Systemic treatment of subclinical mastitis in lactating cows with penethamate hydriodide.

A randomized controlled field trial was performed to evaluate the efficacy of a 3-d treatment regimen with i.m. penethamate hydriodide compared with no treatment in lactating cows with subclinical mastitis. To be included, a cow had to have 2 somatic cell counts (SCC) 300,000 cells/mL at the last 3 monthly controls, 1 or more quarters with SCC >250,000 cells/mL, and the same bacterial species isolated in 2 consecutive samples 2 to 4 d apart. A total of 151 quarters from 92 cows were monitored for 2 mo following treatment. Quarter milk samples were examined for bacteriological cure (BC) and SCC at 14, 28, and 60 d after treatment. Bacteriological cure was defined as not having the same bacterial species isolated from the quarter milk samples taken at 14 and 28 d posttreatment as in the samples taken before treatment. Systemic treatment with penethamate resulted in BC in 59.5% of quarters and 52.2% of cows, compared with 16.7 and 10.9% in the untreated cows. Somatic cell count decreased significantly in the penethamate-treated cows, steadily in the case of BC and transiently when the infections persisted. This study confirms that systemic treatment of subclinical mastitis with penethamate is effective and that BC of infected quarters has a sustained positive effect on milk SCC during the 2 mo following treatment.

Risk factors for new intramammary infections during the dry period in untreated dairy cows from herds using selective dry cow therapy.

This study aimed at investigating risk factors for new intramammary infections (IMI) during the dry period in untreated cows from herds using selective dry cow antibiotic therapy (DCT). A total of 980 uninfected quarters in 347 untreated cows from 28 herds using selective DCT were included in a prospective survey. A herd-level questionnaire and an individual cow-level recording sheet were implemented to collect data on putative risk factors. Quarter milk samples were taken at drying-off and on day 3 after calving to assess the occurrence of new IMI during the dry period. A multivariate model including a herd effect as random and a cow effect as repeated was run at the quarter level. Interactions between risk factors and the cow infection status at drying-off (cow infected in at least one quarter v. uninfected) were checked. Three risk factors were found significantly associated with the risk for new IMI without interaction (P < 0.05): cows infected in at least one quarter at drying-off (v. uninfected cows) (relative risks (RR) = 1.58); long preceding lactation (>355 days v. shorter length) (RR = 1.62); long dry period (>65 days v. shorter length) (RR = 1.46). One risk factor acted only in interaction with the cow infection status at drying-off: in cows uninfected at drying-off, the risk for new IMI was significantly higher in cows with short teats (RR = 1.21) when compared with cows with long or normal teats, while the reverse relationship was observed in cows infected at drying-off. Risk factors can be translated in recommendations, for instance to have dry periods not longer than 2 months. Moreover, as suggested by our results, the efficacy of selective DCT towards the prevention of new IMI would be improved if all infected cows were detected and treated. Criteria to accurately identify these infected cows should be therefore further investigated.

Comparative efficacy of local and systemic antibiotic treatment in lactating cows with clinical mastitis.

The intramuscular administration of penethamate hydriodide over 3 consecutive days and the intramammary administration of an ampicillin/cloxacillin combination were compared in lactating cows suffering from infectious clinical mastitis in one quarter, through an open, randomized, controlled multicenter field trial. Clinical examinations were carried out on d 1 (immediately before treatment), 3, 8, 17, and 22. Milk samples were taken from affected quarters for bacteriological analysis on d 1, 17, and 22, and from all quarters for somatic cell count (SCC) determination on d 1, 8, 17, and 22. There was no significant difference in bacteriological and clinical cure rates between the 2 treatment groups. The systemic treatment with penethamate resulted more frequently in a reduction of the milk SCC below the threshold of 250,000 cells/mL. This also occurred in the adjacent quarters not affected by clinical mastitis but with an SCC above 250,000 cells/mL before treatment. These findings suggest that the parenteral treatment with penethamate provides collateral cure on the quarters of the cows affected by subclinical mastitis. The number of quarters per cow affected by clinical or subclinical mastitis should be considered when selecting an antibiotic treatment by the local or systemic route.

Field trial evaluation of two teat dips containing nisin or polyvinylpyrrolidone iodophor designed for use before and after milking.

