STUDIES OF NOCARDIOSIS IN CATTLE 1 - ISOLATION OF NORCARIDA ASTEROIDES FROML MASTITIS IN CATTLE

A six months survey (2-8/1994) was canied out to determine norcaiidal mastitis in cattle in certain dairy herds. A total 126 milk samples collected from mastitic‘ cows and milk tank. Of which 10 from Al-Khalis station, 15 from A1-Wahda station, 6 from White Good village, 90 from Al-Dejaila station and 5 fromMilktauk. Examination of the samples result in isolation of Norcaitlia asteroides from Al-Dejaila station. The results explained that 25 animals were positive for norcaridal infection with prevalence of 20.8 % of these 25 cases, 5 cases, in pure cultural and 20 cases, mixed with other organisms. Bacteriological examination of mill: tank also resulted in positive for norcaridial isolates. Metastasis to the lung and supramammary lymph node was demonstrated. The results also explained that norcardial isolates from mastitic cows were more virulent to guinea pigs, andthis study revealed that norcardial infection are not rare in cattle.

Training, development, and evaluation of on-farm culturing as a technical resource to reduce the use of antimicrobials in dairy herds in the Midwest Region of Santa Catarina State, Brazil

ABSTRACT: On-farm culturing is a technology booming in Brazil. It is based on the microbiological diagnosis of milk samples collected from clinical cases of bovine mastitis, on the farm where the animals are handled, quickly, simply, and at an affordable cost. With this resource, after 24 h of incubation, the isolated microorganisms are classified as gram positive or gram negative, helping to make decisions regarding the therapy of the animals. Considering the relevance of the Midwestern region of Santa Catarina State in the national dairy production scenario, the objectives of the study were: 1) to promote the technical training of the farmers in three dairy farms located in Treze Tílias-SC, 2) to assist in the implementation and evaluation of on-farm culturing as technological resource viewing the reduced use of antimicrobials in herds. In addition to the rapid acceptance by the farmers and their efficient training, with the use of the technology, there was a 45-50% reduction in the use of antimicrobials in dairy herds. This result demonstrated a significant effect on animal health, and determines an important cost reduction for farmers, as presented in detail in this manuscript.

Virulence Factors and Prevalence of Udder´s Pathogens in Dairy Cows during the Peripartal Period

Data presented in this study described the prevalence of udder pathogens and presence of virulence factors in staphylococci isolated from mastitis in dairy cows. The practical part of study was realized in five different dairy herds of Slovak spotted cattle breed located in Eastern Slovakia with conventional (non-organic) farming. At the beginning of lactation (during first two months after calving) were comprehensively investigated 960 cows from monitored herds. The comprehensive examination included clinical examination, sensory analysis of milk from fore stripping of each udder quarter, followed by assessment of the California mastitis test (CMT) and laboratory analyses of bacteria pathogens. Screening the health status of the mammary gland revealed that 314 cows (32.7%) had positive CMT score (1-3) for one or more quarters. Out of 230 infected milk samples, representing 24.0% of all dairy cows examined, were the most commonly isolated staphylococci (59.1% of positive findings), followed by E. coli (11.3%), streptococci Str. uberis (9.1%), Str. agalactiae (3.4%), and enterococci (6.1%). From 136 isolates of coagulase negative stafylococci (98 isolates) and S. aureus (38 isolates) were detected some virulence factors such as production of hemolysins (lysines ß and δ), gelatinase, biofilm, and hydrolyze of DNA. Isolated S. aureus, S. chromogenes and S. warneri had the most numerous representation of detected virulence factors, as demonstrated by the increased incidence of clinical forms of mastitis compared to less virulent strains.

