Assessment of brucella abortus and antimicrobial residues in raw Cattle Milk In Bukombe District, Tanzania
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Date
2017
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Sokoine University of Agriculture
Abstract
A cross sectional study was carried out in January 2017 with the aim of estimating the
seroprevalence of Brucella circulating antibodies, detection of Brucella abortus in raw
cattle milk, assess the risk factors for infection and establish the presence and levels of
antimicrobial residues in raw milk in Bukombe district, Tanzania. A total of 221 blood
samples from purposively selected lactating cows in 17 villages were collected and
analysed for Brucella circulating antibodies using Rose Bengal Plate Test and c-ELISA.
Also 221 raw milk samples were collected from the same cows and analysed for
antimicrobial residues using Delvo SP® test and subsequently, Tetracyclines
(Chlortetracycline, Tetracycline and Oxytetracycline) were analysed and quantified in 10
Delvo test positive milk samples using HPLC. Milk samples of seropositive animals (n=3)
were analyzed by PCR to detect bcsp31gene of B. abortus using B4/B5 primer sets. The
overall animal seroprevalence of brucellosis was 1.4% (n=219) and herd seroprevalence
was 3.8% (n=52). One milk sample was confirmed to contain bcsp31gene of B. abortus.
The proportion of antimicrobial residue contaminations in milk was 11.6%. Tetracyclines
were confirmed and quantified in 9/10 of selected Delvo positive raw milk samples.
Tetracyclines concentration was 6.1±5.8 ug/l with the mean concentrations of
oxytetracycline and tetracycline being 7.7±5.3 ug/l and 9.6 ±16.9 ug/l respectively which
were all below the recommended MRL of 100 µg/l. Interestingly, 70% of the quantified
samples had oxytetracycline and only 40% had tetracycline. It is concluded that Bovine
brucellosis is present in Bukombe district albeit at low prevalence (1.4%). Also detection
of antimicrobial residues in raw milk samples (11%) may pose risk to consumers
especially children who frequently drink milk. It is recommended that veterinarians in
cooperation with other stakeholders and farmers to observe good livestock practices.
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MSC DISSERTATION
Keywords
Brucella abortus, Antimicrobial residues, Bukombe District, Tanzania, Brucella Saroprevalence, Raw cattle milk