Microbial System for Identification of Antibiotic Residues in Milk

[EN] The aim of this study was to evaluate the ResScreen (R) microbiological system for the identification of antibiotic residues in milk. This microbiological system consists of two methods, the BT (betalactams and tetracyclines) and BS (betalactams and sulfamides) bioassays, containing spores of G. stearothermophilus subsp. calidolactis, culture media and indicators (acid-base and redox). The detection limits of 29 antimicrobial agents were calculated using a logistic regression model. Both methods detect residues of penicillin-G, ampicillin, amoxicillin, cloxacillin, oxacillin, cephalexin, cefoperazone and ceftiofur (R) at levels close to their Maximum Residue Limits (MRL). The BT bioassay also presents good sensitivity to tetracycline and oxytetracycline residues, whereas the BS bioassay detects sulfadiazine, sulfamethoxazole and sulfathiazole residues in milk. The simultaneous use of both bioassays identifies betalactam, tetracycline and sulfamide residues in milk. Neomycin, tylosin and lincomycin residues can also be detected, but these molecules arc positive with the BT and BS bioassays, e.g., betalactams, given the microorganisms' sensitivity to these molecules.This research work has been carried out as part of the CAI+D'09/11 Project (No. 033-173 Res.C.D. No. 100/09) and supported by financial assistance from the Universidad Nacional del Litoral (Santa Fe, Republica Argentina).Nagel, OG.; Molina Pons, MP.; Althaus, RL. (2011). Microbial System for Identification of Antibiotic Residues in Milk. Journal of Food and Drug Analysis. 19(3):369-375. http://hdl.handle.net/10251/80981S36937519

Characteristics of ripened Tronchon cheese from raw goat milk containing legally admissible amounts of antibiotics

[EN] The aim of this study was to evaluate the transfer of the most widely used antibiotics in dairy goats from milk to cheese as well as their effect on the cheese-making process and cheese characteristics during ripening. Antibiotic-free milk was spiked individually with 7 veterinary drugs (amoxicillin, benzylpenicillin, cloxacillin, erythromycin, ciprofloxacin, enrofloxacin, and oxytetracycline) at an equivalent concentration of the European Union maximum residue limit. Spiked goat milk was used to make mature Tronchon cheeses, which were analyzed at 0, 30, and 60 d of maturation to determine pH, chemical composition, proteolytic and lipolytic activities, and color and textural properties. A sensory evaluation of 60-d ripened cheeses was carried out. Cheeses from raw antibiotic-free goat milk were made simultaneously to be used as reference. The cheese-making process was unaffected by the presence of most antibiotics evaluated. Only erythromycin and oxytetracycline significantly increased the time required for cheese production (122 +/- 29 and 108 +/- 25 min, respectively). However, variable amounts of antibiotics, ranging from 7.4 to 68%, were transferred from milk to cheese, with oxytetracycline and quinolones showing the highest retention rates. In general, antibiotic residues present in the cheeses at the beginning of maturation decrease significantly along time. Thus, beta-lactams and erythromycin residues were not detectable after 30 d of ripening. However, relatively high concentrations of enrofloxacin (148 +/- 12 mu g/kg) and ciprofloxacin (253 +/- 24 mu g/kg) residues were found in the cheeses after 60 d of maturation. The quality characteristics of the Tronchon cheeses were only slightly affected by such substances, with few significant differences in the free fatty acid concentration and color and textural properties of the cheeses. Results herein indicate that the use of goat milk containing antibiotics, such as quinolones, at the European Union maximum residue limit for cheese production could adversely affect the safety of the final products because relatively high concentrations of these substances could be retained in soft and semi-mature cheeses, making it necessary to assess the risk for consumer health. Studies on the partition of the antibiotic substances during cheese-making, using specific technologies, would be convenient to guarantee the safety of cheese and related products.This work is part of the AGL-2013-45147-R Project funded by Ministerio de Ciencia e Innovación (Madrid, Spain). P. Quintanilla thanks Universitat Politècnica de València (Valencia, Spain) for the grant received for the development of this work (PAID-2014, UPV).Quintanilla-Vázquez, PG.; Beltrán Martínez, MC.; Molina Casanova, A.; Escriche Roberto, MI.; Molina Pons, MP. (2019). Characteristics of ripened Tronchon cheese from raw goat milk containing legally admissible amounts of antibiotics. Journal of Dairy Science. 102(4):2941-2953. https://doi.org/10.3168/jds.2018-15532S29412953102

