Inhibition of alpha-glucosidase in cattle by Castanospermum australe: an attempted phenocopy of Pompe''s disease

Pompe's disease is characterised by an absence of lysosomal alpha-glucosidase, but this enzyme is also inhibited by Castanospermum australe seeds. Four calves were fed C. australe seeds at the rate of 0.15 g/kg body weight for periods from 1 to 4 days. Lymphocyte alpha-glucosidase activity was reduced by at least 90%, with the majority of inhibition occurring within 8 h of dosing. Several weeks elapsed before activity returned to normal. Significant inhibition of muscle alpha-glucosidase occurred and the ratio of plasma alpha-glucosidase activity measured at pH 5.6 relative to that at pH 3.7 was depressed. In an attempt to induce Pompe's disease, 2 calves were dosed with 1.2 g C. australe seed/kg body weight/day for 13 months. Lymphocyte and muscle alpha-glucosidase activities were markedly reduced over the entire period of feeding, but the animals showed no clinical signs of disease. Tissue cells were not vacuolated nor did they show any apparent accumulation of glycogen. Despite significant inhibition of alpha-glucosidase in skeletal and cardiac muscle, liver, kidney and brain, it is suggested that there was sufficient residual enzyme to prevent induction of a phenocopy of Pompe's disease.     

New infection with Corynebacterium pseudotuberculosis reduces wool production

SUMMARY The effect of natural Corynebacterium pseudotuberculosis infection on wool production and quality in sheep was examined in light of evidence that artificial C pseudotuberculosis infection causes wool production loss. A toxin ELISA was used to identify sheep that had been infected with C pseudo tuberculosis. Greasy and clean fleece weights and fibre diameter were compared in infected and uninfected sheep. C pseudotuberculosis infection caused a 3.8 to 4.8% decrease in greasy wool production and a 4.1 to 6.6% decrease in clean wool production. C pseudotuberculosis infection did not affect fibre diameter. The effects of caseous lymphadenitis (the disease caused by C pseudotuberculosis infection) cause an annual loss of about $17 million in wool production to the Australian wool industry.     

The efficacy of ivermectin jetting fluid for control of blowfly strike on sheep under field conditions

SUMMARY Seventeen trials involving 5737 sheep were conducted to test the efficacy of ivermectin jetting fluid (30 ppm in water) for the control of blowfly strike when applied to sheep either by standard hand jetting or through an automatic jetting race. Sheep were observed for up to 14 weeks after treatment and all strikes recorded. The level of fly challenge varied between trials, resulting in strike rates in untreated sheep ranging between 0 and 94%. At 12 weeks after treatment there were 93% fewer strikes in hand jetted sheep and 84% fewer strikes in machine jetted sheep when compared with untreated sheep. At this time point there was a 90%, 86% and 93% reduction in poll, body and breech strikes, respectively, when hand jetting was used, whereas machine jetting reduced poll, body, breech and pizzle strikes by 84%, 81%, 79% and 100%, respectively.     

The Queensland Poisonous Plants Committee: its history and functions

SUMMARY The Queensland Poisonous Plants Committee was established in 1937 with Professor HR Seddon as chairman. It has functioned since that year, interrupted by two periods of inactivity in 1951–9 and 1962–8. Professor Seddon, first Dean of the Queensland Veterinary School, and Dr Selwyn Everist, Queensland Government Botanist after the Second World War, provided the main impetus for committee activities in its early and middle years, respectively. The strength of the body has been its multi-disciplinary approach using contributions from veterinarians, chemists and botanists. The research work of the committee members and their associates has provided most of our current knowledge of the toxins and effects of poisonous plants in Queensland. Much of the information generated is of international significance. In equal partnership with the United States Department of Agriculture, the committee initiated a series of international symposia on plant poisoning of animals, hosting the second. This group held its 4th gathering of world authorities in the field in 1993. The committee's activities have long influenced the veterinary profession in Australia through the close involvement of its members in undergraduate and post-graduate teaching in the Queensland Veterinary School since 1951. The present committee has members from the Departments of Primary Industries, Health, and Environment and Heritage, CSIRO and the University of Queensland.     

