Occurrence Of Clinical Mastitis Research Articles

An observational study to investigate the association of teat skin condition with clinical mastitis risk

The importance of teat canal integrity and its adjacent tissues in the dynamics of IMI is well documented, whereas research on the relationship between teat skin condition and clinical mastitis occurrence is scarce. The objective of this ambidirectional cohort study was to investigate the association of teat skin condition with clinical mastitis occurrence in a closed cohort from a commercial dairy farm with a thrice daily milking schedule in the Northeast of the United States. We tested the hypothesis that quarters with teats with altered skin condition would have higher odds of clinical mastitis than those with normal skin. Teat skin condition from 2,670 cows was assessed during a single visit and categorized into (1) normal, (2) dry skin, (3) skin lesion, and (4) dry skin and skin lesion. Cows were monitored for 2 wk after the teat skin condition assessment and the occurrence of clinical mastitis at the quarter level was documented. A generalized linear mixed model with a logit link and a binomial distribution revealed an association between teat skin condition and the occurrence of clinical mastitis. Compared with quarters with teats with normal teat skin, the odds (95% confidence intervals) of clinical mastitis were 0.98 (0.60–1.60) for teats with dry skin, 1.88 (0.97–3.66) for teats with a skin lesion, and 4.87 (1.71–13.85) for teats with dry skin and a skin lesion. We conclude that quarters from teats with dry skin and skin lesions had higher odds of clinical mastitis. In addition, we found evidence that quarters with teats with skin lesions have higher odds of clinical mastitis than those with normal teat skin, though future studies are needed. The results from this study show that teat skin condition should be considered in mastitis control programs on dairy operations.

Impact of temporal variations and risk factors associated with udder inflammation in Hardhenu cattle (Bos taurus × Bos indicus).

This study aimed to explore the occurrence and risk factors associated with clinical mastitis within the Hardhenu cattle herd over a span of 14 years (2008-2021). A comprehensive analysis of 1515 lactation records was conducted to ascertain the incidence of clinical mastitis. The investigation determined an overall incidence rate of 26.80% in the studied population. A significant relationship between the year and clinical mastitis incidence was established through Chi-square analysis (p < .05). Temporal variations in clinical mastitis odds were apparent, with the highest odds (ranging from 0.91 to 1.00) observed during the initial years of 2008-2009 and 2009-2010. Logistic regression revealed that odds values for clinical mastitis incidence were highest in 2008-2009 (1.00), succeeded by 2009-2010 (0.91), 2012-2013 (0.88), 2018-2019 (0.67) and reaching the lowest in 2021-2022 (0.35). Subsequent rankings included 2010-2011 (0.39), 2014-2015 (0.43) and 2019-2020 (0.45). Parity was found to be significantly associated with clinical mastitis occurrence. When compared to Parity 3, both Parity 1 (odds ratio: 1.516, 95% confidence interval: 0.881-2.612) and Parity 2 (odds ratio: 2.626, 95% confidence interval: 1.568-4.398) exhibited higher odds values for clinical mastitis incidence. While the period of calving did not exert a significant influence on clinical mastitis incidence, a heightened occurrence was observed during the rainy season within the targeted population. These findings offer valuable insights into the patterns of incidence, temporal fluctuations, and non-genetic determinants impacting clinical mastitis within the Hardhenu cattle. The implications of this study can facilitate the development of targeted strategies and management protocols aimed at enhancing udder health and overall productivity in dairy cattle.

Association of CXCR1 gene polymorphism with clinical mastitis, reproductive disorders and performance traits in Hardhenu (Bos taurus × Bos indicus) cattle.