Enrofloxacin Treatment on dairy goats: Presence of antibiotic in milk and impact of residue on technological process and characteristics of mature cheese

[EN] Lately quinolones, particularly enrofloxacin, have been incorporated as a veterinary treatment of small ruminants, like goats, whose milk is highly appreciated for the manufacture of traditional cheeses. This study aims to evaluate the influence of the presence of enrofloxacin in milk (from goats previously treated with this antibiotic), on the characteristics (chemical composition; colour, texture, volatile profile and sensory evaluation) of mature cheese at 0, 30 and 60 days. Three batches of cheeses were made from milk obtained at three different times with respect to the animals¿ antibiotic administration (24 h before treatment, 24 h after treatment, and after the withdrawal period). The manufacture process of cheese is not affected by enrofloxacin in any way; therefore, it will remain unnoticed in the production line. A transfer of enrofloxacin, and its metabolite ciprofloxacin, to the cheese produced with milk obtained 24 h after treatment was observed. The presence of antibiotic residues does not produce significant changes in any of its compositional, texture and colour characteristics, when compared to the cheeses made before veterinary treatment with antibiotic-free milk, with the only exception of some compounds of the volatile fraction. Enrofloxacin and its metabolite show high stability during the cheese maturation (51% of both remain after 60 days of ripening). In general, the presence of this antibiotic has lesser effects on all the characteristics of the cheese compared to those modifications produced during the maturation time. Sensory measures of odour, colour, appearance and texture attributes, as well as the global preference, are also not affected by this antibiotic, which would imply a risk for the population since its presence would go undetected.This work is part of the AGL-2013-45147-R Project funded by Ministerio de Ciencia e Innovación (Madrid. Spain). P. Quintanilla thanks Universitat Politècnica de València for the grant received for the development of this work (PAID-2014, UPV).Quintanilla-Vázquez, PG.; Beltrán Martínez, MC.; Escriche Roberto, MI.; Molina Pons, MP. (2021). Enrofloxacin Treatment on dairy goats: Presence of antibiotic in milk and impact of residue on technological process and characteristics of mature cheese. Food Control. 123:1-9. https://doi.org/10.1016/j.foodcont.2020.1077621912

Interference of non-specific detergents in microbial inhibitor test results for screening antibiotics in goat s milk

