Avaliação dos principais métodos de deteção de mastites subclínicas em caprinos de raça serrana
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2015
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A produção de leite de cabra é um sector dinâmico e tem uma importância vital
no rendimento das explorações de raça Serrana. A habitual presença de mastites
subclínicas constitui um dos problemas mais importantes em cabras de aptidão
leiteira, com impacto negativo na economia da exploração e sobre a saúde pública e
animal. A estratégia contra as mastites subclínicas requer a implementação de
programas de vigilância e controlo. Nesse sentido o diagnóstico precoce é
fundamental. Os produtores de cabras de raça Serrana beneficiarão sobretudo de
ferramentas baratas e/ou eficientes que, preferencialmente, possam ser utilizadas na
exploração. Importa por isso investigar os principais métodos de detecção de mastites
em caprinos de raça Serrana.
O objetivo deste trabalho foi avaliar e comparar a utilidade da contagem de
células somáticas (CCS) pelo método fluoro-optoelectrónico e o teste californiano de
mastites (TCM) como potenciais indicadores de mastite em caprinos de raça Serrana
sem sintomatologia clínica de infecção intramamária. Analisamos ainda a influência de
alguns fatores não-infecciosos nas CCS do leite de cabra sem infecção intramamária:
número de lactações, fase de lactação, nível de produção de leite e número de filhos
nascidos ou desmamados. Quisemos também testar as potencialidades da medição
da amilóide A do leite como bioindicador de diagnóstico de mastites subclínicas em
caprinos.
Nesse sentido esta tese foi dividida da seguinte forma:
Capítulo 1 a 9 – Revisão bibliográfica sobre mastites em caprinos: sinais
clínicos, lesões, etiologia, patogenia, epidemiologia, consequências, tratamento e
controlo. Faz-se ainda uma breve referência às características do leite de cabra e à
importância da raça Serrana no contexto nacional.!
Capítulo 10 – Estudo da relação entre contagem de células somáticas, teste
californiano de mastites e a contagem bacteriana por cultura no diagnóstico de
mastites subclínicas em caprinos de raça Serrana. Durante duas lactações após o
desmame das crias, com periodicidade semanal, fez-se a colheita de forma asséptica
de leite de metades mamárias de cabras sem sintomatologia clínica de mastite
(n=2233). Cada amostra, foi submetida a cultura bacteriana (PCA), ao TCM e à
contagem de células somáticas pelo método fluoro-optoelectrónico. Consideraram-se
com presumível infecção intramamária (IIM) as amostras com 5 ou mais colónias
idênticas (≥ 500 UFC/ml). Observou-se uma prevalência aparente de 23,5% de
mastites subclínicas (n=2233). As IIM aumentaram com o nº de lactações. Verificou-se
uma associação entre CCS e a cultura bacteriana (p< 0,001). A pontuação “zero” do TCM esteve associada à ausência de infecção e as restantes pontuações à presença
de IIM (p< 0,05). As correlações encontradas entre a cultura bacteriana e os métodos
indiretos foram muito baixas, devido à provável influência de factores não infecciosos.
O TCM e o CCS tiveram uma correlação razoável (r= 0,4) e existem diferenças
significativas entre as médias de CCS em todos os grupos de TCM (p< 0,05). Sugere-se que as pontuações TCM ≥1 sejam consideradas positivas.
Capítulo 11 – Estudo das potencialidades da utilização das contagens de
células somáticas na monitorização de mastites subclínicas em cabras de raça
Serrana. Este trabalho teve dois objectivos: (i) determinar a influência de fatores
infecciosos e não infeciosos (nº de lactações, fase da lactação, nível de produção e nº
de crias) nas CCS; e (ii) propor um limiar fisiológico de contagem de células somáticas
(CCS) em caprinos da raça Serrana.! Em metades mamárias livres de infecção
(n=1708) as CCS aumentaram com o nº de lactações (p<0,05). As CCS sofreram um
pequeno decréscimo ao longo da lactação, que foi simultâneo ao pequeno aumento da
produção durante esse período. Cabras com ≥ 3 crias nascidas ou desmamadas
apresentam maiores CCS ao longo da lactação. O efeito da interação entre fatores (nº lactações xf ase lactação; nº lactações x nº crias desmamadas) também teve efeito das CCS. Propõe-se um limiar fisiológico de 1254 x 103 células/ml para as CCS
individuais na raça Serrana, que deve ser interpretado em função da fase de lactação
e do nº de lactações (primíparas/multíparas).
