BOAS PRÁTICAS NO MANEJO DE VACAS DE LEITE E SUA RELAÇÃO COM A MELHORIA DA CONTAGEM BACTERIANA TOTAL E CONTAGEM DE CÉLULAS SOMÁTICAS

O objetivo deste trabalho foi avaliar como a introdução de boas práticas pode impactar na Contagem Bacteriana Total (CBT), Contagem de Células Somáticas no tanque (CCST) e Contagem de Células Somáticas individual (CCS), em oito fazendas de leite no Sul de Minas Gerais durante o período de um ano. A CBT e CCST foram acompanhadas por meio de coletas no tanque das propriedades e a CCS de amostras dos animais e, também, foram coletadas amostras para cultura microbiológica do leite dos animais. Das 8 propriedades, 2 já trabalhavam com programa de qualidade antes do início do projeto e as outras já haviam implantado algumas boas práticas e precisavam melhorá-las, visto que duas propriedades apresentaram muitas falhas na rotina. O trabalho mostrou que, nas propriedades onde as boas práticas tinham muitas falhas, o perfil de patógenos causadores de mastite foi contagioso e, mesmo depois de implementadas várias práticas, houve uma queda na CCS, mas não suficiente para atingir os parâmetros legais. As propriedades que já haviam implementado algum tipo de boas práticas tiveram um perfil microbiológico de patógenos secundários, principalmente, as propriedades que já trabalhavam com qualidade antes do projeto. Nas cultura microbiológica, foram isolados Staphylococcus coagulase negativa (SCN) (22,74%), Streptococcus sp. (12,01%), S. agalactiae (7,39%), Enterococcus (3,14%), S. uberis (3,14%), Corynebacterium (1,66%), alga (0,55%) e coliformes (0,55%). 18,48% das amostras não cresceram. O trabalho mostrou que a CBT dessas fazendas se manteve abaixo dos níveis legais, mas a CCST oscilou, durante o ano, o que foi associado a falhas na implementação das boas práticas e sazonalidade durante o período.

The objective of this work was to evaluate how the introduction of good practices can affect Total Bacterial Count (TBC), bulk tank somatic cell count (BTSCC) and individual Somatic Cell Count (SCC) in eight dairy farms in southern Minas Gerais, Brazil, during one year. TBC and BTSCC were monitored by collections done in the tanks of the properties and the SCC of animal samples, also collecting samples for the microbiological culture of the milk. Of the eight properties, two already used a quality program before the beginning of the project, and the others had already implemented a few good practices and had the need to improve them, with two properties presenting many flaws in the routine. The work showed that in the properties in which the good practices presented many flaws, the profile of pathogens responsible for mastitis was contagious and, even after implementing many practices, there was decrease of SCC, however, not enough to influence legal parameters. The properties that had already implemented any type of good practice, presented microbiological profile of secondary pathogens, especially of properties presenting quality work before the project. In the microbiological cultures, negative Staphylococcus coagulase (NSC) (22.74%), Streptococcus sp. (12.01%), S. agalactiae (7.39%), Enterococcus (3.14%), S. uberis (3.14%), Corynebacterium (1.66%), algae (0.55%) and coliforms (0.55%) were isolated. Of the samples, 18.48% did not grow. The work showed that the TBC of these farms remained below the legal levels, however, BTSCC varied during the year, which was associated to the flaws in the implementation of the good practices and seasonality during the period.

Avaliação da sensibilidade da cultura de leite do tanque para isolamento de agentes contagiosos da mastite bovina

Samples of bulk tank milk from 33 herds were collected at the dairy processing plant and cultured, as a means of detecting specific (contagious) bovine mastitis pathogens. Somatic cell counts (SCC) were made on a Fossomatic 90. Two and three weekly consecutive samples were obtained from 13 and 12 herds, respectively. Only one sample was examined from eight herds. Three daily consecutive samples of bulk milk and individual quarter samples from all lactating cows from four herds (A, B, C and D) were also examined. Milk from individual quarters were cultured on blood agar, while tank milk samples were cultured on TKT, Mannitol Salt, MacConkey agars and Sabouraud containing chloramphenicol. Staphylococcus aureus was recovered from 26 of the 33 herds sampled in the dairy processing plant. Nine of these samples also contained Streptococcus agalactiae. Nine herds had SCC above 500,000 ml-1. The remaining 23 herds had SCC levels below 400,000 ml-1. S. aureus and S. agalactiae were isolated from five of the nine herds with high SCC, S. agalactiae from one and S. aureus from three. Six herds had SSC below 200,000 ml-1. S. aureus and S. agalactiae were isolated from one, S. aureus from three, while the other two were negative for both pathogens. The results of herds A, B, C and D sampled at the farms showed that S. aureus was isolated from 1.8%, 19.2%, 17.0% and 8.4% of the animals and 0.9%, 5.9%, 5.4% and 2.2% of the mammary quarters, respectively. S. agalactiae was isolated from herds A, C and D. Within these herds the percentages of isolation were, respectively, 1.8%, 10.6% and 8.4% for the cows and 0.46%, 3.8% and 3.7% for the mammary quarters. S. aureus was recovered from all three bulk tank cultures from herds A, B and D. Only the third sample from herd C was positive for S. aureus. S. agalactiae was recovered from all samples collected from herd D, two samples from herd C and one sample from herd A. Coliforms were isolated from all tank samples from herds A, B, C and D and from all but one sample collected in the processing plant. Yeasts were recovered from 16 herds sampled at the processing plant and from all tank samples from herds A, B, C, and D. Neither coliforms or yeasts were isolated from the individual animals of herds A, B, C and D. These findings indicate that the milk was contaminated during or after milking, probably due to deficient hygiene and cleaning procedures. The analysis of the bulk tank milk cultures showed that the test was sensitive enough to detect contagious mastitis pathogens. The sensitivity of the test increased when more than two consecutive samples were examined.

