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1.
A study was designed to provide decision support for health management in growing hogs. A dynamic, stochastic systems model for a confinement, continuous production hog growing enterprise (including nursery, grower and finisher phases) was developed to simulate the economic effects of disease, available floor space and feed additives using farm- specific data. Modeling techniques included: discrete and distributed (continuous) delays; triangular probability density functions; autocorrelation; table look-up functions; an alpha-beta tracker; non-linear, constrained optimization. The model was designed to be initialized with the system's current status, using an accompanying production/financial database to achieve individual-farm specificity. Initialization of rate variables required ‘reverse optimization’ of historical system performance. Model predictions are based on an adjustment approach, where changes in current performance are dictated by changes in disease rates, available floor space and feed additive use. These effects vary randomly, but are autocorrelated between production phases, between similar diseases and over time.  相似文献   

2.
Salmonella in the mesenteric lymph nodes of healthy sows and hogs   总被引：1，自引：0，他引：1  
Mesenteric lymph nodes were collected from healthy sow and slaughter hogs that had been kept in holding pens for an average of 10 and 2 days, respectively, before slaughter at an abattoir. Salmonella was isolated from 58.2% (67/115) of the sows and 31.3% (16/51) of the slaughter hogs. This difference in Salmonella prevalence was significant (chi 2 = 10.22, P less than 0.005); therefore, the hypothesis that there would be no significant difference in the infection rates of sows and slaughter hogs was rejected.  相似文献   

3.
An information management system is described that combines information on physical, biological and financial aspects of market hog production. Data collection methods are described. Data on feed use were the most difficult to collect reliably on-farm. Off-farm, it was critical that health data at slaughter be obtained without disrupting normal hog marketing routines. A summary of diseases observed in market hogs at slaughter is provided. Sample size estimations to achieve statistical confidence in market hog disease prevalence rates at slaughter are presented for number of shioments per farm per year and number of hogs per shipment. Results indicate that slaughter health checks should be performed at least four times annually and at least 50 hogs should be evaluated per shipment. Recommendations for future efforts include decreasing the total amount of data to be collected and improving producer incentives to collect data.  相似文献   

4.
Digests of diaphragms from 33 482 hogs slaughtered in the mid-atlantic states were examined for the presence of Trichinella spiralis larvae. The samples were obtained from 7 slaughterhouses, ranging in slaughter capacity from less than 50 per day to more than 4000 per day. The sources of the hogs varied from “backyard” operations, raising hogs for home use, to commercial farms. The means by which hogs were brought to the slaughterhouse also differed; the larger slaughterhouses often purchased directly from the producer while the smaller slaughterhouses (1000 hogs per day or less) usually purchased through dealers or brokers. Infected hogs were detected more frequently than was expected from previously-published prevalence studies; overall, 0.58% of samples examined contained T. spiralis larvae. All of the infected hogs were marketed through the smaller slaughterhouses (less than 1000 per day) and nearly all were marketed through brokers. The mean number of larvae per gram of diaphragm, determined by slaugterhouses type, ranged from 0.5 to 74.6; most infections were light although 5 had counts of 1000–2480.Most of the positive samples were obtained from one slaughterhouse, the data from which exhibited marked differences in the frequency of infection by day of the week; 128 positive samples of the total of 190 found were obtained on Fridays, although only 10% of all samples were obtained on that day. Analysis of the geographic origin of shipments containing infected hogs revealed that most originated in New Jersey and Pennsylvania, although the hogs shipped from the latter state might originated in New England or Maryland. Attempts to trace back infected hogs for further epidemiological investigation were largely futile, owing to the absence of an identification system.  相似文献   

