Dealing With Deadstock: A Case Study of Carnivore Conflict Mitigation From Southwestern Alberta

Livestock deaths are an unfortunate reality for livestock producers and dead livestock (i.e., deadstock) disposal options can have implications beyond the ranch itself. In Alberta, Canada, natural disposal (i.e., disposing of the carcass in a manner that allows for scavenging) has increased since the 2003 detection of bovine spongiform encephalopathy (BSE) in Canadian cattle. Prior to BSE, rendering companies removed deadstock for free. However, rendering companies started charging producers to remove deadstock to offset costs associated with new regulatory requirements enacted by the Canadian Food Inspection Agency, which has resulted in increased on-farm natural disposal of deadstock. This increase has ecological implications because deadstock are a major attractant for large carnivores. Carnivores feeding on deadstock are often near other agricultural attractants such as stored grain and feed, silage, and living livestock, which can exacerbate conflict potential and pose a risk to human safety. To help mitigate conflicts associated with deadstock, the Waterton Biosphere Reserve's (a local non-profit) Carnivores and Communities Program (CACP) supported expansion of community deadstock removal efforts beginning in 2009, including reimbursement of on-farm removal costs, bear-resistant deadstock bins, and a livestock compost facility (operational 2013–2014). Here, we present an evaluative case study describing the development, implementation, and results of the deadstock removal program, including the compost facility. We tracked the number of head of livestock removed each year, the number of participating landowners, the average cost per head, and total program costs. We also used an online survey to assess participants' perspectives of the deadstock removal program and future needs. To date, the CACP has removed >5,400 livestock carcasses, representing between 15.1 and 22.6% of available carcasses in the program area, and 67.3% of livestock owners indicated they currently use the deadstock removal program to dispose of deadstock. Average cost to compost an animal was significantly less than other removal methods ($36.89 composting vs. $79.59 non-composting, one-tailed t-test, unequal sampling variances: t = 4.08, df = 5.87, p = 0.003). We conclude by discussing both ecological and social implications for deadstock removal as a conflict mitigation measure and make suggestions for future management considerations.

Coexistence with Large Carnivores Supported by a Predator-Compensation Program

Compensation programs are used globally to increase tolerance for and help offset economic loss caused by large carnivores. Compensation program funding comes from a variety of sources, and in Wyoming and Idaho, USA and Alberta, Canada this includes revenue from hunting and fishing license sales. We review the patterns of livestock depredation and compensation costs of Alberta's predator-compensation program, and compare Alberta's program to compensation programs in neighboring Canadian and American jurisdictions. Current compensation costs in Alberta are well below historic levels, but have been rapidly increasing in recent years due to an increase in depredation events coupled with increased cattle prices. That increase has caused push back from Alberta's hunting and fishing community that finances the compensation program, although less than 3.6% of Alberta's license levy dollars are used for predator compensation. Hunting effort in Alberta is highest on the same privately owned lands with livestock depredation problems, suggesting that private lands support habitats for hunted ungulate species as well as carnivores. Although compensation programs do not prevent depredation events themselves, compensation programs effectively can support the maintenance of wildlife habitats on private lands.

American marten respond to seismic lines in northern Canada at two spatial scales

Development of hydrocarbon resources across northwest Canada has spurred economic prosperity and generated concerns over impacts to biodiversity. To balance these interests, numerous jurisdictions have adopted management thresholds that allow for limited energy development but minimize undesirable impacts to wildlife. Used for exploration, seismic lines are the most abundant linear feature in the boreal forest and exist at a variety of widths and recovery states. We used American marten (Martes americana) as a model species to measure how line attributes influence species’ response to seismic lines, and asked whether responses to individual lines trigger population impacts. Marten response to seismic lines was strongly influenced by line width and recovery state. Compared to forest interiors, marten used open seismic lines ≥ 3 m wide less often, but used open lines ≤ 2 m wide and partially recovered lines ≥ 6 m wide similarly. Marten response to individual line types appeared to trigger population impacts. The probability of occurrence at the home range scale declined with increasing seismic line density, and the inclusion of behavioral response to line density calculations improved model fit. In our top performing model, we excluded seismic lines ≤ 2 m from our calculation of line density, and the probability of occurrence declined > 80% between home ranges with the lowest and highest line densities. Models that excluded seismic lines did not strongly explain occurrence. We show how wildlife-derived metrics can inform regulatory guidelines to increase the likelihood those guidelines meet intended management objectives. With respect to marten, not all seismic lines constitute disturbances, but avoidance of certain line types scales to population impacts. This approach provides the ecological context required to understand cause and effect relationships among socio-economic and ecological conservation goals.

Probabilistic neural networks modeling of the 48-h LC50 acute toxicity endpoint to Daphnia magna

Two modeling experiments based on the maximum likelihood estimation paradigm and targeting prediction of the Daphnia magna 48-h LC50 acute toxicity endpoint for both organic and inorganic compounds are reported. The resulting models computational algorithms are implemented as basic probabilistic neural networks with Gaussian kernel (statistical corrections included). The first experiment uses strictly D. magna information for 971 structures as training/learning data and the resulting model targets practical applications. The second experiment uses the same training/learning information plus additional data on another 29 compounds whose endpoint information is originating from D. pulex and Ceriodaphnia dubia. It only targets investigation of the effect of mixing strictly D. magna 48-h LC50 modeling information with small amounts of similar information estimated from related species, and this is done as part of the validation process. A complementary 81 compounds dataset (involving only strictly D. magna information) is used to perform external testing. On this external test set, the Gaussian character of the distribution of the residuals is confirmed for both models. This allows the use of traditional statistical methodology to implement computation of confidence intervals for the unknown measured values based on the models predictions. Examples are provided for the model targeting practical applications. For the same model, a comparison with other existing models targeting the same endpoint is performed.

