WE ARE WHAT we eat, as the saying goes. We keep diligent tabs on our food consumption by studying food labels for their ingredients, nutritional values and benefits. But a component that often escapes notice is the presence of antibiotics. Antibiotics were first introduced in broiler production in the 1940s, to enhance growth and feed efficiency and to reduce the mortality rate. Later, antibiotics were used as a growth promoter in poultry feed; and although no rigorous testing had been done, this practice soon became widespread.
The growth promotion induced by antibiotics is closely related to the reduction of pathogens (bad bacteria) in the gut. Normally, antibiotics provided to healthy animals as growth promoters are at concentrations lower than 200g per ton of feed, and is done for more than 14 days. Although there is a common “wash out period” whereby farm animals are free of the drug, its traces can still be found in their meats.
Simultaneously, antibiotics stimulate resistance in bacteria, and it has been suggested that animal feed may serve as a reservoir for antibiotic-resistant bacteria that may rapidly spread across the food chain. A direct transmission of the bacteria can likewise occur during the handling of farm animals by farm workers. To illustrate, a high prevalence of antibiotic-resistant bacteria has been detected in the stool samples of healthy poultry workers at an antibiotic-exposed farm.
This undeniably alarming risk has resulted in the European Union (EU) banning antibiotic growth promoters in the poultry industry. The mandate was a success, and coupled with consumer pressure, many countries, including the US, have begun slowly phasing out its use.
But issues still persist nonetheless. In farm animals, it is found that there are increased incidences of gut-related diseases; this is due to pathogen overgrowth in the small intestine (a sign of poor gut condition), increased water content in stools, and malabsorption.
In 2015 a group of third-year undergraduates of Bioprocess Technology at Universiti Sains Malaysia embarked on a community project to assess the effects of antibiotic consumption. Farizal Hamidon, the owner of Teroka Jaya Farm in Balik Pulau, provided chicks from his farm for the experiment. These chicks were divided into three categories: i) those fed on feed containing antibiotics as growth promoters, ii) those fed on feed without growth promoters, and iii) those fed on feed with the addition of a probiotic (Lactobacillus sakei Probio65, sponsored by Probionic Corp., South Korea). After 42 days, the chickens reached the ideal slaughter weight.
Upon slaughter, analyses were carried out. Gut pathogens were noted to be higher in chickens fed on normal feed, while those fed with antibiotic growth promoters or probiotics had a lower concentration of gut pathogens.
But is not a healthier gut indicative of a longer lifespan?
The surface area of the gut is covered with minute hair-like structures arranged in a zig-zag manner. These facilitate nutrient absorption and prevent the invasion of pathogens. Upon closer evaluation, the USM team found that chickens fed with feed containing antibiotics had shorter hair-like structures. Shorter “hair” infers less surface area for nutrient absorption.
These hair-like structures are also primarily arranged to stand erect, in a neat arrangement. Interestingly, the chickens fed with antibiotic-laced feed had disorganised structures. Although having managed to grow to the slaughter weight, the chickens were growing unhealthily. The gut was unfit to sufficiently absorb nutrient for a proper growth process. This may also explain why antibiotic-fed chickens had a higher mortality rate than probiotic-fed ones: in fact, the mortality rate for the latter was lowered by 20%.
Probiotics, the “Friendly Bacteria”
The trend for the use of probiotic products first took root in Japan in the late 1980s, and soon gained enough traction to sweep the Asia Pacific, the EU and the US. The market for probiotics is a growing one, owing to in-depth studies linking together diet, nutrition and health. In 2015 that market reached $33.19bil and was expected to hit $46.55bil by 2020, indicating a compound annual growth rate of 7.0%.
Public acceptance has also increased for therapies that use probiotics instead of synthetic drugs. An increase in demand for dietary supplements also contributed to Asia Pacific and Europe dominating the market in 2014. But future projections suggest that the market will be concentrated in China, Japan and India.
Probiotics are showing promise in the poultry industry as well; with the market recording a compound annual growth rate of 7.7%. These are supplemented into animal feed for ducks, chickens and cattle, and in aquaculture, for fishes and prawns. The myriad benefits observed in commercial animals show an increase in feed conversion efficiency and egg/milk production, as well as a lowering of disease incidences and mortality rates.
Indeed, probiotics can replace antibiotics as growth promoters in farmed animals for a healthier meat supply.