***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Heifer mastitis is a well-known problem , with several pathogens being involved . Several generic risk factors associated with the likelihood of intramammary infections ( IMI ) in fresh dairy heifers have been identified before . Yet , a need exists to identify pathogen group-specific factors , as the effect of ( groups of ) pathogens on udder health and milk yield is different . The aim of the present study was to identify pathogen group-specific risk factors for IMI in heifers participating in a prepartum antimicrobial treatment trial , allowing us to test the hypothesis that different factors are of importance between treated and untreated control heifers as well . Data from a clinical trial in which end-term heifers were treated systemically ( over 3 consecutive days ) 2 wk before calving with penethamate hydriodide  ( n=76 ) or remained untreated  ( n=73 ) , were available . Several potential risk factors at the herd , heifer , and quarter level were recorded in the first 3 d in milk . Quarters from untreated heifers supplemented with ≥4 mg of selenium/d prepartum were significantly less likely to be infected with coagulase-negative staphylococci ( CNS ) , whereas quarters were more likely to be infected with CNS when assistance during calving was needed . Udder edema before calving significantly decreased the odds of IMI with major pathogens . In treated heifers , no factors were detected that were associated with the likelihood of CNS IMI , whereas quarters from heifers were significantly more likely to be infected with major pathogens when they were housed in the calving pen more than 1 d and when they had been in contact with the lactating cows before calving . The risk factors for IMI that were identified in treated heifers were different than those in untreated heifers , independent of the pathogen group that was considered . It looks as if prepartum treatment not only changed the likelihood of infection , but also the factors that were associated with infection . However , except for treated heifers with an IMI with major pathogens , only a small proportion of the variation could be explained in the final models . Therefore , factors other than those that were studied could explain the likelihood of infection OBJECTIVE To determine whether prepartum intramammary treatment of dairy heifers with pirlimycin hydrochloride  would reduce the prevalence of intramammary infection ( IMI ) and lower the somatic cell count ( SCC ) during early lactation or improve 305-day mature equivalent milk production . DESIGN Prospect i ve clinical trial . ANIMALS 183 Holstein-Friesian heifers ( 663 quarters ) from 2 dairy farms . PROCEDURE Heifers were assigned to treatment and control groups . Treated heifers received a single 50-mg dose of pirlimycin in each mammary quarter approximately 10 to 14 days prior to parturition . Prepartum mammary gl and secretions and postpartum milk sample s were collected for bacterial culture . Postpartum milk sample s were also collected for determination of SCC or California mastitis testing and were tested for pirlimycin residues . Mature equivalent 305-day milk production data were recorded . RESULTS Treated heifers in herd A had a higher overall cure rate , higher cure rates for IMI caused by coagulase-negative staphylococci ( CNS ) and Staphylococcus aureus , lower SCC , and lower prevalence of chronic IMI , compared with control heifers . Treated heifers in herd B had a higher overall cure rate and cure rate for IMI caused by CNS , compared with control heifers , but postpartum California mastitis test scores and prevalence of chronic IMI did not differ between groups . Mature equivalent 305-day milk production did not differ between herds or treatment groups . No pirlimycin residues were detected in postpartum milk sample s. CONCLUSIONS AND CLINICAL RELEVANCE Results suggest that prepartum treatment of dairy heifers with pirlimycin may reduce the prevalence of early lactation IMI , particularly IMI caused by CNS , without causing pirlimycin residues in milk Abstract AIMS : The main aim was to investigate the effectiveness of a novel internal teat sealant ( ITS ) formulation containing bismuth subnitrate and the antiseptic chlorhexidine , in adult cows ( Trial A ) and nulliparous heifers ( Trial B ) , to reduce the incidence