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A unique endoxylanase offers potential for better egg quality through improved gut health

26 February 20186 min reading

Since eggshell quality has a significant impact on the profitability of layer farms, enzyme choice must be made taking into consideration not only the effects on energy uplift and performance, but also the effects on egg quality.

Kurt Van de Mierop

Kurt Van de Mierop - Manager, Nutrex, Belgium

In many countries across Asia, the use of xylanases is historically associated with periods when wheat based diets are used in which they are believed to be essential due to their viscosity reducing capacity to improve wheat digestibility and litter quality. Once those periods of wheat use pass and corn becomes available or cheaper, the use of xylanases is often abandoned or seen as a secondary activity at best. What is often forgotten, is that corn, and many other vegetable raw materials, also contain significant amounts of arabinoxylan (AX), the substrate for xylanase. However, the arabinoxylan is largely insoluble and difficult to degrade which imposes different requirements to a xylanase to have a beneficial effect in such diets.

Many forget, or are simply not aware of, the fact that the amount of difficult to degrade insoluble AX present in vegetable materials, (wheat, corn and other raw materials alike) offers a unique potential for enzyme mediated in vivo production of prebiotic oligosaccharides. The partial hydrolysis of soluble and insoluble AX into smaller arabinoxylan oligosaccharides (AXOS) makes them ferment faster and favours desirable microbiota. This results in the production of important levels of desired SCFAs, particularly butyrate, and improves morphological and histological changes in the small intestine as well.

EFFECT ON GUT HEALTH AND EGGSHELL QUALITY Improved intestinal health not only influences nutrient digestibility, but also affects carcass composition and the quality of egg(shell)s. Poor eggshell quality is one of the most important issues in the poultry industry, influencing the economic profitability of egg production and hatchability. Cracked or broken shells account for 80-90% of eggs that are routinely downgraded. One of the main concerns is the decrease of eggshell quality as hen age increases, because the incidence of cracked eggs can exceed 20% at the end of the laying period. Furthermore, the high breaking strength of eggshells and the absence of shell defects are essential for protection against the penetration of pathogenic bacteria into the egg. In the past, several studies have shown the positive effects of Nutrase Xyla on microbiota composition. Alireza et al. (2015) designed a study to unravel the true mechanism by which gut microbiotas are affected by the addition of feed enzymes. The bacterial xylanase significantly increased the number of bacteria belonging to Clostridium cluster IV (butyrate producers) and butyryl CoA-acetate CoA-transferase genes (Table 1). In addition to the effect on microbiota, the intestinal morphology was also clearly affected, since villus length and villus/crypt ratio increased by 24% and 42%, respectively. The results suggest that Nutrase Xyla likely affects the gut microbial profile through a combination of providing readily fermentable AX fragments together with an overall change in digesta composition as substrate for gut microbiota.

Promotion of good intestinal health and feed intake can help to obtain better eggshell quality. Due to the lower pH caused by enhanced production of SCFA, an increased bioavailability of minerals can be expected. At the same time, increased production of butyrate may improve the absorptive capacity of the intestinal mucosa.

RESULTS OF TRIALS To study the ‘side’ effect of xylanases on egg quality, a number of trials were conducted in co-operation various reputed research institutes. The main results of these trials are summarised in Table 2. In the first, a significant increase in laying rate (92.4% vs 95.3%) was observed for the hens in the bacterial endo-xylanase group when compared with a negative control group. FCR also improved significantly by 5.1% for the enzyme group versus the negative control group. Besides the influence on performance, a significant enzyme effect on eggshell was also seen. The incidence of broken or cracked eggs decreased from 2.33 to 1.63%.

The objective of the second trial was to evaluate whether NSP enzymes from different origins had similar effects on performance and eggshell parameters in commercial layers. Feeding laying hens diets supplemented with either a fungal cocktail enzyme (FX) or Nutrase Xyla had no significant effect on their performance. However, laying rate, egg weight and daily egg mass were numerically higher for the Nutrase Xyla supplemented laying hens compared with their FX-supplemented counterparts.

Eggs from hens fed Nutrase Xyla had a significantly thicker eggshell and had fewer cracked eggshells than hens fed FX. The third trial was set up to evaluate the effect of Nutrase Xyla on performance and eggshell quality in older layers (54 – 74 weeks of age). Supplementing the feed with Nutrase Xyla significantly improved the laying percentage (87.9% vs 83.7%) and egg mass (58.3 g vs 55.3 g), resulting in a significantly better feed conversion ratio (1.974 vs 2.085).

The incidence of broken and dirty eggs was moderate and comparable between treatment groups, whereas the incidence of soft-shelled eggs was significantly lower (0.04% vs 0.47%) for the Nutrase Xyla group. Also a significantly higher Haugh units (HU) value for the laying hens fed the diets supplemented with Nutrase Xyla (90.14 vs 87.60) was noticed. Supplementing a bacterial endo-1,4-b-xylanase resulted in more efficient egg production and increased HU when compared with the negative control diet (Delezie et al. 2015).

CONCLUSIONS Based on these results, we conclude that Nutrase Xyla not only reduces the anti-nutritional effects of the non-starch polysaccharides, but also contributes to in vivo creation of prebiotic AXOS which are fermented in the ceca to produce high levels of butyrate. The benefits of butyrate in terms of eggshell quality are widely accepted, so if use of Nutrase Xyla can reduce or replace the addition of butyrate, feed prices will drop distinctly while maintaining the positive effects. Since eggshell quality has a significant impact on the profitability of layer farms, enzyme choice must be made taking into consideration not only the effects on energy uplift and performance, but also the effects on egg quality.

Since many years, Nutrex has been working intensively on researching the detailed mode of action and unique set of properties to demonstrate the capacity of Nutrase Xyla to improve production performance and intestinal health in all sorts of diets and production systems.

References are available on request. The gut of layers that received a diet of corn and an enzyme supplement showed healthier villus height and crypth depth (upper picture) than chickens that received no enzyme in the diet (trial results shown in table 1)

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