With a population of over 164.7 million people, there was extensive economic pressure on broiler chicken (main part of poultry industry) as a vital source of animal protein for the teeming population of Bangladesh. The poultry industry in Bangladesh had 304.11 million birds and produces 44.40 lack metric tons of poultry meat annually Source BBS 2020, DLS 2020-2021. Demand for animal sourced protein for human consumption has increased day by day.

Antibiotics either natural or synthetic origins are used to both prevent proliferation and destroy bacteria. They are routinely used to treat and prevent infections both in humans and animals. However, scientific evidence suggests that the massive use of these compounds has led to increased problem of antibiotic resistance (Forgetta et al., 2012; Furtula et al., 2010), and presence of antibiotics residues in food and environment (Carvalhoand Santos, 2016; Gonzalez Ronquillo and Angeles Hernandez, 2017), compromises human and animal health (Diarra et al., 2010). This resistance was rendering antibiotics powerless against the deadly infections. It has now been recognized by the world health organizations (WHO) as one of the top health challenges for this modern era. Some of the causes are widely accepted for example, the use of antibiotics in poultry feed as growth promoters, overuse and inappropriate use of antibiotics for nonbacterial infections. 

Many of the antibiotics used to treat bacterial infections in humans also have veterinary applications. The poultry industry uses antibiotics to improve meat production through increased feed conversion, growth rate promotion and disease prevention. Antibiotics used successfully at sub-therapeutic doses in poultry production to promote growth (Chattopadhyay, 2014;  Khodambashi Emami et al., 2012; ) and protect the health of birds by modifying the immune status of broiler chickens (Lee et al., 2012). This is mainly due to the control of gastrointestinal infections and microbiota modification in the intestine ( Singh et al., 2013). The mechanism remains unclear, but antibiotics are likely to act by remodeling microbial diversity and relative abundance in the intestine to provide an optimal microbiota for growth. For example, meta-genome sequencing approaches have demonstrated that diets with salinomycin (60 ppm) has an impact on microbiome dynamics in chicken ceca (Fung et al., 2013). A change in the intestinal microbiota of chickens can influence their immunity and their health. However, changes in the intestinal microbiota of chickens can be influenced by several factors. These factors include housing conditions, exposure to pathogens, diet composition and the presence of antibiotics in feed (Lee et al., 2012).

Antibiotics abuse has resulted in drug residues in animal products (Gonzalez Ronquillo and Angeles Hernandez, 2017). Several antibiotics such as penicillin, tetracycline, macrolide, aminoglycoside and amphenicol have been detected in foods (Diarra and Malouin, 2014). Residues in livestock production can actually have adverse impact on human health; this is the case for tetracyclines, which interfere with teeth development in young children (Kummerer, 2009). China is the first country in using antibiotics in food animals with a percentage of 23%. The order of the other countries was as follows: United States (13%), Brazil (9%), India (3%) and Germany (3%) (Van Boeckel et al., 2015). In a number of countries has banned the use of certain antibiotics in livestock and poultry production. Most common used Legislation regarding the control of antibiotic residues in animals and their products that were given in European Union (EU) Council Directive 96/23/EC. The use of antibiotics in animal feed was prohibited in Bangladesh in 2010 by passing the Fish and Animal Feed Act. 2010. 

Study Area and Study Design

A survey was conducted in all 8 division of Bangladesh. At the starting of my study periods I made a Questionnaire (normal practice). There were two parts of questionnaire where 1st part was Field level survey on available use of antimicrobial drugs for broiler production in Bangladesh and 2nd part was antimicrobials used by the farmers in the current flock with some other information. 1stQuestionnaire contain name of antibiotics (list) used though water or feed or both with dose and used frequency (Disagree -, Nether disagree or Agree +, Agree ++, strongly Agree +++) and 2ndQuestionnaire contain Name of Farm, Name of Farm Owner, Address, Mobile Number, farm size, Medicine and Feed Used in the current flock (Mathers N, Fox N. and Hunn A. Surveys and Questionnaires. The NIHR RDS for the East Midlands / Yorkshire & the Humber, 2007.)