Capítulo 12 - Utilização da Amilóide A do leite no diagnóstico das mastites
subclínicas em caprinos.! Foram realizadas colheitas de leite (n=288) de forma
asséptica às metades mamárias de 12 cabras a meio da lactação, durante 6 semanas
consecutivas nos anos de 2010 e 2011. Foram definidos quatro grupos de metades
mamárias segundo os resultados microbiológicos e as CCS: com mastites subclínicas,
saudáveis, com mastites latentes e inespecíficas. O grupo das metades mamárias
saudáveis apresentou a média geométrica mais baixa (6,17±1,11 μg/ml). Valores mais
elevados, e significativamente diferentes, observaram-se nas mastites subclínicas
(11,52±1,13 μg/ml) e nas inespecíficas (14,34±1,08 μg/ml). A média das latentes
(8,46±1,25 μg/ml) é diferente das inespecíficas mas não tem diferenças significativas
relativamente às saudáveis nem às subclínicas (p<0,05).! Os dados sugerem que a
quantidade de MAA em caprinos está dependente de fatores infeciosos e não
infeciosos. Assim, a sua utilização como indicador de infeção intramamária está
dependente da compreensão da importância relativa de cada um desses fatores.
Goat milk production is a dynamic industry and a substantial part of farm income to Serrana breed producers. Subclinical mastitis is common and one of the most important diseases in dairy goat production with negative impact on animal and human health. Moreover is responsible for high economic losses. The fight against subclinical mastitis requires the implementation of surveillance and control programs. Several methods to diagnose subclinical mastitis are available but Serrana goat farmers would mainly benefit from cheap and efficient diagnostic methods, as well as from diagnostic tolls that can be used at the farm level. The aim of the research presented in this thesis was to evaluate and compare the value of somatic cell count (SCC) measured by fluoro-opto-electronic method and California Mastitis Test (CMT) as possible markers for intramammary infection in Serrana goats without clinical symptoms of mastitis. Furthermore we investigated the importance of some non-infectious factors that can modify SCC values in goat milk without intramammary infection: parity, stage of lactation, production level and number of kids born or weaned. Additionally, we studied the potential value of measuring milk amyloid A as a diagnostic marker for the detection of subclinical mastitis in goats. With this purpose, three studies were carried out as described below: Chapter 1 to 9 - A review of the scientific literature concerning mastitis in dairy goats: clinical signs, lesions, aetiology, pathogenesis, epidemiology, consequences, treatment, disease control, characterization of the goat milk and Serrana breed. Chapter 10 - A study of relationship between somatic cell count, California mastitis test and bacterial counts in the diagnosis of subclinical mastitis in Serrana goats. Udder half milk samples were collected weekly after weaning of kids during two consecutive lactations (n=2233). Only clinically healthy animals were included in the study. Milk samples were analysed for SCC, CMT and for bacterial growth in plate count agar (PCA). Intramammary infection (IMI), defined as grow of udder pathogens was found in 23.5% of the milk samples. The IIM increased with parity. SCC are associated with bacterial grow (p<0.001). CMT = 0 was associated with freedom of IMI while other CMT scores was associated with IMI. The correlations between bacterial grow and the indirect methods (SCC and CMT) were very low likely due the influence of non-infectious factors. The CMT and SCC have a reasonable correlation (r = 0.40) and there are significant differences between the geometric means of SCC in all CMT groups (p <0.05). It is suggested that the CMT ≥1 scores are considered positive. Chapter 11 - A survey of how to perform somatic cell count as a monitoring tool of subclinical mastitis in Serrana goats. This study had mainly two objectives: (i) determine the influence of infectious and non-infectious factors (parity, stage of lactation, production level and number of kids born or weaned) in the SCC; and (ii) propose a physiological threshold of SCC in Serrana goats. In udder half milk samples without bacterial growth (n = 1708) SCC increased with parity (p <0.05). The SCC experienced a slight decrease during lactation while individual production of milk had a small increase during the same period (p <0.05). Goats with ≥ 3 kids born or weaned have higher SCC throughout lactation (p <0.05). The interaction between factors (parity x stage of lactation; parity x number of kids weaned) also affects SCC. We propose a physiological threshold of 1254 x 103 cells / ml for individual SCC in Serrana goats, which must be interpreted according to lactation stage and parity (primiparous / multiparous). Chapter 12 – We investigated the potential value of use milk Amyloid A (MAA) in the diagnosis of subclinical mastitis in goats. Udder half milk samples (n=288) from twelve clinically healthy dairy goats were collected on six consecutive weeks in mid lactation during 2010 and 2011. Four udder-halves groups were categorised based on the single udder-half heath status and the analysis of SCC of its milk sample: subclinical mastitis status (SM), uncertain subclinical mastitis (UM), latent subclinical mastitis (latent) and healthy udder-half (HU). The HU group had the lowest geometric mean of MAA concentration (6.17 ± 1.11 μg/ml). Higher values (p<0,05) have been observed in SM group (11.52 ± 1.13 μg/ml) and UM group (14.34 ± 1.08 μg/ml). The latent group (8.46 ± 1.25 μg/ml) is different from UM group (p<0.05). However we observed a lack of significant differences among latent and HU or SM groups (p <0.05). The data suggest that the concentration of MAA in goats depends of infectious and non-infectious factors. The influence of these factors should be taken into account in the establishment of reliable diagnostic MAA thresholds for IMI.