Antimicrobial Selection for the Treatment of Clinical Mastitis and the Efficacy of Penicillin Treatment Protocols in Large Estonian Dairy Herds

Clinical mastitis (CM) is the most common microbial disease treated in dairy cows. We analyzed the antimicrobial usage in cows with CM (n = 11,420) in large dairy herds (n = 43) in Estonia. CM treatment data were collected during a 12-month study period. The antimicrobial usage was observed during the 21 days from the initiation of treatment, and the incidence of antimicrobial-treated CM was calculated for each study herd. The effect of intramammary (IMM), systemic, and combined (systemic and IMM) penicillin treatment of CM on the post-treatment somatic cell count (SCC) was analyzed using the treatment records of 2222 cows from 24 herds with a mixed multivariable linear regression model. The median incidence of antimicrobial-treated CM was 35.8 per 100 cow-years. Procaine benzylpenicillin and marbofloxacin were used in 6103 (35.5%, 95% CI 34.8–36.2) and 2839 (16.5%, 95% CI 16.0–17.1) CM treatments, respectively. Post-treatment SCC was higher after IMM penicillin therapy compared to systemic or combination therapy. Treatment of CM usually included first-choice antimicrobials, but different antimicrobial combinations were also widely used. The effect of procaine benzylpenicillin to post-treatment SCC was dependent on the administration route, cow parity, and days in milk. Further studies should evaluate the factors affecting veterinarians’ choice of antimicrobial used in the treatment of CM.

Allele and genotype frequency for milk beta-casein in dairy cattle in the northern region of Tocantins State, Brazil

At present, there is a concern about the quality of milk and diseases related to its consumption, as it can generate discomfort and allergic reactions in some individuals due to its protein components. Thus, the present study was developed to identify the allele and genotype frequencies of genes for β casein, A1 and A2, in dairy herds in the region of Araguaína-TO, Brazil. Genetic material from 421 animals (crossbred dairy cattle in lactation) was used. All animals were numbered for identification, and DNA samples were extracted from hair bulbs. Samples for two markers from the polymorphic regions were characterized and confirmed by real time PCR using the ABI Prism® 7500 Sequence Detection System (Applied Biosystems). Allele and genotype frequencies were determined using the TaqMan™ detection system, where the primer and probe release different fluorescence signals for each allele of the polymorphism. The sampled herd showed frequencies of 28.27% for the A1 allele and 71.73% for the A2 allele. Genotype frequencies were 52.96% (223/421) for A2A2; 37.53% (158/421) for the A1A2 genotype; and 9.50% (40/421) for the A1A1 genotype. The frequency of the A1 allele for β-casein in dairy herds from the northern region of Tocantins was low and is per the results of previous studies. Although the A2A2 genotype of β-casein had a high relative frequency, the A1A2 genotype is still rather frequent, warranting greater selection pressure.

Tryptophan, Kynurenine and Kynurenic Acid Concentrations in Milk and Serum of Dairy Cows with Prototheca Mastitis

The aim of this work was to investigate serum and milk levels of tryptophan (TRP), kynurenine (KYN), and kynurenic acid (KYNA), as well as the activity of indoleamine 2,3-dioxygenase (IDO) in cows with mastitis due to Prototheca algae. The study was prompted by previous research showing a link between the KYN pathway of TRP metabolism and bovine mastitis of bacterial etiology. The study was carried out over a 2-year period (2018–2019) and included quarter milk and serum samples collected from six dairy herds in Poland. The samples were obtained from healthy cows and cows with Prototheca mastitis of either clinical and subclinical manifestation, as determined upon direct measurement of the somatic cell count or indirectly by performing a California Mastitis Test on suspected quarters. Both TRP and KYN concentrations were significantly lower in milk of mastitic cows compared to healthy animals (0.8 vs. 8.72 µM, p = 0.001; 0.07 vs. 0.32 µM, p = 0.001, respectively). The difference in TRP and KYN concentrations in the sera of the two animal groups was much less pronounced (25.55 vs. 27.57 µM, 3.03 vs. 3.56 nM, respectively). The concentration of KYNA was almost at the same level in milk (1.73 vs. 1.70 nM) and in serum (80.47 vs. 75.48 nM) of both mastitic and healthy cows. The data showed that the level of TRP and its metabolites in serum was conspicuously higher compared to milk in all cows under the study. The activity of IDO was significantly higher in milk of cows with Prototheca mastitis compared to healthy animals (71.4 vs. 40.86, p < 0.05), while in serum it was pretty much the same (135.94 vs. 124.98, p > 0.05). The IDO activity differed significantly between serum and milk both for mastitic (135.94 vs. 71.4, p < 0.05) and healthy cows (124.98 vs. 40.86, p < 0.001). In conclusion, low values of TRP and KYN concentrations or elevated IDO activity in milk samples might be used as markers of mastitis due to infectious causes, including Prototheca spp.