Dairy Sheep Flocks Research Articles

Genome-wide association studies for citric and lactic acids in dairy sheep milk in a New Zealand flock

The objectives of this study were to estimate genetic parameters for citric acid content (CA) and lactic acid content (LA) in sheep milk and to identify the associated candidate genes in a New Zealand dairy sheep flock. Records from 165 ewes were used. Heritability estimates based on pedigree records for CA and LA were 0.65 and 0.33, respectively. The genetic and phenotypic correlations between CA and LA were strong-moderate and negative. Estimates of genomic heritability for CA and LA were also high (0.85, 0.51) and the genomic correlation between CA and LA was strongly negative (-0.96 ± 0.11). No significant associations were found at the Bonferroni level. However, one intragenic SNP in C1QTNF1 (chromosome 11) was associated with CA, at the chromosomal significance threshold. Another SNP associated with CA was intergenic (chromosome 15). For LA, the most notable SNP was intragenic in CYTH1 (chromosome 11), the other two SNPs were intragenic in MGAT5B and TIMP2 (chromosome 11), and four SNPs were intergenic (chromosomes 1 and 24). The functions of candidate genes indicate that CA and LA could potentially be used as biomarkers for energy balance and clinical mastitis. Further research is recommended to validate the present results.

Subacute Rumen Acidosis in Greek Dairy Sheep: Prevalence, Impact and Colorimetry Management.

Subacute rumen acidosis (SARA) is a current issue in intensive livestock farming, and it is particularly associated with feeding high-concentrate diets. This study investigated the prevalence and impact of SARA in forty-two Greek dairy sheep flocks by recording rumen pH, milk composition, and milk yield over a period of nine months. Moreover, it explored the use of computerized rumen colorimetry as a management and diagnostic tool for SARA in dairy sheep. In culled ewes, computerized rumen mucosal colorimetry was applied, and rumen wall samples taken for histological examination. SARA cases were identified in 19 farms (45%, n = 42). Farms with SARA cases had lower milk fat levels, while milk yield and milk protein levels did not differ based on the SARA status of the farms. In culled ewes, rumen color was significantly associated with the flock's SARA status, and affected ewes showed increased thickness in non-keratinized and total epithelial layers. It was concluded that computerized rumen mucosal colorimetry in aged, culled ewes shows promise as an indicator, post mortem, of SARA present in dairy sheep flocks whose impact can be minimized by making significant changes in dietary management.

Estimation of genetic parameters for production, composition and processability of milk from dairy sheep in a New Zealand flock

ABSTRACT This paper aimed to estimate the heritability and genetic correlations for processability (milk coagulation properties, cheese yield, and heat stability), milk production, and milk composition of dairy sheep in a New Zealand flock. Test-day records from 169 ewes were obtained during the 2021–2022 season. Heritability estimates for yield traits (milk, fat, protein, and lactose yield) were moderate and ranged from 0.33 to 0.38. Whereas heritability estimates for processability traits were lower and ranged from 0.17 to 0.27. The genetic correlations indicated that poorer milk coagulation properties were associated with lower mammary health indicated by higher SCS, higher pH, and lower lactose content. Additionally, a higher ratio of casein to calcium i.e. lower availability of soluble calcium was associated with poorer milk coagulation properties. Higher yields of milk, fat, protein, and lactose were associated, but to a smaller degree, with better MCP. It is proposed that genetic improvement of dairy sheep for higher yields of fat and protein, and for lower SCS, could indirectly improve milk processability for cheese-making. However, it is recommended that larger studies involving more dairy sheep flocks are conducted to validate the present results before developing a selection index for this industry.

Risk Categorization in On-Farm Welfare in Different-Sized Dairy Sheep Flocks.

