Association between days post-conception and lactation persistency in dairy cattle.

Determining the optimal insemination moment for individual cows is complex, particularly when considering the effects of pregnancy on milk production. The effect of pregnancy on the absolute milk yield has already been reported in several studies. Currently, there is limited quantitative knowledge about the association between days post-conception (DPC) and lactation persistency, based on a lactation curve model, and, specifically, how persistency changes during pregnancy and relates to the days in milk at conception (DIMc). Understanding this association might provide valuable insights to determine the optimal insemination moment. This study, therefore, aimed to investigate the association between DPC and lactation persistency, with an additional focus on the influence of DIMc. Available milk production data from 2005 to 2022 were available for 23,908 cows from 87 herds located throughout the Netherlands and Belgium. Persistency was measured by a lactation curve characteristic decay, representing the time taken to halve milk production after peak yield. Decay was calculated for 8 DPC (0, 30, 60, 90, 120, 150, 180, and 210 d after DIMc) and served as the dependent variable. Independent variables included DPC, DIMc (≤60, 61-90, 91-120, 121-150, 151-180, 181-210, >210), parity group, DPC × parity group, DPC × DIMc, and variables from 30 d before DIMc as covariates. The results showed an increase in decay, which is to say, a decrease in persistency, during pregnancy for both parity groups, albeit in different ways. Specifically, from DPC 150 to DPC 210, multiparous cows showed a greater decline in persistency compared with primiparous cows. Furthermore, a later DIMc (cows conceiving later) was associated with higher persistency. Except for the early DIMc groups (DIMc <90), DIMc does not affect the change in persistency by gestation. The findings from this study contribute to a better understanding of how DPC and DIMc during lactation influence lactation persistency, enabling more informed decision-making by farmers who wish to take persistency into account in their reproduction management.

Transmission dynamics of lumpy skin disease in Ethiopia.

Lumpy skin disease (LSD) is a severe disease of cattle caused by a Capripoxvirus and often caused epidemics in Ethiopia and many other countries. This study was undertaken to quantify the transmission between animals and to estimate the infection reproduction ratio in a predominantly mixed crop-livestock system and in intensive commercial herd types. The transmission parameters were based on a susceptible-infectious-recovered (SIR) epidemic model with environmental transmission and estimated using generalized linear models. The transmission parameters were estimated using a survival rate of infectious virus in the environment equal to 0·325 per day, a value based on the best-fitting statistical model. The transmission rate parameter between animals was 0·072 (95% CI 0·068-0·076) per day in the crop-livestock production system, whereas this transmission rate in intensive production system was 0·076 (95% CI 0·068-0·085) per day. The reproduction ratio (R) of LSD between animals in the crop-livestock production system was 1·07, whereas it was 1·09 between animals in the intensive production system. The calculated R provides a baseline against which various control options can be assessed for efficacy.

Temporal and spatial distribution of lumpy skin disease outbreaks in Ethiopia in the period 2000 to 2015.

BACKGROUND: Lumpy skin disease (LSD) is an infectious viral disease of cattle caused by a virus of the genus Capripoxvirus. LSD was reported for the first time in Ethiopia in 1981 and subsequently became endemic. This time series study was undertaken with the aims of identifying the spatial and temporal distribution of LSD outbreaks and to forecast the future pattern of LSD outbreaks in Ethiopia. RESULTS: A total of 3811 LSD outbreaks were reported in Ethiopia between 2000 and 2015. In this period, LSD was reported at least once in 82% of the districts (n = 683), 88% of the administrative zones (n = 77), and all of the regional states or city administrations (n = 9 and n = 2) in the country. The average incidence of LSD outbreaks at district level was 5.58 per 16 years (0.35 year-1). The incidence differed between areas, being the lowest in hot dry lowlands and highest in warm moist highland. The occurrence of LSD outbreaks was found to be seasonal. LSD outbreaks generally have a peak in October and a low in May. The trend of LSD outbreaks indicates a slight, but statistically significant increase over the study period. The monthly precipitation pattern is the reverse of LSD outbreak pattern and they are negatively but non-significantly correlated at lag 0 (r = -0.05, p = 0.49, Spearman rank correlation) but the correlation becomes positive and significant when the series are lagged by 1 to 6 months, being the highest at lag 3 (r = 0.55, p < 0.001). The forecast for the period 2016-2018 revealed that the highest number of LSD outbreaks will occur in October for all the 3 years and the lowest in April for the year 2016 and in May for 2017 and 2018. CONCLUSION: LSD occurred in all major parts of the country. Outbreaks were high at the end of the long rainy season. Understanding temporal and spatial patterns of LSD and forecasting future occurrences are useful for indicating periods when particular attention should be paid to prevent and control the disease.