In a first trial involving six commercial dairy herds and 291 cows for a period of eight months, pre-milking udder sanitation by dipping teats in a 0.25% polyvinylpyrrolidone (PVP) iodophor product followed by wiping with paper towels was compared in each herd with traditional teat washing and wiping with individual udder cloths. The incidence of new intramammary infections by Staphylococcus aureus, Streptococcus uberis and Corynebacterium bovis were significantly (P < 0.05) reduced, respectively by 48%, 60% and 47%. There were no significant differences in the two groups of cows for other intramammary infections, total bacterial counts, clostridia spore counts, iodine residues in milk or teat condition scores. In a second trial involving nine commercial dairy herds and 367 cows for a period of seven months, a teat dip containing nisin used before and after milking was compared in each herd with a classical 0.5% iodophor product used in the same way. There was no significant difference in the incidence of new intramammary infections, in spite of a higher rate of new Staphylococcus aureus infections in the group of cows teat-dipped with the nisin product (P = 0.06). It was concluded that pre-dipping with teat dips specifically designed to be safely used before milking can be more efficient than traditional pre-milking udder preparation. These teat dips, when used before and after milking, seem to be as efficient as products which should normally be restricted to post-milking use.

Risk factors associated with contamination of raw milk by Listeria monocytogenes in dairy farms.

A case-control study involving 128 selected dairy farms was conducted to assess the association of several suspected risk factors with the odds of contamination of raw milk by Listeria monocytogenes. Using logistic regression, we found that poor quality of silage (pH > 4.0), inadequate frequency of cleaning the exercise area, poor cow cleanliness, insufficient lighting of milking barns and parlors, and incorrect disinfection of towels between milkings were significantly associated with milk contamination by L. monocytogenes. More attention to preparing silage and good milking and barn hygiene are important for diminishing the risks of exogenous contamination of raw milk by L. monocytogenes.

Efficacy of a germicidal post milking barrier-type teat dip in preventing intramammary infections.

Five commercial dairy herds with 269 lactating cows participated for 12 months in a field trial to determine the effectiveness of a barrier teat dip containing chlorous acid/chlorine dioxide germicide. The right quarters of the cows in two herds and the left quarters of the cows in three herds were dipped in the experimental teat dip after the removal of the milking machine. The other quarters were dipped in a conventional 0.5 per cent iodophor product. Compared with this control product, teat dipping with the experimental dip reduced the number of new intramammary infections by 18.8 per cent, infections with major pathogens by 13.6 per cent, infections with minor pathogens by 16.8 per cent and clinical mastitis by 33.3 per cent. Statistical analysis indicated a trend towards decreased intramammary infections with coliforms and coagulase-negative staphylococci when the experimental teat dip was used. It was concluded that under the conditions of this investigation it was effective in preventing new infections due to both contagious and some environmental pathogens. However, the data suggested that it could adversely affect the condition of the skin of the teat when it was used after incorrect preparation of the udder.

[Cell concentration of individual cow's milk: effect of the status of mammary infection, parity, lactation stage and milk production]. / Concentration cellulaire du lait individuel de vache: influence de l'état d'infection mammaire, du numéro, du stade de lactation et de la production laitière.

The relative effect of the intramammary infections and of different factors related to the cow (parity, stage of lactation, milk yield) on the individual cell counts, were studied for 30 months on the 62 black-and-white Holstein cows of an experimental herd. During this period, the cows were regularly submitted to bacteriological tests for intramammary infections, individual cell counts and controls of the milk yield. The infection status of the cows at the time of counting was the main factor affecting the cell concentrations in the milk: the values ranged from around 5 X 10(4) cells/ml in the absence of infection in the four quarters, to values that were on average twice as high in the case of infection by a minor pathogen and ten times as high in the case of infection by a major pathogen. The mean cell concentrations in the milk of uninfected cows were significantly lower during the first lactation; they varied during the lactation according to a curve which had the form of an inverted lactation curve. The mean cell count during a lactation was independent of the mean milk yield per day of lactation. In cows infected by a major pathogen, the effect of the number and stage of lactation was different. Only the variation apparently associated with the stage of lactation had a sufficient amplitude to bring the mean cell concentrations of uninfected cows close to the values recorded in cows infected by a minor pathogen. The average results from cows infected by a major pathogen were, however, much higher at all stages of lactation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Relation between the cell concentration of individual cow's milk, milk production and the cow's susceptibility to mammary infection]. / Relation entre concentration cellulaire du lait individuel, production laitière, et sensibilité des vaches aux infections mammaires.