The objective of the present work was to categorize the risks in the on-farm welfare of dairy sheep in semi-extensive systems in order to highlight if risks in welfare vary according to the farm size. To the best of our knowledge, this study constitutes one of the few categorizations of the risks in the welfare of dairy sheep reared semi-extensively. The survey was conducted on 12 semi-extensive dairy sheep farms in Tuscany (Central Italy), which were classified according to flock size: <500, from 500 to 1000, and >1000. The results showed an adequate rating for all the farms included in the study. The most critical issues concerned the ratio between the number of stockpersons and the number of animals within the farms, the small decubitus areas, the lack of udder cleaning procedures during milking operations, and, in terms of biosecurity, the lack of prevention, control, and eradication plans for the most important infectious ovine diseases. The results show that different items in the five areas evaluated, including the assessments of management of the flock, the number of daily inspections, and the hygiene of the water supplies are associated with the farm size. In large farms, the assessment of management of the flock was better, but the number of daily inspections and the hygiene of the water supplies were worse.

Stress related to wild canid predators near dairy sheep farms associated with increased somatic cell counts in bulk-tank milk

We investigated the association between wild canid predators reported near sheep farms throughout Greece and somatic cell counts in bulk-tank milk as a reflection of milk quality. The study included 325 dairy sheep flocks, where bulk-tank milk somatic cell counts and total bacterial counts were measured and staphylococci were isolated. Farms were divided into three groups: Cohort A (farms with no reports of wild canid predators nearby), B (farms with canid predators (golden jackal and grey wolf) nearby yet with no experience of livestock losses to predation) and C (farms with canid predators nearby and livestock losses to predation). Somatic cell counts in bulk-tank milk of Cohort C farms were significantly higher, + 43% and + 29%, compared to those for Cohorts A and B, respectively: 0.617 × 106 cells mL−1 versus 0.433 × 106 or 0.477 × 106 cells mL−1, respectively. The presence of wild canid predators near sheep farms was associated with lower quality milk potentially indicative of stress consistent with the potential effects of a landscape of fear. Increasing biosecurity measures at livestock farms, e.g., fencing, and presence of livestock guard dogs could minimise predation risk, whilst also improving livestock welfare by reducing predator-associated stress.

Longitudinal Study of Antibiotic Resistance of Staphylococci from Cases of Subclinical Mastitis in Sheep in Greece: Incidence and Risk Factors.

The present paper extends a previous publication on a field study of subclinical mastitis in sheep and focuses on the following laboratory characteristics of the staphylococcal isolates: antibiotic resistance and association with biofilm formation. The specific objectives of the present study were (a) to describe the incidence of isolation of antibiotic-resistant staphylococci from cases of mastitis throughout the milking period in dairy sheep flocks and (b) to identify relevant risk factors, which would contribute to the sustainable control of the infection. Staphylococcal isolates from subclinical mastitis were evaluated for antibiotic resistance to 18 antibiotics. Antibiotic resistance was detected in 57 of the 179 staphylococcal isolates from subclinical mastitis (31.8%). Resistance was recorded against 11 antibiotics, most often against ampicillin (63.2% of resistant isolates), penicillin (63.2%) and tetracycline (47.4%). Isolates resistant to ampicillin and penicillin were recovered in all 12 farms. Twenty-one multidrug-resistant isolates (11.7%) were also recovered. The incidence risk of isolation of staphylococci resistant to at least one (any) antibiotic throughout the study period was 23.8%. The incidence risk of isolation of staphylococci resistant to oxacillin was 5.0%; that of isolation of multidrug-resistant staphylococci was 8.8%. With regard to increased incidence risk of isolation of staphylococci resistant to at least one (any) antibiotic and increased incidence risk of isolation of staphylococci resistant to oxacillin, the omission of anti-staphylococcal mastitis vaccination of ewes emerged as a risk factor. With regard to increased incidence risk of isolation of multidrug-resistant staphylococci, the following variables emerged as risk factors: (a) higher number of antibiotics used on the farm for the treatment of mastitis and (b) younger age of lambs taken away from their dam. Most biofilm-forming antibiotic-resistant staphylococci were recovered from farms where anti-staphylococcal mastitis vaccination was not applied (55.9% versus 44.1% from farms where anti-staphylococcal mastitis vaccination was applied).