The present study investigated the presence of CXCR1 gene polymorphisms and their association with clinical mastitis, reproductive disorders and performance traits in Hardhenu cattle. Genotyping of the targeted SNP rs211042414 (C>T) at the g.106216468 loci of the CXCR1 gene was performed through PCR amplification and Bsa1 restriction enzyme digestion. The genotypic frequencies revealed three genotypes: CC, CT and TT, with the C allele being the most prevalent. Significant associations were found between the targeted SNP and clinical mastitis occurrence using chi-square and logistic regression analyses. The CC genotype showed higher susceptibility to clinical mastitis with a higher odds ratio of 3.47 compared to TT (1.00) and CT (2.90) genotypes (p < .05). Furthermore, least squares analysis revealed significant associations between genotypes and performance traits such as total milk yield, 305-day milk yield and peak yield (p < .05). The CC genotype exhibited higher milk yields than CT and TT genotypes, indicating a positive association between the C allele and increased milk production. These findings have practical implications for the genetic improvement of Hardhenu cattle. Incorporating the identified CXCR1 gene polymorphisms into existing selection criteria can help enhance disease resistance and milk production traits. However, further validation with a larger sample size is necessary to strengthen the observed associations and ensure their practical applicability.

Herd-Level Risk Factors for Lameness, Leg Injuries, Thin Body Condition and Mastitis on Algerian Dairy Farms

Abstract This present study aims to investigate the relationship of herd characteristics and management practices with the prevalence of clinical and severe lameness, hock and knee injuries, thin cows, and mastitis at the herd level on Algerian dairy farms. Altogether 1210 dairy cows from 107 farms were examined and the clinical aspects related to studied affections were recorded. Multivariable regression models were built to analyse the relationship between the risk factors and the occurrence of health indicators. Overlay, the health outcomes were multifactorial, with pasture access (P &lt; 0.001), scraping frequency (P &lt; 0.01), and floor regularity (P = 0.05) as the main factors causing lameness. Factors associated with both hock and knee injuries (score ≥ 2) were lower cow number (P &lt; 0.01), more days spent on pasture (P &lt; 0.001), and poorer straw amount for bedding (P &lt; 0.001). Some farming practice, in particular, providing proper amount of concentrate feeds (P &lt; 0.001), higher scraping frequency (P &lt; 0.01), thicker bedding (P &lt; 0.001), and having younger dairy cows (P = 0.058), were associated with a lower within-herd prevalence of thin cows. While, more days on pasture increased the percentage of under-conditioned cows (P &lt; 0.01). The inadequate hygienic conditions of the floor (P &lt; 0.001), improper milking procedures (P &lt; 0.05), and shorter dry period (P &lt; 0.05) increased the clinical mastitis occurrence. Our results highlighted the specific management practices responsible for increasing health risks and provided useful information for the farmers and veterinarians to make preventive and controlling strategies for lameness, leg injuries, low body condition and mastitis on dairy farms.

Effects of pathogen-specific clinical mastitis occurrence in the first 100 days of lactation 1 on future mastitis occurrence in Holstein dairy cows: An observational study

The objective of this observational study was to estimate effects of clinical mastitis (CM) cases caused by different pathogens (Streptococcus spp., Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., and CM cases with no growth) occurring in the first 100 d in lactation 1, of a dairy cow on the future rate of occurrence of different types of CM during a cow's full lifetime. The outcomes were occurrence of Streptococcus spp., Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., and CM cases with no growth, after the first 100 d of lactation 1, until a cow's removal through death or sale in that or a subsequent lactation. Data, including information on CM cases, milk production, and event dates (including death or sale dates), were collected from 14,440 cows in 5 New York State Holstein herds from January 2004 until February 2014. Generalized linear mixed models with a Poisson distribution and log link function were fit for each pathogen. The individual cow was the unit of analysis. Escherichia coli was a predictor of future occurrence of E. coli, Klebsiella spp., and CM cases with no growth. Early-occurring Klebsiella spp. was a predictor of future cases of Klebsiella spp. Cases with no growth were predictors of future occurrence of Staphylococcus spp., E. coli, Klebsiella spp., and cases with no growth. Thus, E. coli and cases with no growth occurring early in lactation 1 appear to be consistent risk factors for future cases of CM, whether cases with the same pathogen or a different pathogen. In this study, farm effects on later pathogen occurrence differed somewhat, so treatment protocol and culling strategy may play a role in the findings. Nevertheless, the findings may help farmers in managing young cows with CM in early productive life, especially those with E. coli or cases with no growth, in that they may be more susceptible to future CM cases in their later productive life, thus meriting closer attention.

