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.

I n the past two decades many substances of natural or synthetic origin were studied as potential alternatives to antibiotic growth promoters (AGP) and some of them, particularly immunomodulators (IMs) and nutraceuticals (NCs), have shown to be capable of stimulating functions of the immune system and improving general health. At the same time, they were shown to be harmless for animals and the environment. Promising results have been obtained with natural clay minerals, zeolites among which clinoptilolite (CPL) is the best known as zootechnical and biomedical feed ingredient widely reported in scientific literature and used in farm animal nutrition. CPL has a potential to replace AGP due to its unique anti-bacterial properties, safety and efficacy as dietary supplement in food animals unifying potentials of an IM and NC. Currently, there INTRODUCTIONT he phrase "survival of the fittest" as an alternative to "natural selection" has been adopted and published in 1868 by Charles Darwin (1), and nowadays is becoming so true because of the rapid emergence of antibiotic resistant strains of pathogenic microbes of biomedical, particularly veterinary importance. This is a consequence of non-clinical use and misuse of dietary antibiotics for more than sixty years to prevent bacterial infections and to enhance performance in livestock production, mostly in chickens and pigs (2). Namely, the increased sanitary problems in intensive farming of food animals have been overcome thus far by adding sub-therapeutic doses of antibiotic growth promoters (AGP) infeed to enhance production efficiency by increasing growth rate, improv- ing feed utilization and reducing mortality from clinical disease is well documented particularly in swine production systems (3). However, the consumers especially in developed countries are becoming increasingly concerned about drug residues in meat and other animal products (4). In addition, it has been suggested that the continuous use of antibiotics may contribute to a reservoir of drugresistant bacteria (5) which may be capable of transferring their resistance to pathogenic bacteria in both animals and humans (6). As a result, many countries have banned or are banning the inclusion of antibiotics in diets as a routine means of growth promotion. The first experience of an AGP ban in Sweden in 1986 indicated a reduction in growth and an increase in morbidity and mortality rates in weaned pigs, which emphasized the importance of antibiotic use in intensive swine production(7). The total ban of dietary AGP in the EU countries since January 1, 2006 (EU Regulation No. 1831 and the elimination of their use in animal feed and water in the USA effective January 1, 2017 (FDA, CVM 2012, VFD Basics 2017) has had a serious influence on both health and performance of food animals underlining the need to develop alternative dietary and non-dietary strategies to evaluate the potential antimicrobial agents for their replacement (8). According to the World Health Organization, most antibiotics will not ...

The objectives of this study were to examine the influence of body condition of cows on metabolic and antioxidative status, as well as to investigate the relationship between metabolic indicators of lipid mobilization and oxidative stress during transition period. The study was conducted on 24 Holstein-Friesian dairy cows divided into 2 groups according to their body condition score (BCS) as optimal (n = 12; BCS from 3.25 to 3.75) or adipose (n = 12; BCS ≥4). Metabolic status (glucose, triglycerides, total cholesterol, HDL cholesterol, NEFA and BHB), paraoxonase-1 (PON1) and apolipoprotein A-I (ApoA-I) were analysed in sera taken on days -30, -10, -2, 0, 5, 12, 19, 26 and 60 relative to parturition. Adipose cows had significantly higher glucose concentration at parturition being significantly decreased after parturition on days 12 and 19. Total cholesterol and HDL-C concentrations were the lowest at parturition and significantly higher on days 26 and 60 after parturition in both groups of cows. Both investigated groups had significantly higher NEFA concentration from parturition until day 19 after parturition, indicating energy deficit and an increased lipid mobilization after calving. There were no significant differences in BHB concentration during transition period in both groups. No significant differences were found in PON1 activity and ApoA-I concentration during transition period in both groups of cows. However, in adipose cows, although not significantly different, PON1 was decreased from calving until day 19 after parturition indicating a disturbance in antioxidative status in adipose cows. PON1 significantly positively correlated with total cholesterol and HDL-C concentrations and negatively with NEFA indicating a strong relationship of PON1 with lipid metabolism. Significant positive correlation between NEFA and BHB in both groups of cows points out on energy deficit during transition period that cows tend to overcome by lipid mobilization providing alternative source of energy needed for parturition and lactation.

The metabolism of proteins in the blood serum in Boer and Saanen goats was investigated during puerperium. Twenty Boer goats (10 primiparous and 10 pluriparous) and 10 Saanen goats (five primiparous and five pluriparous) between 2 and 5 years of age were used in this research. Blood for analysis was taken every fourth day from day 3 until day 40 post-partum. Blood samples were collected by jugular puncture. In the obtained blood serum, the concentration of total proteins (PT) and albumin (ALB), and the activity of enzymes aspartate aminotransferase (AST) [the Enzyme Commission number (EC number) 2. 6. 1. 1.], gamma-glutamyltransferase (GGT) (EC 2. 3. 2. 2.), creatine kinase (CK) (EC 2. 7. 3. 2.) and alkaline phosphatase (AP) (EC 3. 1. 3. 1.) were determined by spectrophotometry. These parameters were in physiological ranges in Boer goats and in Saanen goats, without significant differences according to number of kids per doe. According to the research results of the blood serum in goats during puerperium, there were no significant differences in the concentration of ALB. Boer goats had significant higher (p < 0.05) concentration of PT and enzyme activity of AP, CK and GGT. Saanen goats had only enzyme activity of AST significantly higher (p < 0.05). Enzyme activity of alkaline phosphatase was significant higher (p < 0.05) in pluriparous goats in both breeds than in primiparous. The obtained results may represent a contribution to a better understanding of protein metabolism during puerperium in dairy and meat goats and for diagnostic purposes.

It has been suggested that the time of insemination has effect on the calves' sex ratio because of the differences in timing of capacitation, motility and survival time of the X and Y spermatozoa in the female reproductive tract. We have conducted a field trial to study the effects of different semen deposition sites on the sex ratio and fertility in cattle. Two groups of 450 cows were inseminated via artificial insemination: group A was inseminated into the uterine body and group B was inseminated deep into the uterine horn ipsilateral to the ovary with dominant follicle. After applying several exclusion criteria, a total of 607 pregnant cows were considered for data analysis (group A = 318 and group B = 289 cows). The conception rate was 7% higher (p < 0.05) in the group A, with 23% more of the male calf pregnancies (p < 0.001). At the same time, 18% more of the female calves were calved in the group B (p < 0.005). The difference in male calves between the two groups was 21% and in female calves was 20% (p < 0.001). We conclude that semen deposition site plays a significant role in differences in gender ratio observed after calving. Intracornual semen deposition resulted in a higher ratio of female calves, whereas uterine body deposition site resulted in higher male calves ratio, probably contributing physiologically to the differences in motility, capacitation time, the lifespan of X vs Y spermatozoa and to the pronounced shift of X spermatozoa in the female genital tract.