In young calves on dairy farms the animal prevalence of extended-spectrum and AmpC β-lactamase-producing Escherichia coli (ESBL/AmpC-EC) is significantly higher compared with the animal prevalence in young stock and dairy cows. Hitherto it was unknown at what age antimicrobial resistant bacteria appear for the first time in the gut of calves on dairy farms, and how long these infections persist. The aim of this study was to examine the prevalence of ESBL/AmpC-EC, the number of excreted ESBL/AmpC-EC (in cfu/g of feces), as well as the ESBL/AmpC genotypes in young dairy calves (0-21 d of age) and the variation of these parameters between calves of different ages. Next to this, the course of shedding ESBL/AmpC-EC during the first year in dairy calves was studied. In a cross-sectional study, fecal samples from 748 calves, from 0 to 88 d of age, on 188 Dutch dairy farms were collected. The prevalence of calves testing positive for ESBL/AmpC-EC in a phenotypic assay was determined for different age categories (per 2 d of age). Positive samples were subjected to a semiquantitative test to determine the numbers of ESBL/AmpC-EC per gram of feces and for a selection of ESBL/AmpC-EC isolates the ESBL/AmpC genotype was determined. Ten of the 188 farms were selected for a longitudinal study based on the presence of at least 1 female calf with ESBL/Amp-EC in the cross-sectional study. These farms were additionally visited 3 times with a 4-mo interval. All calves that were sampled in the cross-sectional study were, if still present, resampled during the follow-up visits. Results show that from the day of birth ESBL/AmpC-EC can be present in the gut of calves. The phenotypic prevalence of ESBL/AmpC-EC was 33.3% in 0- to 21-d-old calves and 28.4% in 22- to 88-d-old calves. The prevalence of ESBL/AmpC-EC positive calves varied per age category among calves up to 21 d of age: significant increases and decreases at an early age were shown. Results of the longitudinal study show that after 4, 8, and 12 mo the prevalence of ESBL/AmpC-EC positive calves dropped to 3.8% (2/53), 5.8% (3/52), and 2.0% (1/49), respectively. This indicates that early gut colonization in young calves with ESBL/AmpC-EC is transient and does not lead to long-term shedding of these bacteria.

Monitoring and surveillance systems have an increasingly important role in contemporary society ensuring high levels of animal health and welfare, securing export positions, and protecting public health by ensuring animal health and product safety. In the Netherlands, a voluntary monitoring and surveillance system is in place since 2003 to provide a broad overview of livestock trends in addition to disease-specific surveillance systems, including insight into the occurrence and prevalence of new and emerging non-notifiable diseases and disorders. Being a major surveillance component of this monitoring and surveillance system for small ruminant health in the Netherlands, an annual data analysis on routine census data is performed to retrospectively monitor trends and developments regarding goat health and welfare. This paper aims to describe the process of the data analysis on goat farms in the Netherlands in 2020 and subsequent results are discussed. The data analysis provides key monitoring indicators such as animal and farm density, mortality, animal movements, and numbers and origin of imported small ruminants. Trends were analysed over a five-year, period and associations between herd characteristics and herd health are evaluated. Results showed that in 2020 the Dutch goat population consisted of 670,842 goats, distributed over 14,730 unique herds and increased by 2.3 % compared to 2019. Between 2016 and 2020, although probably underestimated, recorded mortality rates showed a decline on both small-scale and professional farms, with a strongest decrease on farms with herd sizes over more than 200 animals. Seventy-five percent of all professional farms registered animal introductions, in addition to 63 % of small-scale farms, including 2439 imported goats. Performing risks analyses requires demographic knowledge of the goat industry. During and after several disease outbreaks, such as bluetongue and Schmallenberg virus disease, the data analysis proved to function as a valuable tool, however, appeared just as important for recording outbreak-free data. Since its start in 2006, the concept of the data-analysis has continuously been improved, and will in the future be further developed, especially if more complete data sets become available. Subsequently, data analysis will increasingly support monitoring and surveillance of goat health and welfare.

The aims of our study were to calculate the most appropriate cut-off value for milk samples in a serum-validated Mycobacterium avium subsp. paratuberculosis (MAP) ELISA and to analyze MAP ELISA responses in milk samples from vaccinated and nonvaccinated dairy goats in the Netherlands. Analyzed herds were representative for location and herd size of dairy goat herds in the Netherlands. A significantly higher proportion of the analyzed 49 herds were organic as compared with the total Dutch dairy goat population. First, the MAP ELISA was optimized using 992 paired serum and milk samples. At a cut-off of 25 S/P%, the relative sensitivity (Se) was 58.4% (n = 992, 95% CI: 48.8%−67.6%) and relative specificity (Sp) was 98.5% (n = 992, 95% CI: 97.5%−99.2%), as compared to serum ELISA results. The percentage of positively tested herds was 78.2% (n = 49, 95% CI: 63.4%−88.1%). The percentage of positive milk samples per herd (n = 22) was on average 4.6% (median, min, and max of 4.7%, 0.0%, and 10.7%, respectively). Average age of ELISA-positive (3.2 years) and -negative goats (3.2 years) was not different. Significantly more vaccinated goats tested positive (6.7%) as compared with nonvaccinated goats (1.1%). This study shows that a high number of vaccinated and nonvaccinated commercial dairy goat herds in the Netherlands have MAP-ELISA-positive goats.