Udder health of dairy cows with an extended voluntary waiting period from calving until the first insemination.

This study aimed to evaluate the effect of an extended voluntary waiting period (VWP) on SCC, SCC elevations and clinical mastitis incidence during the complete lactation and the first 6 weeks of the next lactation. Holstein-Friesian dairy cows (N = 154) were blocked for parity, expected milk yield, calving season and breeding value for persistency and were randomly distributed across 3 VWP (50, 125, or 200 d: VWP-50, VWP-125, VWP-200). Cows were monitored from calving until 6 weeks into the next lactation, or until culling. An elevation of SCC in milk was defined as SCC in milk ≥200 000 cells/ml after two previous weeks with SCC < 200 000 cells/ml. Over the complete lactation, extending the VWP did not affect SCC elevations and the occurrence of clinical mastitis per lactation or per cow per year. There was no clear effect of VWP length on SCC in the complete lactation, except that multiparous cows in VWP-125 had a higher SCC compared with multiparous cows in VWP-50. Dry-off antibiotic usage per cow per year was lower in VWP-200 compared with VWP-50 for multiparous cows. In the first 6 weeks of the next lactation, cows in VWP-200 had a higher SCC compared with cows in VWP-50, with no effect of VWP on the number of elevations of SCC or the occurrence of clinical mastitis. Extending the VWP may therefore be used to reduce the frequency of transition periods and the associated use of dry-cow antibiotics, with limited impact on udder health, and a similar occurrence of SCC elevations and clinical mastitis per year.

Prevalence and Phylodiversity of ESBL-Producing Coliforms Isolated from Ruminant Mastitis in Nigeria

Abstract The public health threat posed by Extended-spectrum beta-lactamase producing E. coli (ESBL-EC) in food animal production systems has attracted global attention. Data on the prevalence, diversity and genetic characteristics of ESBL-producing coliforms are key to advocacy on promoting responsible antimicrobial stewardship and proper planning of control strategies. The coliforms were isolated from 1052 milk samples of 160 cows, 103 ewes and 103 does with mastitis in Plateau State, Nigeria and analysed for ESBL production by phenotypic, biochemical, antimicrobial sensitivity and genetic characterization. The percentage of occurrence of clinical mastitis in cows, ewes, and does were 0.2 %, 0 %, 1.5 % respectively, while the percentage occur-rence of subclinical mastitis in ruminants were 18.1 %, 28.2 % and 38.3 % respectively. From the 677 isolates, 31.3 % (n = 212) were ESBL producing coliforms, with a prevalence of 48.6 %, 18.4 %, 12.7 %, 8.9 %, 5.7 %, 3.8 % and 1.9 % for E. coli, K. pneumoniae, C. freundii, K. aerogenes, S. marcescens, K. oxytoca and E. cloacae, respectively. The genetic characterization revealed a higher prevalence of bla CTX-M than bla TEM in the samples analysed (24.39 % vs. 12.19 %). High pairwise identity was observed among the bla CTX-M and bla TEM gene sequences obtained in this study, but they displayed high phylodiversity with sequences from ruminants and humans from other climes. The bla SHV gene was not detected. Multidrug resistances especially to the commonly used antimicrobials; ofloxacin, gentamycin and streptomycin in veterinary practice in Nigeria were observed. This has public health implications considering the fact that consumption of raw unpasteurized milk is a common practice in some cultures in Nigeria. Such practise will facilitate the transfer of multidrug resistant coliforms to humans resulting in the complications of treatment outcomes. To the best of our knowledge this is the first genetic characterization of ESBL-producing agents from ruminant mastitis in Nigeria.

Udder and teat morphometry in relation to clinical mastitis in dairy cows.

