Incidence Of Mastitis Research Articles

Genome-wide scan for selective sweeps identifies novel loci associated with resistance to mastitis in German Holstein cattle.

Domestication and selection significantly changed phenotypic and behavioural traits in modern domestic animals. In this study, to identify the genomic regions associated with mastitis, genomic data of German Holstein dairy cattle were analysed. The samples were genotyped using the Bovine 50 K SNP chip. For each defined healthy and sick group, 133 samples from 13,276 genotyped dairy cows were selected based on mastitis random residual effects. Grouping was done to infer selection signatures based on XP-EHH statistic. The results revealed that for the top 0.01 percentile of the obtained XP-EHH values, five genomic regions on chromosomes 8, 11, 12, 14 and 26 of the control group, and four regions on chromosomes 3, 4 (two regions) and 22 of the case group, have been under selection. Also, consideration of the top 0.1 percentile of the XP-EHH values, clarified 21 and 15 selective sweeps in the control and case group, respectively. This study identified some genomic regions containing potential candidate genes associated with resistance and susceptibility to mastitis, immune system and inflammation, milk traits, udder morphology and different types of cancers. In addition, these regions overlap with some quantitative trait loci linked to clinical mastitis, immunoglobulin levels, somatic cell score, udder traits, milk fat and protein, milk yield, milking speed and veterinary treatments. It is noteworthy that we found two regions in the healthy group (on chromosomes 12 and 14) with strong signals, which were not described previously. It is likely that future research could link these identified genomic regions to mastitis. The results of the current study contribute to the identification of causal mutations, genomic regions and genes affecting mastitis incidence in dairy cows.

Effect of Housing on Lameness, Body Condition Score and Udder Health of Sahiwal Dairy Cattle

Background: Lameness is a huge problem in intensive livestock production, leading to enormous losses in terms of stress to animals, less reproductive ability and increased chances of mastitis. Zero grazing system is needed for today’s intensive livestock production, but it has also led to increased lameness chances, unnecessarily increased body condition score and increased mastitis incidences. On the other hand, pasture grazing promotes cows to exhibit natural behaviour, which improves the health and welfare of animals. Methods: Present study was aimed to find effect of housing on lameness, body score and udder health of Sahiwal cows. 204 Sahiwal cows were included in the study out of which 50 were reared on pasture and the rest were stall-fed. Lameness and body condition scoring was done and milk samples were collected using aseptic techniques. Result: Clinical lameness is quite low in Sahiwal i.e. 6% with no significant difference between pasture grazing and stall fed animals. Stall fed animals revealed significantly more claw lesions than pasture grazed animals. Grazing animals revealed significantly lower body condition score than stall fed animals. In term of udder health, stall fed animals revealed higher odds of mastitis than pasture grazed animals.

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, Diagnosis and Improving the Effectiveness of Therapy of Mastitis in Cows of Dairy Farms in East Kazakhstan.