5.
The levels of production, ascarid burden and respiratory disease were measured on 15 purposively selected swine herds, and the relationships between the various measures of ascarid burden were examined. On each farm 30 randomly selected pigs were weighed and rectal fecal samples were collected at approximately 11, 15, 19 and 22 weeks of age, and at slaughter. Fecal ascarid-egg counts and duration of infection were combined to calculate a composite measure of ascarid burden called "lifetime burden". At the abattoir the carcass weight and levels of anteroventral pneumonia, atrophic rhinitis, and liver lesions were recorded for each hog. The number of ascarids in the small intestines were counted. Study hogs were marketed at an average of 189 +/- 22 days. The average dressed carcass weight was 77.0 +/- 5.9 kg and the mean average daily gain was 0.519 +/- 0.071 kg/day. The percent of hogs with ascariasis varied widely among farms, no matter what measure of ascariasis was used; the percent with intestinal ascarids at slaughter ranged from 0% to 96%, the percent that shed ascarid eggs during their lifetime ranged from 0% to 100%, and the range for hogs with liver lesions ranged from 27% to 100%. Of the hogs slaughtered, 82% had milk spot lesions, 32% shed ascarid eggs during their lifetime and 35% had intestinal ascarids. The latter had an average of 12 intestinal ascarids. Anteroventral pneumonia occurred in 55% of the slaughtered hogs and 9% had atrophic rhinitis scores of five. The percent of hogs per farm with pneumonia ranged from 17% to 96%. The percent of hogs per farm with atrophic rhinitis scores of five ranged from 0% to 57%.  相似文献   

6.
The following data on ascarid burden were collected on an individual basis for 380 hogs marketed in the fall of 1987: a series of fecal ascarid-egg counts during the growing period; the level of milk spot lesions on the liver at slaughter; and the number of ascarids in the small intestines at slaughter. The presence of milk spots had a high sensitivity, very low specificity, and a high negative predictive value as a screening test for ascariasis in individual hogs. Results were consistent whether ascariasis was measured as the presence of intestinal ascarids at slaughter (sensitivity 91%, specificity 22%, negative predictive value 82%), or by a positive fecal egg count during the hog's lifetime (sensitivity 96%, specificity 24%, negative predictive value 93%). The presence of milk spots does not necessarily indicate that an ascarid infection has been established in the small intestine. The absence of milk spots, however, is a reliable indicator of the absence of an established ascarid infection, provided that the prevalence of ascariasis is equal to or less than that observed in this study. The severity of the ascarid infection in an individual hog could not be ascertained by the number of milk spot lesions on the liver.  相似文献   

7.
Records of a California abattoir were reviewed for the 46-month period August 1977 through May 1981, and data were collected for 23 ranches which only marketed hogs born and raised in California. Passed for cooking (PFC) rates (per 100 000 animals slaughtered) due to lymph node lesions listed as TB (mycobacteriosis) by inspectors were roasters (32–50 kg) 0, market hogs (82–105 kg) 243, and sows (> 145 kg) 125. Effective exposure to disease-causing factors seemed to have taken place at 2–3 months of age or earlier. Time series analysis of hog PFC rates for the 23 California ranches combined demonstrated statistically significant, regular cycles of 6 and 24 months duration with seasonal peaks of PFC rates in June and December. Based on an estimated incubation period of 4–6 months, animals were at greatest risk of effective exposure to factors associated with lymph node lesions during the periods December–February and June–August.  相似文献   

8.
A survey of anteroventral (AV) lung lesions, pleuritis and serology for Mycoplasma hyopneumoniae (MH) and Actinobacillus pleuropneumoniae (AP) was conducted on a minimum of 25 slaughter hogs from each of 18 randomly sampled Prince Edward Island farms (producing over 1,000 market hogs per year). The data were analyzed to evaluate the potential role of these two agents as risk factors for the two conditions, using crude and multivariable techniques, as well as individual and herd data. Anteroventral lung lesions were present in 50.5% of hogs at slaughter, and pleuritis was present in 15.4% of the hogs. Least squares multivariable regression was used to analyze the simultaneous ability of MH, AP and MH/AP interaction to predict the herd prevalence of AV lung lesions. Only MH was associated with AV lung lesions (p = 0.035). In spite of this statistical significance, MH accounted for only 53% of the herd variation in prevalence of lung lesions (R2 = 0.529). As well, some herds maintained very low levels of lung lesions despite moderate (up to 30%) prevalence of MH. Discrepancies between the analytic techniques suggested herd-level factors play an important role in the development of lung lesions. Pleuritis did not appear to be associated with either of the agents studied (p = 0.478).  相似文献   