The present study was undertaken to explore the association of occurrence of clinical mastitis with udder and teat morphometry in cattle. The relationship of nine udder and eight teat morphometric traits with the occurrence of clinical mastitis was analysed using a binomial logistic regression model. A significant association of the udder and teat morphometric traits with the occurrence of mastitis was observed both in Karan Fries and Sahiwal cattle. The rear udder height, rear udder width, udder width and fore udder attachment were found to be the important udder morphometric traits associated with the occurrence of mastitis. In both groups, mastitic animals had broader rear udder width, lower rear udder height and loose fore udder attachment with lengthy and thicker teats. The inclusion of udder and teat morphometric traits in the selection and breeding program of Karan Fries and Sahiwal cattle may help in selection of animals for mastitis resistance.

Short communication: Variance and autocorrelation of deviations in daily milk yield are related with clinical mastitis in dairy cows

Daily milk production, and fluctuations therein, can provide information on health and resilience of dairy cows. We studied variance and autocorrelation of deviations in daily milk yield in relation to the occurrence of clinical mastitis (no, early or later in lactation). Individual lactation curves were fitted to 305-d lactations of 414 dairy cows using quantile regression. Log-transformed variance (lnVar) and autocorrelation of the quantile residuals of daily milk yield (predicted – observed) were evaluated for intervals until 30 and until 305 days in milk (DIM). Cows were classified as having no mastitis (n = 249), early mastitis that first occurred before 30 DIM (n = 29); or later mastitis (n = 136). Subsequently, linear models were used to assess effects of mastitis and parity class (primiparous or multiparous) on lnVar and autocorrelations; and logistic regression analyses were performed to predict mastitis from lnVar or autocorrelation and parity. From 10 to 30 DIM, lnVar was greater for cows with early mastitis than for cows with no or late mastitis, and autocorrelation tended to be lower for cows with early mastitis than for cows with no mastitis. The lnVar and autocorrelation from 10 to 30 DIM were not predictive of late mastitis. From 10 to 305 DIM, lnVar was greater and autocorrelation was lower for both cows with early and late mastitis than for cows with no mastitis; and both were predictive of having mastitis in the 305-d lactation. Primiparous cows had lower lnVar than multiparous cows. In cows without mastitis, autocorrelation values were positively correlated with lnVar. Results confirm that increased lnVar is associated with clinical mastitis.

Isolation and Identification of Major Pathogenic Bacteria from Clinical Mastitic Cows in Asella Town, Ethiopia.

Mastitis is a multietiological and complex disease causing inflammation of the parenchyma of mammary glands and is a problem in many dairy cows. The objective of this study was to isolate and identify the pathogenic bacteria that cause bovine clinical mastitis. A cross-sectional study was undertaken between November 2018 to April 2019 on a small scale and government dairy farms in Asella town. Cow's udder and teats were physically examined to detect clinical mastitis. A total of 83 milk samples were collected from 46 cows that show clinical sign of mastitis from a total of 12 farms. Isolation and identification of major bacterial species were carried out by culturing different media and using primary and secondary biochemical tests. Out of the 83 samples collected and examined, all (100%) were positive for the cultural isolation of bacterial species. The bacteria were identified to genus and species level. Among the 83 isolates, 32 (38.6%), 24 (28.9%), and 6 (7.2%) were Staphylococcus aureus, Staphylococcus intermedius, and Staphylococcus hyicus, respectively. Other bacteria like Escherichia coli 12 (14.5%) and Streptococcus species 2 (2.4%) were also isolated. Bacillus species 2 (2.4%), Proteus species 2 (2.4%), and 3 (3.6%) of them were mixed bacterial infections. The present study revealed that both contagious and environmental bacterial pathogens were responsible for the occurrence of clinical mastitis. Proper milking practices and farm husbandry practices and future detailed studies up to the species level and on antibiotic profiles of the pathogens are needed.