Association between Dictyocaulus viviparus status and milk production parameters in Dutch dairy herds.

The objective of this study was to estimate the association between Dictyocaulus viviparus bulk tank milk (BTM) test results and milk production and milk composition parameters in adult Dutch dairy cattle herds. Bulk tank milk samples were collected in August and November 2013, and ELISA tests were performed. Two hundred BTM positive (BTM+) and 200 BTM negative (BTM-) herds were selected based on their BTM test result of November 2013, obtained from a list of farms that participated in the Dutch GD Animal Health voluntary monitoring program for controlling nematode infections. The relationship between D. viviparus BTM status and 3 production parameters (milk production, milk fat %, and milk protein %) in summer (June to August 2013) and autumn (September and October 2013) was investigated using generalized linear mixed models. Production data were available for 126 BTM- herds and 109 BTM+ herds. Results showed that a positive D. viviparus status was associated with decreased milk production (June: -1.01, July: -1.19, August: -1.68, September and October: -1.33kg/cow per d). Milk fat percentage was 0.14% and 0.08% lower during summer and autumn, respectively, in BTM+ herds. No significant association was demonstrated between a positive BTM test result and milk protein percentage. Because a strong correlation was present between the BTM status for D. viviparus and that for Ostertagia ostertagi, these losses cannot be attributed to one of the two parasites. However, it is clear that these parasite infections have a considerable effect on production.

Evaluation of selected risk factors for different stages of digital dermatitis in Dutch dairy cows.

Digital dermatitis (DD) is a painful infectious disease in dairy cattle that causes ulcerative lesions of the skin just above the coronary band, mainly of the hind legs. Estimates for DD prevalence at cow level in the Netherlands range from 20% to 25%. In this study, risk factors for the various stages of DD were identified and quantified. The hind legs of 6766 cows on 88 farms were scored by trained interns, using the M-scoring system (M0-M4.1). Farms in this study were a convenience sample, based on the prevalence of DD as recorded at the latest herd trim, geographical location and willingness of the farmers to participate. A survey with questions about cow environment and herd management was conducted by the intern at the day of scoring. The data were collected between August 2017 and January 2018. DD was found on 38.6% of the scored legs; 49.8% of the cows had DD on at least one leg and M4 was the most frequent stage (20.9%). Not removing manure on a regular basis resulted in lower odds for M2, M4 and M4.1 compared to cleaning by automatic scrapers ten times a day or more (odds ratio [OR]= 0.16, 0.49 and 0.18, respectively). The odds for M2 and M4 lesions were higher in cows aged 3-5 years than in first-calved cows (OR> 1.5 and > 1.7, respectively). Rubber flooring in the passageways resulted in lower odds for both M1 and M2 (OR, 0.06 and 0.32, respectively). Prophylactic use of footbaths treatment with an alternative active compound resulted in significant higher odds for M4 lesions than formalin and a combination of formalin and copper sulphate (OR= 1.69 and 2.04 respectively). The odds for an M4.1 lesion were lower in cows from smaller herds (n = 50-100) compared to large herds (n >100; OR= 0.67).

Genome-wide association study of insect bite hypersensitivity in Dutch Shetland pony mares.

