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In raw milk production, mastitis represents one of the most im portant diseases and a major cause of economic loss in the dairy industry. During the last decades, antimicrobial drugs have been used daily on dairy farms. Monitoring of antimicrobial drug residues (ADR) in raw milk is required by Food Safety Law in Repub lic of Serbia. The presence of ADR in milk is undesirable from several aspects. From the human health point of view, allergic reactions, even anaphylaxis or sensitization to the drug, are possible. Also, the microbiome of milk consumers, exposed to low con centrations of the drug, can develop resistance to that drug, which later can be transferred to other, related microorganisms. In the dairy production, ADR in raw milk could delay or inhibit fermentation and curdling, due to the effect of ADR on the starte r culture. According to the current regulations, the trade of raw milk containing ADR above the permitted, prescribed limit is forbidden. However, ADR are occasionally found in raw milk. In accordance with perspective approach to ensure food safety and the longitudinal integrated safety assurance (LISA), it is necessary to monitor ADR in raw milk. In this research, the most common causes of ADR in raw milk were examined. Data were collected from the laboratories of the Faculty of Agriculture in Novi Sad and the Scientific Veterinary Institute "Novi Sad", as well as from dairy farms and dairy facilities which cooperate with those laboratories. In the dairies, when buying raw milk from farms, raw milk must be examined for ADR. Also, according to Good Manufactu ring Practice, in some dairies participating in this research, the yogurt test is used to select raw milk for the production of fermented milk products. In most cases, when the presence of inhibitory substances in raw milk was proved, ADR were found. It is known, that excretion of antimicrobials depends on drug amount and application method, chemical characteristics of drug, physiological statu

This study aimed to investigate whether diet and different goat production systems affect the quality of milk, white-brined cheese and whey. It also aimed to determine the suitability of goat’s milk for the production of white-brined cheese. The physicochemical composition and hygienic quality of raw goat’s milk were studied, as well as the fatty acid profile and nutritional indices of milk and white-brined cheese. Traditional white-brined cheeses were produced from bulk goat milk from two farms in three samples. The results confirmed that different husbandry systems and diets influence the physicochemical composition of goat milk and cheese and their fatty acid profile. Milk and cheese from grazing goats contained significantly more (p<0.05) fat, protein, total solids and a higher percentage of cheese yield. Nutritional indices were also more favourable, with a lower atherogenic (AI) and thrombogenic (TI) index and a higher health-promoting index (HHP) and hypocholesterolemic/hypercholesterolemic ratio (HH). Goat grazing contributed to a higher content of n-3 fatty acids in milk and cheese and thus to a lower n-6/n-3 ratio. Cheese-making efficiency and protein recovery in the curd (%REC) was better with pasture milk, whereas fat recovery was better with milk from housed goats. Consumers rated the unripened white cheeses from both production systems the highest. In addition, the production of white cheese with brine results in good quality whey with significant health benefits. Natural pasture provides significantly more benefits to goats than confinement, especially in the early stages of use. This contributes to the high nutritional value of goat’s milk, cheese and whey.

The purpose of this study was to examine possible relationship between milk urea and fertility of dairy cows using field data. This study also evaluated the influence of environmental factors on milk urea (MU) and the relationship between MU and daily milk yield, milk fat and protein percentage. The data were collected at 11 dairy farms in the Vojvodina region. Reproductive data and MU measurements were obtained from cows that calved between June 2013 and October 2015 and had a successful conception after calving. Statistical data processing was carried out by applying General Linear Model procedure, Statistics 13. Parity, calving season, season of milk control and farm were included in the models as fixed effects. Significant differences in MU concentrations were observed between farms (P lt 0.01), seasons (P lt 0.01) and parity (P lt 0.05). Highly significant (P lt 0.01) positive relationships were found between MU concentration and milk yield, fat and protein percentage and days open. Cows with MU levels below 10 mg dL(-1) had the lowest day open interval (135.59 days) and cows with MU higher than 35 mg dL(-1) had the longest days open interval (163.18 days). The cows with the lowest mean MU values ( lt 10 mg dL(-1)), had the shortest days open interval (72.62 days), but cows with mean MU values between 20.01-25.00 mg dL(-1) had the longest days open interval (161.78 days). Results of this study indicate that increased MU levels appear to have a negative effect on dairy cow fertility.