9.
Effect of atrophic rhinitis on growth rate in Illinois swine herds   总被引：4，自引：0，他引：4  
Influence of atrophic rhinitis (AR) on mean daily weight gain (MDG) was studied in hogs randomly selected from 7 farrow-to-finish herds in Illinois. Herds were selected to obtain a wide range of clinical signs and lesions of the disease; thus, prevalence of clinical signs of AR in finishing hogs ranged from 0% to 20% among herds, and in hogs examined at slaughter the proportion of hogs with turbinate lesions ranged from 5% to 92%. None of the herds investigated had any obvious problems with pneumonia; nevertheless, hogs with moderate to severe pneumonic lesions were excluded from the study, to minimize any combined effect of AR and pneumonia. In 3 herds, MDG in AR-free pigs was 15% to 18% better than in pigs with severe AR lesions. Prevalence of clinical signs ranged from 5% to 20%, and of turbinate lesions, from 66% to 92%. In 4 herds in which MDG appeared to be unaffected by AR, prevalence of clinical signs of the disease ranged from 0% to 5%, and of turbinate lesions, from 5% to 74%. No consistent pattern of influence on AR lesions was found for bacterial infections, as determined by culturing of nasal swab specimens on MacConkey agar and blood agar.  相似文献   

10.
A prospective study was conducted to assess the effect of introduction of piglets from farrow-to-finish farms on the global performance of all-in all-out fattening batches in Galicia (NW Spain). Two hundred and thirty-nine fattening batches from 48 fattening farms integrated in a cooperative were used in the study. All-in all-out fattening batches were classified according to the category of farm that supplied the piglets. Origin F was a fattening batch where all feeder piglets came from one or more farrow to feeder units versus origin FF, in case a group of piglets or all piglets of the batch came from farrow-to-finish farms. Productive parameters of fattening batches included in the study were recorded. Crude comparisons of performance of 37 fattening batches from origin F and 202 from origin FF were made. Mixed multiple linear regression models were used to assess the association between type of origin of feeder piglets and the following parameters: feed consumed per market hog, percentage of deaths (mortality) and time to slaughter. In all models, variables with presumable relationships with the outcomes were offered to the models as well as the biologically plausible interaction terms.

Mortality was higher in fattening batches with piglets coming from farrow-to-finish farms (0.67% higher than origin F; P < 0.05). Time to slaughter was longer when feeder piglets were from origin FF (3.1 days longer; P < 0.05).

We found a significant effect of type of origin on feed consumed per marketed hog. Additionally, a significant interaction was found: feed consumed per marketed hog was higher for fattening batches with all piglets from farrow-to-finish farms if slaughtered before 109 days and vice versa. A Monte Carlo simulation model was used to assess the economic impact of using origin F or FF as source of piglets. Results of the model indicated that the difference in expected profit per marketed hog between the types of sources of piglets was small (€11.50, S.D. 1.79 for origin F versus €10.44, S.D. 2.72, for origin FF).  相似文献   


11.
A bioeconomic model was developed and used to evaluate economic implications of embryo transfer for steer production. Sensitivity analysis indicated that the net returns were strongly influenced by pregnancy and growth rates. Matching of recipient and embryo sizes reduced dystocia prevalence and resulted in as much as a $98 saving per transfer in costs associated with dystocia. Optimal weight and age and net returns at slaughter were found to be a function of mature size and growth rate. Varying growth rates resulted in optimal slaughter weight and net present value (NPV) ranging from 403 to 494 kg and $156 to $273, respectively, for medium-sized steer genotypes characterized by a mature size of 600 kg. The optimal slaughter weight ranged from 456 to 607 kg and NPV from $182 to $344 for large-sized steer genotypes characterized by a mature size of 750 kg. The results showed that high pregnancy rates and embryos with high growth rates generated the greatest profitability from investment in embryo transfer. The model has a wide potential application in formulating optimal biological and economic strategies for matching embryo genetic resources to physical and economic environments for commercial beef production.  相似文献   