Insect bite hypersensitivity (IBH) is the most common allergic disease present in horses worldwide. It has been shown that IBH is under genetic control, but the knowledge of associated genes is limited. We conducted a genome-wide association study to identify and quantify genomic regions contributing to IBH in the Dutch Shetland pony population. A total of 97 cases and 91 controls were selected and matched on withers height, coat colour and pedigree to minimise the population stratification. A blood sample was collected from participating Shetland pony mares, their IBH phenotype was scored and the owner filled in a questionnaire. A total of 40 021 single-nucleotide polymorphisms (SNPs) were fitted in a univariable logistic model fitting an additive effect. Analysis revealed no effects of population stratification. Significant associations with IBH were detected for 24 SNPs on 12 chromosomes [-log(10) (P-value) > 2.5]. Odds ratios of allele substitution effects of the unfavourable allele were between 1.94 and 5.95. The most significant SNP was found on chromosome 27, with an odds ratio of 2.31 and with an allele frequency of the unfavourable allele of 0.72 in cases and 0.53 in controls. Genome-wide association studies on additional horse populations are desired to validate the identified associations, to identify the genes involved in IBH and to develop genomic tools to decrease IBH prevalence.

Relationship between ambient temperature at sampling and the interferon gamma test result for bovine tuberculosis in cattle.

Bovine tuberculosis (bTB) is a disease of significant economic and zoonotic importance, therefore, optimising tests for the identification of Mycobacterium bovis infected cattle is essential. The Interferon Gamma (IFN-γ) Release Assay (IGRA) can diagnose M. bovis infected cattle at an early stage, is easy to perform and can be used alongside skin tests for confirmatory purposes or to increase diagnostic sensitivity. It is known that IGRA performance is sensitive to environmental conditions under which samples are taken and transported. In this study, the association between the ambient temperature on the day of bleeding and the subsequent IGRA result for bTB was quantified using field samples from Northern Ireland (NI). Results of 106,434 IGRA results (2013-2018) were associated with temperature data extracted from weather stations near tested cattle herds. Model dependent variables were the levels of IFN-γ triggered by avian purified protein derivative (PPDa), M. bovis PPD (PPDb), their difference (PPD(b-a)) as well as the final binary outcome (positive or negative for M. bovis infection). IFN-γ levels after both PPDa and PPDb stimulation were lowest at the extremes of the temperature distribution for NI. The highest IGRA positive probability (above 6%) was found on days with moderate maximum temperatures (6-16 °C) or moderate minimum temperatures (4-7 °C). Adjustment for covariates did not lead to major changes in the model estimates. These data suggest that IGRA performance can be affected when samples are taken at high or low temperatures. Whilst it is difficult to exclude physiological factors, the data nonetheless supports the temperature control of samples from bleeding through to laboratory to help mitigate post-collection confounders.

Effects of flooring and restricted freestall access on behavior and claw health of dairy heifers.

Claw health, locomotion, feed intake, milk yield, body weight, activity, and lying and standing behavior of dairy heifers were monitored in a single dairy herd during the first 3 mo after calving. During the first 8 wk after calving, 2 treatments were applied: restricted freestall access by closing the stalls between 2300 h and 0500 h (yes or no) and alley flooring (concrete or rubber topped slatted floors). Apart from treatments, housing was identical. The animals were kept in small groups (n=4 to 6) in adjacent barn pens. Thereafter, the animals were kept in 1 group in a freestall section with concrete slatted floor and unrestricted access to the stalls for 5 wk. All animals were fed the same partial mixed ration. We hypothesized that (1) hard flooring causes high mechanical load of the claws and (2) restricted freestall access causes prolonged standing bouts and reinforced effects of hard flooring on claws. The heifers had only minor claw lesions before first calving, and the prevalence and severity of sole hemorrhages increased during the first 3 mo after calving (from 0.24 ± 0.08 to 1.18 ± 0.14 and from 0.04 ± 0.01 to 0.24 ± 0.02, respectively), particularly in the outer hind claws. Animals kept on rubber alley flooring had lower average hemorrhage scores in wk 9 (0.13 ± 0.03 vs. 0.21 ± 0.03) and wk 14 (0.20 ± 0.03 vs. 0.27 ± 0.03) after calving, had a slower feed intake (3.05 ± 0.14 vs. 3.46 ± 0.14 g/s) and spent more time feeding (7.3 ± 0.3 vs. 6.6 ± 0.3 min/h) than animals kept on hard concrete alley floors. Restricted freestall access resulted in fewer standing bouts per day (14.4 ± 1.0 vs. 17.9 ± 1.0) and more strides per hour (99.8 ± 5.4 vs. 87.2 ± 5.4) without changing overall standing time (15.0 ± 0.3 vs. 14.7 ± 0.3 h/d) and did not affect the occurrence of sole hemorrhages. The animals with no overnight freestall access spent more time standing (55.9 ± 0.9 vs. 35.8 ± 0.9 min/h) and feeding (7.8 ± 0.3 vs. 4.3 ± 0.3 min/h) between 2300 and 0500 h and less during the rest of the 24-h period (31.3 ± 0.8 vs. 37.0 ± 0.8 min/h and 6.8 ± 0.3 vs. 7.6 ± 0.3 min/h). Thus, the animals adapted to restricted freestall access, that caused increased overnight standing, by additional lying down during the day and used part of the extra standing time at night for feeding. The restrictions probably had only a minor effect on the mechanical load of their claws. Therefore, the first part of the hypothesis was confirmed and the second part was rejected.

