Bulk Tank Milk Somatic Cell Count Research Articles

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.

The effects of novel electrical teat dipping on some mastitis parameters in dairy herds.

Electrical teat dipping (ETD) is a novel, patented method developed by the authors to control mastitis in dairy cows. Here we evaluate the efficacy of ETD in reducing the incidence of clinical mastitis and bulk tank milk somatic cell count (BTMSCC) on three dairy farms over 6 months. ETD was applied for morning and evening milking on three farms, while conventional teat dipping (CTD) was applied on the other three farms. The number of animals and quarters with clinical mastitis and monthly BTMSCC measurements were recorded. We found that the incidence of clinical mastitis was lower on farms using ETD than those using CTD. However, the BTMSCC did not significantly change throughout the study. Based on these findings, we conclude that ETD effectively reduces mastitis rates on dairy farms.

Detecting intramammary infection at the end of lactation in dairy cows

To reduce antimicrobial use, infusion of antimicrobials into only infected cows at the end of lactation (selective dry cow therapy) is preferable to infusion of every cow with antimicrobials. Use of selective dry cow antimicrobial therapy requires differentiation of probably infected from uninfected cows to enable treatment allocation. Milk somatic cell count (SCC) has been used to distinguish between cows with and without intramammary infection (IMI). However, SCC may be influenced by milk yield, stage of lactation, breed, and herd-level variables such as prevalence of infection. Cut points for SCC, to distinguish between cows with and without an IMI, may need to differ between cow age groups and breeds, or among herds. This study evaluated associations between SCC and major pathogen IMI in one or more quarters of 2,606 cows from 36 herds in 4 regions of New Zealand. In the last week of lactation, cows selected at random had milk samples collected from each quarter, and the teat-end condition and hygiene of the udder were scored. Herd- and cow-level data including age, breed, milk volume, and SCC at each production were recorded, and bulk tank milk SCC and volume of milk shipped were collated. At cow level, the association between average, maximum, and last cow-composite SCC, and presence of a major pathogen IMI in one or more quarters of cows, was examined using receiver operator curves. Predictive logistic regression models were then developed that included potential effect modifiers such as age, milk yield, and bulk tank milk SCC. The population average prevalence of major pathogen IMI was 7.2% of cows (95% confidence interval = 5.9-8.6), and this varied significantly between herds. The average, maximum, and last cow-composite SCC of lactation were all predictive of presence of a major pathogen IMI and did not differ in their ability to discriminate infected from uninfected cows. However, the optimal cut points for the last SCC, the maximum SCC, and average SCC were 108, 152, and 105 × 1,000 cells/mL, respectively. Inclusion of age, bulk tank SCC, and history of clinical mastitis improved overall model fit. However, inclusion of these variables did not improve the discriminatory power of maximum cow-composite SCC used alone. We conclude that cow-composite SCC on its own resulted in sensitivities and specificities of between 0.76 and 0.86, and 0.71 to 0.80, respectively, for determination of presence of major pattern IMI, and the predictive value was not improved by addition of other predictor variables.

The occurrence and distribution of livestock-associated methicillin-resistant Staphylococcus aureus ST398 on German dairy farms

