The occurence and toxicity of indospicine to grazing animals

Indospicine is a non-proteinogenic amino acid which occurs in Indigofera species with widespread prevalence in grazing pastures across tropical Africa, Asia, Australia, and the Americas. It accumulates in the tissues of grazing livestock after ingestion of Indigofera. It is a competitive inhibitor of arginase and causes both liver degeneration and abortion. Indospicine hepatoxicity occurs universally across animal species but the degree varies considerably between species, with dogs being particularly sensitive. The magnitude of canine sensitivity is such that ingestion of naturally indospicine-contaminated horse and camel meat has caused secondary poisoning of dogs, raising significant industry concern. Indospicine impacts on the health and production of grazing animals per se has been less widely documented. Livestock grazing Indigofera have a chronic and cumulative exposure to this toxin, with such exposure experimentally shown to induce both hepatotoxicity and embryo-lethal effects in cattle and sheep. In extensive pasture systems, where animals are not closely monitored, the resultant toxicosis may well occur after prolonged exposure but either be undetected, or even if detected not be attributable to a particular cause. Indospicine should be considered as a possible cause of animal poor performance, particularly reduced weight gain or reproductive losses, in pastures where Indigofera are prevalent

Campylobacter fetus subsp. venerealis small animal infection model

Bovine genital campylobacteriosis (BGC), caused by Campylobacter fetus subsp. venerealis (Cfv), is associated with production losses in the Australian meat and dairy industry. The objective of this pilot study was to develop a reliable guinea pig model for BGC abortion to facilitate future studies of Cfv pathogenicity, abortion mechanism and vaccine efficacy. Four groups (A-D) of 5 guinea pigs (1 control per group) at 42 days gestation were inoculated with laboratory isolates of Cfv via intra-peritoneal (IP) injection. Groups A, B, C and D were injected with four different isolates; Q41 at 8.4x107 cfu/ml, 258 at 1x108 cfu/ml, 540 at 1x108 cfu/ml, and 540 at 1.2x104 cfu/ml respectively. Tissues from dams and aborted foetuses were examined using culture and histology. The study was approved by the University of Queensland Animal Ethics Committee. Groups B and C had abortion rates of 100% and 75% respectively within a time period of 19-168 hours while Group A produced no abortions within 7 days of IP injection. The occurrence of Cfv isolated from peritoneum, uterus horns, placental sites, amniotic fluid and foetal stomach content varied. One dam in Group D aborted one foetus. No control animals aborted and Cfv was not isolated in Group D and the controls. Histologicial examination showed tissue changes associated with placentitis, suggesting that Cfv induces inflammation, placental detachment and abortion. Strain virulence variation appears to be present. Intra-peritoneal administration of Cfv to pregnant guinea pigs is a promising small animal model for investigation of BCG abortion