Questionnaire Preparation

At the starting of my study periods I made a Questionnaire (normal practice) form with direct consultation of 29 newly promoted upazila livestock officer at BCS Livestock Academy, Savar, Dhaka, Bangladesh who previously worked as an either veterinary surgeon or poultry production officer under the Department of Livestock Services (DLS), Bangladesh. After that I also send that questionnaire in three senior field level practitioner for making corrections and finally I got approval from my academic supervisor.

Study Participants and Sample Size

Either Upazila Livestock Officer or Veterinary surgeon and farmers were participating in the survey. There was 492 upazila livestock office in Bangladesh among that if I discard hilly and dairy zone it became 305, by using www.smartsurvey.co.uk/sample-size-calculator total sample size (no. of upazila) were171 at 95% confident level and margin of error 5%.

As total number of farm (small scale, medium scale and large scale farm) in Bangladesh was 76278 by using 95% confident level with 5% error of margin, so sample size was 382. (www.smartsurvey.co.uk/ sample-size-calculator).

Data Collection 

Data collection was performed during December, 2020 to August, 2021 by a trained Upazila Livestock Officer or Veterinary surgeon or Livestock Extension officer who had either Animal Husbandry or Veterinary science background. For getting maximum information, I send questionnaire though e-mail and discussed over telephone to 305 upazila livestock office in charge (discarding dairy and hilly zone) among 492 upazila livestock office (Either Upazila Livestock Officer or Veterinary surgeon). Field level survey on available use of antimicrobial drugs for broiler production in Bangladesh (1st part of questionnaire) was filled by Upazila Livestock Officer and/or Veterinary surgeon or Livestock Extension officer. For the 2nd part of questionnaire, Upazila Livestock Officer or Veterinary surgeon or Livestock Extension officer visited the selected farms and invited a responsible farmer (owner /manager) of the farm, to participate in the study. Written informed consent was obtained from all farmers after they agreed to participate in the study. The questionnaires were self-completed and each questionnaire took about 30min to complete. All participants in questionnaire were selected by random sampling.

Data Management and Analysis 

Excel sheet was used for data entry. Descriptive statistics were used to scrutinize characteristics of the study farms and farmers. The farms were classified into 3 categories based on the total number of chickens: small (<1,000), medium (1,000 - 2,000), and large (>2,000). The illustration of the patterns of antibiotic used in broiler production was done by using Hierarchical heat map analysis. Factor analysis on knowledge about the use and resistance of antibiotic was performed to reduce the number of variables and used for model adjustment. Multinomial logistic regression was used to examine associated factors for antibiotic use. 

208 Upazila Livestock office incharge (Upazila Livestock Officer or Veterinary surgeon) and 385 farmers from broiler farms willingly participate in the study.

Demographic Structure and Characteristics of Respondents

The Upazila Livestock office incharge (Upazila Livestock Officer or Veterinary surgeon) were both male and female, aged between 29 and 52 years and had worked in livestock services for between 2 and 22 years. Among the 208 officers 5 had PhD education, 35 had doctor in veterinary medicine (DvM) education and 168 had master in science (MS) of different department under the facultry of Animal Husbandry and/or veterinary science faculty. They also have different training on livestock and poultry production either/both in-country and abroad. The order of Upazila Livestock office in charge (participate) in bangladesh was Dhaka> Chitagong> Rajshahi> Rangpur> Khulna> Barishal> Mymensing> Sylhet.

The poultry farmers were either male or female, aged between 22 and 55 years and worked in poultry farm from 1 to 26 years. For all participants, poultry farming was the main income source with some supplementary income from seasonal crops. The majority reported a monthly income between 10,000 and 45,000 Taka (US$115 –523) from their poultry business. The flock size of the farms ranged from 500 to 5,000 birds on the day of interview. The order of broiler farmers (participates) in bangladesh was Dhaka> Khulna> Rajshahi> Chitagong> Mymensing> Rangpur> Sylhet. The Upazila Livestock office in charge (Upazila Livestock Officer or Veterinary surgeon) who interviewed as a key informant was male or female and had been working in that Upazila for 1-5 years but they served in the upazila level (in different upzila) for 2-22 years.