Coxiella burnetii occurrence in dairy herds in Gabrovo Region, Bulgaria, evaluated by serological and molecular analyses of bulk-tank milk samples

This study investigated the occurrence of Coxiella burnetii in dairy cattle, goat herds and sheep flocks in the Gabrovo Region, central Bulgaria, to identify the potential sources of Coxiella burnetii infection diagnosed in veterinarians and farm workers in this region. To detect infection on livestock farms, we tested bulk-tank milk (BTM) for the presence of antibodies and/or the Coxiella burnetiid genome using ELISA and PCR, respectively. A total of 81 herds were tested, including 23 dairy cattle herds, 43 sheep herds, 9 goat flocks, and 6 mixed flocks (sheep and goats). By ELISA, antibodies against Coxiella burnetii were detected in 30.4% of the BTM tested samples from cattle farms, 60.4% of the sheep farms, and 11.1% of the goat BTM samples. The results were inconclusive in 6.98% of the tested sheep milk samples and 11.1% of the goat milk samples. There was a statistically significant correlation between the herd size and the ELISA S/P % values on the dairy cattle farms. Excretion of the pathogen in milk was detected by PCR in 9 out of 67 BTM samples, including 5 out of 19 cattle BTM samples, 3 out of 39 sheep BTM samples and 1 out of 5 goat BTM ones. The results indicate that C. burnetii infection is widely prevalent in the region, which calls for adequate control and prophylactic measures to reduce the health risks from the transmission of this zoonosis to humans.

Longitudinal Study of Subclinical Mastitis in Sheep in Greece: An Investigation into Incidence Risk, Associations with Milk Quality and Risk Factors of the Infection.

The objectives of this work were (a) to describe the incidence risk of subclinical mastitis in dairy flocks throughout the milking period, (b) to present potential associations of subclinical mastitis with the quality of milk and (c) to identify risk factors for high-incidence risk of the infection. A longitudinal study was performed in 12 dairy sheep flocks in Greece. Mammary secretion samples from 240 ewes and bulk-tank milk samples were collected in four repeated visits over a period of six months for bacteriological, chemical and cytological examinations. Overall, the incidence risk of subclinical mastitis throughout the study period was 51.7%, and it varied among farms from 25.0% to 75.0%. The respective figure for staphylococcal subclinical mastitis was 48.8%. The incidence risk of recurrence of subclinical mastitis among ewes in the flocks was 35.4%. The most frequently identified bacteria from cases of subclinical mastitis were S. aureus and S. simulans; of the mastitis-causing staphylococcal isolates, 65.4% were biofilm-forming. Somatic cell counts in bulk-tank milk progressively increased as the lactation period advanced, with significant increases seen on the third and fourth visits to the farms. Somatic cell counts in bulk-tank milk correlated well with prevalence of subclinical mastitis in flocks. A significant inverse correlation and a significant positive correlation were seen for prevalence of subclinical mastitis versus total protein content or added water in bulk-tank milk. During multivariable analysis, younger age of newborns when taken away from the dam and consequently delayed start of milking of ewes, omission of anti-mastitis vaccination of ewes and lack of employed staff on the farms emerged to be significantly associated (positively) with increased incidence risk of subclinical mastitis.