[EN] Cleaning and disinfection of dairy equipment is essential to ensure the hygienic quality of milk. Occasionally, some farmers use washing-up liquids and disinfectants for home use, especially when cleaning procedures are carried out manually. Residues of detergents and disinfectants in milk may interfere with the response of microbial inhibitor tests used for screening antibiotics in milk. Therefore, the aim of this study was to evaluate the interference of non-specific detergents in screening tests (BRT MRL; Delvotest SP-NT MCS; Eclipse 100) for goat s milk. Twelve replicates of eight concentrations of five washing-up liquids (0 1%) and one disinfectant (0 1%) were analysed. The results showed that the presence of washing-up liquids at concentrations of ≥1 ml/l leads to positive results in microbial tests. In particular, the product containing sodium laureth sulphate and ethanol produced the largest number of positive outcomes. The presence of disinfectant based on sodium hypochlorite did not affect the test response. The detection capabilities of microbial inhibitor tests for penicillins were also studied in milk with and without cleaning products, calculating the dose response curve with eight concentrations of amoxicillin, ampicillin, benzylpenicillin and cloxacillin, respectively. The detection limits of the screening tests for penicillins were not modified substantially by the cleaning product based on sodium laureth sulphate and ethanol. Residues of cleaning agents in milk can be avoided when specific detergents and disinfectants for milking equipment are used and good cleaning practices are applied.This work forms part of the Project AGL 2009-11524 financed by the Ministry of Science and Innovation (Madrid, Spain).Romero Rueda, T.; Beltrán Martínez, MC.; Althaus, RL.; Molina Pons, MP. (2016). Interference of non-specific detergents in microbial inhibitor test results for screening antibiotics in goat s milk. Journal of Applied Animal Research. 45(1):159-163. https://doi.org/10.1080/09712119.2015.1129341S159163451Beltrán, M. C., Berruga, M. I., Molina, A., Althaus, R. L., & Molina, M. P. (2015). Performance of current microbial tests for screening antibiotics in sheep and goat milk. International Dairy Journal, 41, 13-15. doi:10.1016/j.idairyj.2014.09.007Carlsson, Å., Björck, L., & Persson, K. (1989). Lactoferrin and Lysozyme in Milk During Acute Mastitis and Their Inhibitory Effect in Delvotest P. Journal of Dairy Science, 72(12), 3166-3175. doi:10.3168/jds.s0022-0302(89)79475-3Dubeuf, J.-P., de A. Ruiz Morales, F., & Castel Genis, J. M. (2010). Initiatives and projects to promote the Mediterranean local cheeses and their relations to the development of livestock systems and activities. Small Ruminant Research, 93(2-3), 67-75. doi:10.1016/j.smallrumres.2010.03.001LÓOPEZ, M. B., JORDÁN, M. J., GRANADOS, M. V., FERNÁNDEZ, J. C., CASTILLO, M., & LAENCINA, J. (1999). Viscosity changes during rennet coagulation of Murciano-Granadina goat milk. International Journal of Dairy Technology, 52(3), 102-106. doi:10.1111/j.1471-0307.1999.tb02081.xMERIN, U., ROSENTHAL, I., BERNSTEIN, S., & POPEL, G. (1985). The effect of residues of detergents and detergents-sanitizers on the performance of antibiotic test and the organoleptic quality of milk. Le Lait, 65(649-650), 163-167. doi:10.1051/lait:1985649-65011Oh, D.-H., & Marshall, D. L. (1993). Antimicrobial activity of ethanol, glycerol monolaurate or lactic acid against Listeria monocytogenes. International Journal of Food Microbiology, 20(4), 239-246. doi:10.1016/0168-1605(93)90168-gPontefract, R. D. (1991). Bacterial Adherence: Its Consequences in Food Processing. Canadian Institute of Food Science and Technology Journal, 24(3-4), 113-117. doi:10.1016/s0315-5463(91)70033-3Romero, T., Beltrán, M. C., Althaus, R. L., & Molina, M. P. (2014). Detection of antibiotics in goat’s milk: effect of detergents on the response of microbial inhibitor tests. Journal of Dairy Research, 81(3), 372-377. doi:10.1017/s0022029914000259Romero, T., Beltrán, M. C., Pérez-Baena, I., Rodríguez, M., & Molina, M. P. (2014). Effect of the presence of colostrum on microbial screening methods for antibiotic detection in goats’ milk. Small Ruminant Research, 121(2-3), 376-381. doi:10.1016/j.smallrumres.2014.07.007ROMERO, T., BELTRÁN, M. C., REYBROECK, W., & MOLINA, M. P. (2015). Effect In Vitro of Antiparasitic Drugs on Microbial Inhibitor Test Responses for Screening Antibiotic Residues in Goat’s Milk. Journal of Food Protection, 78(9), 1756-1759. doi:10.4315/0362-028x.jfp-15-020Sierra, D., Sánchez, A., Contreras, A., Luengo, C., Corrales, J. C., Morales, C. T., … Gonzalo, C. (2009). Detection limits of four antimicrobial residue screening tests for β-lactams in goat’s milk. Journal of Dairy Science, 92(8), 3585-3591. doi:10.3168/jds.2008-1981Valladao, M., & Sandine, W. E. (1994). Quaternary Ammonium Compounds in Milk: Detection by Reverse-Phase High Performance Liquid Chromatography and Their Effect on Starter Growth. Journal of Dairy Science, 77(6), 1509-1514. doi:10.3168/jds.s0022-0302(94)77090-9Zeng, S. S., Escobar, E. N., & Brown-Crowder, I. (1996). Evaluation of screening tests for detection of antibiotic residues in goat milk. Small Ruminant Research, 21(2), 155-160. doi:10.1016/0921-4488(95)00822-