Treatment with ivermectin of sarcoptic mange in pigs

Ivermectin injectable solution (1% w/v) was highly effective against Sarcoptes scabiei var suis when administered subcutaneously once to swine at 300 mcg/kg body weight. There were significantly (P < 0.05) fewer Sarcoptes mange mites counted on pigs treated with ivermectin than on untreated pigs at each count up to day 56 after treatment. The results indicate ivermectin should provide an efficient, practical means of control of sarcoptic mange in intensive piggeries.     

The relationship of scrotal circumference to testicular weight in rams

Scrotal circumference (SC), testicular diameter (TD) and testicular weight (TW) were measured at necropsy of 148 Merino rams of varying age (yearling: 110, 2- to 3-year-old: 5, 4-year-old: 28, greater than 7-year-old: 5). These rams, although culled from flocks in north western Queensland for poor conformation or advancing age, had no clinically palpable or gross necropsy lesions of the genitalia. Despite the fact that SC measurement was performed at necropsy on scrota with greatly varying wool cover and its diverse content of plant material (burrs and grass seeds), the correlation of SC with TW was positive, high and significant (r = 0.92, P less than 0.01). This correlation was greater than that between TD and TW (r = 0.91, P less than 0.01) even though both were measured after dissection of the scrotal contents. The clinically convenient SC measurement deserves wider application as an estimate of testicular weight and therefore fertility in rams.     

Pyrrolizidine alkaloidosis of cattle associated with Senecio lautu

Summary Serious incidents of pyrrolizidine alkaloidosis of cattle in 10 herds exposed to the Australian native plant, Senecio lautus (Asteraceae), were seen in central Queensland during 1988–1992. The deaths of 226 cattle were recorded. A mean of 8% of cattle died in affected groups (range 2 to 58%). Sickness and deaths usually occurred some months after access to S lautus. Typically, affected cattle lost body condition to the point of emaciation before dying and had persistent diarrhoea. Some animals developed abnormal behaviour and died after a shorter illness. Liver specimens from affected cattle in all herds contained lesions consistent with pyrrolizidine alkaloidosis. Thin layer chromatography of extracts of blood and liver samples from cattle from 5 herds detected pyrrolic metabolites. The identity of these was confirmed by mass spectroscopy on samples from one herd. Unseasonal autumn and winter rain after a dry summer appeared to favour growth of S lautus at the expense of other pasture species. A subsequent dry period promoted consumption of S lautus and was followed by a cluster of poisoning incidents.     

Differential Expression of IGF Family Members in Heat‐Stressed Embryos Produced In Vitro from OPU‐Derived Oocytes of Nelore (Bos indicus) and Holstein (Bos taurus) Cows

The IGF system is related to embryo quality. We aim to determine the effect of the heat stress on the mRNA expression of IGF1 and IGF2, IGFR1 and IGFR2, IGFBP2 and IGFBP4, and PAPPA in in vitro production (IVP) blastocysts from Nelore and Holstein after ovum pick up (OPU) to better understand the differences between these breeds. Oocytes from four Nelore and seven Holstein were collected in six OPU sessions. Following in vitro maturation and fertilization using six Nelore or Holstein sires, embryos were divided into control (cultured at 39°C) and heat stress (HS; exposed to 41°C for 9 h). Blastocysts were submitted to RNA extraction. The IGF1 expression was higher in blastocysts under HS in both breeds, and the expression of IGFBP2 and IGFBP4 was higher in Holstein blastocysts under HS. The high PAPPA expression and the low expression of IGFBP2 and IGFBP4 are associated with a more efficient degradation of IGFBPs, which results in greater IGF bioavailability in Nelore blastocysts and may contribute to the superior HS tolerance in Nelore, when compared to Holstein.