Influence of Mastitis and Repeat Breeding Incidence on Participation in the Animal Insurance Program for Dairy Farmers in Ba Vi, Hanoi, Vietnam

The livestock insurance program for dairy farmers in Vietnam targeting various acute diseases began in 2011 as a pilot project; however, due to vaccination campaigns, outbreaks of such diseases are rare. The objective of this study was to investigate the effects of mastitis and reproductive failure-which chronically affect the farming economy-on the decision to participate in the insurance program. A survey involving a questionnaire and milk sampling from apparently healthy animals was conducted on the 38 participating and 59 non-participating dairy farms in the livestock insurance program in Ba Vi, Hanoi, Vietnam, in August 2014. Microbiological tests were performed to detect sub-clinical mastitis, whereas the questionnaire was administered to collect information regarding farm management and the occurrence of clinical mastitis and reproductive failure over the previous three months. There were no significant differences in the proportion of farms having cows with clinical mastitis (insured: 8/38 farms, 21.1% vs. non-insured: 13/58 farms, NA = 1, 22.8%, p = 1) and repeat breeders (insured: 16/36 farms, NA = 2, 44.4% vs. non-insured: 20/57 farms, NA = 2, 35.1%, p = 0.49) over the previous three months. The proportion of farms having cows with sub-clinical mastitis at the time of the survey was also not significantly different between insured (5/38 farms, 13.2%) and non-insured (7/59 farms, 11.91%) farms (p = 1). Based on the obtained results, neither endemic disease nor farm management is respectably involved in the decision of farms to participate in the animal insurance program targeting acute animal infectious diseases.

Evaluation of production parameters and health of dairy cows treated with pegbovigrastim in the transition period

The aim of this study was to evaluate the effects of pegbovigrastim injection (Imrestor, Elanco Animal Health, Greenfield, IN) on production parameters and postpartum disease occurrence (retained placenta, metritis, displaced abomasum, and clinical mastitis) in dairy cows. Study cows (n = 270) were blocked by parity group (multiparous or primiparous) and randomly assigned to control (CON, n = 144) or pegbovigrastim treatment (IMR, n = 126). Ten ± 4 days before expected calving and again at calving, IMR cows received 2.7 mL of Imrestor and CON cows received 2.7 mL of 0.9 % saline. Milk yield, fat, protein, lactose, solids nonfat (SNF) percent, and somatic cell count (SCC), body condition, hygiene, and lameness were evaluated weekly. Animals were evaluated for metritis twice weekly through rectal temperature, palpation, and uterine discharge evaluation until 30 days in milk. Farm personnel recorded other postpartum diseases. The MIXED procedure of SAS was used to evaluate milk composition and milk yields were analyzed as repeated measures in time with block, treatment, calving month, and lactation week included in mixed models. The GLIMMIX procedure was used to evaluate mastitis and metritis occurrence. Variables entered a model if P ≤ 0.10 when screened individually. Variables with P ≤ 0.10 were kept in the final model. Milk yield, fat, protein, lactose, SNF, and log of SCC were not significantly affected by treatment. Clinical mastitis occurrence did not differ between treatments, but only 17 cases were detected. Compared to CON, IMR treated cows had increased clinical metritis incidence, and were 2.46 times more likely to develop the disease. No difference was observed on puerperal metritis ocurrence. Cows given pegbovigrastim injections had increased odds of developing clinical signs of metritis, but no negative effects on milk production or composition were observed.

Negative effects of occurrence of clinical mastitis from calving to end of the voluntary waiting period on reproduction in Holstein cows

The objective was to evaluate the effects of clinical mastitis (CM) on reproductive performance in high-milk?producing cows before the service period. The data of Holstein Friesian cows (n = 550) in a commercial farm was retrospectively evaluated. The diagnosis of CM was made by the presence of visible abnormalities in milk or symptoms of inflammation of one or more of the quarters. Cows were checked to detect CM prior to each milking. Calving to first service interval (CFSI), calving to conception interval (CCI), and services per conception (SC) were evaluated as reproductive parameters. Calving to first service interval (83.68 ± 3.18 vs. 74.57 ± 1.08; P < 0.05) and CCI (168.48 ± 8.59 vs. 132.86 ± 3.44; P < 0.001) were prolonged by 11.77% and 26.81%, respectively, and the number of SC (3.16 ± 0.21 vs. 2.42 ± 0.09; P < 0.001) was increased by 30.58% in cows experiencing CM. The culling candidate rate in nonpregnant cows was higher in the mastitis group (4.35%; 6/132) than in the healthy group (0.48%; 2/418). Calving season, time period of CM, and lactation number were not associated with the negative effects of mastitis in reproductive performance (P > 0.05). In conclusion, CM in early lactation has an adverse impact on reproductive performance in high-milk?producing dairy cows. The negative effects of CM on CFSI, CCI, and SC were not interrelated with calving season, the timing of CM, or parity.