Alternative hormone-free reproduction management of a dairy sheep flock disrupts the farm's annual feeding system calendar and its associated strategies

Hormone-free (HF) reproduction in dairy sheep is a way to meet current societal demands, but it requires being prepared for collateral impacts on related system components. The efficiency of HF practices (e.g., using the male effect for estrus induction and synchronization) is uncertain compared with hormonal treatment (HT). For example, these practices can lead to higher variability in the flock physiological stage patterns throughout the year, which has direct consequences for feeding regimens. The objective of this work was to simulate the impacts of HF reproduction management, including artificial insemination (AI), on the temporal distribution of productive performance and nutritional requirements of a conventional dairy sheep flock. Using the REPROsheep2.0 model, 6 scenarios were compared over one typical production season for the same flock (n = 597 Lacaune ewes) intensively reared in the Roquefort region of France. These scenarios depicted reproduction with HT and AI in mid-May (Early); HT and AI in July (Summer Late); HT and AI in November (Autumn Late); and their HF versions (HF-Early; HF-Summer Late, and HF-Autumn Late, respectively). In all HF scenarios, a reduction in the number of ewes lambing and consequently in the annual milk production of the farm was observed (-1 to -7%). This affected annual performance with a subsequent decrease of total annual nutritional requirements (-2 to -6%). The HF scenarios resulted in a staggering of lambing events with a 7- to 14-d shift in the appearance of milk production peaks and related nutritional requirements compared with the HT scenarios. Transitioning from conventional to HF reproduction management, while preserving AI, would increase farm workload, lengthen milking period operations, and necessitate a readjustment of feeding management strategies with regard to available feed resources. Depending on the production season, the observed delay in the distribution of nutritional requirements could be either an attractive or an unfavorable outcome for farmers. The delay may be concordant, for example, with the recently observed impacts of climate change on seasonal forage availability in Mediterranean regions (less spring herbage production and warmer temperatures) that are affecting farmers' decision-making about the most efficient use of forage and feed resources.

Associations between small ruminant lentivirus infection and total milk yield and somatic cell count in a dairy sheep flock.

Small ruminant lentiviruses (SRLVs) are lentiviruses of sheep and goats, formerly known as maedi-visna (MV) in sheep and caprine encephalitis and arthritis in goats. In sheep, SRLVs commonly cause progressive pneumonia, wasting and indurative mastitis. SRLVs have a long latent period, and chronic production losses are often not recognised until very late. Few studies quantifying the production losses in ewes have been published, and none have been published under UK flock husbandry conditions. Production records of milk yield and somatic cell count (SCC) from a dairy flock of 319 milking East Friesian × Lacaune ewes identified as MV infected via routine serological screening for SRLV antibodies were used in multivariable linear regression modelling to estimate the impact of SRLV status on total milk yield and SCC. Milk yield was reduced in seropositive ewes by 8.1%-9.2%over an entire lactation. SCC counts were not significantly different in SRLV-infected andunifectedanimals. Further parameters, such as body condition score or clinical mastitis, that were not available may have clarified the underlying cause of milk yield drop. The study demonstrates substantial production losses in anSRLV-affected flock and highlightsthe impact of the virus on afarm'seconomic viability.

Evaluation of backfat and longissimus dorsi thickness ultrasound measurements as predictors of negative energy balance in pre-partum dairy ewes

