addition, lysozyme increased TTAD of crude fat and acid detergent fibre, relative to the SP and control groups, respectively. In addition, the incorporation of Spirulina, individually and supplemented with enzymes, did not impair meat quality traits. Surprisingly, no protective effect against lipid oxidation was observed with the inclusion of Spirulina in pork after 7 days of storage. This study indicates that growth performance of post-weaning piglets was impaired by the incorporation of 10% Spirulina in the diets, which is mediated by an increase in digesta viscosity and a lower protein digestibility, as a consequence of the resistance of microalga proteins to the action of endogenous peptidases. In addition, it also indicates that lysozyme, in contrast to Rovabio^® Excel AP, is efficient in the degradation of Spirulina cell wall in piglet's intestine. However, the digestion of proteins liberated by Spirulina cell wall disruption is still a challenge.     

Simultaneous analysis of the intestinal parasites and diet through eDNA metabarcoding

Agricultural expansion and intensification are having a huge impact on plant and arthropod diversity and abundance, affecting food availability for farmland birds. Difficult food access, in turn, can lead to immunosuppression and a higher incidence of parasites. In the studies designed to examine changes in the diet of birds and their parasites, metabarcoding is proving particularly useful. This technique requires mini-barcodes capable of amplifying the DNA of target organisms from fecal environmental DNA. To help to understand the impact of agricultural expansion on biodiversity, this study sought to design and identify mini-barcodes that might simultaneously assess diet and intestinal parasites from the feces of farmland birds. The capacity to identify diet and parasites of 2 existing and 3 newly developed mini-barcodes was tested “in silico” in relation to the behavior of a reference eukaryotic barcode. Among the newly designed mini-barcodes, MiniB18S_81 showed the higher taxonomic coverage of eukaryotic taxa and a greater amplification and identification capacity for diet and parasite taxa. Moreover, when it was tested on fecal samples from 5 different steppe bird species, MiniB18S_81 showed high taxonomic resolution of the most relevant diet and parasite phyla, Arthropoda, Nematoda, Platyhelminthes, and Apicomplexa at the order level. Thus, the mini-barcode developed emerges as an excellent tool to simultaneously provide detailed information regarding the diet and parasites of birds, essential for conservation and management.     

Seroepidemiology of canine babesiosis and ehrlichiosis in a hospital population

Canine ehrlichiosis and babesiosis have a worldwide distribution with geographic variation in prevalence and main clinical manifestations. We prospectively determined seroprevalence of canine babesiosis and ehrlichiosis, and risk factors for seropositivity. Three hundred and eighty-one dogs were randomly selected to represent the canine population at a Veterinary Teaching Hospital in south Brazil (latitude 23° S). Dogs were tested with a point-of-care ELISA for Ehrlichia canis antibodies and IFA to confirm previous exposure to Babesia vogeli. Multiple logistic regression analysis was then used to estimate adjusted odds ratio (OR) and their 95% confidence intervals. One hundred and thirty-six (36%) dogs were seropositive for B. vogeli antibodies, whereas 87 (23%) dogs were seropositive to E. canis antibodies. Fifty-four (14%) dogs seroreacted to both agents. Adult dogs previously infested with ticks were more likely to seroreact to B. vogeli or E. canis. Superficial bleeding (OR = 12.4) was more common in dogs exposed to B. vogeli, whereas neurological signs (OR = 7.7) were more common in dogs seropositive to E. canis. Neurological signs (OR = 12.0) and lameness (OR = 12.8) were more prevalent in dogs that seroreacted to both organisms. Owners of dogs with ticks were more likely to have been exposed to ticks themselves (OR = 3.2). Canine babesiosis and ehrlichiosis appear to be highly prevalent in this hospital population. Clinical signs differed from the most common signs in other regions with bleeding occurring more in dogs seropositive to babesiosis, but not ehrlichiosis; neurologic signs in dogs with E. canis antibodies; and lameness in dogs that seroreacted to both organisms.     

Enriching Artemia nauplii with a high DHA‐containing lipid emulsion: search for an optimal protocol

This study aimed to investigate practical strategies to optimize the use of a high‐docosahexaenoic acid (DHA) lipid emulsion (M70), a product with great potential in live prey enrichments for marine larviculture. Considering its particularly high content in DHA (22:6n‐3), the adequate utilization of the emulsion for Artemia enrichments was evaluated in a series of six experiments. More specifically, the bioencapsulation efficiency of M70 into Artemia nauplii was tested under different experimental conditions of oxygen source, aeration flow, incubation temperature, concentration and dosage, as well as nauplial densities. Our results showed that an optimal utilization of M70 is achieved with incubation temperatures of 28°C, moderate aeration flows and nauplial densities of 300 ind per mL. In addition, the emulsion can be dispensed in the enrichment medium in one single dose of 0.8 g L^?1, with no apparent detrimental effects on its oxidative stability and Artemia nauplii survival during enrichment.     

Genetic parameter estimation for pre- and post-weaning traits in Brahman cattle in Brazil

Beef cattle producers in Brazil use body weight traits as breeding program selection criteria due to their great economic importance. The objectives of this study were to evaluate different animal models, estimate genetic parameters, and define the most fitting model for Brahman cattle body weight standardized at 120 (BW120), 210 (BW210), 365 (BW365), 450 (BW450), and 550 (BW550) days of age. To estimate genetic parameters, single-, two-, and multi-trait analyses were performed using the animal model. The likelihood ratio test was verified between all models. For BW120 and BW210, additive direct genetic, maternal genetic, maternal permanent environment, and residual effects were considered, while for BW365 and BW450, additive direct genetic, maternal genetic, and residual effects were considered. Finally, for BW550, additive direct genetic and residual effects were considered. Estimates of direct heritability for BW120 were similar in all analyses; however, for the other traits, multi-trait analysis resulted in higher estimates. The maternal heritability and proportion of maternal permanent environmental variance to total variance were minimal in multi-trait analyses. Genetic, environmental, and phenotypic correlations were of high magnitude between all traits. Multi-trait analyses would aid in the parameter estimation for body weight at older ages because they are usually affected by a lower number of animals with phenotypic information due to culling and mortality.