The objective of this study was to investigate the occurrence and distribution of methicillin-resistant Staphylococcus aureus (MRSA) on 20 German dairy farms. Farms were selected based on previous MRSA reports from phenotypic susceptibility testing of mastitis pathogens. Samples were collected from predefined groups of cows, young stock, farm personnel, and the environment. A high MRSA-positive test rate was detected in swab samples from milk-fed calves (22.7%; 46/203). In postweaning calves, the MRSA-positive test rate was 9.1% (17/187). From prefresh heifers, both nasal swabs and udder cleft swabs were collected if possible. Including both sample types, the MRSA-positive test rate in prefresh heifers was 13.0% (26/200). The positive test rate was 8.9% (17/191) in nasal swabs and 6.5% (11/170) in udder cleft swabs. In quarter milk samples (QMS), the MRSA-positive test rate was 2.9% (67/2347), and on cow level, 7.9% (47/597) of the dairy cows were affected. Among all cows included in this study, the geometric mean of somatic cell counts was higher in QMS that carried MRSA (345,000 cells/mL) in comparison to all QMS (114,000 cells/mL). No differences in parity or the affected mammary quarter position on the udder were observed among the 47 infected cows. Methicillin-resistant S. aureus was also detected in boot swab samples (dust), teat liners, and in suckers from automatic calf feeders. All isolates belonged to livestock-associated sequence type 398 and most common staphylococcal protein A (spa)-types were t011 and t034. Most isolates harbored the staphylococcal cassette chromosome mec (SCCmec)-type V, with the exception of some isolates with SCCmec-type IVa on 1 farm. Similar MRSA genotypes in samples from humans and dairy cows underline the possible zoonotic and reverse-zoonotic transmission of livestock-associated MRSA strains from dairy farms. Similar MRSA genotypes in pig and cattle barns were detected on only 1 of 5 farms that kept both cattle and pigs. Similar MRSA spa-types were detected in samples from different sources (dairy cows, young stock, environment, and humans), suggesting a possible contagious transmission on some of the farms. Sporadically, up to 3 different MRSA spa-types were detected in QMS from the respective farms. On MRSA-affected farms, improper milking hygiene procedures and elevated bulk-tank milk somatic cell counts (>250,000 cells/mL) were observed. The occurrence of livestock-associated MRSA ST398 in different samples from dairy farms, and especially in young calves, should be considered for future MRSA-monitoring programs and biosecurity guidelines.

Epidemiological evaluation of subclinical mastitis of dairy cows in Greece

Subclinical mastitis, diagnosed by elevated somatic cell count (SCC) in milk, is an important monitoring parameter of dairy cows’ udder health, related to their productivity and welfare. The present retrospective study aims to evaluate the epidemiology of subclinical mastitis (SCM) among the 37 herds of the Holstein Association of Greece participating in the milk quality recording system “ΙΩ”, from the start of 2015 until the end of 2018. The herds’ inclusion criterion was the consistency of monthly SCC recording throughout at least one full year between 2015 and 2018, with a maximum interval of 61 days between two consecutive monthly SCC recordings. Twenty-six herds (8630 cows) in 2015, thirty herds (10763 cows) in 2016, thirty herds (10945 cows) in 2017 and twenty-six herds (9597 cows) in 2018 were included. The prevalence of SCM and chronic SCM, the incidence rate of new cases of SCM, as well as the average somatic cell score and bulk tank milk SCC were determined for each of the four years. The results indicate a progressive deterioration of udder health from the onset of the cow’s productive life until culling. A year-over-year increase in the number of cows with subclinical mastitis led to an overall SCM prevalence of 34.5%, chronic SCM prevalence of 26.9% and a bulk tank milk SCC of 463000 cells/mL, in 2018. The average somatic cell score, a base 2logarithm of individual cow’s SCC, was found persistently above the subclinical mastitis indicative cut-off in all four years, with a peak in 2018. At herd level, the incidence rate of new SCM cases was 12 new cases / 100 cows / month; the highest incidence rate was observed in the early lactation stage group (1-60 days-in-milk), in all four years, reaching a peak of 31 new cases / 100 cows / month, in 2018. In 2018, prevalence of heifers’ SCM and chronic SCM was23.4% and 16.9%, respectively. Despite the adequate average 305-days milk yield (9608 kg in 2018), the results were indicative of poor udder health status, pointed out by reduced duration of cows’ productive life (less than 3 lactations)and lower milk quality (elevated SCC). The severity and wide spreading of subclinical mastitis in Greek dairy herds highlights the necessity of a national mastitis control program, aiming to improve the productive efficacy, management decisions accuracy and quality of produced milk.