Simple SummaryMastitis is an inflammation of the mammary gland that occurs in response to adverse mechanical, physical, chemical and biological factors. The use of antibiotics as a treatment has a negative impact on milk quality. This paper proposes the treatment of mastitis with a drug that contains natural, environmentally friendly and pharmacologically active preparations. The inclusion of the preparation into the scheme of treatment allows to treat effectively inflammatory processes in the udder of cows and restore their productivity with minimal time and expenses. The drug has anti-inflammatory, antimicrobial and stimulating healing effects.In the present work, the prevalence, etiological factors and effective treatment scheme of mastitis in cows of dairy farms “Balke” and “Madi-R” in Eastern Kazakhstan were investigated. In total, 210 heads were investigated on two farms. The incidence of mastitis in cows on dairy farms is not the same in different years. Average clinical mastitis was detected in 35.4% of cows in 2016, 19.6% in 2017, 28.5% in 2018, and in 2019 in 16.4% of cows. The prevalence rates of subclinical mastitis by year had some differences. So, in 2016—36.5% of cows, then in 2017—21.5%, 2018—19.3% and in 2019—22.6%. In cows with udder inflammation, serum calcium 9.37 ± 0.15 mg/% with a range of 8.0 to 10.8 mg/%, phosphorus 3.58 ± 0.07 mg/% (3.0 to 4.3 mg/%), reserve alkalinity 363.46 ± 6.69 mg/% (320 to 440), carotene 0.49 ± 0.03 mg/% (0.220 to 0.988 mg/%), which are in the lower limit of physiological parameters. The drug “Dorob” was tested during the study of comparative effectiveness of treatment methods. The results of the study showed that this drug has anti-inflammatory, antimicrobial and stimulating healing actions. The treatment of the sick cows with catarrhal mastitis has shown that a total of 8 cows have recovered in the control group and 10 cows in the experimental group with the preparation “Dorob”. The period of recovery in the control group was 8.8 ± 0.39, and in the experimental group—6.2 ± 0.28 (p < 0.05). The drug does not contain antibiotics and hormonal preparations. The inclusion of the drug in the scheme of treatment allows for effectively treating inflammatory processes in the udder of cows and restoring their productivity with minimal cost of time and money.

Integrated system for the prevention and treatment of mastitis in lactating cows

The disease of cows with mastitis is a serious problem in the intensive use of animals and the financial well-being of dairy farms [1,5]. The development of animal health programs, as well as the introduction of an integrated approach to the prevention of mastitis using modern pharmacotherapy, is the main task of veterinary medicine today [10,11]. Different groups of microorganisms cause mastitis; recently, frequent cases of participation of Klebsiella, gram-negative polymorphic microorganisms, can be noted [7,8]. Analysis of statistics shows that mastitis becomes recurrent in 40% of cases. The repeated occurrence of mastitis occurs as a result of the weakening of the body and the immune system, as well as the development of bacterio-resistance [9]. In our scientific work (2015-2021), various methods of preventive and therapeutic measures were used on farms. The main ones were: preparation of the udder for milking, treatment of milking and dairy equipment with disinfectants, compliance with machine milking regimes. Every year, the latest drugs were used to treat mastitis and increase the overall resistance of the body and the immune system [2,3]. The purpose of this article is to create a unified approach in the prevention and treatment of mastitis, thereby pursuing the preservation of the health of dairy cows, obtaining environmentally friendly products and reducing the economic damage to farms. In the complex use of modern medicines to increase the overall resistance and immune system of the body, as well as the processing of milking and dairy equipment, the incidence of mastitis in cows was reduced by 2 times. The use of new anti-mastitis drugs showed high efficiency, which reached 86.7-96.7% of each, and when two drugs were used simultaneously, it was 98.2% [4].

Association of Lactoferrin and Toll-like Receptor 2 Genotypes with Mastitis and Milk Components in Vietnamese Holstein Cattle.