12.
Three slaughter checks were performed for each of 21 swine producers at 6-month intervals. Two slaughter checks were performed during the winter, and 1 slaughter check was performed during the summer. Lesions of atrophic rhinitis and pneumonia were evaluated during the slaughter checks. Two types of farrowing facilities and 4 types of grower/finisher facilities were used by the swine producers. Lesions of atrophic rhinitis and pneumonia were compared among seasons and among types of facilities. Lesions of both atrophic rhinitis and pneumonia varied with season. Lesions of atrophic rhinitis were more severe among hogs slaughtered in the summer, whereas lesions of pneumonia were more severe among hogs slaughtered in the winter. Lesions of atrophic rhinitis were more severe in hogs farrowed in central, enclosed farrowing houses and finished in enclosed, mechanically ventilated buildings than in hogs farrowed individually in sow huts and finished on dirt lots. Knowledge of disease patterns associated with season and facilities is useful for assessment of herd health status and for implementation of control programs.  相似文献   

13.
Often, the prevalence of an infection in the animal-production sector is determined at the group level. The prevalence at animal level (p) gives more-precise information on the infection status of the sector. This paper shows that pooled-sample data together with mathematical models allow for estimation of p. For this, model assumptions have to be made on the variation of p between groups separated in space and/or time. Formulas were derived for four models that were based on different assumptions. Model 1 assumed that p has the same value for all groups. Models 2–4 assumed that some of the groups were not infected. In addition, model 2 assumed that p has the same value for all infected groups; model 3 assumed that for an infected group, p is equal to either p1 or p2; and model 4 assumed that p was Beta distributed among infected groups. The models were applied to data sets on Salmonella infection in broiler flocks, including serotype data dominated by S. Hadar and S. Paratyphi B, var. Java. Based on likelihood-ratio tests, models 3 and 4 consistently fitted significantly better to the data. The applicability of model 4 is numerically bounded, related to the shape of the Beta distribution of p. Model calculations show that flock-level prevalence of Salmonella is much higher after than before slaughter. This difference (which possibly is related to different types of samples) is much smaller at the animal level. An important result of the estimation of p is that it in turn allows for an estimation of the proportion of false-negative groups — which is important in estimating the effect of veterinary or public-health measures.  相似文献   

14.
The performance of indirect fluorescence antibody test (IFAT) for serological diagnosis and screening of lumpy skin disease (LSD) was evaluated using methods without gold standard. Virus neutralization test (VNT) was used as the second test and the study sites were selected from two different geographical places in Ethiopia to get different disease prevalence. The analysis of conditional dependent Bayesian model for the accuracy of IFAT showed that sensitivity, specificity, prevalence of the population Pi1 and the population Pi2 were 0.92 (0.89–0.95), 0.88 (0.85–0.91), 0.28 (0.25–0.32) and 0.06 (0.048–0.075), respectively. The posterior inferences obtained for VNT sensitivity, specificity and conditional correlation between the tests for sensitivity (rhoD) and specificity (rhoDc) were 0.78 (0.74–0.83), 0.97 (0.95–0.99), 0.052 (−0.03–0.15) and 0.019 (−0.01–0.06), respectively. The interval estimation of conditional correlation for both sensitivity and specificity clusters around zero and thus conditional dependence between the two tests was not significant. Although accuracy measure would not be the only basis for test selection, the result of our study demonstrated that IFAT has a reasonable high accuracy to be used for the diagnosis and sero-surveillance analysis of LSD in the target population.  相似文献   

15.
Florida has the largest population of feral swine in the U.S.A. Feral swine have recreational and economic importance to hunters, trappers, taxidermists, and also to dealers who sell feral swine to hunting clubs. Hunters spent over 522 00 man-days hunting feral swine during the 1980–1981 hunting year. They killed nearly 103 000 hogs which they valued at over $58 each, for a total value of nearly $6 million. Trappers caught 25 000 head valued at about $ 700 000, and landowners collected about $1.2 million in hunting lease fees. Taxidermists received about $389 000 in gross income from mounting feral swine. Sales of feral swine to hunting clubs amounted to about $81 000.