Application of statistical process control for monitoring bulk tank milk somatic cell count of smallholder dairy farms

Background and Aim:Consistency in producing raw milk with less variation in bulk tank milk somatic cell count (BMSCC) is important for dairy farmers as their profit is highly affected by it in the long run. Statistical process control (SPC) is widely used for monitoring and detecting variations in an industrial process. Published reports on the application of the SPC method to smallholder farm data are very limited. Thus, the purpose of this study was to assess the capability of the SPC method for monitoring the variation of BMSCC levels in milk samples collected from smallholder dairy farms.Materials and Methods:Bulk tank milk samples (n=1302) from 31 farms were collected 3 times/month for 14 consecutive months. The samples were analyzed to determine the BMSCC levels. The SPC charts, including the individual chart (I-chart) and the moving range chart (MR-chart), were created to determine the BMSCC variations, out of control points, and process signals for each farm every month. The interpretation of the SPC charts was reported to dairy cooperative authorities and veterinarians.Results:Based on a set of BMSCC values as well as their variance from SPC charts, a series of BMSCC data could be classified into different scenarios, including farms with high BMSCC values but with low variations or farms with low BMSCC values and variations. Out of control points and signals or alarms corresponding to the SPC rules, such as trend and shift signals, were observed in some of the selected farms. The information from SPC charts was used by authorities and veterinarians to communicate with dairy farmers to monitor and control BMSCC for each farm.Conclusion:This study showed that the SPC method can be used to monitor the variation of BMSCC in milk sampled from smallholder farms. Moreover, information obtained from the SPC charts can serve as a guideline for dairy farmers, dairy cooperative boards, and veterinarians to manage somatic cell counts in bulk tanks from smallholder dairy farms.

Farm-level risk factors for bovine mastitis in Dutch automatic milking dairy herds

Automatic milking systems (AMS) are installed on a growing number of dairy farms worldwide. Management to support good udder health might be different on farms with an AMS compared with farms milking with a conventional milking system, as risk factors for mastitis on farms using an AMS may differ. The aim of this study was to identify farm level factors associated with mastitis on Dutch dairy farms using an AMS. In 2008, risk factor data were collected using a questionnaire combined with on-farm recordings of cow, stall, and AMS hygiene on 135 farms. These risk factor data were linked to 4 udder-health-associated dependent variables: average herd somatic cell count (HeSCCav), variance of the average herd somatic cell count (SCC) on test days (HeSCCvar), the average proportion of new high SCC cases (NHiSCC), and the farmer-reported annual incidence rate of clinical mastitis (IRCM). We employed regression models using multiple imputation to deal with missing values. Due to the high dimensionality of the risk factor data, we also performed nonlinear principal component analysis (NLPCA) and regressed the dependent variables on the principal components (PC). Good hygiene of cows and of AMS were found to be related to a lower HeSCCav and less NHiSCC. Effective postmilking teat disinfection was associated with a lower NHiSCC. A higher bulk tank milk SCC threshold for farmers' action was related to more NHiSCC. Larger farm size was related to lower HeSCCvar but higher NHiSCC. Negative attitude of farmers to animal health, higher frequency of checking AMS, and more time spent on viewing computer data were all positively related to higher IRCM. An NLPCA with 3 PC explained 16.3% of the variance in the risk factor variables. Only the first 2 PC were associated with mastitis. The first PC reflected older and larger farms with poor cow hygiene and AMS hygiene, and was related to higher HeSCCav and NHiSCC, whereas the second PC reflected newly built smaller farms with poor cow hygiene and low milk production, and was associated with higher HeSCCvar and NHiSCC, but lower IRCM. Our study suggests that many of the risk factors on conventional milking system farms are applicable to AMS farms, specifically concerning hygiene of the cows and the milking machine, but on large AMS farms, udder health may need more attention than on smaller AMS farms. Multiple imputation is instrumental to deal with missing values and NLPCA is a useful technique to process high dimensional data in our study.

Study of the association of atmospheric temperature and relative humidity with bulk tank milk somatic cell count in dairy herds using Generalized additive mixed models

Elevated bulk tank milk somatic cell count (BMSCC) has a negative impact on milk production, milk quality, and animal health. Seasonal increases in herd level somatic cell count (SCC) are commonly associated with elevated environmental temperature and humidity. The Temperature Humidity Index (THI) has been developed to measure general environmental stress in dairy cattle; however, additional work is needed to determine a specific effect of the heat stress index on herd-level SCC. Generalized Additive Model methods were used for a flexible exploration of the relationships between daily temperature, relative humidity, and bulk milk somatic cell count. The data consist of BMSCC and meteorological recordings collected between March 2009 and October 2011 of 10 dairy farms. The results indicate that, an average increase of 0.16% of BMSCC is expected for an increase of 1°C degree of temperature. A complex relationship was found for relative humidity. For example, increase of 0.099%, 0.037% and 0.020% are expected in correspondence to an increase of relative humidity from 50% to 51%, 80% to 81%; and 90% to 91%, respectively. Using this model, it will be possible to provide evidence-based advice to dairy farmers for the use of THI control charts created on the basis of our statistical model.

