Mastitis Problems Research Articles

Success of interventions in mastitis problems with Staphylococcus aureus after the introduction of an automatic milking system.

Staphylococcus aureus (S. aureus) is often the cause of mastitis problems in dairy herds and causes great economic losses. In this study, isolates from a dairy herd with a known S. aureus mastitis problem were examined by means of molecular methods (spa typing, PFGE, and DNA microarray) to investigate their epidemiological relationship and the success of intervention measures. The investigated dairy farm has a herd size of 60 cows and uses a fully automated milking system for milk production. A S. aureus strain, which contaminated the automated milking system and was subsequently spread among the herd through the latter, was suspected to be the origin of the mastitis problem within the herd. Thanks to the applied molecular methods, the common origin of the S. aureus isolates from the collected milk and swab samples could be shown. By culling chronically infected cows, optimising dry cow management and ensuring reliable intermediate cluster disinfection, the bulk milk somatic cell count improved.

Efficiency evaluation of a bivalent vaccine in the prophylaxis of mastitis in cows

Mastitis in cows represents one of the most actual problems in intensive dairy production. The longtime different approaches to the treatment of mastitis have not offered a suitable solution, and the problem of mastitis is still present and acute. Prevention of pathogen penetration into the mammary gland, its colonization and multiplication impose a constant need for regular inspections of milk, as well as preventive and therapeutic measures to reduce the incidence of mastitis. Studies in the field of vaccination of ruminants against mastitis pathogens suggest a limited success in obtaining significant results in immunoprophylaxis. Considering the results of other researchers and our own research, and bearing in mind the problems mastitis caused by Staphylococcus aureus and Streptococcus agalactiae represent, the aim of this study was the preparation and testing of an indigenous vaccine prepared with two stable strains, SAU 7 (S. aureus) and SAG 3 (Str.agalactiae). The dose was 5 mL/cow and consisted of inactivated bacterial S. aureus SAU 7 cells in a concentration of 1x1010 cfu/mL and Str. agalactiae SAG 3 in a concentration of 4 x 109 cfu/mL. The number of somatic cells in the milk samples during the whole study period was higher in vaccinated cows in both groups compared with the control, but this difference was not statistically significant. The concentration of immunoglobulin IgG in the milk of vaccinated cows was significantly higher than the concentration of this class of proteins in the milk of unvaccinated cows.

Risk Factors Associated with Mastitis Occurrence in Dairy Herds in Benisuef, Egypt

A cross sectional study was carried out from April, 2009 till the end of November, 2011 to estimate prevalence of mastitis and its risk indicators in private dairy herd in Beni-suef region. A total of 233 Holstein milking cows were tested using California Mastitis Test (CMT). Prevalence of mastitis at cow level was 42.92 % (100/233), out of which 9.87% (23/233) and 33.05% (77/233) were clinical and subclinical mastitis, respectively. The quarter level prevalence was 29.08 (272/929); from this the clinical and subclinical forms were 5.81 (54/929) and 23.47 % (218/929), respectively. Samples from all 54 active clinical cases and 98.0% (208/211) of positive CMT subclinical quarters were found to be culture positive. A total of 272 bacteria were isolated, the most prevalent being coagulase negative Staphylococcus (CNS; 37.8%), S. aureus (25.8%) followed by E.coli (18.7 %). Other bacterial isolates included Streptoccusagalactiae (11.8 %), Klebsiellapneumonae (3.6 %) and Str.uberis (2.8 %). Risk factors such as age difference, stage of lactation, parity, tick infestation, previous history of clinical mastitis, and farm hygiene were highly significant in the mastitis prevalence (P < 0.01). On the other hand, strong relationship was found between milk production and occurrence of bovine mastitis as, prevalence was higher in adult cows (X 2 = 9.50, P< 0.05), hence the risk of developing mastitis significantly increase (P< 0.003) in lactating cow at ages (3-5 years) , at early lactation stage , with paritynumber (2-4) and during summer months, than those corresponding animals. In conclusion, the potential risk factors associated with mastitis prevalence and severity includes cow's itself and their surrounding environment particularly farm and milking hygiene procedure. Moreover, veterinary supervision, and tick infestation are among the potential risk factors predispose and increase severity of mastitis problem in dairy farm.