Antimicrobial activity in cheese whey as an indicator of antibiotic drug transfer from goat milk

[EN] Raw goat milk spiked with antibiotics was coagulated with rennet, the whey separated and the transfer of 18 antibiotics from the milk to the whey was evaluated by estimating antimicrobial activity of the whey using microbial inhibitor tests. Antibiotic-free whey (negative whey) spiked with different antibiotics was used as a reference. The antimicrobial activity in whey from milk spiked with most b-lactam drugs was lower (0e40%) than that of the reference whey, suggesting that these antibiotics are mostly released from curd and transferred to the whey. However, for most non-b-lactam drugs, an 84e100% reduction in the relative antimicrobial activity in whey was obtained, indicating the higher susceptibility for retention in curd. The traceability of antibiotics through the cheese-making process will make it possible to determine whether control systems are required to prevent the negative implications of the presence of antibiotic drug residues in cheese and whey products.This work is part of the AGL-2013-45147-R funded by the Ministry of Science and Innovation (Madrid. Spain). The authors are grateful to Zeulab, S. L. (Zaragoza, Spain) for their support.Giraldo-Gómez, J.; Althaus, RL.; Beltrán Martínez, MC.; Molina Pons, MP. (2017). Antimicrobial activity in cheese whey as an indicator of antibiotic drug transfer from goat milk. International Dairy Journal. 69:40-44. https://doi.org/10.1016/j.idairyj.2017.02.003S40446

Effect of the inclusion of lemon leaves and rice straw by-products in the diet of dairy goats on the quality characteristics of milk and matured cheeses

[EN] The effect of the dietary inclusion of lemon leaves and rice straw by-products on the quality characteristics of goats' milk and cheese was evaluated. Twenty-six Murciano-Granadina goats were used in a crossover design experiment; milk from each experimental group was collected to produce 60-days matured cheeses. Fat and dry matter content was higher in milk and cheeses from the diet containing by-products; medium-chain fatty acids and total free fatty acids were lower. Triangle tests revealed significant differences in the organoleptic characteristics of the cheeses between diets. However, when sensory attributes differentiating cheeses were evaluated individually, differences did not become significant. The inclusion of lemon leaves and rice straw in balanced diets with soya oil could be beneficial, as it does not appear to adversely affect the quality of milk and related mature cheeses, contributing to the reduction of the cost of the diet and the recycling of agricultural by-products. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).This study was supported by LIFE Project (ref. LIFE2016/CCM/ES/000088 LOW CARBON FEED) , funded by the EU Commission (Brusels, Belgium) .Huanca, N.; Beltrán Martínez, MC.; Fernández Martínez, CJ.; Molina Pons, MP. (2021). Effect of the inclusion of lemon leaves and rice straw by-products in the diet of dairy goats on the quality characteristics of milk and matured cheeses. International Dairy Journal. 120:1-4. https://doi.org/10.1016/j.idairyj.2021.1050821412