Natural antibody isotypes as predictors of survival in laying hens.

To identify possible relationships between survival and titers of natural antibody (NAb) isotypes in serum of laying hens, birds from 12 purebred layer lines of 2 commercial breeds, Rhode Island Red (n = 524) and White Leghorn (n = 538), were monitored for survival during one laying period (from 20 until 70 wk of age). Titers of NAb isotype IgM- and IgG-binding keyhole limpet hemocyanin (KLH) in serum were measured at 20, 40, and 65 wk of age, respectively. Overall, the titers of IgM and IgG binding KLH decreased with aging. At the same age, lines within breed showed significantly different titers of isotypes (P < 0.0001). Multivariable logistic regression analysis showed that NAb isotype IgM and IgG titers at 20 wk of age were associated with survival at 20 to 40 wk of age. In the R breed, odds ratios of 0.56 (P < 0.0001) for IgM and 0.72 (P = 0.02) for IgG were estimated; in the W breed, these were 0.74 (P < 0.01) and 0.99 (P = 0.95) for IgM and IgG, respectively. We conclude that titers of Nab isotypes, especially the IgM-binding KLH at 20 wk of age, are indicative for survival during the laying period. The higher the titers of NAb isotypes, the higher the probability of layers to survive.

The effect of digital lesions and floor type on locomotion score in Dutch dairy cows.

This study describes the effects of floor system, digital dermatitis (DD) and interdigital dermatitis and heel-horn erosion (IDHE) on locomotion performance in 225 dairy cows of 12 commercial dairy herds. Nine herds were kept in cubicle houses with concrete passageways (either solid, slatted, or grooved concrete) and three herds were kept in straw yards. Animals were at most five times examined at monthly intervals for lesion severity of DD and IDHE and for locomotion score. Locomotion score was rated on a scale ranging from 1 to 5 (from normal to severe) and disturbed locomotion (lameness) was defined as a score > or =3. A logistic regression model was used to analyze the 943 observations using lameness (yes/no) as outcome variable. The proportion of observations scored as lame (locomotion score > or =3) increased from 18% 1 month after trimming to 29% at 4 months after trimming. Severe lesions of DD and IDHE were associated with a significantly higher proportion of lame cows. The proportion of animals with disturbed locomotion increased from 16% to 40% as the severity of DD increased and from 17% to 30% with increasing severity of IDHE lesions. Locomotion performance highly differed between the cubicle house and straw yard group. Only 1% of all gaits in straw yard cows were scored as lame, while in cubicle housed cows these percentages varied from 24% to 46% with grooved floors showing the highest average locomotion score. Due to the extreme low incidence of lameness in straw yards, the statistical analysis had to be restricted to observations on concrete floors (n=744). The logistic regression model with lameness (yes/no) as dependent variable and random effects of cow and herd resulted in Odds Ratios for severe DD and IDHE of, respectively, 3.2 and 3.2, both significantly larger than unity. Cows housed at grooved concrete floors showed the highest OR of 6.5 compared to solid concrete floors. Recovery of lameness was poor as disturbance in gait lasted several months.

The effect of becoming BVDV-free on fertility and udder health in Dutch dairy herds.

