Bovine citrullinaemia: a clinical, pathological, biochemical and genetic study

Calves affected with citrullinaemia are clinically normal immediately after birth. In the majority of calves the clinical course of the disease was similar. Within 24 hours of birth they become depressed; then within 3 to 4 days were observed to wander aimlessly or stand with their head pressed against a wall or fence. By day 4 to 5 they become recumbent, developed convulsions, followed by collapse and death. Oedema of the cerebral cortex is a consistent histological lesion. Citrulline concentration in blood, cerebrospinal fluid, eye fluid and cerebral tissue is greatly elevated. Information gathered from pedigrees of affected calves indicate that the defect is widely disseminated throughout the Australian Friesian population.     

Practical aspects of the estimation of the time of ovulation and of insemination in the bitch

The aims of this study were to assess the precision of the estimates of the time of ovulation derived by various methods, and to define the most appropriate methods for the determination of the optimal time for insemination of bitches with fresh semen (artificial insemination or natural mating), or with frozen-thawed semen. In 11 Labrador bitches, ovulation was estimated (plasma LH surge + 48 h) to occur 9 to 20 d after the start of the cycle, 0 to +4 d after the onset of positive postural reflexes (2 bitches showed no positive postural reflexes), -4 to +7 d after reaching a vaginal cytological eosinophilic index (EI) of 100%, over a range of 2.5 to 5.5 d based on plasma progesterone concentrations of 4 to 10 ng/ml, over a range of 2 to 3 or 4 d based on 2 indirect methods of estimating the time of the plasma LH surge from plasma progesterone concentrations. Assuming fertilisation occurs 2 to 3 d after ovulation, these findings indicate that for fresh semen (with an estimated lifespan of greater than 4 days) an appropriate procedure would be to inseminate/mate on the day after the onset of positive postural reflexes; then 3 days later. For bitches not showing positive postural reflexes, insemination should occur when the vaginal EI = 90% and then each 3 d until day 1 of dioestrus (D1). For frozen-thawed semen (with a lifespan of less than 24 h) insemination should occur 4 to 5 d after the plasma LH surge.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rhinocerebral and nasal zygomycosis in sheep caused by Conidiobolus incongruus

The clinical findings, pathology and mycology of a cluster of 5 ovine cases of rhinocerebral and nasal zygomycosis caused by Conidiobolus incongruus are described. All cases were in Border Leicester or Merino x Border Leicester ewes from a flock pastured in a low-lying paddock adjoining a small tidal river in subtropical Queensland (latitude 28 degrees S). These cases of zygomycosis are believed to be the first infections due to C incongruus recorded in animals other than humans. The disease was subacute in 4 animals with a course of up to several weeks. In these, the primary site of infection was the posterior nasal cavity. The lesions extended to the dorsum of the face between the eyes, to the orbital cavity and to the anterior brain and meninges in the cranial cavity. In one animal, where the anterior nasal cavity was affected and iodine treatment used, the course was longer. The fungal granulomas had numerous foreign body giant cells, neutrophils and eosinophils. Fungal hyphae were thin walled, 6 to 8 microns in diameter, with occasional septa and irregular branching. They were cuffed with a wide zone of necrotic cell coagulum, or with homogeneous eosinophilic Splendore-Hoeppli granules.     

Resistance to synthetic pyrethroids in South Australian populations of sheep lice (Bovicola ovis)

SUMMARY Lice were collected from 71 flocks detected as Infested at market Inspection in 1990 and 1991, from 16 flocks where resistance was suspected and from 31 flocks from Kangaroo Island. Susceptibility to cypermethrin was measured by a treated surface technique and survival of lice at 5 ppm or greater was taken as an indication of resistance. The prevalence of resistance was 34% in louse populations from the market inspection sample, 50% in flocks in which resistance was suspected and 68% in flocks from Kangaroo Island. Most resistance factors were in the range 1 to 20 although one louse population with a resistance factor of 91 was found on Kangaroo Island.     

When less is more: heterogeneity in grass patch height supports herbivores in counter-intuitive ways

Herbivores are an integral part of the African landscape and have evolved with the vegetation to create the savanna landscape. Managers of these landscapes can benefit from a better understanding of how indigenous herbivores use the landscape to which they are adapted. In this study we observed which patches were frequently utilised, by doing regular monthly road counts, grass height observations and dung counts on selected short grass patches in the Kruger National Park. Smaller-framed impala and blue wildebeest (meso-herbivores) were most regularly seen on these nutritious patches, while from dung deposits it was clear that the even larger-framed buffalo (mega-herbivores) spent time there. This preference can be explained by considering the nutritional needs and food intake of the herbivores. Smaller-framed herbivores seem to be able to satisfy their dietary requirements on the high-quality forage patches, while larger-framed herbivores seem to supplement the quality forage by also spending foraging time on areas of higher grass biomass. From this insight we propose that range management should take herbivore preferences into account and allow herbivores to select and concentrate their foraging on the most nutritious forage. This approach is likely to decrease inputs while allowing animals to maintain or increase production.