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Pathology of experimentally-induced, acute toxoplasmosis in macropods   总被引:1,自引:0,他引:1  
SUMMARY Thirteen Tammar wallabies (Macropus eugenii) were dosed orally with 500, 1000 or 10 000 oocysts of Toxoplasma gondii, as part of a vaccination trial. Eleven animals died of acute toxoplasmosis 9 to 15 days after challenge. The lesions were similar in all animals, consisting of foci of necrosis and inflammation in the intestines, lymphoid tissue, adrenal cortex, heart, skeletal muscle and brain, and severe generalised pulmonary congestion and oedema. Free and intracellular tachyzoites of Toxoplasma were associated with the lesions. The remaining 2 animals had shown no signs of disease when euthanased four months after challenge. Small, focal, non-suppurative inflammatory lesions were seen in brain, heart and skeletal muscle of these animals and chronic Toxoplasma infection was confirmed by mouse inoculation.  相似文献   
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Objective To provide serological data to support Australia's claim of freedom from porcine reproductive and respiratory syndrome.
Design A national serological survey was designed to provide 99% confidence of detecting at least one infected pig herd in Australia, assuming that at least 5% of herds would have been exposed to porcine reproductive and respiratory syndrome virus and that at least 25% of the 'finisher' pigs in these herds would have antibodies to the virus.
Procedure A two-stage testing regime was used. All samples were tested with a commercially available enzyme-linked immunosorbent assay. If assay reactions were found, all samples from the herd were to be tested using the indirect immunofluorescence antibody assay.
Results Of the 875 samples from 163 herds from all States in Australia, there was some evidence of reactivity in only four samples from four herds on the enzyme-linked immunosorbent assay. Further testing using the indirect immunofluorescence antibody assay according to the study protocol demonstrated that the reactions were not due to the presence of specific porcine reproductive and respiratory syndrome virus antibodies in the sera.
Conclusion The results of this study support the view that Australian pigs are free of porcine reproductive and respiratory syndrome virus.  相似文献   
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AIM: To obtain an estimate of the incidence of assistance at calving in primiparous (first-calving) beef heifers and the prevalence of breeding heifers at 15 months of age in New Zealand in 2006,and to identify factors contributing to farmers' decisions regarding breeding strategies for heifers, using a survey of beef cattle farmers.

METHODS: A questionnaire was sent to farmers listed in a Massey University database and to members of selected breed societies, as well as published in an industry newspaper; 331 valid responses were received. Information was gathered on the age and number of primiparous heifers, number of heifers assisted, and the importance of various reasons for and against breeding heifers at 15 months of age. Respondents were also required to outline the criteria used for selecting bulls to join with heifers, and the strategies used to manage dystocia in primiparous heifers.

RESULTS: Sixty-five (95% CI=58–71)% of respondents had only 2-year-old primiparous heifers in 2006, whilst a further 11 (95% CI=8–16)% had both 2- and 3-year-old primiparous heifers. The mean reported incidence of assisted calving was 7.0 (95% CI=6.4–7.5)% for 2-year-old primiparous heifers and 1.7 (95% CI=1.2–2.2)% for 3-year-old primiparous heifers. The reported incidence of assistance at calving within individual herdsranged from 0 to 100% for 2-year-old heifers. Respondents with bull-breeding herds most commonly observed their primiparous 2-year-old heifers twice daily, whilst respondents with commercial herds most commonly observed them once daily during calving. The most important reason for breeding heifers at 15 months of age was “increased profit”, whereas the most important reason for not breeding them at that age was “concern about rebreeding performance of 2-year-old heifers”. Estimated breeding value (EBV) for birth weight was the factor considered most frequently when selecting bulls to join with maiden heifers; age of bull and body shape of bull were the next most frequently considered factors. Selection of an appropriate bull was the most common strategy used to manage dystocia in 2-year-old beef heifers.