The relations between the cell concentration in the milk from individual cows, their susceptibility to mastitis and milk production capacity were studied for 30 months on the 62 black-and-white French Frisian X Holstein cows of an experimental herd. During this period, the cows were regularly submitted to bacteriological tests for intramammary infections, individual cell counts and controls of the milk production. The cell concentrations in the milk before infection were not different for two groups of cows that showed more or less susceptibility to mastitis. The corrected milk production fell linearly with the logarithmic mean of the lactation cell concentration, leading to a decrease of the yield that was as great as between 100 000 and 200 000 as between 200 000 and 400 000 cells/ml. The reduction in yield was particularly large in cows that presented brief clinical infections followed by persistent inflammatory sequelae. The biological significance of these results and their implications for the control of mastitis were discussed.

[Interpretation of the cell concentration of cow's milk for the diagnosis of mammary infection]. / Interprétation des concentrations cellulaires du lait individuel de vache pour le diagnostic de l'état d'infection mammaire.

The potential utilisation of monthly cell counts per cow to determine their infection status was studied for 30 months on 62 cows from an experimental herd, and by simulation, on different herd models with defined epidemiological characteristics. During this period, the cows of the experimental herd were regularly submitted to bacteriological tests for intramammary infections and individual cell counts. The cows which were not chronically infected by a major pathogen were characterised by cell counts of less than 300 000 cells/ml throughout lactation. The chronically infected cows were characterised by at least two peaks over 300 000 with at least one beyond 800 000, but cell counts could be, at other time intervals, below 300 000 cells/ml. Provided that at least two monthly cell counts were available for each cow, it was possible to discriminate strongly the cows not chronically infected and the cows chronically infected by a major pathogen which are reservoirs of infection. The percentage of correct classifications varied between 74 and 87% in relation with the chosen threshold and the infection status of the herd in which this threshold was used. With the same threshold, there were higher percentages of false negative diagnosis in a herd model where staphylococcal like long-term infections were prevalent and of false positive when there was a high incidence of clinical short-term infections. Monthly cell counts per cow did not correctly reveal short-term clinical infections which are particularly prevalent in herds affected mainly by environmental mastitis. The precision and practical importance of this individual diagnosis was discussed for different herd models.

[Choice of antiseptics for use in footbaths for cattle (author's transl)]. / Le choix des antiseptiques pour les pédiluves destinés aux bovins.

Eight antiseptics to be used in footbaths for cattle, were compared : formol, cuprum sulphate, formol associated with cuprum sulphate, Javel water, Crésyl and some other products more recently introduced into practice. For each one, evolution of antibacterial activity connected with utilization on animals, moistening power and possible injury caused were observed. The best results have been obtained with formol, formol associated with cuprum sulphate and Cresyl which have exhibited persistent high level antibacterial activity without related injury in spite of numerous applications. On the other hand, weak organic matter resistance which seems to characterize Javel water, synthetic phenols, amphoteric amino acids and iodophores makes them unsuitable for use in footbaths.

[Treatment of mastitis in dry cows: treatment of all cows vs treatment of infected cows only (author's transl)]. / Comparaison du traitement des infections mammaires au tarrisement chez toutes les vaches ou chez les seules vaches infectées.

UNLABELLED: Within a herd, three groups have been randomly constituted. -- CONTROL GROUP: No dry cow therapy. -- Total Treatment group: all cows were submitted to dry cow therapy, in their four quarters. -- Limited Treatment group: cows were submitted to dry cow therapy in their four quarters, only if at least one quarter had given a CMT larger than or equal to +++, in the month before drying-off. --The cows were treated either with cloxacillin or with penicillin-streptomycin in 3% monostearate. The number of cows and quarters examinated and treated are given in table 1; the results of treatments are indicated in table 2. No significant differences can be found between Total and Limited Treatment groups; a slight improvement was observed when compared to CONTROL GROUP. Cloxacillin and penicillin-steptomycin gave similar results. The pathogenic and practical signification of these results is discussed.