A similar study was conducted in Urban district, Zanzibar (Sungura, 2010). In that study, a total of 55 smallholder broiler chicken farmers were interviewed in 15 wards in Urban district. The majority of the respondents (80 percent) reported diagnosing and treating chickens themselves with minimal help from veterinary drug sellers. Chicken antimicrobials were dispensed over the counter from agro vet shops without prescription. All the farmers interviewed reported using antibiotics to treat or prevent diseases in their birds. The most commonly used antibiotics were oxytetracycline (used by 100 percent of farmers), sulphonamides (used by 82 percent) and penicillins (used by 50percent). Less common were flumequine (used by 38 percent), piperazine citrate (used by 32 percent), tylosin (used by 23 percent) and neomycin (used by 10 percent). Up to 66 percent of the respondents were aware of drug withdrawal period; however, only 45.5 percent of them complied. Laboratory analysis of antibiotic residues in 70 broiler chicken meat samples showed that 76.4 percent of the meat samples contained antimicrobial residues. Nonga and colleagues (H E Nonga et al., 2010) also studied antibiotic use and residues in commercial layer chicken eggs. The study involved 20 farmers selected randomly from different locations in Morogoro municipality. The study established that up to 65 percent of the farmers reported treating their chickens themselves after getting advice from drug sellers. The most commonly used antibiotics were sulphonamides (used by 100 percent of farmers) and tetracycline (used by 75 percent). Others were chloramphenicol (used by 10 percent) and flumequine (used by 10 percent). All the respondents reported that they did not observe withdrawal periods while selling eggs because they were afraid of economic losses. A total of 70 egg samples randomly selected from the 20 farms were analyzed for antibiotic residues and all were positive for antimicrobial residues. A recent study by Mubito of chicken eggs in Dar es Salaam had similar results as in Morogoro. A questionnaire was administered to 100 commercial chicken farmers and pharmaceutical outlets to obtain information on antibiotic usage, awareness of withdrawal periods and public health concerns. The most frequently used antibiotics were tetracycline (32.2 percent) and sulfonamides (20.8 percent). Others were fluoroquinolones (9.8 percent), macrolides (9.4 percent), polypeptides (8.0 percent), amprolium (6.5 percent), aminoglycosides (6.4 percent), trimethoprim (5.5 percent), furazolidone (0.8 percent) and quinoxalines (0.4 percent). All the famers reported not observing withdrawal periods, for fears of capital loss (Mubito, Shahada, Kimanya, & Buza, 2014a). Ninety-six eggs were analyzed for sulfadiazine and sulfamethazine residues. All the eggs contained sulfadiazine at level ranging from 22 to 230 ng/g (mean, 94.3 ng/g) and 59.4 percent of samples contained sulfamethazine residues ranging up to 94 ng/g (mean, 28.8 ng/g) (Mubito, Shahada, Kimanya, & Buza, 2014b). Cattle Karimuribo and colleagues (2005) studied antibiotic use by 60 dairy farmers in Morogoro municipality. Antibiotics accounted for 54.2 percent of the veterinary drugs they used in cattle. The most commonly used antibiotics were penicillin-streptomycin (used by 84 percent of farmers), oxytetracycline (used by 60 percent) and gentamicin (used by 12 percent). Of 59 milk samples tested for antibiotic residues, a small percentage (1.7 percent) was positive. The study concluded that readily available antibiotics over the counter in agro veterinary shops without any restrictions contributed to the widespread use. A 2006 study examined the presence of antibiotic residues in unpasteurized milk. The study examined 986 milk samples in Dar es Salaam and Mwanza, and detected residues in 36 percent of samples (L. R Kurwijila, Omore, Staal, & Mdoe, 2006). Screening for antibiotic residues in milk was also done in Njombe and Mvomero districts (R. H. Mdegela et al., 2009). A total of 69 smallholder dairy farms with lactating cows participated in the study and involved 91 dairy cattle. Antimicrobial residues were found in 4.5 percent of samples. A study of oxytetracycline residues in milk in Dar es Salaam city involved a total of 100 samples (40 from packed milk in shops, 30 from milk centers and 30 from farmers) (Kaale, Chambuso, & Kitwala, 2008). Oxytetracycline was found in just two samples from the farmers (6.7 percent) at <100 mg/ml. All samples from local milk centers and milk industries (packed) tested negative.
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