CONCLUSIONS: The majority of respondents calved their heifers at 2 years of age, and “increased profit” was the primary motivator. Concern about the rebreeding performance of 2-year-old heifers was the most important reason among the remainder of respondents for not breeding heifers at 15 months of age. Dystocia in 2-year-old heifers was “not a problem” or “a minorproblem” in most herds, but there was much variation amongst herds.  相似文献   
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We report the identification and fine mapping of QTL for birth weight (BWT), preweaning ADG (PWADG), and postweaning ADG on feed (ADGF) in a commercial line of Bos taurus using an identical-by-descent haplotype sharing method. One hundred seventy-six calves of 12 bulls (9 to 30 male calves from each sire) of the Beefbooster, Inc., M1 line were typed using 71 genetic markers from bovine chromosomes (BTA) 2, 6, 14, 19, 21, and 23 (8 to 16 markers from each chromosome). Sixteen haplotypes were found to have significant (P <0.05) associations with BWT at the comparison-wise threshold. The 16 haplotypes span 13 chromosomal regions, two on BTA 2 (9.1 to 22.5 cM and 95.0 to 100.3 cM), three on BTA 6 (8.2 to 11.8 cM, 35.5 to 49.7 cM, and 83.0 to 86.2 cM), three on BTA 14 (26.0 to 26.7 cM, 36.2 to 46.2 cM, and 52.0 to 67.7 cM), one on BTA 19 (52.0 to 52.7 cM), two on BTA 21 (9.9 to 20.4 cM and 28.2 to 46.1 cM), and two on BTA 23 (23.9 to 36.0 cM and 45.1 to 50.9 cM). Thirteen haplotypes spanning seven chromosomal regions significantly affected (P <0.05) PWADG at the comparison-wise threshold. The seven chromosomal regions include two regions on BTA 6 (11.8 to 44.2 cM and 83.0 to 86.2 cM), one on BTA 14 (26.7 to 50.8 cM), one on BTA 19 (4.8 to 15.9 cM), one on BTA 21 (9.9 to 20.4 cM), and two on BTA 23 (17.3 to 36.0 cM and 45.1 to 50.9 cM). For ADGF, 11 haplotypes were identified to have significant associations (P <0.05) at the comparison-wise threshold. The 11 haplotypes represented eight chromosomal regions, one on BTA 2 (9.1 to 22.5 cM), two on BTA 6 (49.7 to 50.1 cM and 59.6 to 63.6 cM), two on BTA 14 (17.0 to 24.0 cM and 36.2 to 46.2 cM), two on BTA 19 (52.0 to 52.7 cM and 65.1 to 65.7 cM), and one on BTA 21 (46.1 to 53.1 cM). The QTL regions identified and fine mapped in this study will provide a reference for future positional candidate gene research and marker-assisted selection of various growth traits.  相似文献   
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As genetic markers, SNP are well suited for the development of genetic tests for production traits in livestock. They are stable through many generations and can provide direct assessment of individual animal's genetic merit if they are in linkage disequilibrium and phase with functional genetic variation. Bovine chromosome 5 has been shown to harbor genetic variation affecting production traits in multiple cattle populations; thus, this chromosome was targeted for SNP-based marker development and subsequent association analysis with carcass and growth phenotypes. Discovery of SNP was performed in a panel of 16 sires representing two sires from each of seven beef breeds and two Holstein sires by PCR amplification and sequencing using primers designed from genomic sequence obtained by low-coverage sequencing of bacterial artificial chromosome (BAC) clones. From 550 SNP, 296 (54%) were tentatively identified as having a minor allele frequency >10%. Forty-five SNP derived from 15 BAC were chosen based on minor allele frequency and were genotyped in 564 steers and their sires. Production and carcass data were collected on the steers as a part of the Germplasm Evaluation (GPE), Cycle VII Project at the U.S. Meat Animal Research Center (Clay Center, NE), which involves of the evaluation of sires from seven of the most popular U.S. breeds. Haplotypes based on seven SNP derived from a BAC containing the bovine genes HEM1 and PDE1B were associated with traits related to carcass fat. Steers homozygous for the major haplotype had 0.15 +/- 0.04 cm less subcutaneous fat, 0.57 +/- 0.18 kg less rib fat, 0.18 +/- 0.07 lower yield grade, 1.11 +/- 0.35% less predicted fat yield, and 0.79 +/- 0.3% greater predicted retail product yield than heterozygotes. The frequency of the major haplotype was 0.70 in the steers, and it ranged from 0.44 (Limousin) to 0.98 (Simmental and Gelbvieh) in a panel consisting of an average of 20 purebred sires from each of the seven breeds. A second set of haplotypes based on four SNP derived from a BAC containing the genes NOL1 and CHD4 was associated with Warner-Bratzler shear force. Steers homozygous for the major haplotype had 0.27 +/- 0.11 kg greater shear force than those heterozygous for the major haplotype and one of two minor haplotypes. The frequency of the major haplotype was 0.59 in the steers and ranged from 0.27 (Hereford) to approximately 0.95 (Angus and Red Angus) in the panel of purebred sires. These results demonstrate the feasibility of targeting QTL regions for SNP-based marker development and that a low level of coverage can identify markers associated with phenotypic traits.  相似文献   
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