Simply SummaryMastitis disease causes huge losses for the dairy industry worldwide. The molecular markers have been shown to be a promising tool for the diagnosis of mastitis infections and the selection of animals with better mastitis resistance. In this study, we surveyed the mastitis incidence in Vietnamese Holstein cows. We also examined the association of polymorphisms in Lactoferrin (LTF) and Toll-like receptor 2 (TLR2) genes with mastitis score and milk component traits. Our results indicated that the interaction between TLR2 genotypes and diseases has a significant impact on the fat and protein percentage of mink. Therefore, TLR2 polymorphism could be used for the selection of cows with better milk compositions.Mastitis is one of the most widespread diseases in dairy cows and causes huge losses for the dairy industry. Molecular markers can be used for the quick diagnosis of mastitis infection, consequently reducing the loss caused by this disease. Lactoferrin (LTF) and Toll-like receptor 2 (TLR2) have been suggested as candidate genes for mastitis; however, their associations with the mastitis incidence and milk components have not been reported in Vietnamese Holstein cows. This study examined the association of TLR2 and LTF polymorphisms with subclinical mastitis and milk components in the Holstein breed raised in Vietnam. Among 192 samples, we identified 44 mastitis-positive samples (22.92%). The mastitis significantly reduced the fat and lactose components in milk (p < 0.001) but increased the protein concentration in milk. A total of 94 (49%) and 98 (51%) cows had AA and AB genotypes for the LTF gene, respectively. No significant association was found between the LTF genotypes and the milk component traits or mastitis incidence (p > 0.05). The interaction between LTF and mastitis incidence was significantly associated with the protein percentage (p = 0.01). A total of 78, 76, and 38 cows had genotypes GG, GT, and TT for the TLR2 gene, respectively. TLR2 genotypes were not significantly associated with mastitis incidence (p > 0.05) but were significantly associated with pH value (p = 0.03). The interaction between TLR2 and mastitis incidence was significantly associated with the fat (p = 0.02) and protein percentage (p = 0.04). Further studies are required to confirm the roles of LTF and TFL2 in mastitis in the Holstein breed in Vietnam.

Selenomethionine protected BMECs from inflammatory injury and oxidative damage induced by Klebsiella pneumoniae by inhibiting the NF-κB and activating the Nrf2 signaling pathway

Klebsiella pneumoniae (K. pneumoniae) is one of the main environmental pathogens causing bovine mastitis. The incidence of bovine mastitis caused by K. pneumoniae is increasing worldwide. Selenium is an essential trace element that has multiple physiological functions, such as antioxidant and anti-inflammatory activities. Therefore, this study aimed to verify whether selenomethionine (SeMet) could contribute to alleviating the inflammatory injury and oxidative damage induced by K. pneumoniae. Bovine mammary epithelial cells were cultured in vitro and pretreated with 4 μM SeMet before being infected with K. pneumoniae. Western blot analysis was used to detect the expression of the related proteins in the NF-κB and Nrf2 signaling pathways. The gene expression levels of IL-1β, IL-6, IL-8, TNF-α, Nrf2, Keap1, NQO-1 and HO-1 were detected using RT–qPCR. The levels of MDA, GSH-PX, SOD, CAT and T-AOC were detected by commercial assay kits. Flow cytometry was used to determine the level of intracellular ROS, and immunofluorescence was used to detect the nuclear localization of Nrf2 protein. Briefly, SeMet downregulated the phosphorylation levels of IκBα and p65 proteins and the gene expression levels of IL-1β, IL-6, IL-8 and TNF-α were also decreased. Moreover, the protein and gene expression levels of Nrf2, NQO-1 and HO-1 were upregulated, and the nuclear expression of Nrf2 protein was also promoted, which enhanced the activity of antioxidant enzymes. In conclusion, SeMet protected BMECs from inflammatory injury and oxidative stress induced by K. pneumoniae by inhibiting the NF-κB and activating the Nrf2 signaling pathway.

Escherichia coli Mastitis in Dairy Cattle: Etiology, Diagnosis, and Treatment Challenges.

Bovine mastitis is an inflammation of the udder tissue parenchyma that causes pathological changes in the glandular tissue and abnormalities in milk leading to significant economic losses to the dairy industry across the world. Mammary pathogenic Escherichia (E.) coli (MPEC) is one of the main etiologic agents of acute clinical mastitis in dairy cattle. MPEC strains have virulence attributes to resist the host innate defenses and thrive in the mammary gland environment. The association between specific virulence factors of MPEC with the severity of mastitis in cattle is not fully understood. Furthermore, the indiscriminate use of antibiotics to treat mastitis has resulted in antimicrobial resistance to all major antibiotic classes in MPEC. A thorough understanding of MPEC’s pathogenesis and antimicrobial susceptibility pattern is required to develop better interventions to reduce mastitis incidence and prevalence in cattle and the environment. This review compiles important information on mastitis caused by MPEC (e.g., types of mastitis, host immune response, diagnosis, treatment, and control of the disease) as well as the current knowledge on MPEC virulence factors, antimicrobial resistance, and the dilemma of MPEC as a new pathotype. The information provided in this review is critical to identifying gaps in knowledge that will guide future studies to better design diagnostic, prevent, and develop therapeutic interventions for this significant dairy disease.