The aim of the study was to investigate the effect of BVDV-free certification of dairy herds on fertility and udder health. Cases were defined as dairy herds that had at least one BVDV-antigen positive animal, subsequently gained the BVDV-free status by participating in the BVDV-control programme of the Animal Health Service (AHS) and maintained this status for at least 2 years. Controls had an unknown status for BVDV and two controls were matched to one case by region and herd size. Data concerning fertility and milk production of all herds were provided by The Dutch Royal Cattle Syndicate (NRS). After validation, data of 79,607 cows of 392 case herds and 124,831 cows of 730 control herds were analysed on ten fertility and three udder health parameters. For the analyses all observations were aggregated at herd level. To account for the matching, differences for fertility parameters were calculated between each of the two pairs of case-control within a matching code. The analyses were performed with these differences as dependent variables. Mixed models and GEE models were used for the statistical analyses of fertility and udder health. Case herds had a significantly lower abortion rate in the BVDV-free period than controls herds (10.3% versus 11.6%, P<0.01) while there was no significant difference for the other fertility parameters. There was no effect on mastitis prevalence or bulk-milk SCC but the mastitis incidence significantly decreased for case herds in the BVDV-free period (cases 0.6 % lower than controls, P<0.05). In our study the effect of getting the BVDV-free status may have been underestimated for several reasons like an unknown status for control herds, not knowing when an acute infection occurred in case herds and not knowing the management for both cases and controls. Interestingly, both significant variables, being abortions and mastitis incidence, are parameters that are more difficult to influence by the farmer than the other parameters (e.g. calving interval).

Milk yield and survival of Holstein-Friesian dairy cattle after laparoscopic correction of left-displaced abomasum.

The milk yield and survival of 91 Holstein-Friesian dairy cows that had had a left-displaced abomasum (LDA) corrected laparoscopically were compared with those of 193 control cows matched for herd, parity and calving date. Ninety per cent of the LDA treatments were performed within four weeks after calving. The risk of being culled during the whole observational period of at least three years was 1.5 times greater for the LDA cows than for their matched herdmates (P<0.01). The risk of being culled in the current lactation was 1.8 times greater for the LDA cows (P=0.01), but risk of being culled after the next calving following the LDA correction was similar for both groups. For the lactation in which the LDA was corrected, there was no difference in the 305-day milk production of 80 of the LDA cows and 182 of the matched cows; however, the mean interval from calving to first service during the same lactation was longer for the LDA cows (115 v 98 days) and the mean calving interval was also longer (451 v 418 days).

Spatial and risk factor analysis of bovine viral diarrhoea (BVD) virus after the first-year compulsory phase of BVD eradication programme in Northern Ireland.

Bovine viral diarrhoea virus (BVDV) causes bovine viral diarrhoea (BVD), which is a contagious pathogen that can have a significant economic impact on cattle industries. In Northern Ireland (NI), the compulsory phase of a BVD eradication programme was implemented in 2016. The aim of this retrospective population based study was to utilize herd-level data after the first year of the compulsory phase (March 2016-March 2017) to determine the spatial distribution and variation of BVDV, to identify clusters of infection, and to quantify some risk factors associated with BVD in NI. Global spatial clustering (autocorrelation) and local spatial hot-spot analyses were used to specify the clustering areas (hot- and cold-spot). A suite of multivariable logistic analyses was performed to estimate the associations of spatial and non-spatial factors (relating to herd characteristics) with the risk of being a BVDV positive herd. Final models were compared by evaluating the model fit and the ability to account for spatial autocorrelation in the study area. There were 17,186 herds included in the analysis. The herd-level prevalence of BVDV was 11.31%. Significant spatial clustering of BVDV positive herds was presented in the central region of NI. A mixed effects logistic model, with a spatial random effect term, was considered the best model. The final model showed that a positive BVDV status during the voluntary phase prior to the compulsory phase started (OR = 2.25; CI 95% = 1.85-2.73), larger herd size (OR = 6.19; CI 95% = 5.22-7.34 for herd size > 100 animals) and a larger number of positive nearest neighbours within 4 km radius (OR = 1.24; CI 95% = 1.05-1.47 for 8-9 neighbours and OR = 1.41; CI 95% = 1.20-1.65 for 10-12 neighbours) were significantly related to the risk of a herd being tested positive for BVDV. The clear spatial pattern from the local spatial clustering analyses could be used for targeted surveillance and control measures by focusing on the central region of NI.