Farm Characteristics 

Table 2 indicates the characteristics of the study farms. Most broiler farms were small (58%) and medium sized (30%), identified as a family business with a small number of employees, and 12% were large sized. Most farmers had more than 10 years experiences in farming. All farms used commercial feeds, the majority of which were pellet feed. Most farms directly discarded their waste products into the environment without any purification. Most farmers were male, middle aged, married and completed a lower school level of education. Few had any formal training in animal husbandry. One-third of farmers families earned less than 2000 BDT per month. The order of broiler farm in bangladesh was Dhaka> Khulna> Rajshahi> Chitagong> Mymensing> Rangpur> Sylhet. The number of broiler farm in Dhaka division was 25.71% (small sized 47.47%, medium sized 39.39% and large sized 13.14%), Khulna division was 15.84%(small sized 68.85%, medium sized 24.59% and large sized 06.56%), Rajshahi division was 12.73% (small sized 69.39%, medium sized 10.20% and large sized 20.41%), Chitagong division was 11.95% (small sized 47.83%, medium sized 36.96% and large sized 15.21%), Mymensingh division was 11.43% (small sized 47.72%, medium sized 38.64% and large sized 13.64%), Rangpur division was 09.87% (small sized 57.89%, medium sized 28.95% and large sized 13.16%), Sylhet division was 04.94% (small sized 73.68%, medium sized 21.05% and large sized 05.27%) and barishal division was 07.53% (small sized 68.97%, medium sized 24.14% and large sized 06.89%).

Patterns of Antibiotic Used in Broiler Production

According to 208 Upazila Livestock office in charges opinion and their interview with farmer and veterinary medicine sales representative showed that all broiler chicken farmers used antibiotics throughout the broiler production system either though water or feed.

This study revealed that farmers habitually used antibiotics. Multiple antibiotics were applied from day 1 of the production cycle to the point of sale. At least 25 antibiotics were used in broiler chicken production in Bangladesh, not only for treatment of chick birds, but also for disease prevention and to promote growth. Most farmers use antibiotics to prevent diseases infection not according to the prophylactic or therapeutic dosage, length of treatment and withdrawal time indicated on the product label, but most of them use a higher or lower dosage and dont respect the recommendations of the drug producer. There are 25 antibiotics identified in this survey, Among those Amoxcillin, Ciprofloxacin, Colistin sulphate, oxytetracyclin, Enrofloxacin, Erythromycin, sulfa-quinoxaline are the most commonly used. 

Policy vs Reality

The national parliament of the Peoples Republic of Bangladesh passed act and rules to restrict the use of antibiotic in food animals to control antibiotic resistance over the last decades. However, there were gap between policy and reality that were shown in Table 5. The implementation of the regulations is deemed a crucial issue.

Limitations

Due to a shortage of knowledge among farmers, some farmers did not report the types of antibiotics used, which may have undervalued the antibiotic use reported in this study.

Over the years, antibiotics have played a significant role in struggling infectious diseases and stimulating poultry growth. Scientific evidence suggests that their enormous use has led to antibiotic resistance and residues in the food and environment which can generate to public health complications. This study reports the extensive use of un-prescribed antibiotics in broiler chicken production in Bangladesh. The major farm was received antibiotics (amoxicillin and ciprofloxacin) and the withdrawal period of antibiotics was not maintained. A rising global concern of antibiotic use in broiler chicken diets due to its potential adverse effects on birds and human health, food safety and the environment has led to a complete ban or restricted use in some countries. Although national regulations of Bangladesh to control antibiotic use are available, they are not well imposed. It is necessary not only to strengthen the monitoring system, veterinary network, antibiotic use guidance issues, but also to improve aware and ethics of farmers and veterinary drug sellers as well as training of diploma-veterinarians or livestock services provider (learn by training or short course), feed dealers or veterinary pharmacists and farmers especially on small and medium scale farms. 

M.A.K. designed the study. K.M.S.I.; and M.A.I. performed the methodology. S.K. carried out the data analysis. M.A.M. composed the manuscript. All the authors checked and approved the final manuscript.

I was grateful to the Governments of the Peoples Republic of Bangladesh for providing research fund and permission.

The authors certify that there is no conflict of interest.