Risk factors associated with subclinical mastitis and its effect on physico-mineral features of camel milk.

This study was carried out to determine the risk factors implicated in camel subclinical mastitis as well as the physico-mineral features of camel milk, there by examining the effect of this disease on those parameters. Milk samples were obtained from 125 lactating multiparous she-camels (aged 10-12years) during early lactation from December 2020 to April 2021. The samples were screened for the presence of subclinical mastitis using the somatic cell count (SCC) test. In total, 73 (58.4%) samples showed the presence of subclinical mastitis, whereas the remaining 52 (41.6%) samples showed negative results for subclinical mastitis. Standard methods were used to appreciate the pH and mineral composition of the milk samples, such as Ca, Na, Cl, and K contents. In camels, unhygienic udder condition was identified as the major risk factor for the incidence of subclinical mastitis. Calf mortality and increased herd size were associated with a higher prevalence of subclinical mastitis. Tick infestations were also significantly associated with increased disease risk. Use of antisuckling devices, increase in milk yield, and weakness of body condition were identified as main risk factors and were primarily associated with the disease. However, udder lesions and deformities, milking frequency, and owner visits had no significant influence on the occurrence of subclinical mastitis. The overall mean pH value was 6.54 ± 0.01 and the mean values of Ca, Na, Cl, and K contents were 148.24 ± 2.55, 53.83 ± 1.52, 124.99 ± 1.80, and 240.22 ± 3.80mg/100g, respectively. When the level of milk from healthy animals and that from camels with subclinical mastitis (SCC > 2.4 × 105) were compared, it showed that Na and Cl contents were significantly increased (p < 0.05) with the increase in SCC (56.52 vs.50.07 and 128.26 vs.120.40mg/100g, respectively). In contrast, there were no notable changes (p > 0.05) in the Ca, K, and pH values. In conclusion, udder hygiene, calf mortality, herd size, tick infestations, use of antisuckling devices, higher milk yield, and body condition were identified as the major risk factors that predispose the camels to subclinical mastitis. Furthermore, an increase in the Na and Cl levels in camel milk was observed along with udder inflammation. Consequently, the elevated Na and Cl levels in milk can be a sign of subclinical mastitis in camels.

The Role of Women on Dairy Goat Farms in Southern Spain.

Simple SummaryThe involvement of women in livestock production is a tradition around the world, where women have been associated with small animal farming, mainly based on family production systems. They used to be responsible for animal care (feeding and milking) and family care (children and the elderly), with the working hours exceeding the daily working time defined in developed countries. Men are responsible for the farm’s management and finances. In Europe, small ruminants are mainly raised in adverse environments. Nevertheless, they contribute to maintaining an open environment and the prevention of fire damage in times of drought. On the farms studied, a lower incidence of mastitis in goats was found when a woman worked on the farm (they milk with more care and patience). In this study, there is a predominance of farms with women and men (a family unit), where the genders both equally participate when making decisions that involve household expenses; however, this shared control usually ends up being transferred to the man. In addition, very few women are the owners of farms or make binding decisions. Finally, the inclusion of women should be recommended throughout the small ruminant productive process: this would help improve farming results and provide an incentive to keep women in rural areas.One of the factors involved in goat milk production is the role of women as farmers. The aim of this study was to evaluate the role of women on dairy goat farms, considering: (1) the profile of women occupationally involved, (2) the organization of the women’s work, (3) the degree of involvement by women in the decision-making on these farms, and (4) the influence of women’s work on productive results. This study was conducted on 52 dairy goat farms in southern Spain. A descriptive analysis and means comparisons were performed to describe the farms where any women were involved or not. In 61.5% of the farms, at least one woman was involved, with an age of 42.2 ± 8.8 years. Very few women were farm owners, although women took binding decisions in 81.25% of these farms. Their work is dedicated to milking and caring for the kids. Women had a positive influence on the productive variables analysed, and for mastitis in herds, the incidence was lower in herds where women participated (p < 0.01). In conclusion, it is recommended to include women’s work as a factor when characterizing dairy goats farms’ systems to evaluate their positive effect on a farm’s performance.