Sales of feral swine through commercial livestock auctions were limited to 1620 head valued at only $16 800 in 1980. Thus, feral swine are important to Florida from a recreational standpoint, but not from the perspective of commercial agriculture.

If African swine fever were to enter Florida, there are many socio-economic factors associated with feral swine that must be carefully evaluated for eradication to be successful.  相似文献   


16.
Paratuberculosis is a chronic infection affecting cattle and other ruminants. In the dairy industry, losses due to paratuberculosis can be substantial in infected herds and several countries have implemented national programmes based on herd-classification to manage the disease. The aim of this study was to develop a method to estimate the probability of low within-herd prevalence of paratuberculosis for Danish dairy herds. A stochastic simulation model was developed using the R® programming environment. Features of this model included: use of age-specific estimates of test-sensitivity and specificity; use of a distribution of observed values (rather than a fixed, low value) for design prevalence; and estimates of the probability of low prevalence (PrLow) based on a specific number of test-positive animals, rather than for a result less than or equal to a specified cut-point number of reactors.

Using this model, five herd-testing strategies were evaluated: (1) milk-ELISA on all lactating cows; (2) milk-ELISA on lactating cows ≤4 years old; (3) milk-ELISA on lactating cows >4 years old; (4) faecal culture on all lactating cows; and (5) milk-ELISA plus faecal culture in series on all lactating cows.

The five testing strategies were evaluated using observed milk-ELISA results from 19 Danish dairy herds as well as for simulated results from the same herds assuming that they were uninfected.

Whole-herd milk-ELISA was the preferred strategy, and considered the most cost-effective strategy of the five alternatives. The five strategies were all efficient in detecting infection, i.e. estimating a low PrLow in infected herds, however, PrLow estimates for milk-ELISA on age-cohorts were too low in simulated uninfected herds and the strategies involving faecal culture were too expensive to be of practical interest. For simulated uninfected herds, whole-herd milk-ELISA resulted in median PrLow values >0.9 for most herds, depending on herd size and age-structure. None of the strategies provided enough power to establish a high PrLow in smaller herds, or herds with a younger age-structure. Despite this, it appears as if the method is a useful approach for herd-classification for most herds in the Danish dairy industry.  相似文献   


17.
试验以肌细胞生成素(myogenin,MyoG)基因作为屠宰性状候选基因,以相同饲养条件下13周龄的贵妃鸡为研究对象,采用PCR扩增产物直接测序,检测该基因单核苷酸多态性(single nucleotide polymorphisms,SNPs),并进行MyoG基因SNP位点与屠宰性状的相关性分析。结果发现,在研究群体中检测到4个SNPs位点,存在T-T-A-G、T-T-A-A、C-C-A-G和C-C-G-A共4种单倍型,分别命名为H1、H2、H3和H4,经序列对比,可构建出H1H1、H1H2、H1H3、H1H4和H2H3共5种双倍型,对所定义的5种双倍型与贵妃鸡屠宰性状间进行关联分析,结果均未达到显著水平。  相似文献   

