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By Christophe Bostvironnois, DVM, Johanna van der Stroom, DVM, PhD, Marco Saggiorato, DVM, Elanco Animal Health, Houten, the Netherlands (vanderstroom_johanna@lilly.com)Highly scientific diagnostic research with microarrays enables us to study the heritable influence of the environment on the birds
(epigenetics). In the future this will help us to better understand, for example, the influence of feeding and eating habits of breeders on their off spring, the broilers.
(epigenetics). In the future this will help us to better understand, for example, the influence of feeding and eating habits of breeders on their off spring, the broilers.More applicable in the daily practice are DNA-based techniques to study and monitor changes in intestinal microbial profiles. And even more practical, there is now an on-farm test to analyse the level of Clostridium perfringens that appears to correlate with performance.
Intestinal bacteria and performance
For centuries, scientists have been studying bacteria. Aerobic culturing used to be the standard until the late 1950s. Cultured bacteria were considered to be the cause or at least strongly correlated with the cause of an illness. Thus, for many illnesses, especially diarrhoea, no cause was found. When anaerobic techniques for diagnosing diseases became available the number of ‘causes’ that were found more than doubled.
However, it became more realised that not every species found was causing a disease. And still, a cause was not yet found for most diarrhoea. The development of the modern DNA techniques finally permits us to better understand the bacteria in the intestines. We now know that the microbial communities of birds differ from those of mammals. The composition of these communities determines, for a large part, the effectiveness of digestion. By studying different profiles, the Finnish Alimetrics researcher Apajalahti (2007) could differentiate between profiles in birds that were able to get high metabolisable energy from the feed, i.e. low feed conversion and birds with a much higher feed conversion (Graph 1).
C. perfringens level as early indicatorOne of the microbial communities is formed by a group of Clostridia, being C. perfringens. Studies by Elwinger (Germany) indicated in 1992 that the presence of higher levels of C. perfringens was associated with reduced performance. In 2007, Apajalahti, Lee and de Lange demonstrate that during the first 7-14 days of the bird’s life, the subset of microbial communities is formed (Graph 2).
Multi factorial production diseases
Most of today’s diseases in intensive animal husbandry don’t respond to the postulates of Koch (showing a causal relationship between a causative microbe and a disease). This indicates that these diseases are not caused by one virus or bacteria, and neither is there a single-approach solution of a vaccine or antibiotic. It can be assumable that this is even more applicable for intestinal disorders. In addition to the common aspects, like housing, ventilation, litter type, vaccination schedule, stocking density and quality, quality of the day-old bird, ‘epigenetics’ might play an important role. US researcher Ferket defines epigenetics as "any heritable influence on gene activity that does not involve a change in the DNA sequence". He indicates that how we feed and manage broiler breeders as well as feed and manage broiler hatchlings, can determine the physiological response and health of the birds for the rest of their lives. Thus, this might include a change in the broiler’s natural intestinal microbial profile, the level of C. perfringens, and the resulting performance.
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