Detection of antibiotics in goats' milk: Comparison of different commercial microbial inhibitor tests developed for the testing of cows' milk

[EN] Nine microbial inhibitor tests validated for cows' milk (BR-AS Special, CMT-Copan Milk Test, Delvotest SP-NT, Delvotest T, Brilliant Black Reduction Test MRL, Charm Blue Yellow II, Charm CowSide II, Eclipse 100, Eclipse 3G) were applied to milk samples from 200 different individual goats. Interpretation of the results was based on visual and instrumental reading. Samples initially testing positive were retested and also tested after a milk pre-treatment (heat treatment, fat removal or fat removal followed by heat treatment). With instrumental reading, most microbial tests commonly used for bovine milk were suitable for goats' milk (specificity 95%), except for BR-AS Special, Charm Blue Yellow II and Delvotest SP-NT. However, visual reading of the results decreased the specificity, with 95% specificity only for CMT-Copan Milk Test, Eclipse 3G and Delvotest T. Fat removal followed by heat treatment proved the most appropriate milk treatment to reduce false positive results for almost all tests.This work forms part of the grant EEBB-I-13-06255 financed by the Ministry of Science and Innovation (Madrid, Spain). The authors are grateful to Analytik in MilchProduktions-und Vertriebs-GmbH, Charm Sciences Inc., DSM Food Specialties, ZEULAB S.L. for their technological support. The authors thank MCC-Vlaanderen and Comite du Lait for the assistance with milk quality and composition analysis and appreciate the cooperation of the commercial dairy goat farms: J. VanWaes (Zaffelare, BE), 't Eikenhof (Lokeren, BE) and 't Leenhof (Zele, BE).Romero Rueda, T.; Van Weyenberg, S.; Molina Pons, MP.; Reybroeck, W. (2016). Detection of antibiotics in goats' milk: Comparison of different commercial microbial inhibitor tests developed for the testing of cows' milk. International Dairy Journal. 62:39-42. https://doi.org/10.1016/j.idairyj.2016.07.004S39426

Microbiological method using Bacillus megaterium with fusidic acid for detection of macrolides in milk

[EN] The microbiological method to attain a sensitive detection of macrolides using Bacillus megaterium in agar medium with fusidic acid was designed. To this aim, Mueller-Hinton medium fortified with glucose at pH 8.0, a combination of redox indicators (brilliant black and toluidine blue) and different concentrations of fusidic acid were tested. The addition of fusidic acid in the culture medium improves the sensitivity of this bacteria test and decreases the detection limits of bioassay. The addition of 200 μg/l of fusidic acid detects 35 μg/l of erythromycin, 58 μg/l of tylosin, and 57 μg/l of tilmicosin in milk. This microbiological bioassay could be used as an alternative method of commercial screening test for detecting macrolides in milk, in order to maintain food safety.Partly supported by the Universidad Nacional del Litoral, Santa Fe, Argentina, CAI+D-11 Projects PI 501 201101 00575 LI, H.C.D. Resol 205/13, and Agencia Nacional de Promocion Cientifica y Tecnologica, PICT 2011-368 Res. No. 140/12.Tumini, M.; Nagel, OG.; Molina Pons, MP.; Althaus, RL. (2016). Microbiological method using Bacillus megaterium with fusidic acid for detection of macrolides in milk. Czech Journal of Food Sciences. 34(1):9-15. https://doi.org/10.17221/307/2015-CJFSS91534

Effect of subclinical mastitis on the yield and cheese-making properties of ewe's milk