Influence of milking method, disinfection and herd management practices on bulk tank milk somatic cell counts in tropical dairy herds in Colombia

The aims of this study were to evaluate the effects of milking method, disinfection practices and other management factors on the bulk tank milk somatic cell count (BTSCC) in tropical dairy herds and to examine potential interactions with time. One hundred and thirty farms in the Northern region of Antioquia, Colombia, were visited once per month for 24 months. A two level linear mixed model for repeated measures was used to assess the impact on log transformed BTSCC (lnBTSCC). The geometric mean of the BTSCC for all herds was 262,330 cells/mL. The two-level linear mixed model showed that lnBTSCCs in hand milked herds were significantly higher than in machine milked herds. Fore-stripping corresponded with a 27% increase in lnBTSCC and failing to post-dip corresponded with a 45% increase in lnBTSCC. The two way interactions of sampling month with milking method, singeing udders and pre-dipping were significant. The lowest predicted lnBTSCC was observed in machine milked herds that practised both pre-dipping and singeing of udders. This study suggests that milking procedures and disinfection practices can interact with time and have substantial effects on lnBTSCC.

Prevalence of Bovine Mastitis Pathogens in Bulk Tank Milk in China.

The objectives of this study were to estimate the herd prevalence of major mastitis pathogens in bulk tank milk (BTM) in China dairy herds, to determine the relationship between the presence of mastitis pathogens and bulk tank milk somatic cell counts (BTSCC), and to investigate the impact of different dairy cattle farming modes and region on bacterial species. BTM samples collected from 894 dairy herds in China were examined for the presence of mastitis pathogens. The Flinders Technology Associates (FTA) cards were used for BTM sample collection, storage, and transportation and bacterial DNA amplification by real-time PCR. Among contagious pathogens, Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus dysgalactiae were detected in 50.1, 92.2, and 72.3% of the 894 BTM samples, respectively. Among environmental pathogens, E. coli, Streptococcus uberis, Enterococcus spp., Klebsiella spp., Serratia marcescens, Corynebacterium bovis, and Arcanobacterium pyogenes were detected in 28.6, 8.9, 35.7, 20.0, 1.3, 17.0, and 67.2% of the BTM samples, respectively. Staphylococcal β-lactamase gene was detected in 61.7% of the BTM samples. The presence of Staphylococcus aureus and Arcanobacterium pyogenes were significantly associated with high BTSCC, respectively. Significant differences were found in presence of Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus dysgalactiae in BTM sampled from the small household farms, dairy-farming communities, and large-scaled dairy farms. There were significant differences in the presence of Streptococcus agalactiae, Streptococcus dysgalactiae, Arcanobacterium pyogenes, staphylococcal β-lactamase gene, Staphylococcus spp., Klebsiella spp., Enterococcus spp., and Streptococcus uberis in BTM among Inner Mongolia, Heilongjiang, and Hebei province. In conclusion, contagious mammary pathogens are predominated among pathogens in BTM samples in China.

An estimation of the clinical mastitis incidence per 100 cows per year based on routinely collected herd data