of new intramammary infection ( IMI ) between treatment and calving and reduce the prevalence of IMI within 6 days following calving . METHODS : In Trial A dairy cows ( n=326 ) without history of clinical mastitis and with a maximum composite milk somatic cell count < 200,000 cells/mL during the current lactation were enrolled from three spring-calving mainly pasture-based herds immediately following the final milking . In Trial B all heifers ( n=166 ) were enrolled from two herds approximately 3 weeks before the start of calving . Gl and s were r and omly assigned to controls or treatment with ITS , and mammary secretion sample s were taken from all gl and s prior to treatment , and on two occasions 0–4 and 3–6 days post-calving to determine the incidence of new IMI and the prevalence of IMI immediately post-calving . Additionally , cows in Trial A were monitored for cases of clinical mastitis ( CM ) in the non-lactating period and animals in both trials were monitored for cases of CM within 30 days of calving . RESULTS : The ITS reduced the estimated incidence of new IMI with both major and any pathogens compared to control gl and s in cows ( 6.2 vs. 14.2 % and 14.7 vs. 32.8 % , respectively ) and in heifers ( 3.0 vs. 13.1 % and 13.4 vs. 25.3 % , respectively ) ( p<0.001 ) . The ITS reduced the estimated prevalence of a major or any pathogen compared to untreated controls at both 0–4 and 3–6 days post-calving , in both cows and heifers . Additionally , the ITS reduced the incidence of CM in the non-lactating period in cows ( −1.0 % , p=0.01 ) and in the 30 days following calving in heifers ( −2.0 % , p=0.06 ) , and tended to reduce the estimated incidence of CM in cows post-calving ( −1.7 % , p=0.10 ) . CONCLUSIONS : The novel ITS reduced the incidence of new IMI , and the prevalence of IMI at calving in both adult cows and heifers , and reduced the incidence of CM in the non-lactating period of cows and in the first 30 days after calving in heifers . CLINICAL RELEVANCE : The results of these trials demonstrate the efficacy of a novel ITS for the control of mastitis in likely uninfected dairy cows over the non-lactating period and in heifers in late pregnancy Abstract AIM : To describe aspects of management of dairy heifers before calving and determine risk factors for clinical mastitis postpartum in heifers , at the herd level , under pasture-based management systems in the Waikato and Taranaki regions of New Zeal and . METHODS : Dairy herdowners ( n=578 ) provided information via a prospect i ve survey about their practice s for rearing heifers and management of mastitis . A proportion of herdowners ( n=250 ) subsequently provided data on the cases of clinical mastitis in their herds , including the date , cow identification , age and quarter affected from cases occurring in the 4 months after the planned start of calving ( PSC ) in the subsequent lactation . The relationship between management factors and the proportion of heifers diagnosed with clinical mastitis within a herd was examined using bivariate and multivariate analyses . RESULTS : The herd average percentage of heifers with clinical mastitis was 13.6 ( 95 % confidence interval (CI)=12.3–14.9)% , and multiparous cows with clinical mastitis was 9.0 ( 95 % CI=8.2–9.8)% in the first 4 months of lactation . There were positive relationships between the proportion of heifers with clinical mastitis and average milk production per cow ( kg milksolids/ lactation ; p<0.001 ) , number of cows milked per labour unit ( p=0.003 ) , stocking rate ( < > 3.30 cows/ha ; p=0.002 ) , and incidence of clinical mastitis in multiparous cows ( % /120 days ; p<0.04 ) , in the final multivariate model . The proportion of heifers with clinical mastitis per herd was lower in herds that milked their lactating cows in multiple groups ( p=0.02 ) . CONCLUSIONS : The risk of clinical mastitis  in heifers was significantly associated with management practice s. It may be possible to reduce the incidence of clinical mastitis in heifers by modification of management practice s at the herd level , and further studies are required to investigate this A vaccine was developed against bovine mastitis based on inactivated , highly encapsulated Staphylococcus aureus cells ; a crude extract of Staph . aureus exopolysaccharides ; and inactivated , unencapsulated Staph , aureus