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Institute
In this species differentiation study of Corynebacterium spp. (C. spp.), quarter foremilk samples from 48 farms were included. These were obtained from both clinically healthy cows and those with clinical mastitis. First, all samples were examined cyto-microbiologically and all catalase-positive rods were differentiated using the direct transfer method in MALDI-TOF MS. C. bovis, C. amycolatum, C. xerosis, and five other species were identified with proportions of 90.1%, 7.7%, and 0.8% for the named species, respectively, and 1.4% for the remaining unnamed species. In addition, somatic cell count (SCC) was determined by flow cytometry. Based on this, the isolates were classified into four udder health groups: “latent infection”, “subclinical mastitis”, “clinical mastitis” and “others”. Approximately 90% of isolates of C. bovis and C. amycolatum were from latently and subclinically infected quarters. Of the C. bovis isolates, 5.8% were obtained from milk samples from clinical mastitis, whereas C. amycolatum was not present in clinical mastitis. The distribution of groups in these two species differed significantly. The geometric mean SCC of all species combined was 76,000 SCC/mL, almost the same as the SCC of C. bovis. With 50,000 SCC/mL, the SCC of C. amycolatum was slightly below the SCC of C. bovis. Through the species-level detection and consideration of SCC performed here, it is apparent that individual species differ in terms of their pathogenicity. Overall, their classification as minor pathogens with an SCC increase is confirmed.
Although Corynebacterium spp. can be regularly associated with subclinical and clinical mastitis cases in dairy cows, knowledge on their reservoirs in dairy farms is sparse. Therefore, samples were collected at 10 visits with 14 day intervals from bedding material (n = 50), drinking troughs (n = 20), different walking areas (n = 60), cow brushes (n = 8), fly traps (n = 4), the passage to pasture (n = 9) as well as milking liners (n = 80) and milker gloves (n = 20) in one dairy cow farm. Additionally, quarter foremilk samples from all lactating cows (approximately 200) were collected at each visit. All samples underwent microbiological examination and cultured isolates were identified using MALDI-TOF MS. Most Corynebacterium spp. that were cultivated from milk were also isolated from the housing environment and milking-related niches (C. amycolatum, C. confusum, C. stationis, C. variabile, C. xerosis) or from milking-related niches only (C. frankenforstense, C. pilosum, C. suicordis). C. bovis was not cultivated from any environmental niche, while being the dominant species in milk samples. This study demonstrates that many Corynebacterium spp. present in milk samples can also be isolated from the cows’ environment. For C. bovis, the most relevant Corynebacterium species with regard to intramammary infections, it indicates that environmental reservoirs are of little relevance.
Corynebacterium spp. are frequently detected in bovine quarter milk samples, yet their impact on udder health has not been determined completely. In this longitudinal study, we collected quarter milk samples from a dairy herd of approximately 200 cows, ten times at 14 d intervals. Bacteriologically, Catalase-positive and Gram-positive rods were detected in 22.7% of the samples. For further species diagnosis, colonies were analyzed by MALDITOF MS. Corynebacterium bovis, C. amycolatum, C. xerosis and 10 other Corynebacterium spp. were detected. The three aforementioned species accounted for 88.4%, 8.65% and 0.94% of all cultured Corynebacterium spp., respectively. For further evaluation of infection dynamics, the following three infection definitions were applied: A (2/3 consecutive samples positive for the same species), B (≥1000 cfu/mL in one sample), C (isolated from a clinical mastitis case). Infections according to definition B occurred most frequently and clinical mastitis with Corynebacterium spp. occurred once during sampling. Life tables were used to determine the duration of infection. According to infection definition A, infection durations of 111 d and 98 d were obtained for C. bovis and C. amycolatum, respectively. Exemplarily, longer lasting infections were examined for their strain diversity by RAPD PCR. A low strain diversity was found in the individual quarters that indicates a longer colonization of the udder parenchyma by C. bovis and C. amycolatum.
In a foster cow system, one or more calves are reared by a foster cow. With regard to the growing rejection towards the early separation of cow and calf after calving, such alternative rearing methods with prolonged cow–calf contact are coming more into focus. Nevertheless, there is a lack of recent studies investigating the effects of suckling multiple calves on the udder health of a foster cow. The present study aimed to initially describe the status and development of the udder condition and the microbial colonisation during the foster period. Thereby, the objectives were to determine whether suckling multiple calves was associated with an increase in intramammary infections (IMI) and a deterioration of udder constitution. A total of 99 Holstein Friesian foster cows from a large organic dairy farm in eastern Germany were included in this pilot study. Each foster cow was suckled by 3–4 calves and not additionally milked. Quarter milk samples were taken for cytomicrobiological examination at the beginning and end of the approximately 3.5 months suckling period. At the same time, the udders of 91 of these foster cows were clinically examined by visual assessment and manual palpation. In both the first and second examination (E1 and E2, respectively), Corynebacterium ssp. and non-aureus staphylococci (NaS) constituted the most frequently detected pathogen species in the 385 examined udder quarters. Classifying the quarters into mastitis categories was significantly different between the two examinations (p = 0.001). The number of quarters considered as healthy increased from E1 to E2 by 8.5%. At the same time, the number of quarters with mastitis decreased by 2.6%, the number of quarters with non-specific mastitis by 11.4% and the number of quarters with a latent infection increased by 5.4%. In total, 69.4% of the 121 infected udder quarters in E1 were bacteriologically cured in E2. A cytological cure was achieved in 28.1% of the 385 quarters. Both the bacteriological and cytological cure rate were spontaneous. A new infection occurred in 23.1% of the 385 examined udder quarters and was mainly attributable to infections with Corynebacterium spp. and NaS. During the suckling period, mainly new infections occurred and amounted to 73% in relation to presumed persistent infections (18.9%). The new infections were mainly attributable to infections with Corynebacterium spp. and NaS. Pasteurella spp. were also found in high percentages. A total of 10.1% of the quarters showed an increase in somatic cell count (SCC) above the threshold of 100,000 cells/mL from E1 to E2, indicating a new subclinical mastitis. Regarding udder condition, significant changes during the foster period were an increase in udder skin and teat lesions, a decrease in udder oedema, an increased amount of udder quarters with a consistency considered as normal and an increase in the number of udders showing no sign of udder cleft dermatitis. Moreover, teat length, circumference, and diameter increased significantly (p < 0.05). In conclusion, there is a possibility that suckling multiple calves improves udder health in terms of mastitis but leads to an increased pathogen transmission at the same time, resulting in an increase in latent infections. Additionally, pathogens as Pasteurella spp., which are usually located in the upper respiratory system, could be detected in the mammary gland. The changes concerning the udder condition were manifold. However, it has not yet been conclusively clarified whether all these changes are exclusively due to calf suckling. Further investigations with a non-suckled control group are required.