Amostras de leite total (leite do tanque) de 33 rebanhos foram coletadas na plataforma de recepção da indústria laticinista e cultivadas para detectar patógenos específicos (contagiosos) da mastite. Foi feita a contagem de células somáticas (CCS) das amostras utilizando o equipamento Fossomatic 90. Em 13 e 12 rebanhos avaliaram-se duas e três amostras semanais consecutivas, respectivamente, e em oito avaliou-se apenas uma. Foram também examinadas três amostras diárias consecutivas do leite do tanque e amostras dos quartos mamários individuais, coletadas na própria fazenda, de todas as vacas em lactação de quatro rebanhos (A, B, C e D). As amostras de leite dos quartos mamários individuais foram cultivadas em ágar sangue e as amostras do tanque, em placas de TKT, Sal Manitol, MacConkey e Sabouraud contendo cloranfenicol. Dos 33 rebanhos cujas amostras foram obtidas na plataforma de recepção da indústria, isolou-se Staphylococcus aureus de 26, nove desses em associação com Streptococcus agalactiae e em três rebanhos isolou-se somente S. agalactiae. Nove rebanhos tiveram CCS acima de 500.000 ml-1 e 21, abaixo de 400.000 ml-1. Em cinco dos nove rebanhos com CCS acima de 500.000 ml-1 foram isolados S. aureus e S. agalactiae, em três, apenas S. aureus e em um, apenas S. agalactiae. Seis rebanhos apresentaram CCS abaixo de 200.000 ml-1; de um deles foram isolados S. aureus e S. agalactiae, de três, S. aureus e os outros dois foram negativos para estes dois patógenos. Os resultados encontrados nos quatro rebanhos cujas amostras foram coletadas na própria fazenda mostraram que S. aureus foi isolado nas seguintes porcentagens dos animais: 1,8%, 19,2%, 17,0% e 8,4% e dos quartos mamários: 0,9%, 5,9%, 5,4% e 2,2%, respectivamente, para os rebanhos A, B, C e D. S. agalactiae foi isolado dos rebanhos A, C e D. Nestes três rebanhos, as porcentagens de isolamento foram, respectivamente, 1,8%, 10,6% e 8,4% para as vacas e 0,46%, 3,8% e 3,7% para os quartos mamários. S. aureus foi isolado de todas três amostras do tanque dos rebanhos A, B e D. Somente a terceira amostra do rebanho C foi positiva para S. aureus. S agalactiae foi recuperado de todas as amostras do rebanho D, duas do rebanho C e de uma do rebanho A. Todas as amostras do tanque dos rebanhos A, B, C e D apresentaram contaminação com coliformes e somente uma das amostras coletadas na plataforma de recepção da indústria foi negativa para coliformes. Leveduras foram isoladas de 16 amostras coletadas na indústria e de todas amostras do tanque dos rebanhos A, B, C e D. Não foram isolados coliformes ou leveduras dos quartos mamários dos animais destes rebanhos, sugerindo que ocorreu contaminação do leite durante ou após a ordenha, provavelmente devido a deficiências nos processos de limpeza e higienização. A análise dos resultados das culturas do leite do tanque mostrou que o exame foi específico para detectar os patógenos contagiosos da mastite. A sensibilidade do teste aumentou quando se examinaram mais de duas amostras consecutivas.

Detecção molecular de Streptococus agalactiae em amostras de leite bovino obtidas de tanques de expansão

pt

Mastitis is the most common infectious disease affecting dairy cattle and remains the most economically important disease of dairy industries around the world. Streptococcus agalactiae is a contagious pathogen that can only survives in the mammary gland, often associated to subclinical mastitis and is highly infectious. The bacteria can cause an increase of bulk tank bacterial counts (BTBC) and somatic cell counts (BTSCC). The microbiological characterization of S.agalactiae in bulk tank samples is an auxiliary method to control contagious mastitis. Therefore there are some limitations with time consuming cultures or identification methods and additional concerns about the conservation and transport of samples. Molecular identification, based on polymerase chain reactions (PCR) can identify the pathogen even when it is not viable for culturing. Bulk tank samples of 247 dairy farms were cultured in 10% bovine blood agar, followed by BTBC and S.agalactiae isolation and biochemical characterization. This gold standard method was then compared to molecular identification. The DNA extraction was taken by cell lyses with proteinase K and a phenol/chloroform protocol. The selected specie specific primers of 16S rRNA genes were used to identify S.agalactiae. Mean values of BTBC were 1,08 x 106 UFC/mL and the bacteria was identified by microbiological methods in 98 (39,6%) and by PCR in 110 (44,5%) of the samples. The results showed a sensibility of 0,8571 l 0,0353 (CI95%=0,7719 - 0,9196) and specificity of 0,8255 l 0,0311 (CI95%=0,7549 - 0,8827). The lack of significant differences of both the microbiological and molecular results (k=0,6686 l 0,0477 and CI95% = 0,5752 - 0,7620) indicated substantial agreement with the methods. This suggests that PCR of bulk tank samples can be used to detect contagious mastitis caused by S.agalactiae