SUMMARY Tuberculosis was diagnosed in 3 otariid seals found dead on beaches at 3 locations on the south coast of Western Australian between May 1990 and March 1991. This confirms that tuberculosis is present in the 2 native seals (Neophoca cinerea and Arctocephalus forsteri) in Western Australian waters. Mycobacterium sp isolated from the lungs of 2 of the seals were studied to determine the similarity of the strains to each other, to the strains isolated during 1986 from Australian sea lions and New Zealand fur seals kept in captivity at a marine park near Perth, Western Australia, and to a strain isolated in 1988 from a seal trainer who worked with the infected captive seals for 3 years. After restriction endonuclease analysis (REA) with the endonucleases Bst Ell, Bcl I and Pvu II, one of the wild seal strains appeared to have identical DNA fragment patterns to the strains from the captive seals and the seal trainer. The other wild seal isolate had identical REA profiles using Bst EII and Bcl I, but a minor difference was detected using Pvu II. Differences in these isolates were more clearly seen in restriction fragment length polymorphisms after hybridisation with two DNA probes. The secretory protein MPB70, present in M bovis, was not detected in wild seal isolates using sodium dodecyl sulphate polyacrylamide gel electrophoresis and Western blotting techniques. Analysis of protein and DNA fragment profiles indicated that seal tuberculosis isolates form a unique cluster within the M tuberculosis complex. 相似文献
Our understanding of the basis to immunoglobulin formation in cattle has benefited substantially from the application of molecular biology over the past decade. It is now established that both the lambda light chain and heavy chain repertoires are founded upon the frequent expression of single gene families and subgroups of segments which are of conserved sequence. It is likely that a functional kappa locus exists in the bovine genome but this isotype comprises as few as 5% of bovine light chains. Similarly, alternative but non-expressed V(H) gene families are present posing intriguing but unresolved questions about the regulation of immunoglobulin synthesis. The heavy chain frequently bears a third complementarity-determining region which is atypically long but the processes which expand this region of the reading frame and its contribution to the interaction with antigen remain matters of speculation. Opportunities exist to map the major immunoglobulin loci and to define the membership and sequence diversity of the gene families which dominate each repertoire. However, it is already evident that cattle cannot generate significant diversity from rearrangement and junctional imprecision alone. Elucidation of the mechanism(s), dynamics and tissue distribution of immunoglobulin diversification in cattle, thus, remain key challenges in this branch of veterinary immunology. 相似文献
For a number of years, the laying ration fed to the hens at the Canadian Random Sample Egg Production Test has contained foodstuffs of animal origin to the extent of 3 per cent meat meal, 2 per cent fish meal, 1 per cent dried whey and 2 per cent tallow. Recently, over a period of 2 years, this ration was compared with a modification in which all of the animal products except tallow were removed. The proportions of the remaining ingredients in the modified diet were adjusted to keep protein, energy, calcium and phosphorus levels comparable in the two rations.
In the first test year, the modified diet was slightly superior to the control diet in terms of egg numbers, egg weight and egg quality. In the second year, there were no significant differences in these traits between diets. Although 17 strains were tested in the first year, and 14 in the second, no significant strain × ration interactions occurred in any performance trait.
These trials provided no evidence that the laying hen responds to unknown factors contained in animal products. There was also no evidence that the removal of animal products adversely affected protein quality, although dietary protein levels may not have been low enough to reveal such a change. 相似文献
Groups of 8 steers weighing 300–400 kg (660–880 Ib) were rotationally grazed on a ryegrass-dominant pasture for 115 days. The systems compared were zero grazing (Z), field grazing conducted at the same stocking rate (FC), and field grazing conducted at a stocking rate varied with the intention of giving the same liveweight gain per uiimal as zero grazing (FV). Mean daily liveweight gains were: Z, 0.98; FC, 0.78; FV, 0.90 kg/animal (2.2, 1.7 and 20 Ib/animal), and liveweight gains/unit area were in the ratio 100:78:85. Organic-matter intake, measured on four occasions, was, on average, Z, 6.54; FC, 6.18; FV, 687 kg/head daily (14.4, 13.6 and 15.1Ib). From these results it appears that a comparison of zero grazing and field grazing made at the same stocking rate is likely to underestimate the potential of field grazing for beef production from grass. 相似文献