Bio-economic models for deriving economic values for cattle: a review

Abstract. Bio-economic models for deriving economic weights in livestock have a significant development in recent years providing integrated assessment of biological and economic parameters of production systems and possibilities for achieving economic sustainability through inclusion in the selection index. Economic weights (EW) of traits have been calculated for different species of farm animals in the years. However, this review focuses on large ruminant aiming to summarize studies on calculation of economic values for dairy, beef and dual-purpose cattle. A method of research selection was used according to the productive direction (for milk, meat and dual-purpose), as well as according to the studied traits. In conclusion, it could be summarized that with regard to breeding objectives, economic weights of breeding traits need to be recalculated at certain time-periods and redefined in order to be relevant to the current market situations. Recently, there has been a tendency for functional traits to have an increasing economic influence and some of them should be included in the breeding goal. Moreover, the increased interest among customers in animal welfare and quality of dairy farm products will probably lead to the incorporation of health traits as clinical mastitis incidence and somatic cells score in the breeding objective. It is possible as well the relative importance of feed efficiency traits to increase in the future due to increasing requirements to mitigate the environmental impact of production systems.

Subclinical Mastitis Detected during the Last Gestation Period Can Increase the Risk of Stillbirth in Dairy Calves.

We hypothesized that subclinical mastitis detected during the last gestation period can increase the risk of stillbirth in dairy calves. The aim was to investigate the relation of subclinical mastitis detected during the last gestation period and its pathogens with the stillbirth of calves. Cows from the 210th day of pregnancy were selected for the study. They were divided into two groups: the first group-subclinical mastitis was confirmed on the farm by the California mastitis test (CMT); the second group of cows-mastitis was not confirmed by the CMT test. Groups of cows were compared according to the results of their calving-the number of stillborn calves. A stillborn calf was defined as a calf that dies at birth or within the first 24 h after calving, following a gestation period of 260 days. Our results suggest that decreasing the incidence of subclinical mastitis during the last gestation period (from the 210th day of pregnancy) can decrease the risk of stillbirth in dairy calves. Further, it is important to identify the pathogen because the highest risk of stillbirth was found in cows with mastitis caused by Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, pathogenic Staphylococci and other Streptococci. Cows at the first calving had a 1.38-1.65-times higher risk of having stillborn calves than cows of parity ≥ 2. From a practical point, veterinarians and farmers can consider the effect of subclinical mastitis during late gestation on the risk of stillbirth and it could help for strategies of optimizing reproductive performance in dairy cows.

A retrospective on claims regarding clinical mastitis in the subsequent lactation, after use of an internal teat sealant in the dry period.

Infusion of an internal teat sealant into the mammary gland of the dairy cow at drying off has been claimed to reduce the incidence of clinical mastitis over many months in the subsequent lactation, despite the absence of any ingredient of the sealant remaining for that long. However, these claims have been poorly substantiated, often by lack of identification on when the infection occurred in the period from calving to disease, if the infection was present at post calving sampling and if the pathogen causing the disease was that causing an earlier infection. Moreover, no hypothesis on how any effect on clinical mastitis might occur has been advanced in any of the publications claiming the effect. That the effect might occur is only reported in a minority of publications, and the possibility that this is relatively specific to Gram-negative pathogens is reviewed.

Does diabetes mellitus and insulin resistance lead to lactation failure?