Non-esterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) concentrations in blood serum are the most used indicators of energy status in dairy sheep. Ultrasound measurement of backfat thickness (BFT) and longissimus dorsi muscle thickness (LDT) is a non-invasive and on-field applicable technique, with no established critical thresholds for assessing energy balance in dairy sheep. The objective of the present study was to evaluate the use of ultrasound indices of BFT and LDT as image biomarkers of negative energy balance in pre-partum dairy ewes. The study was conducted in four commercial dairy sheep flocks in Central Macedonia Region of Greece, that each one reared a specific breed of purebred sheep. The final number of ewes with full records used in statistical analysis was 177 (flock A-Assaf.E, = 49, flock B-Chios = 46, flock C- Lacaune = 42 and flock D-Frizarta = 40). All animal measurements were performed one month (−30 ± 4d) and two weeks (−15 ± 4d) prior to estimated lambing date. Body condition score was assessed by palpation at the lumbar region. BFT and LDT were determined with ultrasonography after body condition scoring, to avoid bias on BCS estimation. The sum of BFT and LDT (TotalT), the LDT: BFT ratio (RatioT) and the difference in BFT (Δ_BFT) and LDT (Δ_LDT) between the two measurements were calculated. Blood sampling of ewes was performed on − 15d for serum BHBA and NEFA measurements. Negative energy balance status was defined as serum BHBA > 0.8 mmol/L or NEFA > 0.3 mmol/L. The receiver operating characteristic (ROC) analysis was used to define thresholds for fat and muscle reserves and mobilization parameters to predict elevated BHBA or NEFA status. All variables with a significant area under the ROC curve were transformed into binary variables and used in 2 multifactorial binary logistic regression models to assess the association of fat and muscle reserves and mobilization parameters with BHBA and NEFA status. Ewes with Δ_BFT > 0.65 mm had 3.2 times (P = 0.002) increased probability to have serum NEFA > 0.3 mmol/L. Moreover, ewes with BFT(−30d) > 6.86 mm, had 6.7 times (P < 0.001) increased probability to have serum NEFA > 0.3 mmol/L. Ewes with a BFT loss had 6.7 times (P < 0.001) increased probability to have serum BHBA > 0.8 mmol/L. Moreover, ewes with TOTAL_T(−15d) ≤ 25.6 mm, had 5.3 times (P < 0.001) increased probability to have serum BHBA > 0.8 mmol/L. The results showed that ultrasound measurements of BFT and LDT the last month of gestation can be used as a reliable alternative to BCS or metabolic profiling for the assessment of energy status in dairy sheep. Measuring BFT one month prior to lambing or TotalT two weeks prior to lambing can both provide reliable estimations.

Sheep and goats are reservoirs of colistin resistant Escherichia coli that co‐resist critically important antimicrobials: First study from Jordan

AbstractThere is a knowledge gap on colistin‐resistant and mobilized colistin‐resistant (mcr) Escherichia coli in sheep and goats worldwide. This study determined the prevalence and antimicrobial resistance of mobilized colistin‐resistant (mcr) E. coli in dairy sheep and goat flocks in Jordan. A total of 948 milk samples were collected from 155 flocks across Jordan. The milk samples were pre‐enriched in MacConkey broth and then plated on MacConkey agar supplemented with 8 mg/l colistin and the presence of mcr‐1 gene in the isolates was tested by polymerase chain reaction. In total, 1,158 E. coli isolates were colistin resistant, with 74.8% herd‐level prevalence and 39.5% individual animal prevalence. Sixty‐one (5.3%) of 1,158 phenotypically colistin‐resistant E. coli harbored mcr‐1, with 23.9% herd‐level prevalence and 6.6% individual animal prevalence. About 77.1% of the mcr‐1 E. coli resisted one or more antimicrobial classes and 37.7% were multidrug resistant. More than 30% of the mcr‐1 positive E. coli isolates were resistant to nalidixic acid, tetracycline, ceftazidime, cefpodoxime and ampicillin, whereas 8–20% of the isolates were resistant to cefotaxime, ceftriaxone, gentamicin, tobramycin, sulfamethoxazole‐trimethoprim, and amoxicillin‐clavulanic acid. This study indicates that small ruminants are reservoirs of colistin‐resistant and mcr‐1 positive E. coli that exhibit co‐resistance to critically important antimicrobials which would pose public health issue and calls for the necessary banning of the use of colistin in small ruminants.

Serological survey of Chlamydia abortus in Greek dairy sheep flocks

Chlamydiosis due to Chlamydia abortus is one of the most common causes of abortion in small ruminant flocks worldwide. Although the causative agent is zoonotic, chlamydiosis is not a reportable disease. There is lack of recent data concerning sheep chlamydiosis in Greece.In the current study, a serological investigation for Chlamydia abortus was conducted. Blood samples from 26 randomly selected sheep flocks not vaccinated against chlamydiosis were collected. From each flock, 15 to 20 blood samples were taken from adult female sheep. In total 464 blood samples were examined. One hundred and six samples were positive (22.8%), while 24 samples (5.24%) were doubtful. Moreover, at farm level, in 18 out of the total number of 26 farms, at least one positive animal was detected (69.2%).Chlamydiosis is considered a highly likely cause of sheep abortion in Greece. Therefore, vaccination of the sheep flocks is strongly recommended for the prevention and control of the disease.