Farm records in investigation of epidemiology, symptomatology and causes of clinical mastitis in a dairy farm

Mastitis is one of the most important diseases in dairy cow farms and one of the most common cause for antibiotic treatment. Aims of this study were: to investigate frequency and trends of clinical mastitis in cows on a large dairy farm, describe clinical characteristics of mastitis and investigate causative infectious agents in selected cases alongside antimicrobial resistance. In our study we used farm records for clinical mastitis recorded for period 2016 and 2017. We also used results of the regular on farm testing of the somatic cell count for 2017. Samples of milk from all clinical mastitis cases were taken during November and December 2017 in order to investigate causative agents and their antimicrobial resistance. Occurrence of clinical mastitis was 205 cases (47.7%) in 2017 compared to 93 cases (29.7%) recorded in 2016. In 2017 reoccurrence of clinical mastitis in same animal was recorded for 93 cows (45.4%). In 2016 reoccurrence of clinical mastitis in same animal was recoded for 49 cows (29.7%). Average course of clinical mastitis in 2016 was 3 days, while in 2017 4.5 days (continuous days of recording a case in farm records). Somatic cell count in more than half of tested animals was higher than 200.000 SC/ml according to the measurements from February and July 2017 (number of cows tested 236 and 169, respectively). Out of 23 milk samples, 20 had bacteriological growth. In 9 samples we identified S.aureus, in 6 streptococcus spp., in 4 coagulase negative staphylococci (CNS) and one sample contained E.coli. Most common resistance was found for lincomycin-spectinomycin (100%) gentamicin (92%), followed by cefquinome (65%), linkomycin (53%) and erythromycin (47%). Isolates of S.aureus were resistant on the largest number of investigated antibiotics.

Identification of polymorphism in the bovine interleukin-17A gene and its association with mastitis in Polish Holstein–Friesian cattle

The main aim of this study was to identify the association between the single nucleotide polymorphism (SNP) in the bovine interleukin-17A (IL-17A) gene and mastitis resistance. Additionally, the connection between the identified polymorphism and the somatic cell score (SCS) was tested. Two hundred and six Polish Holstein?Friesian cows were genotyped using the PCR-RFLP method. One SNP mutation (c.126G>A) was identified within the coding sequence of the analyzed gene. Results of logistic regression analysis displayed no significant association between the IL-17A genotype and clinical mastitis occurrence (Wald chi-square test = 0.74; P = 0.69). The GLM analysis demonstrated that genotype also did not affect the SCS (P = 0.77), while the effects of age at first calving, lactation number, lactation stage, mean milk yield per milking day, and milk yield on the day of milk recording proved to be highly significant (P < 0.01). The present study was one of the first to show an association between polymorphism within the IL-17A gene and selected udder health traits in cattle. An influence of the c.126G>A polymorphism on clinical mastitis and the SCS in the studied set of Polish Holstein?Friesian cows was not found. This suggests that the c.126G>A marker is probably not relevant for genetic selection against mastitis in the analyzed breed.