The aim of this study was to evaluate whether it was possible to (1) estimate the clinical mastitis incidence rate (CMI) for all Dutch dairy herds and (2) to detect farms with a high CMI based on routinely collected herd data. For this study, 240 dairy farms with a conventional milking system that participated in the milk recording program every 4 to 6 wk were randomly selected and agreed to participate. From the initial 240 herds, data of clinical mastitis (CM) registrations and routinely collected herd data of 227 herds were complete and could be used for analysis. Routinely collected herd data consisted of identification and registration records, antimicrobial usage, test-day records from the milk recording program, bulk tank milk (BTM) somatic cell count data and results of diagnostic tests on BTM samples. For each of the 227 herds, the CMI per 100 cows per year was calculated per quarter of the year and was combined with the available herd data. Two models were developed to predict the CMI for all dairy herds and to detect individual herds that belonged to the 25% herds with the highest CMI. Records of 156 (67%) herds were used for development of the models and the remaining 71 (33%) were used for validation. The model that estimated the CMI in all herds consisted of 11 explanatory variables. The observed and predicted averages of the validation herds were not significantly different. The model estimated a CMI per 100 cows per year of 32.5 cases (95% confidence interval=30.2–34.8), whereas the farmers registered 33.4 cases (95% confidence interval=29.5–37.4). The model that aimed at detecting individual herds with a high CMI contained 6 explanatory variables and could correctly classify 77% of all validation herds at the quarter-year level. The most important variables in the model were antibiotic usage for treating CM and BTM somatic cell count. In conclusion, models based on routinely collected herd data gave an accurate prediction of CMI for all Dutch dairy herds and could detect individual dairy herds with a high CMI. With these models it is possible to periodically monitor CMI both at the herd and at the national level, which is valuable for monitoring purposes and can motivate farmers to continuously improve udder health in their herds.

Bulk tank milk somatic cell counts in dairy herds with different bovine viral diarrhoea virus status in Poland

The aim of the study was to examine the effect of bovine viral diarrhoea virus (BVDV) infection on bulk tank milk somatic cell counts (BMSCC). Twenty nine dairy farms supplying milk to a dairy in Eastern Poland were recruited for the study. Bulk milk ELISA and RT-PCR were used to determine the BVDV infection status and the presence of PI animals in the farms. The BMSCC mean values for the BVDV seronegative (218.7×103cells/ml; SD: 89.8) and seropositive (214.9×103cells/ml; SD: 74.0) herds did not differ significantly. To assess the relationship between BVDV infection and BMSCC a multilevel mixed-effects linear model was used. No statistically significant effect of BVDV infection on BMSCC was found. The mean values of BMSCC for the herds with PI individuals measured before (230.1×103cells/ml, SD: 64.9) and after (223.3×103cells/ml, SD: 62.4) the PI removal were not statistically different. An increase in herd size was associated with a significant decrease in BMSCC. An increase in BMSCC was observed during summer (from May to September) compared to during winter (from October to April).

Time-to-event analysis of predictors for recovery from Salmonella Dublin infection in Danish dairy herds between 2002 and 2012

Salmonella Dublin infections reduce gross margins and compromise animal health and welfare in dairy cattle herds. Despite on-going control efforts in several countries the duration and risk factors of a persistent infection have been difficult to study due to a lack of suitable data. This study utilised the unique opportunity to extract systematically collected repeated bulk-tank milk antibody measurements from all the Danish dairy herds during a 10-year period to perform a time-to-event analysis of the factors that affect the duration of test-positivity and the hazards of recovery from S. Dublin at herd level.Recovery was defined as a shift from test-positive to test-negative between two year-quarters followed by at least three more test-negative year-quarters. The average duration of infection was approximately 2 years. Predictors of recovery were tested in a multivariable Cox proportional hazard model allowing herds to recover from infection multiple times over the 10-year surveillance period. The model results were based on 36,429 observations with data on all the predictors, representing 3563 herds with a total of 3246 recoveries. Sixty-seven herds (2.4%) remained test-positive throughout the study period. The rest of the 317 herds that did not have any recoveries were censored, mainly due to a cessation of milk production.Prior recovery from test-positivity turned out not to be a significant predictor of recovery in the model. The effect of the duration of infection on the conditional probability of recovery (i.e. the hazard) was time-dependent: early in the study period, long durations of infection were predictive of a low hazard of recovery. Later in the control programme the effect of duration of infection was reduced indicating a desired effect of an intensified control programme. There was an increasing tendency towards longer durations and lower hazard of recovery with: (i) increasing herd sizes, (ii) increasing bulk-tank milk somatic cell counts, (iii) increasing local prevalence within a 5km radius, (iv) organic farming and (v) recent purchase of cattle from test-positive herds. Participation in a voluntary paratuberculosis control programme reduced the duration of infection, and there were indications that recovery from S. Dublin infection was stimulated by a centrally organised and targeted control campaign. This is the first large-scale study that investigated duration of infection and predictors of recovery from S. Dublin in cattle herds over an extended period of time. The results provide useful knowledge for the design of control programmes for S. Dublin.