High Milk Somatic Cell Counts and Increased Teladorsagia Burdens Overshadow Non-Infection-Related Factors as Predictors of Fat and Protein Content of Bulk-Tank Raw Milk in Sheep and Goat Farms.

This paper presents the results of an extensive countrywide investigation performed in 325 dairy sheep flocks and 119 goat herds throughout Greece. The objectives of the study were (a) to investigate fat and protein content in the bulk-tank raw milk of small ruminant farms in Greece and (b) to identify factors potentially influencing that content and factors that can contribute to increased content. The mean fat/protein contents in bulk-tank raw milk of sheep and goats were 6.16 ± 0.05%/4.43 ± 0.01% and 4.77 ± 0.44%/3.23 ± 0.30%, respectively. Significant differences were seen in protein content between farms in the various parts of the country. For sheep, multivariable analyses revealed breed and age of lamb removal from dams as significant for fat content, and somatic cell counts, management system in the farm, administration of anthelmintic treatment during the last stage of pregnancy, and farmer education as significant for protein content. For goats, significant factors were month into lactation period, age of kid removal from dams, and breed for fat content, and somatic cell counts, month into lactation, grazing duration, and % Teladorsagia larvae in faecal samples for protein content. For concurrently high fat and protein content, in multivariable analyses, the following emerged as significant factors: somatic cell counts in milk, numbers of parasite eggs in faeces, and veterinary collaboration (sheep), and month into lactation and somatic cell counts in milk (goats). The results indicate that high somatic cell counts in milk (reflecting the presence of mastitis) and gastrointestinal parasitic infections (mainly Teladorsagia infection) appear to exert a more significant influence on fat and protein content of milk, in comparison to non-infection-related factors.

Dairy Sheep Played a Minor Role in the 2005-2010 Human Q Fever Outbreak in The Netherlands Compared to Dairy Goats.

Q fever is an almost ubiquitous zoonosis caused by Coxiella burnetii. This organism infects several animal species, as well as humans, and domestic ruminants like cattle, sheep and goats are an important animal reservoir of C. burnetii. In 2007, a sudden rise in notified human Q fever cases occurred in The Netherlands, and by the end of 2009, more than 3500 human Q fever patients had been notified. Dairy sheep and dairy goats were suspected to play a causal role in this human Q fever outbreak, and several measures were taken, aiming at a reduction of C. burnetii shedding by infected small ruminants, in order to reduce environmental contamination and thus human exposure. One of the first measures was compulsory notification of more than five percent abortion within thirty days for dairy sheep and dairy goat farms, starting 12 June 2008. After notification, an official farm inspection took place, and laboratory investigations were performed aiming at ruling out or demonstrating a causal role of C. burnetii. These measures were effective, and the number of human Q fever cases decreased; levels are currently the same as they were prior to 2007. The effect of these measures was monitored using a bulk tank milk (BTM) PCR and an antibody ELISA. The percentage PCR positive dairy herds and flocks decreased over time, and dairy sheep flocks tested PCR positive significantly less often and became PCR negative earlier compared to dairy goat herds. Although there was no difference in the percentage of dairy goat and dairy sheep farms with a C. burnetii abortion outbreak, the total number of shedding dairy sheep was much lower than the number of shedding dairy goats. Combined with the fact that Q fever patients lived mainly in the proximity of infected dairy goat farms and that no Q fever patients could be linked directly to dairy sheep farms, although this may have happened in individual cases, we conclude that dairy sheep did not play a major role in the Dutch Q fever outbreak. BTM monitoring using both a PCR and an ELISA is essential to determine a potential C. burnetii risk, not only for The Netherlands but for other countries with small ruminant dairy industries.

