This paper presents a stochastic simulation model to evaluate the efficacy of regional or national surveys aimed at identifying infection in populations of animals. The process of evaluation involves specification or calculation of cluster-level test sensitivity and specificity, which are derived from two probability distributions of the number of individual-level positive tests expected from non-infected and infected clusters, respectively. Probability distributions for the number of positive clusters expected in a situation of freedom from infection and under various levels of cluster prevalence are specified and used to determine survey properties (the survey being considered a diagnostic system), and ROC curves are drawn. Likelihood ratios allow investigators to state the extent to which a survey result is more likely to be observed if the region or country is infected at a given prevalence than if it is free from infection. The result of a survey carried out to investigate the presence of porcine reproductive and respiratory syndrome (PRRS) in Switzerland is used to illustrate this approach. The model can be adapted to a wide range of survey designs. 相似文献
Increasing fiscal constraints on the government, a lackadaisical performance by public sector animal health and breeding services and pressure from donor partners have prompted the governments of various developing countries to rethink the role of the public sector in the provision of veterinary services. Various countries have started to implement, or have already implemented, privatization of some veterinary services. The results are mixed. It is established that private provision alone is not optimal, and a blend of private and public sector veterinary services is required to utilize the virtues of both.The privatization process has also begun in India. Certain state governments in India are pursuing a cost recovery approach and are encouraging private practitioners to cope with the financial constraints and to deliver broad and effective animal health and breeding services. This paper considers the global aspects of the privatization of veterinary services as well as the scenario in India, so as to gain an insight into the very complex and debatable issue of privatization of veterinary services. 相似文献
Quantitative PCR and visual monitoring of Mycosphaerella graminicola epidemics were performed to investigate the effect of curative and preventative applications of azoxystrobin in wheat field crops. A non-systemic protectant and a systemic curative fungicide, chlorothalonil and epoxiconazole, respectively, were used as references. PCR diagnosis detected leaf infection by M graminicola 3 weeks before symptom appearance, thereby allowing a clear distinction between curative and preventative treatments. When applied 1 week after the beginning of infection, azoxystrobin curative activity was intermediate between chlorothalonil (low effect) and epoxiconazole. When applied preventatively, none of the fungicides completely prevented leaf infection. There was some indication that azoxystrobin preventative treatments may delay fungal DNA increase more than epoxiconazole at the beginning of leaf infection. Both curative and preventative treatments increased the time lapse between the earliest PCR detection and the measurement of a 10% necrotic leaf area. Azoxystrobin only slightly decreased the speed of necrotic area increase compared with epoxiconazole. Hence, azoxystrobin activity toward M graminicola mainly resides in lengthening the time lapse between the earliest PCR detection and the measurement of a 10% necrotic leaf area. Information generated in this way is useful for optimal positioning of azoxystrobin treatments on M graminicola. 相似文献
The effect of buck genetic type and crossbreeding parameters on fertility and prolificacy were estimated using two rabbit sire lines and their reciprocal crosses. The relationship between the reproductive performance of inseminated multiparous does and several semen quality traits was also investigated. The semen characteristics evaluated were: pH (pH), mass and individual motility (MM, IM), percentage of viable spermatozoa (Vi), spermatozoa with normal apical ridge (NAR), normal spermatozoa (NSP), spermatozoa with morphological abnormalities of head (HAP), neck-midpiece (NAP), and tail (TAP), spermatozoa with the presence of proximal (PD) and distal (DD) cytoplasmic droplets.
Fertility was analysed as a continuous trait (kindling rate) or as a binary trait (success or failure of kindling). In the first case, the analysis was performed using GLM procedures of SAS v.8 according to a model that included the fixed factors of buck genetic type, number of ejaculates per pool and week of insemination. In the second case, fertility was analysed using GENMOD procedures of SAS v.8 according to a mixed model including the same fixed factors as before plus the physiological status of the does and the permanent random effect of female. Number of kits born alive and number of stillborn were analysed with MIXED procedures of SAS v.8 with the same model used for the analysis of fertility as a binary trait. Estimates of the estimable functions of crossbreeding genetic parameters of the lines were obtained from the solutions of the corresponding models by generalized least squares using GLM, GENMOD and MIXED procedures. Crossbreeding parameters were estimated according to the model of Dickerson. A linear regression was used to determine the relationship between fertility and litter size and the semen characteristics evaluated.
