Ontogenetic movements of juvenile blacktip reef sharks: evidence of dispersal and connectivity between coastal habitats and coral reefs

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Tests for the depolymerization of polyacrylamides as a potential source of acrylamide in heated foods

This study was conducted to test the possibility that polyacrylamides used in agriculture may contribute to acrylamide formation in heated foods by thermal depolymerization. Two samples of polyacrylamide with low molecular weights of 1.5 and 10 kDa were used to test for in-chain and end-chain depolymerization. They were added as aqueous solutions to filter paper for heating in a drying/dry environment and added to a cooking oil for heating in a fatty environment. The heating conditions were 175 degrees C for 15 and 30 min, respectively. Both regimens were tested in the absence and presence of the redox-active metal ions Fe(III) and Cu(II), and all tests were conducted without the exclusion of atmospheric oxygen. There was no evidence of any significant depolymerization of polyacrylamide to free acrylamide monomer, <0.04%. In fact, residual levels of acrylamide present already in the low molecular weight polymers were seen to fall by 50-80% on heating. Consequently, it is concluded that even if polyacrylamides were to contaminate agricultural crops and foods derived therefrom (which itself is an unproven suggestion), there is no evidence that the polymers would depolymerize on heating of the food to form acrylamide in any significant amount.     

THE OUTDOOR REARING OF AYRSHIRE CALVES ON PASTURE WITH AND WITHOUT SUPPLEMENTARY FEEDING

An experiment conducted in south-west Scotland during 1956 and 1957 to investigate an outdoor method of rearing calves on pasture, with and without supplementary food, is described.
Twenty-four Ayrshire bull calves were put on pasture at 2 weeks of age and received an average of 37 gallons of whole milk up to the time they were weaned at 8 weeks old. Twelve of the calves received no supplementary feeding, but the other twelve each ate 257 lb. of a meal containing oats, linseed cake, flaked maize and fish meal from their 3rd to their 20th week.
The calves were moved around a series of plots (0.4 acre) which yielded an average of 1400 lb. of dry matter per acre at each grazing. The mean crude protein of the herbage dry matter was 17.4% in 1956 and 14.1% in 1957.
The mean daily liveweight-gains of the calves from birth to 20 weeks of age were 1.05 lb. for the unsupplemented calves and 1.14 lb. for the supplemented ones—a non-significant difference, as was also the difference between the mean increases in belly-girth measurements of the two groups.
Parasitic infestation of the two groups was extremely low and 83% of all faeces samples examined contained no worm eggs.
The latest-born calves made the poorest liveweight gains.
The outdoor rearing of calves is discussed.     

An epizootic of bovine ephemeral fever in New South Wales in 2008 associated with long-distance dispersal of vectors

Objective To report the rapid transmission of bovine ephemeral fever ( BEF) virus from north-western New South Wales south to the Victorian border in January 2008 and to present data that suggests an uncommon meteorological event caused this rapid southward dispersal of vectors. Procedure The locations of reported clinical cases, data from sentinel herds and results from a survey of cattle in the southern affected area were examined to delineate the distribution of virus transmission. Synoptic weather charts for January 2008 were examined for meteorological conditions that may have favoured movement of vectors in a southerly direction. Results Cases of BEF and exposure to BEF virus in NSW were confirmed west of the Great Dividing Range, extending from the Queensland border to Finley, on the far North Coast and around the Hunter Valley. A low-pressure system moved south across the state on 18–19 January 2008, preceding the first cases of BEF in the south of NSW by 1–2 days. Conclusion Heavy rainfall in December 2007 provided a suitable environment for vector breeding, resulting in the initiation of and support for continuing BEF virus transmission in north-western NSW. The movement of a low-pressure system south across central western NSW in mid-January 2008 after the commencement of BEF virus transmission in the north-west of the state provided a vehicle for rapid southward movement of infected vectors.     

Effect of breed of cattle on innate resistance to infection with <i>Babesia bovis, B bigemina and Anaplasma marginale

Objective To assess the innate resistance of naive Bos taurus, Bos taurus cross Bos indicus and Bos indicus cattle to virulent Babesia bovis, B bigemina and Anaplasma marginale parasites. Design Groups of 10, pure B indicus, fi B indicus cross,/B indicus cross and pure B taurus steers were infected with virulent B bovis, B bigemina and A marginale parasites. Procedure Sequential infections were carried out by intravenous inoculation of infected blood containing 1 times 10⁸ parasites of B bovis, followed by B bigemina and then A marginale. To assess resistance, measurements were made of parasitaemia, rectal temperature, packed cell volume and the number within a group requiring chemotherapy to control infection. There was a recovery period between each infection. Results Infection with B bovis showed that pure B indicus steers were significantly more resistant to B bovis infection than the other groups, with none of this group requiring treatment. There was no significant difference between fi B indicus cross and/B indicus cross with 30% and 20%, respectively, of steers in these groups requiring treatment. The pure B taurus steers were significantly more affected then those in the other three groups with 80% requiring treatment. Infections of B bigemina produced a mild response in comparison to that of B bovis and none of the steers required treatment. However, the pure B taurus group was significantly more affected than the other three groups for all other measurements. After the A marginale infection, B indicus steers were moderately affected with 50% requiring treatment, whereas 70% of the fi B indicus group, 80% of the /B indicus cross group and 100% of the pure B taurus group required treatment. Conclusions All breeds of cattle, ranging from pure B indicus to pure B taurus may be at risk of severe disease if exposed to virulent A marginale. The results confirm that pure B indicus cattle are relatively resistant to B bovis, but there could be a significant risk of severe mortalities if cross-bred herds are exposed to virulent infection.