Improving bovine udder health: A national mastitis control program in the Netherlands

Because of increasing bulk milk somatic cell counts and continuous clinical mastitis problems in a substantial number of herds, a national mastitis control program was started in 2005 to improve udder health in the Netherlands. The program started with founding the Dutch Udder Health Centre (UGCN), which had the task to coordinate the program. The program consisted of 2 parts: a research part and a knowledge-transfer part, which were integrated as much as possible. The knowledge-transfer part comprised 2 communication strategies: a central and a peripheral approach. The central approach was based on educating farmers using comprehensive science-based and rational argumentation about mastitis prevention and included on-farm study group meetings. Comprehensive education materials were developed for farmers that were internally motivated to improve udder health. In the peripheral approach it was tried to motivate farmers to implement certain management measures using nontechnical arguments. Mass media campaigns were used that focused on one single aspect of mastitis prevention. These communication strategies, as well as an integrated approach between various stakeholders and different scientific disciplines were used to reach as many farmers as possible. It should be noted that, because this intervention took place at a national level, no control group was available, as it would be impossible to isolate farmers from all forms of communication for 5 years. Based on several studies executed during and after the program, however, the results suggest that udder health seemed to have improved on a national level during the course of the program from 2005 to 2010. Within a cohort of dairy herds monitored during the program, the prevalence of subclinical mastitis did not change significantly (23.0 in 2004 vs. 22.2 in 2009). The incidence rate of clinical mastitis, however, decreased significantly, from 33.5 to 28.1 quarter cases per 100 cow years at risk. The most important elements of the farmers’ mindset toward mastitis control also changed favorably. The simulated costs of mastitis per farm were reduced compared with a situation in which the mastitis would not have changed, with €400 per year. When this amount is extrapolated to all Dutch farms, the sector as a whole reduced the total costs of mastitis by €8 million per year. It is difficult to assign the improved udder health completely to the efforts of the program due to the lack of a control group. Nevertheless, investing €8 million by the Dutch dairy industry in a 5-yr national mastitis control program likely improved udder health and seemed to pay for itself financially.

Prevalence of subclinical mastitis and isolated udder pathogens in dairy cows in Southern Vietnam

Dairy production is not traditional in Vietnam. The farmers have little practical knowledge and udder health control is generally lacking. In order to give the farmers appropriate advice, knowledge about the distribution of udder pathogens is crucial. The aim of the study was to investigate the prevalence of sub-clinical mastitis and to identify udder pathogens isolated from smallholder dairy herds in Southern Vietnam. Twenty farms with a herd somatic cell count (SCC) ranging from low (≤ 400 × 10(3)cells/mL) to high (>400 × 10(3)cells/mL) were randomly selected. Milk samples were collected from 458 quarters of 115 clinically healthy cows. SCC was analyzed on farm by a portable cell counter. Bacteriological samples were taken using Mastistrip(©) cassettes and sent to Sweden for examination. For all herds the mean herd SCC was 632 × 10(3)/mL milk. The prevalence of subclinical mastitis at quarter SCC basis was 63.2 % and at cow basis 88.6 %. Only 40 % of all cows were bacteriologically negative in all quarters. Streptococcus agalactiae was the most commonly found bacteria species, isolated from 96 of the 458 quarter samples, in 13 of the 20 farms. The results indicate pronounced subclinical mastitis problems among the dairy cows in this region mainly due to infections with S. agalactiae. The high prevalence of this highly contagious pathogen is probably attributable to the generally poor milking hygiene and low awareness of proper measures to prevent occurrence and spread of udder infections. A strict, targeted action program for the herds in this area is required in order to lower the prevalence of subclinical mastitis.