[EN] This review covers an update of scientific knowledge about productive and technological consequences of subclinical mastitis in sheep milk. The literature reports individual milk yield losses of 2.6-43.1 %, being modulated by several factors as infection severity, production level, causal agents, and unilateral or bilateral IMI (1 or 2 infected glands, respectively). A compensatory increase of milk production from the uninfected gland when only one half was infected has been quantified in 6.6 %, compared with healthy halves of control sheep. This compensatory adaptation highlights the risk of underestimating subclinical mastitis in sheep. The mammary gland response is quick and milk yield losses in absolute terms remained constant within the following weeks, both when infection appear during lactation and when it is present from lambing. With respect to the changes on main components in milk due to subclinical mastitis it has been clearly established a decrease in the concentration of lactose and an increase of that of whey proteins. The role played by lactose as an osmotic regulator results in a more accentuated decrease of its concentration in milk. This is why lactose is considered at present as a reliable potential indicator of subclinical mastitis. Whey proteins increase as a result of the increase of the blood-milk barrier permeability and the increased proteolysis of caseins. However, the content in milk of fat and casein are modified depending on the magnitude of milk yield reduction, being affected by a concentration or dilution effect. In any case, the ratio casein to protein (parameter independent of the milk volume) decreases as a result of infection. The impairment of physical and chemical characteristics due to decreased udder health status is the responsible of the negative effect of increased SCC on the coagulation properties of milk, the curd yield and the quality of cheese. Low ratio of casein to protein in high bulk tank SCC milk enhances the extension of the rennet coagulation time (RCT) and curd firming time (k20) because there are more serum proteins and the stability of casein micelles are reduced as a result of hydrolysis. Those changes in turn led to poor syneresis, lower cheese yield, increased moisture content and lower fat and protein content in cheese. Finally, there is a favourable relationship between lactose and milk technological properties because the decrease of this component in case of mastitis is associated with an increase of milk pH. Thus, the three parameters, SCC, pH, and lactose affect, contemporarily and independently, milk quality and coagulation properties, and this is why have been highlighted as potential indicators traits for improving cheese-making ability of sheep milk.This review is based on knowledge gained during work financially supported by means of a research fellowship from the regional government of Valencia ("Generalitat Valenciana").Martí-De Olives, A.; Peris Ribera, CJ.; Molina Pons, MP. (2020). Effect of subclinical mastitis on the yield and cheese-making properties of ewe's milk. Small Ruminant Research. 184:1-7. https://doi.org/10.1016/j.smallrumres.2019.106044S17184Albenzio, M., Marino, R., Caroprese, M., Santillo, A., Annicchiarico, G., & Sevi, A. (2004). Quality of milk and of Canestrato Pugliese cheese from ewes exposed to different ventilation regimens. Journal of Dairy Research, 71(4), 434-443. doi:10.1017/s0022029904000330Albenzio, M., Caroprese, M., Santillo, A., Marino, R., Muscio, A., & Sevi, A. (2005). Proteolytic patterns and plasmin activity in ewes’ milk as affected by somatic cell count and stage of lactation. Journal of Dairy Research, 72(1), 86-92. doi:10.1017/s0022029904000676Albenzio, M., Santillo, A., Caroprese, M., d’ Angelo, F., Marino, R., & Sevi, A. (2009). Role