A 13-week oral toxicity study of senna in the rat with an 8-week recovery period

Senna was administered by gavage to Sprague Dawley rats once daily at dose levels of 0, 100, 300, 750 or 1500 mg/kg for up to 13 consecutive weeks followed by an 8-week recovery period for selected animals. Dose- and treatment-related clinical signs included abnormal feces, which were seen to varying degrees from animals at 300 mg/kg per day and more. Animals receiving 750 or 1500 mg/kg per day had significantly reduced body weight gain (males only) and, related to the laxative properties of senna, increased water consumption and notable changes in electrolytes in both serum and urine. At both the terminal and recovery phase necropsy, an increase in absolute and relative kidney weights was seen for male and female animals receiving 750 and/or 1500 mg/kg per day. A dark discoloration of the kidneys was observed at necropsy along with histopathological changes in the kidneys (slight to moderate tubular basophilia and pigment deposits) at 300 mg/kg and above. However, there were no indications in laboratory parameters of any renal dysfunction. In addition, for all treated groups, minimal to slight hyperplasia was recorded in the forestomach and large intestine. Following 8 weeks of recovery, with the exception of the brown pigment in the kidneys, there were no histopathological abnormalities. Thus, the biochemical and morphological changes seen following 13 weeks of treatment of senna significantly reversed following 8 weeks of recovery.

Glucocorticoids prolong rat sciatic nerve blockade in vivo from bupivacaine microspheres

BACKGROUND

Previous work showed that incorporation of dexamethasone (0.05 weight/weight percentage) into bupivacaine microspheres prolonged blockade by eight to 13 times compared with that produced by bupivacaine microspheres alone. The determinants of dexamethasone's block-prolonging effect were examined and reported here.

METHODS

Polylactic-co-glycolic acid polymer microspheres (65/35) with 75 weight/weight percentage bupivacaine were prepared. Microspheres were injected adjacent to the rat sciatic nerve, and sensory and motor blockade were assessed. A procedure was developed to test drugs for block-prolonging ability in vivo by placing test drugs in the injection fluid along with a suspension of bupivacaine microspheres.

RESULTS

Dexamethasone alone in suspension did not produce blockade, nor did it prolong blockade induced by aqueous bupivacaine. Bupivacaine microspheres (150 mg drug/kg rat weight) produced blockade for 6 to 10 h. Dexamethasone in the suspending solution of microspheres prolonged block by up to five times. Glucocorticoids prolonged block in proportion to glucocorticoid/antiinflammatory potency. The corticosteroid antagonist cortexolone inhibited dexamethasone's blockade-prolonging action. Durations of blockade with or without dexamethasone were unaltered by hydroxyurea-induced neutrophil depletion. Microspheres were extracted from rats at time points ranging from 7 h to 7 days, and residual microsphere dry weight and bupivacaine content were similar in groups of rats injected with either bupivacaine microspheres or bupivacaine microspheres containing dexamethasone, respectively.

CONCLUSIONS

Glucocorticoids prolong blockade from bupivacaine microspheres. The mechanism appears unrelated to the kinetics of bupivacaine release in vivo.

Prolonged regional nerve blockade. Injectable biodegradable bupivacaine/polyester microspheres

BACKGROUND

Biodegradable microspheres are a useful method of drug delivery because they are both injectable and biodegradable, eliminating the need for surgical implantation or removal. Previous work has characterized implantable preparations of local anesthetics in polymer pellets for prolonged regional anesthesia. In this article, the authors characterize injectable suspensions of bupivacaine-polymer microspheres and examine whether they can produce prolonged blockade of the sciatic nerve in rats.

METHODS

Microspheres were prepared using polylactic-co-glycolic acid polymers loaded with 75% w/w bupivacaine by a solvent evaporation method. Bupivacaine release from microspheres was determined in vitro by ultraviolet spectroscopy and scintillation counting. Sensory and motor blockade of the rat sciatic nerve were assessed in vivo after injection of microsphere suspensions.

RESULTS

Depending on the type of microspheres, the dose, and the additive used, mean duration of sciatic nerve block ranged from 10 h to 5.5 days. Incorporation of 0.05% w/w dexamethasone into the microspheres resulted in significant prolongation of block (up to 13-fold), and only preparations that contained dexamethasone produced blocks lasting beyond 1 day. Bupivacaine was released in a controlled manner in vitro. Dexamethasone does not substantially slow bupivacaine release from microspheres in vitro.

CONCLUSIONS

Prolonged percutaneous blockade of peripheral nerves is feasible. The recovery from blockade is complete, and plasma bupivacaine levels are far below the range associated with systemic toxicity. The mechanisms underlying the dexamethasone block-prolonging effect are under investigation.