Introduction: Non-lactation leads to high incidence of lactational mastitis, abscess (short term) and breast, ovarian cancer (long term) in mothers. In children there is higher incidence of malnutrition, ARI, and under 5 mortality. Faulty feeding techniques and nipple abnormalities are common but correctable factors. Diabetes and insulin resistance is considered as a factor for non-lactation.

The Link Between 15-F2t-Isoprostane Activity and Acute Bovine Endothelial Inflammation Remains Elusive.

Modern dairy cattle suffer from increased incidence and severity of mastitis during major physiological transitions of the lactation cycle. Oxidative stress, a condition resulting from inadequate antioxidant defense against reactive oxygen and nitrogen species, is a major underlying component of mastitis pathophysiology. Isoprostanes (IsoP) are molecules derived from cellular lipid membranes upon non-enzymatic interaction with reactive species during inflammation, and are regarded as highly sensitive and specific biomarkers of oxidative stress. Changes in IsoP concentrations have been noted during major physiological transitions and diseases such as coliform mastitis in dairy cattle. However, the biological role of IsoP during oxidative stress in dairy cows has not been well-elucidated. Therefore, this study aimed to characterize the impacts of IsoP on oxidative stress outcomes in a bovine model of acute endothelial inflammation. Bovine aortic endothelial cells (BAEC; n = 4) were stimulated with 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) or lipopolysaccharide (LPS) with or without 15-F2t-IsoP to determine how IsoP influence oxidative stress outcomes. Our endothelial inflammation model showed relatively decreased reactive metabolites and increased barrier integrity in cells treated with both the agonist and IsoP compared to agonist treatment alone. However, IsoP do not appear to affect oxidative stress outcomes during acute inflammation. Understanding the effect of IsoP on BAEC is an early step in elucidating how IsoP impact dairy cows during times of oxidative stress in the context of acute clinical mastitis. Future studies should define the optimal dosing and treatment timing of IsoP to maximize their cytoprotective potential during acute inflammation.

Interaction of blood calcium with luteal activity, energy metabolites and somatic cells count in post-partum dairy cows.

The aim of the research was to assess whether there was a link between serum calcium (Ca) after calving and serum progesterone, milk somatic cells count and Ca, and other blood metabolites in Achai and crossbred cows. Based on blood calcium level shortly after calving, thirty cows from both breeds were divided into a moderate group (≤10.0mg/dl of Ca) and a high group (>10.0mg/dl of Ca), with samples collected at 0, 7, 14, 21, 28 and 35days post-partum, respectively. On day 35 of the post-partum, crossbred and Achai cows with high blood Ca recorded significantly (p<.01) higher serum progesterone, glucose, triglyceride and milk Ca compared with moderate blood Ca group; however, serum cholesterol was significantly (p<.01) higher in both breeds under high blood Ca. Incidence of subclinical mastitis was significantly (p<.01) higher in crossbred and Achai cows under high blood Ca. The results showed that blood progesterone (OR=2.095), glucose (OR=1.024), triglyceride (OR=4.571), cholesterol (OR=1.111) and milk Ca (OR=1.141) resulted in a greater concentration in crossbred compared to Achai cows. A significant (p<.01) correlation was found between blood Ca and other blood metabolites (progesterone, glucose, triglyceride and cholesterol) in both breeds. In conclusion, greater serum Ca concentration after calving is associated with greater serum progesterone, glucose, triglyceride and milk Ca in crossbred cows; however, the incidence of subclinical mastitis increased.