and Streptococcus spp . cells . This vaccine was tested on 30 heifers during a 7-mo period . The 30 heifers were r and omly assigned to three groups of 10 heifers each . The prepartum group received two injections of the vaccine at 8 and 4 wk before calving , and the postpartum group received two injections at 1 and 5 wk after calving . The control group received two injections of a placebo at 8 and 4 wk before calving . The vaccine or the placebo was administered subcutaneously in the brachiocephalicus muscle of the neck . The frequencies of intramammary infections caused by Staph . aureus were reduced from 18.8 % for heifers in the control group to 6.7 and 6.0 % for heifers in the prepartum and postpartum groups , respectively . This protective effect was maintained for at least 6 mo . The relative risk of mastitis caused by Staph . aureus was 0.31 and 0.28 for heifers in the prepartum and postpartum groups , respectively , compared with that for heifers in the control group . The results of the trial indicated the effectiveness of the vaccine in decreasing the incidence of intrammammary infections caused by Staph . aureus . A slight but nonsignificant increase occurred in fat production in the milk of vaccinated cows . The vaccine had no observable effect on somatic cell count or streptococcal infections This study investigated the effect in heifers of infusion of a bismuth subnitrate teat-canal sealant and bacterial intramammary infection ( IMI ) precalving on prevalence of postcalving IMI and incidence of clinical mastitis in the first 2 wk postcalving . Gl and s ( n = 1,020 ) from heifers ( n = 255 ) in 5 seasonally calving , pasture-fed dairy herds were r and omly assigned within heifer to 1 of 4 treatment groups ( no treatment ; mammary gl and secretion collection ; infusion of a teat sealant ; or sample collection with infusion of teat sealant ) . Heifers within a herd were enrolled on one calendar day , 31 d on average before the planned start of the seasonal calving period . Duplicate milk sample s were collected from each gl and within 4 d after calving for bacterial culture . Herd owners collected duplicate milk sample s , before treatment , for bacterial culture from gl and s they defined as having clinical mastitis . The gl and prevalence of IMI precalving was 15.5 % and did not differ between herds . Bacteria isolated precalving included coagulase-negative staphylococci ( 76.9 % of all bacteriologically positive sample s ) , Streptococcus uberis ( 14.1 % ) , Staphylococcus aureus ( 5.1 % ) , Corynebacterium spp . ( 3.8 % ) , and others ( 0.1 % ) . The presence of an IMI precalving increased the risk of an IMI postcalving 3.6-fold and the risk of clinical mastitis 4-fold , relative to no IMI precalving . Infusion of the teat sealant reduced the risk of postcalving IMI due to Strep . uberis by 84 % , and of clinical mastitis by 68 % . Sampling the gl and s precalving had no effect on postcalving IMI or on clinical mastitis incidence . Use of an internal teat canal sealant in heifers precalving may be a useful tool for reducing the risk of sub clinical and clinical mastitis in heifers The conduct of r and omized controlled trials in livestock with production , health , and food-safety outcomes presents unique challenges that may not be adequately reported in trial reports . The objective of this project was to modify the CONSORT ( Consoli date d St and ards of Reporting Trials ) statement to reflect the unique aspects of reporting these livestock trials . A two-day consensus meeting was held on November 18 - 19 , 2008 in Chicago , IL , United States of America , to achieve the objective . Prior to the meeting , a Web-based survey was conducted to identify issues for discussion . The 24 attendees were biostatisticians , epidemiologists , food-safety research ers , livestock-production specialists , journal editors , assistant editors , and associate editors . Prior to the meeting , the attendees completed a Web-based survey indicating which CONSORT statement items may need to 
    Output:
    
Although variation was observed in the pathogen-specific effectiveness of treatments at reducing rates of disease , antimicrobials , teat sealants , and combinations of vaccines or teat sealants with antimicrobials were consistently effective , whereas vaccines were only effective for contagious pathogens .