of endogenous enzymes in proteolysis of sheep milk. Journal of Dairy Science, 92(1), 79-86. doi:10.3168/jds.2008-1439Albenzio, M., & Santillo, A. (2011). Biochemical characteristics of ewe and goat milk: Effect on the quality of dairy products. Small Ruminant Research, 101(1-3), 33-40. doi:10.1016/j.smallrumres.2011.09.023Albenzio, M., Figliola, L., Caroprese, M., Marino, R., Sevi, A., & Santillo, A. (2019). Somatic cell count in sheep milk. Small Ruminant Research, 176, 24-30. doi:10.1016/j.smallrumres.2019.05.013Auldist, M. J., Coats, S., Sutherland, B. J., Mayes, J. J., McDowell, G. H., & Rogers, G. L. (1996). Effects of somatic cell count and stage of lactation on raw milk composition and the yield and quality of Cheddar cheese. Journal of Dairy Research, 63(2), 269-280. doi:10.1017/s0022029900031769Balcones, E., Olano, A., & Calvo, M. M. (1996). Factors Affecting the Rennet Clotting Properties of Ewe’s Milk. Journal of Agricultural and Food Chemistry, 44(8), 1993-1996. doi:10.1021/jf960138uBastian, E. D., & Brown, R. J. (1996). Plasmin in milk and dairy products: an update. International Dairy Journal, 6(5), 435-457. doi:10.1016/0958-6946(95)00021-6Bianchi, L., Bolla, A., Budelli, E., Caroli, A., Casoli, C., Pauselli, M., & Duranti, E. (2004). Effect of Udder Health Status and Lactation Phase on the Characteristics of Sardinian Ewe Milk. Journal of Dairy Science, 87(8), 2401-2408. doi:10.3168/jds.s0022-0302(04)73362-7Burriel, A. R. (1997). Dynamics of intramammary infection in the sheep caused by coagulase-negative staphylococci and its influence on udder tissue and milk composition. Veterinary Record, 140(16), 419-423. doi:10.1136/vr.140.16.419Burriel, A. R., & Wagstaff, A. (1998). The influence of ewe intramammary infection caused by coagulase-negative staphylococci on the milk constituents total protein, albumin, potassium and sodium. Animal Science, 67(3), 499-502. doi:10.1017/s1357729800032926Caballero-Villalobos, J., Garzón, A. I., Martínez Marín, A. L., Arias, R., Ciocia, F., & McSweeney, P. L. H. (2018). Plasmin activity in Manchega ewe milk: The effect of lactation, parity and health of the udder, and its influence on milk composition and rennet coagulation. Small Ruminant Research, 158, 57-61. doi:10.1016/j.smallrumres.2017.10.005Considine, T., Healy, Á., Kelly, A. L., & McSweeney, P. L. H. (2004). Hydrolysis of bovine caseins by cathepsin B, a cysteine proteinase indigenous to milk. International Dairy Journal, 14(2), 117-124. doi:10.1016/s0958-6946(03)00171-7Dhondt, G., Burvenich, C., & Peeters, G. (1977). Mammary blood flow during experimental Escherichia coli endotoxin induced mastitis in goats and cows. Journal of Dairy Research, 44(3), 433-440. doi:10.1017/s0022029900020392European Union 1994 Council Directive 94/71/EEC of 13 December 1994 amending Directive 92/46/EEC laying down the health rules for the production and placing on the market of raw milk, heat-treated milk and milk-based products. Official Journal of European Community L368 33–37.Fthenakis, G. C., & T.Jones, J. E. (1990). The effect of inoculation of coagulase-negative Staphylococci into the ovine mammary gland. Journal of Comparative Pathology, 102(2), 211-219. doi:10.1016/s0021-9975(08)80126-0Giadinis, N. D., Arsenos, G., Tsakos, P., Psychas, V., Dovas, C. I., Papadopoulos, E., … Fthenakis, G. C. (2012). «Milk-drop syndrome of ewes»: Investigation of the causes in dairy sheep in Greece. Small Ruminant Research, 106(1), 33-35. doi:10.1016/j.smallrumres.2012.04.018González-RodríGuez, M. C., Gonzalo, C., San Primitivo, F., & Cármenes, P. (1995). Relationship Between Somatic Cell Count and lntramammary Infection of the Half Udder in Dairy Ewes. Journal of Dairy Science, 78(12), 2753-2759. doi:10.3168/jds.s0022-0302(95)76906-5Gonzalo, C., Carriedo, J. A., Baro, J. A., & San