Allometric scaling of production and life-history variation in vascular plants

A prominent feature of comparative life histories is the well documented negative correlation between growth rate and life span. Patterns of resource allocation during growth and reproduction reflect life-history differences between species. This is particularly striking in tropical forests, where tree species can differ greatly in their rates of growth and ages of maturity but still attain similar canopy sizes. Here we provide a theoretical framework for relating life-history variables to rates of production, dM/ dt, where M is above-ground mass and t is time. As metabolic rate limits production as an individual grows, dM=dt ~M3=4. Incorporating interspecific variation in resource allocation to wood density, we derive a universal growth law that quantitatively fits data for a large sample of tropical tree species with diverse life histories. Combined with evolutionary life-history theory, the growth law also predicts several qualitative features of tree demography and reproduction. This framework also provides a general quantitative answer to why relative growth rate (1/M)(dM/df ) decreases with increasing plant size (~M-1/4) and how it varies with differing allocation strategies

Chemical containment and eradication of screw− worm incursions in Australia

Screwworms are obligate, invasive parasites of warm-blooded animals. The female flies lay batches of eggs at the edge of wounds or other lesions. These eggs hatch to larvae or screw-worms which feed on affected animals for 6-7 days, burrowing deeply into subcutaneous tissues and causing severe trauma to animals, production loss and potentially death. Susceptible sites include wounds resulting from management practices such as castration, de-horning and ear tagging and lesions caused by the activities of other parasites such as buffalo flies and ticks. The navels of the new born and the vulval region of their mothers following parturition are highly susceptible and body orifices such as nose and ears are also frequent targets for ovipositing screwworm flies. The Old World screw-worm, Chrysomya bezziana (OWS) is considered one of the most serious exotic insect pest threatening Australia's livestock industries and is endemic in a number of our closest neighbouring countries. New World screwworm (NWS), Cochliomyia hominivorax, endemic to South America, has also entered Australia on at least 2 occasions. Many tropical and subtropical areas of Australia are suitable for the establishment of OWS and the potential range is expected to increase with climate change. The Australian screwworm preparedness strategy indicates a program of containment with chemical treatments followed by eradication of OWS using sterile male release and parasiticides. However, there is no longer an operational OWS sterile insect screw-worm facility anywhere in the world and establishing a large scale production facility would most optimistically take at least 2 years. In the interim, containment would be almost totally dependent on the availability of effective chemical controls. A review of chemical formulations available for potential use against OWS in Australia found that currently only one chemical, ivermectin administered by subcutaneous injection (s.c.) is registered for use against OWS and that many of the chemicals previously shown to be effective against OWS were no longer registered for animal use in Australia.18 From this review a number of Australian-registered chemicals were recommended as a priority for testing against OWS. The Australian Pesticides and Veterinary Medicines Authority (APVMA) can issue an emergency use permit for use of pesticides if they are registered in Australia for other animal uses and shown to be effective against OWS. This project tested the therapeutic and prophylactic efficacy of chemicals with potential for use in the treatment and control of OWS

Effects of body size and temperature on population growth

For at least 200 years, since the time of Malthus, population growth has been recognized as providing a critical link between the performance of individual organisms and the ecology and evolution of species.We present a theory that shows how the intrinsic rate of exponential population growth, , and the carrying capacity, rmax K, depend on individual metabolic rate and resource supply rate. To do this, we construct equations for the metabolic rates of entire populations by summing over individuals, and then we combine these population-level equations with Malthusian growth. Thus, the theory makes explicit the relationship between rates of resource supply in the environment and rates of production of new biomass and individuals. These individual-level and population-level processes are inextricably linked because metabolism sets both the demand for environmental resources and the resource allocation to survival, growth, and reproduction. We use the theory to make explicit how and why exhibits its characteristic dependence on body size and rmax temperature. Data for aerobic eukaryotes, including algae, protists, insects, zooplankton, fishes, and mammals, support these predicted scalings for. The metabolic flux of energy and materials also rmax dictates that the carrying capacity or equilibrium density of populations should decrease with increasing body size and increasing temperature. Finally, we argue that body mass and body temperature, through their effects on metabolic rate, can explain most of the variation in fecundity and mortality rates. Data for marine fishes in the field support these predictions for instantaneous rates of mortality. This theory links the rates of metabolism and resource use of individuals to life-history attributes and population dynamics for a broad assortment of organisms, from unicellular organisms to mammals

