PARTNER FEATURE ▶▶▶
Early experience, gene expression and lifelong consequences
Extensive studies of early post-hatch feeding demonstrates its substantial impact on lifetime performance in commercial broilers. Excellent nutrition in this phase is shown to enhance growth rates and increase the proportion of breast muscle up to market age. But what are the mechanisms behind this improvement and, more importantly, how can we take advantage of them?
BY MARK KARIMI, AB-NEO T
he chicken has 39 chromosomes containing 20,000- 23,000 protein coding genes which serve to make up the specific characteristics of that animal. Unfor- tunately, not every gene behaves as it was designed
to and environmental and nutritional experiences can leave a chemical signature which determines whether and how the genes are expressed. This collection of chemical markers is known as the ‘epigenome’.
Epigenetics The epigenome can be affected by positive and negative ex- periences (correct temperature or fluctuations; good/poor hy- giene; quality feed/anti-nutritional factors, etc.) which leave a unique ‘signature’ on the genes. This signature can tempo- rarily or permanently affect how easily genes are switched on or off and epigenetic modification typically occurs in cells that form part of organ systems, consequently influencing their development and function. Changes to the epigenome in early life, when specialised organs such as the gut, heart or lungs are developing, therefore, can have a significant impact on lifetime health and performance. For commercial units this means we can help birds to perform better by giving them a positive early experience in their growing environment. Such a concept could also be used to help birds overcome other complex problems. However, the faster growth, feed efficiency and improved meat quality that
20 ▶ POULTRY WORLD | No. 2, 2022
make the industry successful today have not been without a price. Scientists have discovered that production traits may be closely linked with immune traits, meaning that growth, feed efficiency and meat quality may also be associated with compromised health or a challenge to the broiler’s immune system. Compromising the animal’s immune system at any stage may lead to increases in metabolic disorders, reduced resistance to infection and higher mortality.
Balance The broiler’s intestine is complex and its health is crucial in maximising performance. Gut health is about the balance be- tween diet, proper digestion/absorption, stable and benefi- cial microbiota and the effective immune status of the gut. Nutrients provide energy to organs and tissues but also sup- ply crucial substances for the production of tight junction proteins, mucins, chemokines and cytokines – all essential components of the bird’s immune system. Cytokines are a group of soluble proteic or peptidic mediators produced by an animal’s cells to modify the behaviour of other cells and thus play a key role in immune and inflammatory processes. Scientists highlight two types of inflammation: pathological (classical) and physiological. The industry is familiar with gut pathological inflammation and its consequences (low feed in- take, weight loss, low feed efficiency and uniformity, etc.) but physiological inflammation is widely underestimated. Even under homeostatic conditions, the gut is continually exposed to a multitude of exogenous antigenic, dietary and toxic stimuli, in addition to endogenous stimuli (bacterial-derived meta bolites and components). This may result in low-grade stimulation of the innate immune system which is continu- ously regulated and contained to prevent intestinal damage, and this controlled inflammatory response has been defined as ‘physiological inflammation’. Imbalanced nutrition can break the intestinal homeostasis of the animal, causing uncontrolled and chronic inflammation, and birds may use their energy in unnecessary biosynthesis, so compromising efficiency. However, interactions between nutrients and gut immunity is not limited to intestinal cells
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