Significant differences in fertility were observed among buck genetic types, which were favourable to type R. Differences between lines in maternal genetic effects were relevant and favourable to type R for fertility. Individual heterosis was important but unfavourable for fertility.
A slight correlation was obtained between all semen quality traits and fertility and prolificacy. Two multiple models were found for fertility, including NAP, IM, NSP, buck genetic type and Vi in one model or NAR in other model. Individual motility had an important positive effect, while NAP had a small negative effect. When MM, TAP and buck genetic type were included in a multiple model for the number of kits born alive, both MM and TAP had significant small effects. Individual motility and DD appeared to be related to number of kits stillborn, but only DD had a significant although negligible effect. 相似文献
A restricted maximum likelihood analysis applied to an animal model showed no significant differences (P > 0.05) in pH value of the longissimus dorsi measured at 24 h post-mortem (pH24) between high and low lines of Large White pigs selected over 4 years for post-weaning growth rate on restricted feeding. Genetic and phenotypic correlations between pH24 and production and carcass traits were estimated using all performance testing records combined with the pH24 measurements (5.05–7.02) on slaughtered animals. The estimate of heritability for pH24 was moderate (0.29 ± 0.18). Genetic correlations between pH24 and production or carcass composition traits, except for ultrasonic backfat (UBF), were not significantly different from zero. UBF had a moderate, positive genetic correlation with pH24 (0.24 ± 0.33). These estimates of genetic correlations affirmed that selection for increased growth rate on restricted feeding is likely to result in limited changes in pH24 and pork quality since the selection does not put a high emphasis on reduced fatness. 相似文献
The aim of this study was to analyse racing performance data in Irish greyhounds with regard to genetic and environmental variation. Estimation of heritabilities for racing time (RT) and ranking, and the prediction of breeding values for all greyhounds in the investigated data were carried out. Data from 42,785 races in Ireland in the years 2000-2003 were available. These results were obtained from 42,880 greyhounds on 20 race tracks over a distance of 480 m. Three traits were analysed, RT, ranking and a scaled logarithmic function for RT (ART), which was used to adjust racing time to be normally distributed. The data were analysed with a bivariate animal model. The estimated heritabilities were moderate for RT (0.31) and ART (0.38), but very low for ranking (0.10). The repeatabilities were 0.56 (RT), 0.51 (ART) and 0.13 (ranking). The genetic correlations were very high, 0.99 (RT-ranking) and 0.96 (ART-ranking), while the phenotypic correlation was lower, 0.60 (RT-ranking) and 0.62 (ART-ranking). The genetic trend for the traits as well as the phenotypic change of the average RT was positive. 相似文献
The aim of the present study was to determine the physiological responses of transported Red Sokoto goats (RSG) treated with ascorbic acid (AA). Ten RSG treated orally with ascorbic acid served as experimental subjects, while seven goats treated with sterile water served as the control. The goats were transported for 8 h. The ambient temperature and relative humidity during the study period fluctuated between 21 and 38°C and 51 and 91%, respectively, which indicated that the season was thermally stressful and did not favor transportation of goats. The rectal temperature obtained in the control goats was significantly higher (P < 0.01) than the value in the experimental goats after transportation. There was a significant decrease (P < 0.05) in eosinophil counts and an increase (P < 0.01) in neutrophil counts and neutrophil : lymphocyte ratio recorded in the control goats after transportation, which suggested that the control goats were physically and emotionally stressed. The control goats lost 11.9% of their initial liveweight, while the experimental goats lost only 1.04% after transportation. Multiple stresses, including extreme meteorological factors, acted upon the transported goats and impaired their homeostatic mechanism. In conclusion, AA administration in goats reduced the adverse effects of road transportation stress. 相似文献