A healthy gut and an optimal diet for turkeys are the best prerequisites for ideal nutrient absorption and, consequently, for high performance and well-being. What veterinary aspects need to be considered when it comes to gut health, and how can turkeys be fed healthily and efficiently? Experts Dr Ronald Günther (veterinary specialist in poultry) and Dr Hartmut Meyer (Moorgut Kartzfehn) addressed these questions in an online event organised by the North Rhine-Westphalia Chamber of Agriculture as part of the Fokus Tierwohl network.

Bacterial community in the gut

The community of microorganisms in the gut is called the microbiome. This includes symbionts (the ‘good’ ones), commensals (the ‘neutral’ ones) and pathogens (the ‘bad’ ones). It comprises a wide variety of different microorganisms, such as bacteria, fungi, viruses and protozoa. The microbiome, also known as the gut flora, develops from day-old chicks to adult animals. Its composition varies depending on the section of the gut.  The time food spends in the digestive tract is very short in poultry compared to other animal species, which is why the composition of the gut microbiome also differs significantly. Dr Günther explained that the bacterial community in the gut effectively constitutes an important organ, the health of which is just as important as that of the other organs.

When the gut flora becomes unbalanced, this is referred to as dysbiosis. The causes of dysbiosis are manifold:

Typical pathogens affecting the gut include viruses, bacteria, parasites and fungi. They can destroy the intestinal epithelium, produce toxins and lead to inflammation and disrupted intestinal peristalsis. The associated changes in the gut also lead to shifts in the composition of the gut microbiome. Therefore, adherence to biosecurity standards is also important for maintaining gut health.

However, in addition to infectious agents, other factors such as changes in feed, poor feed quality, mycotoxins in the bedding or a poor housing environment can also lead to dysbiosis. “The main factor behind disrupted gut flora is stress,” emphasises Dr Günther.

How can gut health be ensured?

But how can gut health be restored to balance once dysbiosis has occurred? Various feed additives, such as enzymes, probiotics/prebiotics, phytogenic substances and immunologically active substances, have positive effects on the microbiome. When administered via feed, water or bedding, these products can help build a stable gut flora (preventively). In his presentation, Dr Meyer also cited lignocellulose, rock meal and biochar as practical examples. Vaccines can also influence a healthy gut microbiome by stimulating the production of specific antibodies.

Similarly, gut health can be influenced by various management measures taken by the farmer: a constant supply of feed is necessary to prevent stress in the turkeys. Forced breaks in feeding, e.g. during vaccination campaigns, must be avoided at all costs. Bedding and drinking water hygiene, feed storage and silo hygiene play an important role in this regard. The all-in/all-out strategy can also have a positive impact on gut health, as the house can be cleaned and disinfected during the service period. House disinfection should be targeted; DVG-approved disinfectants should be used for viruses and bacteria. It is important to note that parasites in the barn must be specifically targeted. Dr Günther concludes his presentation by stating: “The service period is the most important phase of livestock management.”

The importance of good gut health

Four functions define good gut health. These include the defence against pathogenic germs, the breakdown of feed into its components, the absorption of digested nutrients and the correct response of the immune system, according to Dr Meyer. The differences in digestive capacity between poultry and other farm animals highlight just how important good gut health is. A bird’s digestive tract is very small in relation to its body weight. This means that feed spends only a short time in the digestive tract. Consequently, feed with high nutrient density and good digestibility is required. Poultry lack the enzyme lactase, and their sucrase activity is very low, which is why certain carbohydrates in feed can only be digested to a limited extent.

In the first weeks of life, chicks have difficulty utilising fats containing saturated fatty acids. After hatching, care should therefore be taken to limit fat intake; otherwise, the chicks may develop diarrhoea or rickets, the litter will become wet, and this may lead to faecal and litter consumption or increased mortality.

Various factors must be taken into account in feed composition not only during rearing but also during fattening; for instance, increased levels of cell wall substances in the feed (crude fibre) can reduce digestibility. Similarly, high proportions of long-chain fatty acids and antinutritional factors such as non-starch polysaccharides have a negative effect on digestibility. Feed digestibility can be improved by adding grit, NSP enzymes and phytase.

Supplementing the diet with wheat also has a positive effect on gut health. The gizzard increases in size by 3 to 5 per cent, the secretion of HCl and pepsin is increased, active and passive digestion is improved, and intestinal peristalsis is stimulated. Thus, feeding wheat can help to reduce diarrhoea. However, turkey farmers must pay attention to certain hygiene aspects. The moisture content of the wheat must not exceed 25%, and condensation (mould growth) must be prevented. Storage, machine hygiene and parasite infestation must also be monitored.

The particle size of the feed must also be taken into account. Small particle sizes reduce the retention time of the feed in the gizzard, leading to inefficient protein digestion, poorer absorption and feed conversion. A high proportion of flour in the feed can lead to inflammation in the gut. Dr Meyer therefore recommends feeding turkeys high-quality pellets.

Both speakers agreed that stress is one of the main factors causing disrupted gut flora in turkeys, which is why turkey farmers should avoid stress in the flock through optimal management.

Author: Viola Erfkämper, North Rhine-Westphalia Chamber of Agriculture