18.
A serological survey was undertaken to determine the prevalence of leptospirosis, and to investigate associations between leptospiral antibody titers, and herd measures of reproduction. Production records and leptospirosis serology were analyzed for 25 slaughter hogs from each of eleven randomly sampled farrow-finish operations on Prince Edward Island. The effect of selected leptospiral serovars on nonproductive sow days per parity (NPSD/P) and the proportion of pigs born dead was evaluated. The four most common serovars to which antibodies were detected were Leptospira icterohaemorrhagiae, L. bratislava, L. autumnalis and L. pomona, with respective prevalences of 57.1%, 35.1%, 3.4% and 1.5% of PEI slaughter hogs. None of these serovars was associated with increased frequency of stillbirths (p greater than 0.05). However, farms with a higher prevalence of L. bratislava antibody titers tended to have more infertility, as measured by NPSD/P (r = 0.738, p = 0.036 with Bonferroni adjustment). Also, farms with L. pomona antibody titers had higher NPSD/P than farms without L. pomona antibody titers (p = 0.0008 with Bonferroni adjustment). There was no association between NPSD/P and antibodies to either L. autumnalis or L. icterohaemorrhagiae (p greater than 0.05).  相似文献   

19.
Eighteen growing Awassi lambs were used in this study to determine the effect of supplementing two levels of yeast and methionine (cyc-methionine) on the trace elements bioavailability, growth rate, and general performance. The lambs were divided to three groups. The dietary treatments were the control diet (C), control diet plus 2 g cyc-methionine/lamb/day (T1) and control diet plus 4 g cyc-methionine/lamb/day (T2).

Lambs fed 2 g/day of cyc-methionine (T1) showed a significantly higher (P < 0.05) copper, zinc, and cobalt concentrations in liver and meat tissues, but not the same trend in kidney. No significant (P > 0.05) effect of time and time × treatment interaction on copper, zinc, cobalt, and manganese concentrations in blood serum, but cobalt and manganese concentration showed significant (P < 0.05) change by time. Moreover, a significantly (P < 0.05) higher total body gain, average daily gain, dressing percentage, and lower feed conversion were detected in lambs from T1 compared with the control and T2 groups.

Feeding 2 g of cyc-methionine to growing lambs increased the net profit by $6.017/lamb and only $3.52/lamb fed 4 g cyc-methionine/day when compared with the control group.

In conclusion, feeding growing Awassi lambs yeast and methionine in a form of cyc-methionine, with a low level of 2 g/day, improve the bioavailability of copper, zinc, and cobalt by growing lambs and their growth performance.  相似文献   


20.
为探究外源褪黑素(MT)在增强烤烟干旱胁迫耐受性中的作用,以耐旱型的‘豫烟6号’和干旱敏感型的‘豫烟10号’为材料,利用15%的聚乙二醇(PEG-6000)模拟中度干旱环境,研究干旱胁迫条件下叶面喷施不同浓度的MT(0,0.1,0.2,0.4mmol·L^-1)对烤烟幼苗的生长、叶绿素含量、光合特性、叶绿素荧光、抗氧化酶活性及活性氧代谢的影响。结果表明:干旱胁迫下外源MT处理可显著增加烤烟幼苗的总根长、总根表面积、根平均直径和根尖数;提高叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、水分利用效率(WUE)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)和光化学猝灭系数(qP),减缓叶片中胞间CO2浓度(Ci)和非光化学猝灭系数(NPQ)的升高,有效减轻干旱胁迫对烤烟幼苗叶片光合作用的气孔限制和非气孔限制;提高叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,增强烟苗的抗氧化性能;降低丙二醛(MDA)含量和O2-^·产生速率,有效缓解干旱胁迫对膜的伤害,增强烟苗耐受性;其中干旱敏感型品种‘豫烟10号’变化幅度大于耐旱型品种‘豫烟6号’;随着外源MT浓度的增加,2个烤烟品种幼苗的生长指标均表现出先升高后降低的趋势,以叶面喷施0.2mmol·L^-1的MT对烟苗生长的促进效果最佳。因此,在干旱胁迫下,叶面喷施适宜浓度的MT能提高烟草幼苗对光能的捕获与转换,增强光合作用,促进烟苗的生长;并能够通过增强烟苗的抗氧化能力,缓解氧化伤害,从而增强烟草幼苗对干旱逆境的适应性,且对干旱敏感型品种‘豫烟10号’的效果更为显著。  相似文献   

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