Survival analysis of factors affecting incidence risk of Salmonella Dublin in Danish dairy herds during a 7-year surveillance period

A national surveillance programme for Salmonella Dublin, based on regular bulk-tank milk antibody screening and movements of cattle, was initiated in Denmark in 2002. From 2002 to end of 2009 the prevalence of test-positive dairy herds was reduced from 26% to 10%. However, new infections and spread of S. Dublin between herds continued to occur.The objective of this study was to investigate factors affecting incidence risk of S. Dublin infection in Danish dairy herds between 2003 and 2009. Herds were considered at risk when they had been test-negative for at least four consecutive year-quarters (YQs), either at the start of the study period or after recovery from infection. Survival analysis was performed on a dataset including 6931 dairy herds with 118,969 YQs at risk, in which 1523 failures (new infection events) occurred. Predictors obtained from register data were tested in a multivariable, proportional hazard model allowing for recurrence within herds.During October to December the hazard of failures was higher (hazard ratio HR=3.4, P=0.0005) than the rest of the year. Accounting for the delay in bulk-tank milk antibody responses to S. Dublin infection, this indicates that introduction of bacteria was most frequent between July and October. Purchase from test-positive cattle herds within the previous 6months was associated with higher hazard of failures (HR=2.5, P<0.0001) compared to no purchase and purchase from test-negative herds. Increasing local prevalence, herd size and bulk-tank milk somatic cell counts were also associated with increasing hazard of failures. The effect of prior infection was time-dependent; the hazard of failures was reduced following a logarithmic decline with increasing time at risk. The hazard was markedly higher in herds with prior infections the first year after becoming at risk again, and then approached the hazard in herds without known prior infections 2–3years after becoming test-negative. This showed that herds with prior infections need to maintain a high level of biosecurity for at least 3years after becoming test-negative for S. Dublin to prevent recurrence. Furthermore, general recommendations for dairy herds wishing to protect their herds against S. Dublin include avoidance of purchase from and contact to test-positive herds. Large herds, herds with test-positive neighbours and herds with high somatic cell counts need to obtain and maintain a high level of biosecurity.

The relationship between antibody status to bovine corona virus and bovine respiratory syncytial virus and disease incidence, reproduction and herd characteristics in dairy herds

BackgroundBovine respiratory syncytial virus (BRSV) and bovine corona virus (BCV) affects cattle worldwide. Our objective was to evaluate the effects of these infections on general health and reproduction parameters measurable on herd level and to explore the association between antibody status and some herd characteristics.MethodsWe collected a pooled milk sample from five primiparous cows from 79 Swedish dairy herds in September 2006. The samples were analysed for immunoglobulin G antibodies to BCV and BRSV with indirect enzyme-linked immunosorbent assays. Herd level data from 1 September 2005 to 30 August 2006 were accessed retrospectively. The location of the herds was mapped using a geographical information system.ResultsTen herds were antibody negative to both viruses and were compared with 69 herds positive to BCV or BRSV or both. Positive herds had a higher (P = 0.001) bulk tank milk somatic cell count (BMSCC) compared with negative herds. The medians for all other analyzed health and reproductive parameters were consistently in favour of the herds negative to both viruses although the differences were not statistically significant. A higher proportion (P = 0.01) of herds used professional technicians for artificial insemination, rather than farm personnel, amongst the 33 herds negative to BCV compared with the 46 positive herds.ConclusionsOur result shows that herds that were antibody positive to BCV and/or BRSV had a higher BMSCC compared with herds negative to BCV and BRSV. There was also tendency that negative herds had a better general herd health compared with positive. A higher proportion amongst the BCV negative herds used external technicians for AI instead of farm personnel, indicating that it is possible to avoid infection although having regular visits. Negative herds were located in close proximity to positive herds, indicating that local spread and airborne transmission between herds might not be of great importance and that herds can stay free from these infection transmission although virus is circulating in the area.