Quantification of Mycobacterium bovis transmission in a badger vaccine field trial.

In the UK and Ireland, Bacille Calmette-Guérin (BCG) vaccination of badgers has been suggested as one of a number of strategies to control or even eradicate Mycobacterium bovis infection in badgers. In this manuscript, we present the results of a badger field trial conducted in Ireland and discuss how the novel trial design and analytical methods allowed the effects of vaccination on protection against infection and, more importantly, on transmission to be estimated. The trial area was divided into three zones North to South (A, B and C) where vaccination coverages of 0, 50 and 100%, respectively, were applied. Badgers were trapped over a 4year period. Badgers were assigned to either placebo or vaccine treatment, with treatment allocation occurring randomly in zone B. Blood samples were collected at each capture, and serology was performed in these samples using a chemiluminescent multiplex ELISA system (Enfer test). The analysis aimed to compare new infections occurring in non-infected non-vaccinated badgers to those in non-infected vaccinated ones, while accounting for the zone in which the badger was trapped and the infection pressure to which this individual badger was exposed. In total, 440 records on subsequent trappings of individual non-infected badgers were available for analysis. Over the study period, 55 new infections occurred in non-vaccinated (out of 239=23.0%) and 40 in vaccinated (out of 201=19.9%) badgers. A Generalized Linear Model (GLM) with a cloglog link function was used for analysis. Statistical analysis showed that susceptibility to natural exposure with M. bovis was reduced in vaccinated compared to placebo treated badgers: vaccine efficacy for susceptibility, VES, was 59% (95% CI=6.5%-82%). However, a complete lack of effect from BCG vaccination on the infectivity of vaccinated badgers was observed, i.e. vaccine efficacy for infectiousness (VEI) was 0%. Further, the basic reproduction ratio as a function of vaccination coverage (p) (i.e. R(p)) was estimated. Given that the prevalence of M. bovis infection in badgers in endemic areas in Ireland is approximately 18%, we estimated the reproduction ratio in the unvaccinated population as R(0)=1.22. Because VES was now known, the reproduction ratio for a fully vaccinated population was estimated as R(1)=0.50. These results imply that with vaccination coverage in badgers exceeding 30%, eradication of M. bovis in badgers in Ireland is feasible, provided that the current control measures also remain in place.

Factors related to the incidence of clinical encephalomyocarditis virus (EMCV) infection on Belgian pig farms.

We set up a matched case-control study of potential risk factors for clinical encephalomyocarditis virus (EMCV) in 58 pig farms in West Flanders (Belgium). In total, 29 farms experienced a clinical outbreak of EMCV confirmed by EMC virus isolation. Mortality was seen only among suckling piglets (18 case farms), in piglets and other age-groups (4 case farms), or only among fattening pigs (7 case farms). Five farms had reproductive problems among the sows. Control farms were matched geographically on farm size and farm type and were selected on the absence of clinical signs. A questionnaire on potential risk factors for EMCV was developed to collect data at both case and control farms. The exploration of the data used clusters of factors associated with clinical EMCV infection: (a) rodents, (b) general farm set up and (c) general hygiene. The multivariable relationships between clinical appearance of EMCV and potential risk factors were tested with conditional logistic regression. The final model on all farms contained presence of mice (OR=8.3) as a risk factor for clinical EMCV infection while the flow of manure up through the slatted floor (OR=0.11) and movement of manure between manure pits in the pig stable (OR=0.14) were protective.

Natural humoral immune competence and survival in layers.