L-selectin gene polymorphism and its association with clinical mastitis, somatic cell score, and milk production in Polish Holstein-Friesian cattle

Bovine mastitis is a widespread disease of the mammary gland, highly contributing to the increase in veterinary costs in dairy industry. In the present study, the genetic polymorphism within bovine L-selectin gene was analysed and its impact on clinical mastitis occurrence, somatic cell score (SCS), and milk production traits in Polish Holstein-Friesian cows was examined. Polymorphism within L-selectin gene, molecule responsible for neutrophil attachment to endothelium, might have a potential role in immune response to bacterial infections and udder health. Two hundred and six Polish Holstein-Friesian cows were genotyped by polymerase chain reaction-restriction fragment length polymorphism method. Two single nucleotide polymorphisms mutations within the coding sequence of L-selectin gene were identified (c.165G&amp;gt;A and c.567C&amp;gt;T). The effect of c.165G&amp;gt;A and c.567C&amp;gt;T mutations on SCS was highly significant (P = 0.0019 and P = 0.0003, respectively). Strong associations (P ≤ 0.0001) were also observed between L-selectin polymorphism and milk production traits (milk yield, milk fat percentage, and milk protein percentage). However, the polymorphism in the analysed gene had no influence on the resistance or susceptibility of cows to clinical mastitis (only the tendency toward significance, P = 0.06 for c.567C&amp;gt;T mutation was found). Potential exploitation of the information on the identified associations in genetic selection needs to confirm the obtained results in further investigations.

The genomic architecture of mastitis resistance in dairy sheep

BackgroundMastitis is the most prevalent disease in dairy sheep with major economic, hygienic and welfare implications. The disease persists in all dairy sheep production systems despite the implementation of improved management practises. Selective breeding for enhanced mastitis resistance may provide the means to further control the disease. In the present study, we investigated the genetic architecture of four mastitis traits in dairy sheep. Individual animal records for clinical mastitis occurrence and three mastitis indicator traits (milk somatic cell count, total viable bacterial count in milk and the California mastitis test) were collected monthly throughout lactation for 609 ewes of the Greek Chios breed. All animals were genotyped with a custom-made 960-single nucleotide polymorphism (SNP) DNA array based on markers located in quantitative trait loci (QTL) regions for mastitis resistance previously detected in three other distinct dairy sheep populations.ResultsHeritable variation and strong positive genetic correlations were estimated for clinical mastitis occurrence and the three mastitis indicator traits. SNP markers significantly associated with these mastitis traits were confirmed on chromosomes 2, 3, 5, 16 and 19. We identified pathways, molecular interaction networks and functional gene clusters for mastitis resistance. Candidate genes within the detected regions were identified based upon analysis of an ovine transcriptional atlas and transcriptome data derived from milk somatic cells. Relevant candidate genes implicated in innate immunity included SOCS2, CTLA4, C6, C7, C9, PTGER4, DAB2, CARD6, OSMR, PLXNC1, IDH1, ICOS, FYB, and LYFR.ConclusionsThe results confirmed the presence of animal genetic variability in mastitis resistance and identified genomic regions associated with specific mastitis traits in the Chios sheep. The conserved genetic architecture of mastitis resistance between distinct dairy sheep breeds suggests that across-breed selection programmes would be feasible.

The effect of Mycobacterium avium ssp. paratuberculosis infection on clinical mastitis occurrence in dairy cows

Endemic diseases can be counted among the most serious sources of losses for livestock production. In dairy farms in particular, one of the most common diseases is Johne's disease, caused by Mycobacterium avium ssp. paratuberculosis (MAP). Infection with MAP causes direct costs because it affects milk production, but it has also been suspected to increase the risk of clinical mastitis (CM) among infected animals. This might contribute to further costs for farmers. We asked whether MAP infection represents a risk factor for CM and, in particular, whether CM occurrences were more common in MAP-infected animals. Our results, obtained by survival analysis, suggest that MAP-infected cows had an increased probability of experiencing CM during lactation. These results highlight the need to account for the interplay of infectious diseases and other health conditions in economic and epidemiological modeling. In this case, accounting for MAP-infected cows having an increased CM occurrence might have nonnegligible effects on the estimated benefit of MAP control.

