The poultry industry is a significant contributor to Philippine agricultural production. Given the rising concerns about antibiotic resistance and food security, farmers need to maximize profit and output while ensuring safe and ecologically sustainable farming practices.

Through a systematic review of the literature, we report that antibiotic growth promotion has positive effects on broiler body weight and feed conversion ratio. However, results also show that unregulated antibiotic use is associated with an increased prevalence of resistance to medically important antimicrobials. Thus, it is essential to understand the mechanisms involved in antibiotic growth promotion in order to find sustainable alternatives for the broiler industry.

Laboratory results show that antibiotic treatment can increase adiposity through the activation of chronic low grade inflammation in broilers. Slight differences in gut microbiomes may explain the observed changes in antibiotic-treated broilers. By reporting the non-therapeutic effects of a local antibiotic treatment protocol, future comparisons with alternative growth promoters may encourage their use in lieu of antibiotics. In line with the increasing concern about antibiotic resistance, survey results show that local broiler poultry farms still widely use medically important antimicrobials for growth promotion. Experimental results show that the use of a local antibiotic treatment protocol can lead to the emergence of antibiotic resistance genes in broiler fecal samples. Furthermore, antibiotic treatment protocols directly influence the antibiotic resistance profiles of broiler fecal samples in local poultry farms.  Using microbial evolution experiments, antibiotic withdrawal was demonstrated to be an effective strategy for mitigating resistant bacteria. 

In summary, this dissertation showed the impacts of antibiotics on the emergence of antimicrobial resistance. It also elucidated underlying cellular and molecular processes that may help design strategies to mitigate the adverse effects of current poultry farming practices.

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*In collaboration with Dr. Ernesto Martin, College of Agriculture, Central Luzon State University, and Dr. Michael Nicdao, Pampanga State Agricultural University