Effects of over-expression of TLR2 in transgenic goats on pathogen clearance and role of up-regulation of lysozyme secretion and infiltration of inflammatory cells

BackgroundToll-like receptor 2 (TLR2) is important to host recognition of invading gram-positive microbes. In goats, these microbes can cause serious mastitis, anthrax, tetanus, and other problems. Transgenic goats constitutively over-expressing TLR2 in many tissues serve as a suitable model for the study of the role of TLR2 over-expression in bacterial clearance.ResultsCapra hircus TLR2 over-expression vector (p3S-LoxP-TLR2) was used to generate transgenic goats by egg microinjection. The integration efficiency was 8.57%. Real-time PCR and immunohistochemical results confirmed that the goats over-expressing the TLR2 gene (Tg) expressed more TLR2 than wild-type goats (WT). Monocyte-macrophages from the bloodstreams of transgenic goats were stimulated with synthetic bacterial lipoprotein (Pam3CSK4) and by the promotion of interleukin-6 (IL-6) and IL-10 expression in vitro. The oxidative damage was significantly reduced, and lysozyme (LZM) secretion was found to be up-regulated. Ear tissue samples from transgenic goats that had been stimulated with Pam3CSK4 via hypodermic injection showed that transgenic individuals can undergo the inflammation response very quickly.ConclusionsOver-expression of TLR2 was found to decrease radical damage to host cells through low-level production of NO and MDA and to promote the clearance of invasive bacteria by up-regulating lysozyme secretion and filtration of inflammatory cells to the infected site.

Mastitis investigation using the DairyCo mastitis plan on a Yorkshire dairy farm

The article describes the use of the DairyCo Mastitis plan in the investigation of high mastitis incidence in a dairy herd. The DairyCo mastitis plan uses software to analyse the herd's mastitis and cell count data in order to enable the mastitis problem to be categorised as predominantly dry period origin or lactation period origin and either environmental or contagious origin. A thorough farm visit and completion of a questionnaire will then allow areas for improvement to be selected which will be most likely to have the greatest benefit in reducing mastitis incidence in the herd in question.

경남지역의 체세포수 문제 목장에서의 젖소 유방염 관리실태 및 발생양상 조사

Survey of mastitis management and incidence of mastitis in the Gyeongnam was started in May to September 2009 to solve mastitis problem statistically valid data for use in estimating mastitis management, isolation and antimicrobial drug susceptibility in 30 dairy farms having over 350,000/ml somatic cell count. In investigation on recognition of farmer about bovine mastitis, the ratio of understanding of differences between infectious and environmental origin, understanding of correlation between superbacteria and using indiscriminate, necessity of pathogen identification, and necessity of antimicrobial sensitivity tests were 80.0%, 73.3%, 33.3%, and 53.3%, respectively. In survey of mastitis management type, regular california mastitis test (CMT), conducting CMT test and empirical self-treatment, when detecting suspected cows, were 30.0%, 40.0%, and 46.7%, respectively. Checking and cleaning pulsators biweekly, cleaning vacuum system and replacing liners every 3~6 month, and getting milking system checked by engineers showed 80.0%, 76.7%, and 76.7% in the questionnaires, respectively. In recognition of farmer about milking hygiene for prevention of bovine mastitis, using individual towels, separated milking (milking order of cows), and teat-dipping disinfection after milking exhibited 13.3%, 86.7%, and 93.3%, respectively. In conclusion, through the questionnaires and laboratory test, we suggest that recognition of farmer about management and incidence of mastitis was very low, thus systemic educational program and public relations about mastitis management were need for dairy farmers.