Dynamics of Neospora caninum-Associated Abortions in a Dairy Sheep Flock and Results of a Test-and-Cull Control Programme.

Neospora caninum is an apicomplexan parasite that can cause abortions and perinatal mortality in sheep. Although ovine neosporosis has been described worldwide, there is a lack of information about the relationship between N. caninum serostatus and the reproductive performance. In this study, we described the infection dynamics in a dairy sheep flock with an abortion rate up to 25% and a N. caninum seroprevalence of 32%. Abortions were recorded in 36% and 9% of seropositive and seronegative sheep, respectively. Seropositive sheep were more likely to abort twice (OR = 4.44) or three or more times (OR = 10.13) than seronegative sheep. Endogenous transplacental transmission was the main route of transmission since 86% of seropositive sheep had seropositive offspring. Within dams that had any abortion, seropositive sheep were more likely than seronegative ones to have female descendants that aborted (OR = 8.12). The slight increase in seropositivity with the age, the low percentage of animals with postnatal seroconversion or with low avidity antibodies, and the seropositivity of one flock dog, indicated that horizontal transmission might have some relevance in this flock. A control programme based on selective culling of seropositive sheep and replacement with seronegative animals was effective in reducing the abortion rate to 7.2%.

ANTIBACTERIAL ACTIVITY OF ESSENTIAL OILS AGAINST PATHOGENS OF IMPORTANCE IN CAPRINE AND OVINE MASTITIS

ABSTRACT Mastitis is an important infirmity that affects dairy goats and sheep flocks. Antimicrobials are widely used in mastitis therapy; however, the phenomenon of bacterial resistance has sparked interest in therapeutic alternatives, especially the research on essential oils from several plant species. Therefore, this study aimed to evaluate the antimicrobial activity of essential oils against pathogens of importance in caprine and ovine mastitis. The essential oils were obtained by hydrodistillation and the chemical composition was analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests were performed to evaluate the antimicrobial activity of the essential oils (EO) of four plants. Fifteen bacterial isolates, previously identified as Staphylococcus spp. and Staphylococcus aureus, were used. The following plant species were used against the 15 bacterial isolates: Lippia origanoides “alecrim pimenta,” Lippia alba “erva cidreira,” Cymbopogon citratus “capim-santo,” and Ocimum basilicum “manjericão.” The first three essential oils presented antimicrobial activity against 100% of the isolates (15/15), with MICs of 560 µg mL-1, 1,173 µg mL-1, and 1,280 µg mL-1, and MBCs of 613 µg mL-1, 1,226 µg mL-1, and 1,333 µg mL-1, respectively. Nevertheless, the essential oil of O. basilicum, which was also tested, exerted no activity against any of the isolates. Carvacrol, citral, geraniol, and estragole were some of the major compounds found. These results can aid other studies that aim to use these essential oils as potential products for subsequent use in the treatment of mastitis in small ruminants.

REPROsheep: A model that integrates individual variability to optimise hormone-free reproduction management strategies for a dairy sheep flock

