It is generally agreed that good gut health is effective against intestinal pathogens and is the cornerstone to competitive poultry production, especially in broilers, where treating intestinal borne pathogens is too time consuming to be considered cost-effective. In the past, this strategy was only made possible through the routine use of antibiotic growth promoters (AGPs) in the feed. However, the realisation that creating and maintaining a healthy intestinal environment can produce comparable, if not better performance withouth using AGPs means that understanding and achieving gut health is essential to productivity and food safety programmes alike.

Understanding gut health

Gut health requires not only the absence of intestinal pathogens, as can be achieved using AGPs, but encompasses questions of effective digestibility and absortion of nutrients, a normal, stable microbiota and a healthy, functional gut mucosa, without inflammation. To this end, it is important to see the gut environment as a living system, influenced by environmental factors, especially those delivered via the feed.

Physiologists have found that maintaining a healthy gut requires up to 25% of the daily protein and 20% of the dietary energy supplied with the feed. This strategy should be carefully planned into the dietary programme, in order to not waste resources (Hittel and Lückstädt, 2017). Furthermore, the judicious use of feed additives can also support gut health through dietary means.

Gut health through the diet

Organic acids have a long history of use in animal nutrition, where they are usually added to stabilize compound feed, but also to enhance animal performance. One of the first reports of improved broiler performance when diets were supplemented with a single organic acid was for formic acid (Vogt et al., 1981) and improvements in broiler performance or their hygienic production conditions using various organic acids have been reported by many sources (as reviewed by Desai et al., 2007). An important limitation, however, is that organic acids are rapidly metabolised in the fore-gut (crop to gizzard) of birds, which can reduce their impact on growth performance. Sodium diformate (traded as Formi NDF, ADDCON), is effective against pathogenic bacteria throughout the gastrointestinal tract (Lückstädt and Theobald, 2009). Reducing the impact of pathogenic bacteria on the broiler, and improving the gut microflora, is an important factor in improving overall gut health. More recent data show how dietary sodium diformate can also improve the gut mucosal structure, measured as the length of the microvilli.

While it has been established that adding sodium diformate to poultry diets can improve digestibility of nutrients, including protein and minerals, it can also affect the mucosal structure of the small intestine and thus influence nutrient absorption.

A trial to prove this concept was conducted at a research farm in Taiwan using 120 day-old male Arbor Acres broilers, randomly allotted into 2 treatment groups, with 3 replications and 20 birds in each pen. The commercially available corn-soy-based feed in one group contained 0.3% Formi NDF while the other group served as a negative control. Feed and water were provided ad libitum. Birds were weighed individually after 14 and 39 days; feed consumption was recorded per pen at the end of the trial. The effects of sodium diformate on performance (final weight, feed conversion ratio, European Broiler Index EBI), protein utilization and villi height were examined after 39 days, giving a measure of the overall gut status.

The inclusion of Formi NDF in the diets of broilers were visible on small intestinal morphology and protein digestibility.

Villus height in the jejunum and ileum of birds at 39 days showed a significant increase in birds fed 0.3% NDF compared to controls (Table 1).

Table 1: Effect of sodium diformate (0.3%) on the morphology of the jejunum and ileum of broilers after 39 days.

Analysis of the protein utilization showed an increase from 61.6% to 63.3% in the birds fed diets containing NDF. This substantial improvement, of almost 3%, may be related to the larger intestinal surface area in NDF fed birds due to the longer villi.

Gut health leads to performance improvements

In broilers, improved zootechnical performance is thought to arise as a result of an improved intestinal microflora, which suppresses pathogenic bacterial species; and improved protein digestion. This was shown in the results of the present study as well as in a previous report under similar conditions (Lückstädt, 2014).

The effect of the additive on performance was already noticeable after only 14 days. At this stage, the body weight of the broilers receiving Formi NDF had increased significantly (P<0.05), by almost 21% (Table 2). At the end of the trial, treated birds were still significantly heavier (2551 g vs. 2316 g; P<0.05), while the FCR improved numerically (1.67 vs. 1.71). As a result, the European Broiler Index, which includes the three most important productivity parameters in animal production – weight gain, survival and feed efficiency – improved markedly by almost 15%.

Table 2: Performance parameters of broilers fed with or without 0.3% Formi NDF for 39 days

Conclusions

As often seen with other additives, the performance improvements recorded are also influenced in part by the hygienic conditions of the study. The current trial was conducted at the research farm of a university, but nevertheless showed that even under these rather "clean" conditions, NDF was able to significantly improve bird gut health and production parameters. Under practical conditions with a higher anticipated "bacterial load", conditions might weigh even more in favour of the additive effects measured. This has been seen with other trials under commercial conditions. It can therefore be concluded that dietary sodium diformate can play an important role in improving broiler production through supporting gut health parameters.

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Article made possible through the contribution of Christian Lückstädt and ADDCON

Effect of dietary sodium diformate on gut health and profitability in broilers