Sources other than unused sawdust can introduce Klebsiella pneumoniae into dairy herds

A longitudinal study was carried out to detect intramammary infections caused by Klebsiella pneumoniae and to identify potential sources of this bacterial species in the environment of the cows. The study was performed in 6 well-managed Belgian dairy herds from May 2008 to May 2009. Monthly (n=13), unused and used sawdust bedding samples as well as individual quarter milk and feces samples were collected from 10 randomly selected cohort cows in each herd. Cases of clinical mastitis of all lactating cows in the 6 herds were also sampled (n=64). From the 3,518 collected samples, 153 K. pneumoniae isolates were obtained, of which 2 originated from milk (clinical mastitis cases). In feces (n=728), used bedding (n=73), and unused bedding (n=73), respectively, 125 (17.2%), 20 (27.4%), and 6 (8.2%) isolates were found. The isolates were fingerprinted by means of pulsed field gel electrophoresis. In total, 109 different pulsotypes were differentiated, indicating a high degree of genetic diversity within the isolates. All isolates from unused bedding belonged to pulsotypes other than those from the other sources, suggesting that sources other than unused sawdust may introduce K. pneumoniae into the herd. Only 2 pulsotypes contained isolates originating from different sources. Pulsotype 10 was found in milk and used bedding and pulsotype 21 was found in feces and used bedding. The 2 milk isolates originated from 2 cows in the same herd but they belonged to a different pulsotype. The results indicate that K. pneumoniae can be prevalent in the environment without causing significant mastitis problems. Most cows were shedding K. pneumoniae in feces, substantiating findings under very different conditions (i.e., American dairy herds). Contamination of used bedding in the cubicles with K. pneumoniae from feces was confirmed, whereas unused bedding was not an important source of K. pneumoniae for the environment of the cows.

Serum calcium and magnesium level in dairy cows at calving

Milk fever and hypocalcaemia are post-partum metabolic diseases affecting about 6% of dairy cows and are due to a fail of the homeostatic metabolism regulating the calcium blood level around 9 and 10mg/100mL. The calcium drainage to the mammary gland along with the reduced capacity of the animal to mobilize calcium from bone reserve lead to a drop of the calcium blood level under 5-6mg/100mL with paresis like clinical symptoms known as milk fever. The incidence of the clinical milk fever is low, however the occurrence of mild hypocalcaemia (subclinical) could be as high as 15- 20% within few days after calving, particularly in multiparous cows. The hypocalcaemia status as for the reduced bone calcium mobilization and intestinal absorption leads to reduced feed intake and make it a good start for ketosis, retained placenta, displaced abomasums and mastitis problems (Beede, 1991). The acid-base balance of the cow in the late pregnancy is determinant for hypocalcaemia

On-farm udder health monitoring

In this article an on-farm monitoring approach on udder health is presented. Monitoring of udder health consists of regular collection and analysis of data and of the regular evaluation of management practices. The ultimate goal is to manage critical control points in udder health management, such as hygiene, body condition, teat ends and treatments, in such a way that results (udder health parameters) are always optimal. Mastitis, however, is a multifactorial disease, and in real life it is not possible to fully prevent all mastitis problems. Therefore udder health data are also monitored with the goal to pick up deviations before they lead to (clinical) problems. By quantifying udder health data and management, a farm is approached as a business, with much attention for efficiency, thought over processes, clear agreements and goals, and including evaluation of processes and results. The whole approach starts with setting SMART (Specific, Measurable, Acceptable, Realistic, Time-bound) goals, followed by an action plan to realize these goals.

The effect of a national mastitis control program on the attitudes, knowledge, and behavior of farmers in the Netherlands