Management Approaches to Reducing or Eliminating Mycoplasma Mastitis in a Dairy Herd

Mycoplasma spp can cause mastitis, arthritis, pneumonia, and metritis in dairy cattle. Progress in control of Mycoplasma spp mastitis, including any management changes made, was evaluated in Utah dairy herds approximately one year after diagnosis on farms that had participated in a mycoplasma prevalence study. Using a questionnaire developed at Utah State University, dairy producers and key management personnel on 10 previously mycoplasma-positive dairy farms in Utah were interviewed. Three farms had evidence that no mycoplasmal cows remained, four had mycoplasma still present, and three were of unknown mycoplasma status. Farms that cultured milk from all clinical mastitis cases for mycoplasma included all of the farms with no further evidence of mycoplasma in cows, and farms with very low prevalence remaining. Of farms that used only bulk-tank monitoring for mycoplasma at the time of the second follow-up survey, all but one were still positive or had unknown status; the only farm using bulk-tank monitoring that was apparently free of mycoplasma had cultured all clinical mastitis cases for several months after diagnosis in the herd, and sold all mycoplasmal cows found. All herds increased lactating cow numbers, and six had decreased bulk-tank milk somatic cell count (SCC). Decreased or eliminated mycoplasma mastitis was associated with approximately 1% less of the herd per month contracting clinical mastitis, and even further reduced treatment for mastitis. Mycoplasma mastitis persisting in dairy herds was associated with observing clinical mastitis moving from one quarter to another, adult cows with droopy ears and nonresponsive respiratory disease in calves.

Short communication: Effect of dry therapy using an intramammary infusion on bulk tank somatic cell count in sheep

A total of 3,141 records of bulk tank milk somatic cell counts (BTSCC) and bulk tank milk total bacterial counts (BTTBC) were obtained over 24 mo from 25 dairy flocks of Assaf ewes belonging to the Consortium for Ovine Promotion in Castilla-León, Spain, in which a complete dry therapy program was carried out in 10,313 ewes using an antibiotic infusion containing 100mg of penethamate hydriodide, 280mg of benethamine penicillin, and 100mg of framycetin sulfate. The selection criteria for all flocks were BTSCC mean values ≥1,000×103 cells/mL and absence of dry therapy before the start of this experiment. Significant effects on log BTSCC were detected for treatment, milking system, flock within milking system, month within flock by treatment, the interactions treatment by milking system and flock by treatment within milking system, and log BTTBC. After dry therapy was implemented, log BTSCC decreased significantly in machine-milked flocks (5.95±0.007) compared with values before antibiotic treatment (6.13±0.008). The effect was observed at the beginning of the second lactation posttreatment (5.98±0.013). However, dry therapy was not effective in hand-milked flocks, suggesting poor hygiene conditions. A significant relationship was found between BTSCC and BTTBC; therefore, programs for improving milk hygiene should be implemented for both BTSCC and BTTBC variables at the same time.

The effect of estrus synchronization treatments on somatic cell count of transitional-anestrus Awassi ewes’ milk

Fifty-three transitional-anestrus Awassi ewes, randomly assigned to three groups: fluorogestone acetate (FGA, n = 18), FGA-Prostaglandin (FGA-PGF, n = 18) and control (n = 17), were used to examine the effect of estrus synchronization protocols and steroid hormones concentrations on milk somatic cell count (SCC). Intravaginal FGA sponge was inserted for 13 days and 600 IU equine chorionic gonadotropin was administered for ewes of FGA and FGA-PGF groups at the time of sponge removal (day 0). In addition, 10 mg was administered to ewes of FGA-PGF group on day 0. Blood and milk samples were collected from all ewes on days -13, -6, 0, 1, 2, 7 and 14. Estradiol had significant positive correlation with the SCC during the periods of sponge insertion (P = 0.015, r = 0.235) and within two days (P = 0.063 r = 0.23) after sponge removal with no correlation with SCC of both udder halves during the luteal phase. Progesterone concentrations, on the other hand, had a significant positive correlation (P < 0.001; r = 0.420) with the SCC of both udder halves during the luteal phase of the experiment, but not during the periods of sponge insertion and expected estrus. SCC returned under the influence of endogenous progesterone on days 7 and 14 to pre-synchronization values. In conclusion, sheep milk SCC is affected significantly with induction of estrus and steroid hormones concentrations. However, peak SCC recorded during estrus was far below the upper limit of the current standard for normal milk. With the current standards for SCC of 1,000,000/ml as legal limit for abnormal milk control programs in sheep, estrus synchronization programs and the estrus status should not be considered when bulk-tank milk SCC is being investigated, but should be considered during the process of setting new standards.