Stochastic bio—economic modeling of mastitis in Ethiopian dairy farms

Mastitis is an inflammation of the mammary gland that is considered to be one of the most frequent and costly diseases in the dairy industry. Also in Ethiopia, bovine mastitis is one of the most frequently encountered diseases of dairy cows. However, there was no study, so far, regarding the costs of clinical mastitis and only two studies were reported on costs of subclinical mastitis. Presenting an appropriate and complete study of the costs of mastitis will help farmers in making management decisions for mastitis control. The objective of this study was to estimate the economic effects of mastitis on Ethiopian market-oriented dairy farms. Market-oriented dairy farming is driven by making profits through selling milk in the market on a regular basis. A dynamic stochastic Monte-Carlo simulation model (bio-economic model) was developed taking into account both clinical and subclinical mastitis. Production losses, culling, veterinarian costs, treatment, discarded milk, and labour were the main cost factors which were modeled in this study. The annual incidence of clinical mastitis varied from 0 to 50% with a mean annual incidence of 21.6%, whereas the mean annual incidence of subclinical mastitis was 36.2% which varied between 0 and 75%. The total costs due to mastitis for a default farm size of 8 lactating cows were 6,709 ETB per year (838 ETB per cow per year). The costs varied considerably, with 5th and 95th percentiles of 109 ETB and 22,009 ETB, respectively. The factor most contributing to the total annual cost of mastitis was culling. On average a clinical case costs 3,631 ETB, varying from 0 to 12,401, whereas a sub clinical case costs 147 ETB, varying from 0 to 412. The sensitivity analysis showed that the total costs at the farm level were most sensitive for variation in the probability of occurrence of clinical mastitis and the probability of culling. This study helps farmers to raise awareness about the actual costs of mastitis and motivate them to timely treat and/or take preventive measures. As a results, the dairy industry will improve.

Factors affecting reproductive performance of dairy cow in Algeria: Effects of clinical mastitis

The objective of the present study was to evaluate the effects of clinical mastitis at the beginning of lactation on reproductive performance of dairy cows in Algeria. Calving to first insemination and calving to conception intervals, number of insemination per conception and conception rate at the first artificial insemination were recorded for 432 cows from 16 dairy herds in Algeria. Cows were examined for clinical mastitis during milking by the personnel or the herd manager. A clinical mastitis case was recognized by the presence of modified milk (more watery, presence of lumps, abnormal odor) or by the presence of signs of inflammation in one or all quarters of the udder. Cows were classified according to the time of clinical mastitis occurrence in three groups: cows presenting clinical mastitis before the first artificial insemination (MG1; n = 62 dairy cows), cows presenting clinical mastitis between the first artificial insemination and pregnancy diagnosis (MG2; n = 54 dairy cows), and cows without any signs of clinical mastitis before or after the first insemination (Control - CG; n = 316 dairy cows). Calving to first artificial insemination and calving to conception intervals for cows with signs of clinical mastitis before the first artificial insemination (137.26 ± 7.36 days and 180.48 ± 7.25 days) and in cows with signs of clinical mastitis after the first artificial insemination (190.85 ± 9.23 and 202.51 ± 10.32 days) were significantly (p < 0.05) higher than that of the clinically healthy cows (111.01 ± 5.42 and 147.32 ± 8.44 days), respectively. The number of inseminations per conception in cows that exhibited clinical mastitis before the first artificial insemination (1.94 ± 0.85) and in cows with signs of clinical mastitis after the first artificial insemination (2.4 ± 0.94) was significantly higher compared to that of the control cows (1.61 ± 0.75) (p < 0.05). Conception rate at first artificial insemination in control cows was significantly (p < 0.05) greater than in cows that exhibit clinical mastitis before or after the first artificial insemination (61.39 compared to 38.71 and 33.33% for CG, MG1 and MG2, respectively). The negative effects of clinical mastitis were observed in both primiparous and multiparous cows. In conclusion, results of our study clearly indicate that, clinical mastitis decreases reproductive performance of dairy cows. Key words: Clinical mastitis, calving to first artificial insemination interval, calving to conception interval, reproduction, dairy cattle.