M. SAMARDŽIJA: Bovine mastitis: a persistent and evolving problem requiring novel approaches for its control -a review. Vet. arhiv 88, 535-557, 2018. ABSTRACT Mastitis in dairy cows is the inflammation of the mammary gland, and is the most important cause of economic losses in the modern dairy industry. Bovine mastitis is often infectious and can be caused by some 150 microbial species. The environment of the dairy cow is heavily colonized by microbiota, while milk is an ideal medium for propagation of the bacteria and causative agents. Staphylococcus aureus is the most common pathogen isolated from the mammary gland capable of causing health disorders in humans. Milk from an infected mammary gland has a different chemical composition compared to milk from healthy cows. Certain differences, such as protein components specific to inflamed tissue, are currently being considered in 2018 M. Benić et al.: Bovine mastitis: a persistent and evolving problem requiring novel approaches for its control the development of diagnostic tools for mastitis. The known risk factors for mastitis can result in mastitis at the quarter, cow and herd levels. Mastitis treatment includes both preventive and therapy measures, and is primarily based on the use of antibiotics. Recent approaches to mastitis therapy have been focused on the design and use of natural therapeutics, such as zeolites, ozone and propolis, that could serve as alternatives to antibiotics.

Background: The bacterial species S. aureus is the most common causative agent of mastitis in cows in most countries with a dairy industry. The prevalence of infection caused by S. aureus ranges from 2% to more than 50%, and it causes 10–12% of all cases of clinical mastitis. Aim: The objective was to analyze 237 strains of S. aureus isolated from the milk of cows with subclinical mastitis regarding the spa, mecA, mecC and pvl genes and to perform spa and multi-locus sequence typing (MLST). Methods: Sequencing amplified gene sequences was conducted at Macrogen Europe. Ridom StaphType and BioNumerics software was used to analyze obtained sequences of spa and seven housekeeping genes. Results: The spa fragment was present in 204 (86.1%) of strains, while mecA and mecC gene were detected in 10 strains, and the pvl gene was not detected. Spa typing successfully analyzed 153 tested isolates (64.3%), confirming 53 spa types, four of which were new types. The most frequent spa type was t2678 (14%). MLST typed 198 (83.5%) tested strains and defined 32 different allele profiles, of which three were new. The most frequent allele profile was ST133 (20.7%). Six groups (G) and 15 singletons were defined. Conclusion: Taking the number of confirmed spa types and sequence types (STs) into account, it can be concluded that the strains of S. aureus isolated from the milk of cows with subclinical mastitis form a heterogenous group. To check the possible zoonotic potential of isolates it would be necessary to test the persons and other livestock on the farms.

Abstract. Transition dairy cows often enter a stage of negative energy balance during which the utilization of energy reserves is reflected in the milk fatty acid (FA) composition. In this study, metabolic status was evaluated by measuring milk FA, ruminal short-chain FA (RSCFA), and serum biochemical parameters in Holstein cows. Samples (milk, rumen contents, and blood) were collected around days 30 (early) and 150 (middle) of lactation, and rumen contents and blood samples were collected 30 days before calving (dry). Fatty acids were extracted and FA composition was determined. Glucose, triacylglycerols, total cholesterol, low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), beta-hydroxybutyric acid (BHB), and non-esterified fatty acid (NEFA) concentrations were determined in serum samples. Lower percentages of saturated FA in milk and higher percentages of monounsaturated FA, polyunsaturated FA, and C18:1n-9 were observed in early lactation compared to mid-lactation. In rumen higher concentrations of propionic acid were determined at mid-lactation compared to early lactation. Acetic and butyric acid concentrations showed no significant differences between sampling intervals. In serum higher glucose concentrations were observed during the dry period and mid-lactation than during early lactation. Lower BHB and higher NEFA concentrations were noted during early lactation compared to mid-lactation and the dry period. Total cholesterol, LDL-C, HDL-C and triacylglycerols showed no significant differences between sampling intervals. The results of the present study suggest that determination of milk FA is a potential indicator of energy status in dairy cows.

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The coccidiostat maduramicin has been approved as a feed additive for chickens and turkeys, although it is prohibited for use in laying hens. In the present study, laying hens were divided into three groups and fed for 14 days with medicated feed containing maduramicin, at three different concentrations: 50, 100 and 500 µg kg(-1). Eggs were collected during treatment and for 26 days after the end of feeding with medicated feed. Maduramicin residues were found exclusively in egg yolk, with the highest concentration in egg yolk of 459 µg kg(-1) for the highest dose. The maximum concentration of maduramicin in whole egg was 16.6 µg kg(-1) for the group receiving feed containing the maximum permitted level of maduramicin in feed (50 µg kg(-1)). The half-life of elimination of maduramicin, calculated for post-treatment days 1-10, was 6.5 days. Twelve days after drug administration, the concentration of the maduramicin in egg yolk for Group 3 (fed with 500 µg kg(-1) maduramicin) still exceeded 20 µg kg(-1), while the concentrations for Groups 1 and 2 were 1.2 and 2.7 µg kg(-1), respectively.

This study’s objective was to estimate the seasonal occurrence of aflatoxin M1 (AFM1) in cow’s milk between winter 2016 and winter 2022 and to assess dietary exposure and risk assessment for the adult Croatian population. In total, 5817 cow milk samples were screened for AFM1 concentrations using the enzyme immunoassay assay (ELISA). For confirmation purposes of AFM1 concentration above the European Union maximum permitted level (MRL), ultra high-performance liquid chromatography with tandem mass spectrometry was performed. In 94.7% of milk samples, AFM1 levels were below the detection limit (LOD) of the ELISA test. For 3.47% of samples, the AFM1 was between the LOD and MRL values. Only 1.87% of all samples exceeded the MRL. The mean value of elevated AFM1 in different seasons ranged between 59.2 ng/kg (autumn 2017) and 387.8 ng/kg (autumn 2021). The highest incidences of positive AFM1 were determined in autumn and winter and the maximum (6.4%) was in winter 2019/2020. The largest percentage of positive samples (69.7%) was found in central Croatia. The estimated daily intakes for positive samples ranged between 0.17 and 2.82 ng/kg body weight/day. Risk assessment indicated a high level of concern during autumn and winter, especially for consumers of large amounts of milk.

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