The Risk Factor of Subclinical Mastitis Incident in Dairy Cattle in KPSP Ijen Makmur, Banyuwangi

Mastitis is an inflammatory disease in the internal tissue of the mammary gland. Subclinical mastitis does not show any changes in the shape of the mammary gland and to detect it can be examined the number of somatic cells in milk. Subclinical mastitis uses the California Mastitis Test (CMT) method as preliminary research to obtain preliminary data on the incidence of subclinical mastitis in KPSP Ijen Makmur, Licin District, Banyuwangi Regency. This research is descriptive research. The detection for this research was carried out by taking milk samples in cows per purposive and reacted CMT reagents issued circularly for 10-15 seconds. Observation of results is determined based on changes inconsistency with the existence of gel and the results of interview farmers as supporting data. The results showed that the influencing factors incidence of subclinical mastitis in KPSP Ijen Makmur, Licin District, Banyuwangi Regency were milk production, age and amount of lactation. In contrast, the biggest factor for reducing the risk of subclinical mastitis is udder health followed by body conditions measured by Body Condition Score.

Association Between Recycled Manure Solids Bedding and Subclinical Mastitis Incidence: A Canadian Cohort Study.

Recycled manure solids (RMS) are increasingly used as bedding for dairy cows. However, potential impact of RMS bedding on animal health is not well described. The objective of this study was to evaluate subclinical mastitis incidence in cows housed on RMS bedding. Twenty RMS farms and a comparative group of 60 straw-bedded farms were enrolled in a 1-year longitudinal study (2018–2019). Data from 11,031 dairy cows were collected. Variations of individual somatic cell count were evaluated using three different methods. First, we compared the cow's mean lactation linear score between cows housed on the two bedding types. Then, we compared across bedding types the risk for a given cow of having a milk test with a linear score ≥ 4. Finally, we evaluated the dynamics of somatic cell count using pairs of tests within a cow. More specifically, we considered that only pairs of DHI tests where the first test yielded a linear score < 4 were at risk of an incident subclinical mastitis event. Then, we defined a newly acquired subclinical mastitis when the second test was ≥ 4. All models were adjusted for putative confounders. We could not highlight a significant association between bedding type and cow's mean lactational linear score (least square mean of 2.47 in cows from RMS farms vs. 2.37 in straw farms; 95%CI for linear score's difference: −0.20, 0.40). Furthermore, we could not find an association between bedding type and the risk of a high linear score (≥ 4). For the latter, cows housed on RMS had 0.93 times the risk of having a high linear score than straw-bedded cows (%95 CI: 0.68, 1.28). Moreover, cows on recycled manure solids farms had 0.73 time the risk of acquiring subclinical mastitis when compared to straw-bedded farms. Again, this risk was not statistically significant (%95 CI: 0.54, 1.00). In our study, RMS bedding was not associated with subclinical mastitis, as measured by somatic cell count, when compared to cows housed on a more conventional bedding, straw bedding.

Economics of reducing antibiotic usage for pathogen-specific clinical mastitis through genomic selection and disease management

The recent introduction of the mastitis resistance trait into the US genomic selection index, Lifetime Net Merit 2018 (NM$), is expected to reduce the incidence of pathogen-specific clinical mastitis (PS-CM) incidence in U.S. dairy herds. To maximize the herd performance by reducing the PS-CM incidence, we compared the herd performance of 6 different replacement selection and PS-CM disease management strategies. We used an agent-based dairy simulation model in which the performance of individual animals was affected by the genetic traits included in the NM$. The genetic trends for the sires used affected the 15 yr herd performance. Each animal had a daily underlying base probability of contracting 5 different types of PS-CM (Staphylococcus aureus, Streptococcus dysgalactiae, Strep. uberis, Escherichia coli and Klebsiella) during lactation. On top of this base probability, the genetic and environmental components of the mastitis resistance trait (MAST) determined the actual incidence of PS-CM. Genomic estimated breeding values were simulated for each animal, based on which replacement selection decisions were made. The PS-CM associated milk loss, increased somatic cell count, decreased conception, and increased mortality and culling were accounted for in the simulated genomic estimated breeding values of different correlated production and reproduction traits included in NM$. The 6 different strategies illustrate the effects of replacement selection and PS-CM management decisions on PS-CM incidence, herd antibiotic use (ABU) and herd economics, over the course of 15 yr. Due to the genetic gain in the MAST, the incidence of PS-CM decreased on average by 10% points in 15 yr, which trickled down to overall reduction in herd ABU. Our PS-CM treatment and prevention strategies were assumed to be based on precise information about the 5 different PS-CM causative pathogens. Hence the corresponding ABU further decreased over the course of 15 years, when compared to blanket PS-CM therapies, which used antibiotics for all cases of CM. Our strategies illustrated the fact that herds combining genomic selection and following precise treatment and prevention strategies for PS-CM could reduce the 15-year cumulative ABU against PS-CM significantly. Capitalizing on the genetic gain in NM$ traits, the average profit per cow per year was higher on average by $1209 in year 15 when compared to year 0 for the 6 strategies simulated. We concluded that three decision strategies (genomic selection for NM$, selective therapy for PS-CM, and selective dry cow therapy for PS-CM prevention) when combined can reduce the incidence of PS-CM and the associated ABU, while increasing the profitability of the herd.

