DAIRY

Author: MONTERO ALONSO ANA.
Year: 2004.
University: POLITÉCNICA DE VALENCIA [www.upv.es].
Place of defense: INGENIEROS AGRONOMOS.
Place of preparation: ESCUELA TECNICA SUPERIOR DE INGENIEROS AGRONOMOS.

Summary: The presence of residues of antimicrobial substances in milk may cause problems should the standpoint of public health (allergies, digestive disorders, drug resistance, etc.) in addition to being the cause of interference in fermentation processes d ela dairy industry. Faced with the possible unreliability of the methods for detecting inhibitors in the milk of sheep, the small number of works carried out in this species and disadvantages that lead to the presence of substances inhibidoreas, both consumers and for technological processes, to address the need for a study on a specific method of screening pair detecting inhibitors (Eclipse  ® 100 ov), and the application of a technique multirresiduo System (Microbiological Multiplaca) for the preliminary identification of antimicrobial residue in milk sheep. The method Eclipse ®, is a technique for microbiological agar diffusion, which are spores of Bacillus stearothermophillus var calidolactis c953, with an acid-base indicator. The milk is placed in pocilos of microplate and after incubation is the interprestación the result. In the event that milk does not contain residues inhibitors, lead to the development of micro and aparerá a change in the coloration of the acid-base indicator in the middle, and blue will start to yellow. If there inhibitors not be revealed changing color. The SMMP is a microbiological method that detects a selectively from the presence of residues of different groups of antimicrobials in the milk. The sample is analyzed through different plates. B. Stearothermophilus var. Calidolactis C953 (beta-lactams), B.subtilis BGA to Ph 8.0 (aminogucósidos), M. Luteus ATCC 9341 (macrolides), E. Coli ATCC 11303 (quinolones), B. Cereus ATCC 11778 (tetracycline) and B. Subtilis BGA, pH 7.0 (sulfonamide). The presence of antimicrobial residue was manifista by aparación a zone of inhibition of microbial growth. The experiments have been performed on 27 antimicrobial belonging to the gurpos of beta-lactams, aminoglycosides, macrolides, queinolinas, tetracyclines and sulfanamidad. To carry out these tests were used sheep's milk samples from healthy animals not treated with medications and presenting a proper hygienic - sanitary chemical composition and quality. The parameters have been assessed, the two methods have been specificity, either through the study of selectivadad, which indicates the presence of false positive results and in the case of SMMP also included a study dela specificity crusade to analyze the influence of antimicrobial studied in the various boards not for its determination. On the other hand have been calculated in both methods and detection limits compared with the Maximum Residue Limits (MRLs) set by European legislation. As regards the method Eclipse ® 100ov, l should be noted that no case had positive results in false positives. The relationship is selectivity for the method Eclipse ® 100ov throughout the experiment proved to be very high in 0.99 in the case of samples without conse 8 rvante and 905 of 0.91 for those containing azidiol, indicating interference it . The detection limits obtained by the technique Eclipse 100ov have proved near the MRLs established by the EU, with those of; 5 penicillin G, 7 ug / kg amoxicillin, 68 ug / kg cloxaciclina, 28 ug / kg oxacillin, 115 ug / kg cephalexin, 110 ug / kg cefoperazone, 170 ug / kg sufadimetxona and 250 ug / kg sulfatizaol. But for the rest of substances tested depart greatly from their respective MRL. As for the SMMP in the milk of sheep, the regression equations, which relacinan concentration and extent of the zone of inhibition of microbial growth presented in all cases high regression coefficients (0,9719-0995). This marks a great linearity in the response and the possibility of establishing a diameter or level decision at concentrations close to the MRLs. The diameters of the zone of inhibition considered decision levels for different groups of antimicrobials were 20 mm for beta-lactams, aminoglucóssidos, macrolides, tetracyclines and sulfonamides, and 22 mm in the case of quinolones. The especificdad of SMMP was evaluated through the selectivity that turned out very high 98-100% and the especificad crusade. The study of the latter were seen significant interference in the case of the plate for the determination of beta lactam antibiotics for the group delos aminoglucósdiod and macrolides, highlighting especially tilisina, for all concentrations of some antibiotics. De un modo general, se puede concluir que los métodos estudiados son válidos, en especial para el análisis de betalactámicos y sulfonamidas, por lo que podrían ser utilizados en el análisis de cribado, así como en la confirmación de identificación de residuos de antibióticos en la sheep's milk.

Author: GUTIERREZ CARRERA SUSANA.
Year: 2005.
University: SANTIAGO DE COMPOSTELA [www.usc.es].
Place of defense: FACULTAD DE VETERINARIA DE LUGO.
Place of preparation: FACULTAD DE VETERINARIA DE LUGO.

Summary: Issues related to the gene frequencies in the grouping Holstein-Frisian of Cantabria, its impact on production traits during the first lactation and the ability cheese either as a pilot in the development of Cantabria PDO cheese, with the ultimate goal of establishing a base solid for selecting cattle whose milk will allocate to the production of cheese. The frequencies of different alleles found are within the limits of frequency reported in cattle Holstein-Frisian European and American, with the most common alleles associated with the largest production of milk and fat. Specifically, they have found the most frequent genotype AB of K-casina and AA of the B-lactoglobulina. The effect of genetic variation on the features productive first lactation is masked by the effect stables. The study by haplotypes of casein was observed that the differences in milk production, fat and protein are primarily a result of the genotypes of k-caseína featuring animals AB of the largest productions. With regard to the effects on the properties of coagulation measures through Formagraph, the results indicate that the alleles B to K-caseína and B-caseína are associated with better times and speeds clotting. As for the process of cheese making, best fitness of milk carrying the BB genotype of the k-caseina followed by the phenotype AB and finally the AA, with higher yields and lower cheese coagulation times and beaten grain . From the results we can recommend a strategy for selecting cattle based on the genotypes of proteins, provided that milk is intended for the manufacture of cheese. It is proposed to give priority to the selection for the allele B to k-casína, because due to the effect of the ligament between this allele and B to B-caseína any work of selection for the allele B, and k - casína implies a selection for the same allele in the system B-caseína.