Exploring Alternatives to Antibiotics

The pressure on the livestock industry to reduce the use of antimicrobials for enhancing growth and production performance purposes is continually growing due to the concerns over drug resistance and drug residues. The era of feeding animals with antibiotics at low levels may be coming to an end. Surveys of drug use on Ontario pig farms have revealed that almost all pigs are fed antibiotics during the immediate post-weaning period. Therefore, alternatives to antibiotics must be available before the ban arrives.

Some of the research areas focused on:

- Genetic selection for disease resistance; genetic modification so that animals produce antimicrobial factors; immune stimulation via vaccination.

- Diet modification that encourages beneficial bacteria and discourages pathogens; addition of beneficial bacteria or immunoglobulins to the diet to provide passive immunity; dietary supplementation of organic acids such as lactic acid, fumaric acid and formic acid.

Summary of the Results from the Trials Completed

E.coli. vaccines, egg-yolk antibody product and a herb extract were investigated in the studies. Results from the trials showed that neither the vaccine nor the egg-yolk product were effective alternatives to antibiotics in controlling E. coli. diarrhea (Table 1 and Table 2). Interestingly, the herb extract containing cinnamon, thyme, and oregano improved growth performance of newly-weaned piglets (Table 3).

The value of dietary supplementation of different organic acids as an alternative to the use of antibiotics in the diets of early-weaned pigs was also investigated at Guelph. Various diets were evaluated: a control diet (containing lincomycin 44 at 1 kg/tonne of feed), a negative control without antibiotics, and rations with either lactic acid, fumaric acid or formic acid included at 0.2%. There were no differences between treatment groups with regards to visceral organ growth, feed conversion efficiency, white blood cell counts, and diarrhea scores.

Table 1. Results of K88 (F4) E. coli vaccination with killed autogenous and a live attenuated vaccine in a herd with endemic post-weaning diarrhea

Table 2. The incidence of mortality and diarrhea in weaned pigs receiving either a control diet or a diet containing egg-yolk antibodies

Table 3. Growth performance of newly-weaned piglets receiving herbal extract (n=162)