Goat milk production is a dynamic industry and a substantial part of farm income to Serrana breed producers. Subclinical mastitis is common and one of the most important diseases in dairy goat production with negative impact on animal and human health. Moreover is responsible for high economic losses. The fight against subclinical mastitis requires the implementation of surveillance and control programs. Several methods to diagnose subclinical mastitis are available but Serrana goat farmers would mainly benefit from cheap and efficient diagnostic methods, as well as from diagnostic tolls that can be used at the farm level. The aim of the research presented in this thesis was to evaluate and compare the value of somatic cell count (SCC) measured by fluoro-opto-electronic method and California Mastitis Test (CMT) as possible markers for intramammary infection in Serrana goats without clinical symptoms of mastitis. Furthermore we investigated the importance of some non-infectious factors that can modify SCC values in goat milk without intramammary infection: parity, stage of lactation, production level and number of kids born or weaned. Additionally, we studied the potential value of measuring milk amyloid A as a diagnostic marker for the detection of subclinical mastitis in goats. With this purpose, three studies were carried out as described below: Chapter 1 to 9 - A review of the scientific literature concerning mastitis in dairy goats: clinical signs, lesions, aetiology, pathogenesis, epidemiology, consequences, treatment, disease control, characterization of the goat milk and Serrana breed. Chapter 10 - A study of relationship between somatic cell count, California mastitis test and bacterial counts in the diagnosis of subclinical mastitis in Serrana goats. Udder half milk samples were collected weekly after weaning of kids during two consecutive lactations (n=2233). Only clinically healthy animals were included in the study. Milk samples were analysed for SCC, CMT and for bacterial growth in plate count agar (PCA). Intramammary infection (IMI), defined as grow of udder pathogens was found in 23.5% of the milk samples. The IIM increased with parity. SCC are associated with bacterial grow (p<0.001). CMT = 0 was associated with freedom of IMI while other CMT scores was associated with IMI. The correlations between bacterial grow and the indirect methods (SCC and CMT) were very low likely due the influence of non-infectious factors. The CMT and SCC have a reasonable correlation (r = 0.40) and there are significant differences between the geometric means of SCC in all CMT groups (p <0.05). It is suggested that the CMT ≥1 scores are considered positive. Chapter 11 - A survey of how to perform somatic cell count as a monitoring tool of subclinical mastitis in Serrana goats. This study had mainly two objectives: (i) determine the influence of infectious and non-infectious factors (parity, stage of lactation, production level and number of kids born or weaned) in the SCC; and (ii) propose a physiological threshold of SCC in Serrana goats. In udder half milk samples without bacterial growth (n = 1708) SCC increased with parity (p <0.05). The SCC experienced a slight decrease during lactation while individual production of milk had a small increase during the same period (p <0.05). Goats with ≥ 3 kids born or weaned have higher SCC throughout lactation (p <0.05). The interaction between factors (parity x stage of lactation; parity x number of kids weaned) also affects SCC. We propose a physiological threshold of 1254 x 103 cells / ml for individual SCC in Serrana goats, which must be interpreted according to lactation stage and parity (primiparous / multiparous). Chapter 12 – We investigated the potential value of use milk Amyloid A (MAA) in the diagnosis of subclinical mastitis in goats. Udder half milk samples (n=288) from twelve clinically healthy dairy goats were collected on six consecutive weeks in mid lactation during 2010 and 2011. Four udder-halves groups were categorised based on the single udder-half heath status and the analysis of SCC of its milk sample: subclinical mastitis status (SM), uncertain subclinical mastitis (UM), latent subclinical mastitis (latent) and healthy udder-half (HU). The HU group had the lowest geometric mean of MAA concentration (6.17 ± 1.11 μg/ml). Higher values (p<0,05) have been observed in SM group (11.52 ± 1.13 μg/ml) and UM group (14.34 ± 1.08 μg/ml). The latent group (8.46 ± 1.25 μg/ml) is different from UM group (p<0.05). However we observed a lack of significant differences among latent and HU or SM groups (p <0.05). The data suggest that the concentration of MAA in goats depends of infectious and non-infectious factors. The influence of these factors should be taken into account in the establishment of reliable diagnostic MAA thresholds for IMI.
Descrição
Tese de Doutoramento em Ciências Veterinárias
Ramo: Sanidade Animal
Palavras-chave
Mastite , Infecções assintomáticas , Contagem de células somáticas , Bactéria , Cultura de células , Caprino , Raça serrana , Teste californiano de mastites , Amilóide A do leite