The relation between survival and levels of humoral components of innate (and specific) immune competence of laying hens was investigated in a population of 1,063 laying hens from 12 purebred layer lines. Natural immune competence of the chickens was studied by measuring levels of natural antibodies (NAb) binding to keyhole limpet hemocyanin (KLH) or lipopolysaccharide (LPS), respectively, and hemolytic (classical and alternative) complement activity at 20, 40, and 65 wk of age. In addition, levels of antibodies binding a Newcastle disease vaccine strain as a measure of specific immunity were investigated at 20 wk of age. A distinction could be made between lines showing high or low immune competence with respect to NAb, complement activity, and specific antibodies. Within lines, significant correlations were found for each of the innate parameters among the 3 ages. The innate and specific parameters were, however, not correlated with each other. Based on the limited data set, it was not possible to draw conclusions on line differences for innate or specific immune competence in relation to survival. However, regardless of line, low levels of NAb binding to KLH or high levels of NAb binding to LPS were detected in chickens that did not survive the laying period. The major difference between the responses of NAb binding to KLH or LPS was that the chickens probably did not encounter KLH, which suggests a reflection of the capacity to respond, whereas the chickens most probably did encounter LPS, which suggests a reflection of the active status of the innate humoral immune system. In conclusion, we propose that levels (KLH) and activation (LPS) of components of natural antibodies are indicative for the probability that chickens survive a laying period.

Quantification of the relative efficiency of factory surveillance in the disclosure of tuberculosis lesions in attested Irish cattle.

In Ireland, factory surveillance of cattle for gross lesions is an important supplementary method for detecting herds infected with bovine tuberculosis (tb), and in recent years between 27 and 46 per cent of all new herd breakdowns in any year have been detected by this method. The aim of this study was to determine the relative efficiency of factories in detecting lesions among attested cattle slaughtered during 2003 and 2004. National databases were available on animal slaughter, programmes of tuberculin testing for bovine tb and laboratory confirmation of suspected lesions. Factories were ranked according to their submission risk (number of animals submitted with lesions/number of attested animals killed) and confirmation risk (number of animals with laboratory-confirmed lesions/number of animals submitted with lesions), adjusting for the risk profile of the animals slaughtered, including potential confounding factors such as their age and sex, whether they were purchased or homebred, the test history of their herd, the prevalence of bovine tb in the area and the season of slaughter. Approximately 3.7 million cattle were slaughtered in 42 Irish export-licensed factories during the two years. Complete data were available for 2,374,987 animals from 84,510 attested herds in 2845 District Electoral Divisions. Samples from 7398 animals with suspected tb lesions were submitted for laboratory examination; 4767 (64.4 per cent) were positive, 2011 were negative and 620 were inconclusive. The average unadjusted submission risk for all the factories was 22 per 10,000, ranging from 0 to 58 per 10,000. The unadjusted factory confirmation risk (excluding factories that had sent in fewer than 10 lesions) varied between 34.3 per cent and 86.3 per cent. The unadjusted and adjusted submission and confirmation risks were highly correlated, and animal-related factors (including their characteristics and origin) therefore did not contribute to the variations in factory-level submission and confirmation risks.

'La fiebre de Malta': An Interface of Farmers and Caprine Brucellosis Control Policies in the Bajío Region, Mexico.

This article shows that socio-economic factors, defined here as practices, knowledge, interests, beliefs and experiences have a role in the adoption of brucellosis control strategies in the Bajío region, Mexico. We combined qualitative and quantitative methods to show that socio-economic factors with regard to goat husbandry and brucellosis control are not taken into account in the current policy to combat the disease in Mexico. Farmers ranked constraints like the price of goat milk more important than the control of the disease. The impact of brucellosis in goats is hidden to farmers, and the term brucellosis is still a strange name to them; it is better known as 'la fiebre de Malta' (Malta fever), which farmers are aware of and which they avoid by not drinking goat milk. Brucellosis control measures cause losses such as abortion due to vaccination and ear infections due to ear tagging. In the villages of the state of Michoacán, the uptake of a vaccination and testing programme was almost complete because it was offered for free, whereas in villages of Jalisco, vaccination was not adopted thoroughly because the cost of vaccination was high for farmers and because of a lack of veterinarians offering the service. Neither compensation for culling suspected infected goats does exist nor the infrastructure, like slaughterhouses, to ensure that goats that are brucellosis seropositive are not resold to neighbouring farmers. This article disputes the idea that brucellosis is confined to the lack of awareness and participation of farmers in control measures, but rather that policies are promulgated without a good knowledge of goat husbandry and farmers' perceptions. We claim that governmental authorities should reformulate the policy to take into account socio-economic factors shaping farmers' behaviour so that effective control measures will be adopted by goat farmers.