Managing reproduction of a dairy sheep flock without using hormones for oestrus induction and synchronisation is an alternative method that complies with agroecological principles, animal welfare and public health concerns. However, shifting from conventional reproductive management to a hormone-free philosophy means leaving more room for individual intraflock variability in oestrus occurrence. The success of establishing alternative hormone-free reproduction systems relies on managing the variability of ewes’ individual responses, which are themselves influenced by individual characteristics. Therefore, the so-called REPROsheep model was built to study the effects of individual ewes’ characteristics, such as age, body condition score (BCS) or milk yield, on individual responses, as well as the overall productive and reproductive performances of the flock. This dynamic agent-based model (ABM) represents individual reproduction and lactation processes in a hormone-free management context. Outputs at the flock level were simulated using this model. Two dynamic outputs (weekly number of ewes lambing and weekly milk yield) and two punctual outputs (total number of ewes lambing and total milk yield) were simulated. Sensitivity analysis showed that the studied outputs were affected by ewe age, pre-mating BCS and milk-yield distributions in the flock. Increasing average age or pre-mating BCS by 0.5 from a starting point of 2.5 and average milk-yield by 50 L from a starting point of 195 L appeared to increase, for one breeding season, the number of ewes lambing, the concentration of those lambing events over one period, as well as total milk yield, whereas decreasing the average value of these factors by the same amount appeared to produce the opposite effect. Management strategies favouring an optimum age and pre-mating BCS, as well as good milk yield for the individuals of the flock, may thus be a lever for optimising performance, especially lambing distribution over time. Therefore, the REPROsheep model seems relevant to determine how a management strategy (affecting flock structure in terms of age, body condition or production potential) can impact the performance of a dairy sheep flock in the context of hormone-free reproduction.

Belgian bulk tank milk surveillance program reveals the impact of a continuous vaccination protocol for small ruminants against Coxiella burnetii

Endemic Q fever in small ruminants remains an ongoing challenge for veterinary and human public health agencies. Though surveillance programs are implemented in Belgium, infection patterns and vaccination profiles, driving variables, as well as geographical clustering were not presented until now. Based on data from a decade of bulk tank milk analysis between 2009 and 2019, shedding in dairy goat herds declined from 16% (8/50) to 6% (10/162), whereas seroprevalence remained between 32% and 40%. Merely up to two shedding dairy sheep flocks were detected until 2019; seroprevalence peaked in 2017 (43%, 12/28) and declined thereafter. The number of animals in the holding influenced significantly (p=.048) the likelihood of shedding, whereas other established risk factors such as uncovered manure, high abortion rates and diversified farm structure could not be confirmed to significantly affect infection on Belgian herd level. Intermittent, incomplete and unsynchronized vaccinated herds shed Coxiella burnetii significantly more often and longer (p<.001) than continuously, complete and synchronized vaccinated herds. Spatial analyses revealed restricted but matching, homogenous clusters with ≤35km diameter, concentrated in the coastal region close to the border to the Netherlands from 2009 to 2012, and broadened, heterogeneous clusters with ≥45km diameter between 2014 and 2016 spreading south-west. Though the majority of human cases was notified in this region, the animal clusters could not be allied with Q fever cases. The impact of environmental factors as well as the role of wildlife, rodents and ticks on the transmission between flocks and to humans remains to be elucidated to harness additional epidemiological drivers of Q fever in Belgium. In conclusion, attempts to reduce the burden of Q fever in Belgium should particularly focus on the timely, complete and synchronized vaccination of flocks, including the breeding sire, and particularity in high-risk areas.

Association of Breed of Sheep or Goats with Somatic Cell Counts and Total Bacterial Counts of Bulk-Tank Milk

The objective was to describe potential associations of somatic cell counts (SCC) and total bacterial counts (TBC) in bulk-tank milk from sheep and goat farms with breeds of these animals in Greece. In total, 325 dairy sheep flocks and 119 dairy goat herds were visited for the collection of milk; the breed of animals in farms was evaluated for a potential association with SCC or TBC. The most frequently seen sheep breeds were the Lacaune (95 flocks) and the Chios (44 flocks). The most frequently seen goat breeds were the indigenous Greek (Capra prisca) (50 herds) and the Murciano-Granadina (13 herds). In a multivariable analysis, the breed and the application of machine-milking in sheep flocks, and the breed and the management system in goat herds emerged as significant factors for increased SCC (&gt;0.75 × 106 cells mL−1) in bulk-tank milk. Further, the month of lactation at sampling in sheep flocks emerged a significant factor for increased TBC (&gt;1500 × 103 cfu mL−1) in bulk-tank milk.