Over the years, much effort has been put into implementing mastitis control programs in herds. To further improve utilization of such programs, there needs to be an understanding of the attitudes, knowledge, and behavior of farmers regarding udder health, and the way this can be influenced by mastitis control programs. This study aimed to explore the effect of a national mastitis control program on Dutch farmers’ attitudes, knowledge, and behavior regarding mastitis. A total of 378 dairy farmers completed a survey on attitudes, knowledge, and behavior regarding mastitis before the start of a national mastitis control program in 2004, and 204 completed a similar survey in the final year of the program (2009). Although the average annual bulk milk somatic cell count (BMSCC) remained the same, the farmers’ self-reported attitudes, knowledge, and behavior changed significantly. The problem level of BMSCC decreased from 285,000 cells/mL in 2004 to 271,000 cells/mL in 2009. More farmers perceived that they had sufficient knowledge about the prevention of mastitis (34% in 2004 vs. 53% in 2009) and they more often perceived that they knew the cause of a mastitis problem (25% in 2004 vs. 37% in 2009). The use of gloves for milking increased from 15 to 46%, the use of a standardized mastitis treatment protocol increased from 7 to 34%, and freestalls were cleaned more often (2.28 vs. 2.51 times/d) in 2009 compared with 2004. Most changes in attitudes, knowledge, and behavior did not differ between groups of dairy farmers whose herds had an initially low (≤162,000 cells/mL), medium (163,000 to 205,000 cells/mL), or high (>206,000 cells/mL) BMSCC. The high BMSCC group significantly decreased their annual BMSCC level by 15,000 cells/mL. Regression analysis showed that the decrease in BMSCC was associated with a change in farmers’ perceptions (e.g., increased perceived knowledge about the effect of the milking machine on mastitis) and with a change in certain management practices (e.g., disinfecting all teats after milking). The results showed that a national mastitis control program affected the attitudes, knowledge, and behavior of farmers regarding mastitis and could contribute to udder health improvement in the long term.

Evaluation of two communication strategies to improve udder health management

Worldwide, programs to improve udder health are implemented using communication tools and methods that inform and persuade dairy farmers. This study evaluated 2 communication strategies used in a mastitis control program in the Netherlands. To improve farmers’ udder health management, tools such as instruction cards, treatment plans, checklists and software were developed following an argument-based comprehensive “central route.” These tools were used during on-farm study group meetings for farmers organized by veterinarians and also during individual veterinarian–farmer interactions. The second strategy aimed at adopting a single management practice to increase the use of milking gloves during milking. This approach followed a straightforward “peripheral” route that used implicit persuasion techniques. Results of an online survey of 374 Dutch dairy farmers showed that most farmers were able and willing to use the educational management tools to increase udder health on their farms. They evaluated the tools positively regardless of the mastitis problems on their farms. This seems to indicate that the central route of communication is most effective when farmers are motivated to work on udder health in general. Results of repeated random telephone surveys before, during, and after the campaign on the use of milking gloves showed that the use of gloves increased from 20.9 to 42.0% of the respondents. Respondents’ opinions about milking gloves also changed favorably, indicating that a relatively short peripheral campaign on a single action can have a sustained effect on farmers’ behavior. Both communication strategies seem to be potentially successful in disseminating knowledge to a specific target group of farmers and in changing that group's behavior. However, to reach as many farmers as possible, the strategies should be combined. When optimizing these strategies, both the farmers’ motivation to work on udder health and the aim of the campaign should be considered. When aiming to improve general udder health management, the central route seems to be effective if farmers are already motivated to optimize their udder health management. For farmers who are less motivated to work on udder health, the peripheral route seems to be most effective when aiming to change a single management practice. The evaluated communication strategies are examples of how management practices to control mastitis can be effectively communicated to farmers. As such, this study contributes to optimizing future programs to control and prevent diseases.

Identification of potential sources of Staphylococcus aureus in herds with mastitis problems

Staphylococcus aureus is a common udder pathogen of dairy cows that often causes herd problems. Various mastitis control programs have been used to combat the problem but have not always been efficient in preventing new Staph. aureus infections, indicating the presence of possible sources of infection other than those traditionally considered. Therefore, the aim of the study was to identify potential sources of infection relevant for Staph. aureus mastitis within 5 dairy herds with udder health problems caused by Staph. aureus. Samples were collected from milk of lactating cows, from body sites, and from the environment of lactating cows, dry cows, late pregnant heifers, young heifers 4 to 12 mo old, and heifer calves 0 to 3 mo old. Isolates of Staph. aureus were identified and compared using pulsed-field gel electrophoresis. Four to 7 unique Staph. aureus pulsotypes were found within each herd, with one strain predominating in milk in each herd. The milk pulsotypes were also frequently isolated in body samples, especially on hock skin, and in the immediate environment of lactating cows, and were sometimes found in other animal groups, especially in dry cows and heifer calves 0 to 3 mo old. The prevalence of Staph. aureus in milk and other types of samples varied markedly between herds. Staphylococcus aureus isolates with genotypes indistinguishable from those found in milk also dominated in extra-mammary sites within the dairy herds studied, and hock skin was identified as an important reservoir of Staph. aureus. The results contribute new knowledge necessary to improve strategies for udder health control in herds.