Urea kao deo neproteinske frakcije azota mleka, predstavlja krajnji produkt metabolizma proteina u predželucima preživara. Portalnim krvotokom toksični amonijak, nastao mikrobiološkom razgradnjom proteina u rumenu dolazi do jetre gde se transformiše u ureu, koja kasnije krvotokom dospeva u mleko. Ishrana, odnosno sadržaj sirovih proteina u obroku ima najveći uticaj na sadržaj uree u mleku. Sadržaj uree sve više se koristi kao parametar pomoću kojeg je moguće pratiti unos sirovih proteina i energije obrokom kod mlečnih krava. Pored ishrane na sadržaj uree u mleku utiču i drugi faktori, kao što su sezona, prinos mleka, stadijum laktacije, paritet i dr. Plodnost krava je veoma važna osobina mlečnih goveda na koju utiče veliki broj faktora. Dosadašnja istraživanja u ovoj oblasti ukazuju na moguću vezu između plodnosti krava i sadržaja uree u mleku. Određivanje sadržaja uree u mleku primenom infracrvene spektrofotometrije u analizi mleka prilikom redovne mesečne kontrole mlečnosti krava pružilo je nove mogućnosti u praćenju kvaliteta mleka. Cilj ovog istraživanja bio je da se utvrdi: 1. variranje sadržaja uree u mleku unutar stada, 2. uticaj paragenetskih faktora (farma, sistem proizvodnje, sistem držanja, sezona, redni broj laktacije i stadijum laktacije) na sadržaj uree u mleku, 3. korelacija sadržaja uree sa parametrima mlečnosti krava i brojem somatskih ćelija i 4. korelacija između sadržaja uree u mleku i dužine servis perioda. U okviru ovog istraživanja analizirano je 46.315 uzoraka mleka, u okviru redovne kontrole mlečnosti, sa 11 farmi sa područija Vojvodine. Od kojih je jedna sa organskom, a 10 farmi sa konvencionalnom proizvodnjom. Određivanje sadržaja uree u mleku vršeno je na aparatu MilcoScan. Prosečan sadržaj uree u mleku (25,18 mg/dl) bio je u okviru optimalnih vrednosti sadržaja uree u mleku. Koeficijent varijacije za sadržaj uree (34,15%) bio je znatno veći od koeficijenta varijacije za ostale sastojke mleka. Dobijeni rezultati u okviru ove doktorske dis, Urea as a part of non-protein fraction of nitrogen in milk represents the final product of protein metabolism in the rumen of ruminants. By portal bloodstream toxic ammonia comes into liver where it is transformed into urea, which comes later into milk by bloodstream. Nutrition and contents of crude proteins in the diet have the greatest influence on the milk urea content. The content of milk urea has been increasingly used as a parameter by which it is possible to monitor balance of energy and crude proteins in the feed of dairy cows. Apart from feeding, milk urea content can be influenced by some other factors as season, milk yield, stage of lactation, parity etc. A great number of factors influence cow’s fertility. Previous research in this field has indicated a possible relationship between the fertility of cows and urea content in milk. Determination of urea content in milk, by infrared spectrophotometric, on monthly bases, for milk recording porpoises, offers new opportunities for milk quality monitor. The aim of this study was to determine: 1. Variations of milk urea content within the herd, 2. The influence of paragenetic factors (a farm, production and housing system, season, parity and stage of lactation) on the milk urea content, 3. The correlation with milk urea content and parameters of milk yield as well as the somatic cells count, 4. The correlation between the milk urea content and the length of open days. This research includes 46,315 samples of milk which were analysed as regular milk recording samples from 11 farms in Vojvodina. There are 10 farms with conventional and only one farm with organic production. Determination of the milk urea contents was carried out by MilkoScan FT+. In the analyzed milk samples the average milk urea content (25.18 mg / dl) was within the optimum values. The coefficient of variation for the milk urea content (34.15%) was significantly higher than the coefficient of variation for the other ingredients in milk. The obta

Possible differences between composition of raw milk due to dairy farming system (organic vs conventional) as well as seasonal variations were investigated. The samples were analysed during one year. A total of 6.782 samples of raw milk were collected (4.496 from organic farming). Dairy farms were located in the northern part of Republic of Serbia (Province of Vojvodina). The principle of analysis of raw milk samples was in accordance with the methodology by midinfrared spectrometry and flow cytometry. The fixed effect of system of farming and season (winter, spring, summer and fall) have shown a high statistical significance (P lt 0.01) on all examined milk parameters except fat, total solids and somatic cell count, where the impact was slightly lower (P lt 0.05). Significant difference wasn't found in number of bacterial colonies (P > 0.05). Composition of milk is also affected by a number of other factors, therefore it is recommended to involve factors such as nutrition of dairy cows, breed and farm management., Cilj rada je bio da se ispitaju razlike između sirovog mleka dobijenog u različitim sezonama i sistemima proizvodnje (organska/ konvencionalna). Uzorci mleka su sakupljani u toku čitave godine. Ukupno je sakupljeno 6782 (od čega 4496 iz organske proizvodnje). Farme su bile locirane na severnom delu Srbije (AP Vojvodina). Sirovi uzorci mleka su analizirani u skladu sa metodologijom infracrvene spektometrije i protočne citometrije. Fiksni uticaji sistema proizvodnje i sezone (zima, proleće, leto i jesen) su pokazali visoku signifikantnu značajnost (P lt 0,01) na sve ispitivane parametre mleka osim na mlečnu mast, ukupnu suvu materiju i ukupan broj somatskih ćelija, gde je uticaj bio signifikantan na nivou (P lt 0,05). Statistički značajna razlika nije pronađena u ukupnom broju bakterija (kolonija) (P > 0,05). Na sastav mleka takođe utiče i veliki broj drugih faktora, stoga je za preporuku da se u ispitivanje uključe i faktori poput ishrane mlečnih krava, rase i farmskog menadžmenta.