-Staphylococci are the main aetiological agents of small ruminants intramammary infections (IMI), the more frequent isolates being S. aureus in clinical cases and coagulase negative species in subclinical IMI. The clinical IMI, whose annual incidence is usually lower than 5%, mainly occur at the beginning of machine milking and during the first third of lactation. These features constitute small ruminant peculiarities compared to dairy cattle. Small ruminant mastitis is generally a chronic and contagious infection: the primary sources are mammary and cutaneous carriages, and spreading mainly occurs during milking. Somatic cell counts (SCC) represent a valuable tool for prevalence assessment and screening, but predictive values are better in ewes than in goats. Prevention is most often based on milking machine management, sanitation and annual control, and milking technique optimisation. Elimination mainly relies on culling animals exhibiting clinical, chronic and recurrent IMI, and on drying-off intramammary antibiotherapy; this treatment allows a good efficacy and may be used selectively by targeting infected udders only. Heritability values for lactation mean SCC scores are between 0.11 and 0.15. Effective inclusion of ewe's mastitis resistance in the breeding goal has recently been implemented in France following experimental and large scale estimations of genetic parameters for SCC scores.ewe / goat / mastitis / somatic cell count / epizootiology
The microbial communities in milks from one herd were evaluated during 1-year of lactation, using molecular methods to evaluate their stability and the effect of breeding conditions on their composition. The diversity of microbial communities was measured using two approaches: molecular identification by 16S and 18S rDNA sequencing of isolates from counting media (two milks), and direct identification using 16S rDNA from clone libraries (six milks). The stability of these communities was evaluated by counting on selective media and by Single Strand Conformation Polymorphism (SSCP) analysis of variable region V3 of the 16S rRNA gene and variable region V4 of the 18S rRNA gene. One hundred and eighteen milk samples taken throughout the year were analyzed. Wide diversity among bacteria and yeasts in the milk was revealed. In addition to species commonly encountered in milk, such as Lactococcus lactis, Lactococcus garvieae, Enterococcus faecalis, Lactobacillus casei, Leuconostoc mesenteroides, Staphylococcus epidermidis, Staphylococcus simulans, Staphylococcus caprae, Staphylococcus equorum, Micrococcus sp., Kocuria sp., Pantoea agglomerans and Pseudomonas putida, sequences were affiliated to other species only described in cheeses, such as Corynebacterium variabile, Arthrobacter sp., Brachybacterium paraconglomeratum, Clostridium sp. and Rothia sp. Several halophilic species atypical in milk were found, belonging to Jeotgalicoccus psychrophilus, Salinicoccus sp., Dietza maris, Exiguobacterium, Ornithinicoccus sp. and Hahella chejuensis. The yeast community was composed of Debaryomyces hansenii, Kluyveromyces lactis, Trichosporon beigelii, Rhodotorula glutinis, Rhodotorula minuta, Candida pararugosa, Candida intermedia, Candida inconspicua, Cryptococcus curvatus and Cryptococcus magnus. The analyses of microbial counts and microbial SSCP profiles both distinguished four groups of milks corresponding to four periods defined by season and feeding regime. The microbial community was stable within each period. Milks from winter were characterized by Lactococcus and Pseudomonas, those from summer by P. agglomerans and Klebsiella and those from autumn by Chryseobacterium indologenes, Acinetobacter baumanii, Staphylococcus, Corynebacteria and yeasts. However, the composition of the community can vary according to factors other than feeding. This study opens new investigation fields in the field of raw milk microbial ecology.
A study was carried out to assess the efficacy of vaccination, using a phase I Coxiella burnetii-inactivated vaccine (Coxevac®; CEVA), within three goat herds experiencing Q fever abortions waves. The stratification of the population (n = 905) was based on parity and on infection status related to both serological and qPCR vaginal shedding results. Control (n = 443) and vaccinated (n = 462) groups were established in each farm. Vaccination was administered to does before mating and to kids after active immunity acquisition (at least 3–4 months old). The vaccine effectiveness was analyzed at subsequent farrowing on both clinical incidence and vaginal shedding at the delivery day. Among the 231 animals considered as susceptible, that is, seronegative nonshedders, about 90% were infected whatever the group, showing that vaccination did not prevent infection under high infection exposure. Fortunately, vaccination induced an overall decrease in shedding levels. A significant average difference between groups was estimated to 1.16 log(10) bacteria per swab for primiparous and even higher (1.81 log(10)) for initially susceptible ones. Thus, in a clinical context, vaccination should be implemented first in renewal animals. Indeed, young animals are those which best respond to vaccination by significantly reducing C. burnetii burden and, conversely, which excrete bacteria most massively if not vaccinated.
Udder-half infections were recorded throughout a lactation for 1,060 goats belonging to eight commercial herds. Bacteriological examination from aseptic milk samples and somatic cell counts (SCC) determined by Fossomatic cell counting were performed at the beginning, the middle, and the end of lactation. Coagulase-negative staphylococci (CNS) were the prevalent microorganisms isolated. Geometric means of SCC for uninfected halves or halves infected by CNS or major pathogens were 272 x 10(3) cells/mL, 932,000 x 10(3) cells/mL and 2,443,000 x 10(3) cells/mL, respectively. Two field trials were carried out for evaluation of effectiveness of systematic treatment at drying-off (1 syringe by half) by a combination of penicillin, nafcillin, and dihydrostreptomycin labeled for bovines. In the first trial, all goats (n = 217) of two herds were treated immediately after the last milking, and two herds (n = 196) were used as untreated controls. In the second trial, 215 goats were treated at drying-off. There were no untreated controls. Dry period cures were determined by bacteriological examination of udder-half milk samples collected aseptically at drying-off and 2 wk after parturition. Impact of treatment on SCC was determined from composite milk samples collected monthly after kidding. At parturition, in the first trial, 40 of 202 (19.8%) udder halves were spontaneously cured in the control group vs 169 of 217 (77.9%) in the treatment group. In the second trial, 141 out of 215 treated halves were cured. During the first 75 d in lactation, geometric mean SCC was significantly lower for treated goats than for control goats. After 75 d, SCC for treated and control goats were similar. These data suggest that other methods are required to prevent new intramammary infections throughout the lactation in order to keep a low SCC in goat milk. To determine whether this could be accomplished through teat dipping, half of the goats in five commercial herds were dipped (n = 294) after morning and evening milkings through the lactation (10 mo) with a teat dip product containing nisin. Undipped goats (n = 292) served as a control group. No difference was found for SCC in milk between the dipped and undipped groups. It was concluded that systematic treatment of goats at drying-off is an efficient method for the cure of subclinical mastitis and control of SCC at the beginning of the following lactation and that effectiveness of postmilking teat disinfection remains to be demonstrated.
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