Aspectos citológicos e microbiológicos do leite em propriedades no sistema orgânico de produção

A produção de leite no sistema orgânico tem despertado o interesse dos produtores rurais, pelo aumento de consumo de produtos naturais. Estudaram-se os aspectos citológicos e microbiológicos do leite no sistema orgânico de produção em quatro propriedades no município de Botucatu, SP, utilizando métodos como CMT, exame microbiológico das amostras positivas, contagem de células somáticas (CCS/mL de leite) e Contagem de Unidades Formadoras de Colônias (UFC de microrganismos mesófilos/mL de leite) em amostras individuais de leite em animais com pelo menos um teto positivo ao CMT. Foi também realizado a CCS/mL de leite e UFC/mL de leite, e exame microbiológico de amostras de leite do conjunto (tanque) de cada propriedade. Das 150 glândulas mamárias examinadas, 66 (44,00%) amostras foram positivas ao CMT, com isolamento de Corynebacterium bovis em 37,90%, Staphylococcus aureus (18,20%), S. epidermidis (15,20%), Streptococcus uberis (3,00%) e S. dysgalactiae (3,00%), e isolamento de mais de um agente bacteriano em 7,60% das amostras. Os valores de CCS/mL das amostras do leite de conjunto estiveram dentro dos limites de normalidade em três das quatro propriedades (&lt; 400x10³), por outro lado considerando a UFC/mL em três das quatro propriedades observou-se altos índices (8,5x10(5); 1,5x10(6); 4,1x10(5)). Obteve-se o isolamento de microrganismos ambientais, como Escherichia coli e Pseudomonas aeruginosa, sugerindo a contaminação do leite durante ou após a ordenha, o que reforça a importância de atividades de educação sanitária para obtenção higiênica do leite.

Effect of prepartum dry cow antibiotic treatment in dairy heifers on udder health and milk production

A high percentage of heifers calve with intramammary infections. One of the measures available to control intramammary infections is treatment with antibiotics before calving. In this study, the effects of prepartum treatment of nonlactating heifers with a 600-mg cloxacillin dry cow treatment on the prevalence of culture-positive milk samples at calving and 10 to 14 d in milk (DIM), the incidence of clinical mastitis, somatic cell count (SCC), and milk production during first lactation were quantified. A total of 184 heifers on 13 dairy farms were treated with antibiotics 8 to 10 wk before the expected calving date. Another 185 heifers served as untreated controls. Coagulase-negative staphylococci were the most frequently isolated group of bacteria in the treatment and control groups at calving (32 and 42%), and at 10 to 14 DIM (15 and 19%), respectively. The prevalence of minor pathogens at calving was lower in the treatment group compared with the control group (34 and 43%, respectively). Staphylococcus aureus was the most frequently isolated major pathogen in the treated and control heifers at calving (4 and 5%) and at 10 to 14 DIM (2 and 3%), respectively. The prevalence of major pathogens was lower in the treated heifers at 10 to 14 DIM compared with the control group (4 and 6%, respectively). Cumulative incidence risk of clinical mastitis during the lactation was 9 and 18% in the treatment and control groups, respectively. Treatment with cloxacillin 8 to 10 wk before calving resulted in a lower prevalence of culture-positive milk samples at calving and lower quarter milk SCC in early lactation [30,000±4,600 (standard deviation) cells/mL in treated heifers versus 40,000±4,600 cells/mL in control heifers], and was associated with lower average test-day SCC (55,000±1,400 cells/mL in treated heifers versus 71,000±1,500 cells/mL in control heifers) and lower incidence of clinical mastitis throughout lactation. The improved udder health resulted in a higher average test-day milk production in the first lactation (24.5±3.2kg in treated heifers versus 23.6±3.1kg in control heifers). Dairy farms with heifer mastitis problems need to analyze their mastitis management. Prepartum treatment of heifers with dry cow antibiotics may be helpful by decreasing the prevalence of mastitis-causing pathogens at calving and at 10 to 14 DIM.