Mycobacterium avium subspecies paratuberculosis (MAP) is endemic in the Dutch dairy goat population causing economic loss, and negatively influencing welfare. Moreover, there are concerns about a potential zoonotic risk. Therefore the industry’s objectives are to decrease MAP prevalence, limit economic losses as well as reduce the concentration of MAP in (bulk) milk. To diminish within-farm spread of infection, vaccination, age dependent group housing with separation of newborns from adults, as well as rearing on artificial or treated colostrum and milk replacers are implemented. However, the importance of MAP contaminated colostrum and milk as a route of infection in dairy goat herds is unknown. Therefore the aim of this study was to detect the presence of MAP DNA in colostrum and milk from dairy goats in infected herds. A convenience sample of 120 colostrum samples and 202 milk samples from MAP infected dairy goat herds were tested by IS900 real-time Polymerase Chain Reaction (PCR) for MAP DNA. Furthermore, 22 colostrum samples and 27 post mortem milk samples of goats with clinical signs consistent with paratuberculosis from known infected herds were tested. The majority of samples were from goats vaccinated against MAP. Positive or doubtful PCR results were obtained in none of the 120 and two of the 22 colostrum samples, and in eight of the 202 and four of the 27 milk samples Negative PCR results were obtained in the remaining 140 (99%) colostrum samples and 217 (95%) milk samples.

The duration of excretion of dry cow antimicrobials is hard to predict and therefore the level of antimicrobial residues in colostrum can differ considerably between cows. The feeding of colostrum with antimicrobial residues to newborn calves may lead to antimicrobial resistance in calves. The aim of this study was to quantify the prevalence and residue level of dry cow antimicrobials in colostrum from dairy cows. Additionally, the association between antimicrobial residues in colostrum and the prevalence of extended spectrum and AmpC β-lactamaseproducing Escherichia coli (ESBL/AmpC-EC) in colostrum and in the feces from young dairy calves was evaluated. The work described in this paper consists of 3 studies. In the first study, in 75 of 118 colostrum samples antimicrobial residues were found, in 50 of 88 β-lactam treated cows, and in 25 of 30 cows treated with a combination of an aminoglycoside and a β-lactam. In cows that had been dried off with a combination of an aminoglycoside and a β-lactam, in significantly more samples antimicrobial residues were found. In 38 of the colostrum samples tested, antimicrobial concentrations (mainly cloxacillin) exceeded the Maximum Residue Limit. The prevalence of antimicrobial positive colostrum samples presented was much higher than earlier described. In the second study 28 dairy cows from 8 farms were dried off with either cloxacillin or a combination of neomycin and benzylpenicillin. Because in study 1 the tendency of a negative association was found between the use of teat sealants and the presence of antimicrobials in colostrum, it was hypothesized that with the striping of the teat sealant much of the antimicrobial residues was removed. This hypothesis could not be confirmed by comparing antimicrobial concentrations in the first streams of the first milking and the remainder of that milking. The 22 clocaxilin treated cows were followed up for 6 subsequent milkings, during which a decrease in the concentration of antimicrobial residues was found. In the third study, 87 cows from 10 herds were included of which 58 cows were dried off with cloxacillin while 29 cows were dried off without antimicrobials. Cows were compared with respect to antimicrobial residues in the first 5 milkings after calving and the occurrence of ESBL/AmpC-EC in the feces from their calves, collected at d 1, d 7 and d 14 of life. Significantly higher percentages of ESBL/AmpC-EC positive samples were found in feces samples collected at d 7 and d 14 compared with the d 1 samples. No significant differences were found in the prevalence of ESBL/AmpC-EC positive fecal samples between calves born from cows that had been dried off without antimicrobials and those that had been dried off with cloxacillin. Given the fact that cloxacillin does not select for ESBL/AmpC-EC, this was not unexpected. This study showed that colostrum from cows dried off with antimicrobials often contains antimicrobial residues. Although no effect of these residues on the prevalence of ESBL/AmpC-EC in fecal samples of calves was found in this study, we recommend to minimize antimicrobial use at drying off and to respect withdrawal recommendations.