Anaesthetic management of a bovine for ventral midline coeliotomy approach to hysterotomy

An eight-year-old, multiparous Chianina cow presented for the removal of a term, emphysematous calf following a dystocia. Delivery of the calf trans-vaginally intact or piecemeal by fetotomy was impossible due to the partially closed cervix. A midline coeliotomy approach to hysterotomy under general anaesthesia was elected in order to reduce peritoneal spillage of uterine content. This case report aims to discuss the peri-anaesthetic management of the cow, specifically the ventilation strategy, approach to premedication and analgesic protocol.https://wileyonlinelibrary.com/journal/vrc2hj2022Companion Animal Clinical Studie

Transinfection of buffalo flies (Haematobia irritans exigua) with Wolbachia and effect on host biology

Buffalo flies (Haematobia irritans exigua) (BF) and closely related horn flies (Haematobia irritans irritans) (HF) are invasive haematophagous parasites with significant economic and welfare impacts on cattle production. Wolbachia are intracellular bacteria found widely in insects and currently of much interest for use in novel strategies for the area wide control of insect pests and insect-vectored diseases. In this paper, we report the transinfection of BF towards the development of area-wide controls

In-paddock walk-over weighing: understanding the factors affecting its potential for the Australian Sheep industry

The association between liveweight and a range of production and economic outcomes has been demonstrated in sheep production systems. Change in ewe liveweight affects her wool production, reproductive performance, survival and lifelong performance of her progeny. Similarly, liveweight in young sheep post-weaning is strongly associated with their survival. This breadth of sheep production parameters with demonstrated association with liveweight suggests that regular liveweight monitoring would provide a robust and versatile tool for managing sheep flocks. Walk-over weighing (WOW) technology has the potential to remotely monitor sheep liveweight either individually or collectively and is commercially available. It functions by collecting liveweight data as sheep voluntarily cross a weighing platform as part of their normal daily routine. The liveweight data is then collected, processed and interpreted by livestock managers to aid nutritional management. Despite the documented benefits of managing ewe liveweight, and the potential of WOW to aid ewe liveweight management, there is a paucity of literature on the subject. This thesis draws on a series of experiments, data analyses and economic models to investigate the factors affecting WOWs potential for commercial application

Failure to detect equid herpesvirus types 1 and 4 DNA in placentae and healthy new-born thoroughbred foals

Equid herpesvirus type 1 is primarily a respiratory tract virus associated with poor athletic performance that can also cause late gestation abortion, neonatal foal death and encephalomyelopathy. Horizontal transmission is well described, whereas evidence of vertical transmission of equid herpesvirus type 1 associated with the birth of a healthy foal has not been demonstrated. This study sampled a population of Thoroughbred mares (n = 71), and their healthy neonatal foals and foetal membranes, to test for the presence of both equid herpesvirus types 1 and 4 using a quantitative polymerase chain reaction assay. Foetal membrane swabs and tissue samples were taken immediately post-partum, and venous blood samples and nasal swabs were obtained from both mare and foal 8 h after birth. Neither equid herpesvirus type 1 nor equid herpesvirus type 4 nucleic acid was detected in any sample, and it was concluded that there was no active shedding of equid herpesvirus types 1 and 4 at the time of sampling. Consequently, no evidence of vertical transmission of these viruses could be found on this stud farm during the sampling period.This article is based on the MSc thesis of L.J.B. entitled ‘Failure to detect equid herpesvirus type 1 DNA in thoroughbred placentae and healthy new-born foals’. (http://hdl.handle.net/2263/67946)The Wits Health Consortium and a University of Pretoria Postgraduate Bursary. The article processing charges were partially funded by the South African Veterinary Association.http://www.jsava.co.zaam2020Production Animal Studie