Retention of internal teat sealants over the dry period and their efficacy in reducing clinical and subclinical mastitis at calving

Internal teat sealants (ITS) reduce the risk of new intramammary infections over the dry period by forming a physical barrier to pathogen ingress. As the first and last 2 wk of the dry period are high-risk periods for new infections, maintaining an effective barrier in this period is a key requirement. Few studies have systematically examined sealant retention and none have done so under New Zealand pastoral conditions, where cows frequently move to separate grazing for dry periods, typically 80 to 90 d long. This multi-herd study was a split-udder equivalence trial comparing 2 ITS formulations for retention and efficacy in preventing periparturient clinical and subclinical mastitis. Both ITS contained 65% (2.6 g) bismuth salts, which contribute to the barrier within the teat canal, emulsified in ≤1.4 g of mineral oil. However, one ITS additionally contained <10% amorphous silica. At dry-off, treatment was randomly allocated to diagonal teat-pairs within 409 cows on 4 farms. All cows met industry best practice criteria for ITS treatment alone. The study unit was quarter within cow and farm. Outcomes included clinical mastitis (CM) incidence for the last 7 d of the dry period and first 42 d of lactation, subclinical mastitis (SCM) incidence 96 h after calving, and quantity of residual after centrifuging 50 mL of colostrum collected from each quarter within 24 h of calving. Proportional outcomes were analyzed using Bayesian mixed models with a binomial distribution and logit link function, whereas the quantity of residual was analyzed using Bayesian finite mixture models and cluster bootstrapping. We set a region of probable equivalence (ROPE) of ±2.5% between proportions and ±0.2 g for residual weight. Records were available for 1,596 quarters (399 cows). We detected no meaningful difference in incidence of CM or SCM attributable to differences in sealant: the model predicted treatment differences of 0.00 with a 95% highest density interval (HDI) of ±1.00%. Across all cows and farms, the marginal difference in the percentage of quarters with CM was 0.11% (95% HDI: -2.11 to 2.49%), and for SCM 0.00 (95% HDI: -1.98 to 1.94%). Including the quantity of residual recovered at calving did not improve fit or predictive ability of the models predicting CM or SCM, and the coefficient spanned the null value. The distribution of the weight of material recovered at calving was multi-modal; for 25% of quarters, more residual was recovered than inserted. When the residual weight was less than or equal to the median residual weight (2.06 g; range: 0.19-6.03 g), there was a ≥90% probability that any treatment difference in residual was ≤0.2 g. When the residual weight was between the median and 75th percentile (4.40 g; 95% HDI: 4.00 to 4.75 g), there was no clear difference in residual between products. Above the 75th percentile, there was a 90% probability that the residual from quarters differed by product type (difference = 0.36 g, 90% HDI: 0.20 to 0.54 g). In conclusion, both products had equivalent efficacy for SCM and CM. As the quantity of residual increased, the difference in residual weight recovered increased but this may represent increases in debris rather than indicating a more effective barrier.