HACCP-based quality risk management approach to udder health problems on dairy farms

Against the background of prevailing udder health problems on dairy farms, this paper discusses a new approach to mastitis control. Current udder health control programmes, such as the 'five-point plan', are highlighted and their drawbacks indicated. The concept and principles of hazard analysis critical control points (HACCP) are introduced. The eight core elements of this concept are dealt with by using the example of a dairy herd with a mastitis problem due to Staphylococcus aureus. The various steps to be taken in the development of a HACCP-based quality risk management programme are illustrated through the application of core elements. Finally, it is shown that the HACCP key words, structure, organisation, planning, communication and formalisation; which do not frequently appear in conventional herd health and production management programmes can contribute to better udder health. The role of the veterinarian can be paramount and of added value, if he/she is willing to invest in new knowledge and skills, such as the HACCP concept, farm economics, animal nutrition, and particularly the role of coach to the dairy farmer in the implementation of preventative measures in relation to udder health.

Herd health planning: farmers' perceptions in relation to lameness and mastitis

Between December 2002 and December 2003, the herd health planning activities on 61 dairy farms in the uk were compared with several measures of lameness and mastitis. Lameness had been...

Relationship of Teat-end Hyperkeratosis to Incidence of Clinical Mastitis and Composite Milk Somatic Cell Count in a Large Holstein Dairy Herd with an Environmental Mastitis Problem

Several studies have demonstrated a positive association between teat-end hyperkeratosis (TEHK) and subclinical or clinical mastitis. Some studies found no positive correlation between them. To the knowledge of the authors, there is only one longitudinal study which demonstrated a negative association between teat-end callosity thickness and clinical Escherichia coli mastitis (Neijenhuis et al, 2001). The objective of this study was to determine whether TEHK is associated with an increased risk of clinical or subclinical mastitis in a large Holstein dairy herd in Tehran province of Iran, in which the monthly incidence rate of clinical mastitis was 9% prior to the beginning of the study.

Effects of length of dry period on yields of milk fat and protein, fertility and milk somatic cell score in the subsequent lactation of dairy cows

The objective was to utilize data from modern US dairy cattle to determine the effect of days dry on fat and protein yield, fat and protein percentages, days open, and somatic cell score in the subsequent lactation. Field data collected through the dairy herd improvement association from January 1997 to December 2003 and extracted from the Animal Improvement Programs Laboratory national database were used for analysis. Actual lactation records calculated from test-day yields using the test-interval method were used in this study. The model for analyses included herd-year of calving, year-state-month of calving, previous lactation record, age at calving, and days dry as a categorical variable. Fat and protein yield was maximized in the subsequent lactation with a 60-d dry period. Dry periods of 20 d or less resulted in substantial losses in fat and protein yield in the subsequent lactation. In contrast to yields, a short dry period was beneficial for fat and protein percentages. Short dry periods also resulted in fewer days open in the subsequent lactation; however, this was entirely due to the lower milk yield associated with shortened dry period. When adjusted for milk yield, short dry periods actually resulted in poorer fertility in the subsequent lactation. Long days dry improved somatic cell score in the subsequent lactation. Herds with mastitis problems should be cautious in shortening days dry because short dry periods led to higher cell scores in the subsequent lactation compared with 60-d dry.