Presence of Mycoplasma species and somatic cell counts in bulk-tank goat milk

This cross-sectional study performed on dairy goat herds was designed to establish the relationship between the presence of Mycoplasma species in bulk-tank milk samples from different farms and the bulk-tank milk somatic cell count (BTMSCC) in an area where contagious agalactia (CA) is endemic. Three BTMSCC thresholds, used in payment schemes or as legal requirements for milk quality in Europe and the USA, were considered: (1) 2,000,000 cells/ml; (2) 1,500,000 cells/ml and (3) 1,000,000 cells/ml. Of the 1068 milk samples tested, 7.9% ( n = 84) showed the presence of Mycoplasma spp. ( Mycoplasma agalactiae 82% and Mycoplasma mycoides subsp. mycoides large colony 17%). Somatic cell counts for bulk-tank samples containing mycoplasmas were higher than those recorded for negative samples (1,176,000 cells/ml vs. 875,000 cells/ml; P < 0.001). Two-by-two table analyses revealed that the presence of mycoplasmas in bulk-tank milk increased the risk of surpassing all SCC thresholds considered, with the highest risk for Mycoplasma positive bulk-tank milk samples exceeding the threshold of 1500 × 10 3 cells/ml (odds ratio = 2.42 (1.49 < OR < 3.91). Our results indicate that the presence of mycoplasmas in goat milk had yet another economic consequence and a further incentive to encourage the implementation of specific programs for disease control.

The effect of estrus synchronization treatment on somatic cell count of transitional-anestrus local-Damascus cross breed goats’ milk

An experiment was conducted to examine the effect of estrus synchronization protocols and steroid hormones concentrations on somatic cell count (SCC) of transitional-anestrus local-Damascus cross goats' milk. Fifty-six goats (2-4-year old) were randomly assigned to three groups: fluorogestone acetate (FGA, n = 19), FGA-Prostaglandin (FGA-PGF, n = 19) and control (n = 18) groups. Intravaginal sponge containing 40 mg FGA was inserted for 13 days and an injection of 600 IU equine chorionic gonadotropin (eCG) was administered for goats of FGA and FGA-PGF groups at the time of sponge removal (day 0). In addition, goats of FGA-PGF group were injected with 10 mg dinoprost tromethamine (PGF2alpha) on day 0. Five fertile local-Damascus cross bucks were turned-in with all goats on day 0. Blood and milk samples were collected from all goats on days -13 (beginning of experiment), -6, 0, 1, 2, 7, 13 and 20 (end of the experiment). Four-year old and second-parity goats had significantly higher (p < 0.05) SCC of both udder halves than 2- and 3-year old and first-parity goats, respectively. There was a significant effect (p < 0.05) for treatment and number of kids born in the last kidding season on SCC of both udder halves. Neither estradiol nor progesterone concentrations were correlated with SCC in goats in this experiment. The SCC of both udder halves and left udder halves in goats of the control and FGA groups, respectively, increased significantly (p < 0.05) after sponge removal and buck introduction when compared with day 0, with no differences in the FGA-PGF group. This increase in SCC of the control and FGA groups coincided with peak estrus behavior. However, SCC was far below the upper limit of the current standard for normal milk. In conclusion, induction of estrus with progestagen based programs and buck introduction may cause temporary significant increase in SCC. However, the SCC values during this period of temporary increase were still in the range of acceptable values for normal milk. With the current standards for SCC of 1,000,000/ml as legal limit for abnormal milk control programs in goats, estrus synchronization programs and the estrus status should not be considered when bulk-tank milk SCC is being investigated.