01 Nov 2022
Gastrointestinal tract microbiota develops as soon as chicks hatch and become exposed to the external environment.
Besides the environmental, chemical and biological challenges posed by
modern intensive production systems, the first feed which is offered to chicks already contains a natural microbial community. This microbial community can be colonized with pathogens during feed processing and transport.
In addition to pathogens, feed can also contain mycotoxins, heavy metals, pesticides, herbicides and other toxic contaminants.
Many of these feed contaminants have anomalous effects on the microbiota of adult birds, and these adverse effects are likely to be amplified in naïve birds.
On the other hand there is not enough literature regarding the effects of other contaminants like: radiation, chemical, industrial and toxic waste on the intestinal microbiota of birds.
The first bacteria to settle in the gut can attach to epithelial cells without competition. These are able to quickly establish themselves, grow, and modulate the intestinal environment to meet their needs.
Early bacterial colonists have the most important influence on the development of the host’s immune system and overall ability to thrive.
While gut microbial communities take around two years to mature in humans, the time period to maturity in poultry, is significantly reduced.
| Studies report that birds’ microbiota stabilizes greatly by the third day. |
The critical process of intestinal colonization in the absence of maternal microbial inoculum of birds occurs through bacteria found in the natural microbiota of food as well as bacteria from the environment, including the litter and open field.
Range of factors that influence the colonization and maturation of the microbiota. (Image created with Mindthegraph).
Microbial Contamination
Adequate biosecurity measures are critical for early post-hatching feeding. considering the fact that early access of pathogens to the virgin gut can lead to mortality, lifelong colonization and permanent elimination of pathogens.
It is unreasonable to expect animal feed raw materials to be sterile. Granulation of finished feed converts crushed feed into dense granules, which reduces dust, and food waste. However, it does not eliminate microbes from feed.
The process involves the application of steam and pressure similar to a basic sterilization process in an autoclave. However, the duration of steam treatment is much shorter (from seconds to ~4 minutes of total heating time)in order to preserve the nutrients. Temperature is also less severe (65–78 °C) with a recommended pressure of 241–276 kPa.
Therefore, the granulation process helps with disinfection yet it does not sterilize the feed material. As it contributes to reducing the microbial load of finished feed, but it does not eliminate it entirely.
Salmonella
Studies show that feed and factories are a major source of Salmonella contamination in the poultry industry.
Data regarding feeding and Salmonella in birds differs between studies and countries.
Gosling et al. summarized the literature on the widespread contamination of feed mills with Salmonella. They concluded that ingredient inlet wells were Salmonella hotspots which extended to all stages of growth, shipping, processing, storage, and finished feed.
These authors suggested the use of less toxic organic acids for the decontamination of Salmonella and E. coli instead of the widely used formaldehyde-based treatments.
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