Primitivo, F. (1994). Factors Influencing Variation of Test Day Milk Yield, Somatic Cell Count, Fat, and Protein in Dairy Sheep. Journal of Dairy Science, 77(6), 1537-1542. doi:10.3168/jds.s0022-0302(94)77094-6Gonzalo, C., Ariznabarreta, A., Carriedo, J. A., & San Primitivo, F. (2002). Mammary Pathogens and Their Relationship to Somatic Cell Count and Milk Yield Losses in Dairy Ewes. Journal of Dairy Science, 85(6), 1460-1467. doi:10.3168/jds.s0022-0302(02)74214-8Gonzalo, C., Tardáguila, J. A., De La Fuente, L. F., & San Primitivo, F. (2004). Effects of selective and complete dry therapy on prevalence of intramammary infection and on milk yield in the subsequent lactation in dairy ewes. Journal of Dairy Research, 71(1), 33-38. doi:10.1017/s0022029903006526Grufferty, M. B., & Fox, P. F. (1988). Milk alkaline proteinase. Journal of Dairy Research, 55(4), 609-630. doi:10.1017/s0022029900033409Hernández-Ramos, P. A., Vivar-Quintana, A. M., & Revilla, I. (2019). Estimation of somatic cell count levels of hard cheeses using physicochemical composition and artificial neural networks. Journal of Dairy Science, 102(2), 1014-1024. doi:10.3168/jds.2018-14787Klei, L., Yun, J., Sapru, A., Lynch, J., Barbano, D., Sears, P., & Galton, D. (1998). Effects of Milk Somatic Cell Count on Cottage Cheese Yield and Quality. Journal of Dairy Science, 81(5), 1205-1213. doi:10.3168/jds.s0022-0302(98)75680-2Le Roux, Y., Colin, O., & Laurent, F. (1995). Proteolysis in Samples of Quarter Milk with Varying Somatic Cell Counts. 1. Comparison of Some Indicators of Endogenous Proteolysis in Milk. Journal of Dairy Science, 78(6), 1289-1297. doi:10.3168/jds.s0022-0302(95)76749-2Leitner, G., Chaffer, M., Caraso, Y., Ezra, E., Kababea, D., Winkler, M., … Saran, A. (2003). Udder infection and milk somatic cell count, NAGase activity and milk composition—fat, protein and lactose—in Israeli-Assaf and Awassi sheep. Small Ruminant Research, 49(2), 157-164. doi:10.1016/s0921-4488(03)00079-8Leitner, G., Chaffer, M., Shamay, A., Shapiro, F., Merin, U., Ezra, E., … Silanikove, N. (2004). Changes in Milk Composition as Affected by Subclinical Mastitis in Sheep. Journal of Dairy Science, 87(1), 46-52. doi:10.3168/jds.s0022-0302(04)73140-9Leitner, G., Silanikove, N., & Merin, U. (2008). Estimate of milk and curd yield loss of sheep and goats with intrammamary infection and its relation to somatic cell count. Small Ruminant Research, 74(1-3), 221-225. doi:10.1016/j.smallrumres.2007.02.009Leitner, G., Merin, U., & Silanikove, N. 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Control and prevention of antibiotic residues and contaminants in sheep and goat s milk

[EN] The use of veterinary drugs to treat mastitis and other pathologies in dairy sheep and goats is a usualpractice in current production systems. The risk of antibiotic residues in milk on farms is high if goodfarming practices are not applied, in this sense control measures must be implemented to prevent drugresidues from entering the food chain. Moreover there are other compounds that may contaminate milkvia the environment, water or animal feed, such as mycotoxins that are one of the most harmful contam-inants given their negative effects on consumer health. This work presents the problems that arise whenresidues and contaminants are present in sheep and goat s milk. It also addresses the causes and theconsequences of their presence, and the main measures of prevention and control required to guaranteemilk that is safe for consumers and of high quality for the dairy industry.Berruga Fernandez, MI.; Molina Casanova, AM.; Althaus, RL.; Molina Pons, MP. (2016). Control and prevention of antibiotic residues and contaminants in sheep and goat s milk. Small Ruminant Research. 142:38-43. https://doi.org/10.1016/j.smallrumres.2016.02.023S384314