New results on the effects of Progres® in laying hens were recently presented in the 7th International Conference on Poultry Intestinal Health (ICPIH2022), Cartagena De Indias, Colombia by Dr. Hannele Kettunen, Hankkija Finnish Feed Innovations. The trial with 1280 Rhode Island laying hens proved that Progres® at 700 g/ton improved eggshell quality and reduced the proportion of dirty eggs.  

As for meat poultry, gastrointestinal problems negatively affect the performance of laying hens. Previous studies have shown that the resin acids of Progres® improve gut barrier functions in chicken by reducing inflammation-associated collagen breakdown in small-intestinal mucosa. Hankkija FFI wanted to study the effect of Progres® on layers with or without a subtle challenge to the intestinal condition.

For the present experiment, a novel salt stress challenge model was designed for investigating the effects of Progres® in laying hens. It has been previously seen in laboratory animal models that too high dietary salt up-regulates inflammatory processes on gut mucosa. In laying hens, excess dietary salt is known to increase the proportion of dirty eggs.

The present experiment was conducted with 1280 Rhode Island laying hens at the experimental facility of Zootests, France. The birds were randomized into four treatments, 320 hens/treatment, and housed in cages of 20 birds/cage. The birds were 47 weeks old when the 42-day trial started. The comparability of the replicates was ensured by a pre-trial follow-up for weeks 42-46.

Figure 1. Trial design

The dietary treatments for the 42 days were as follows:

T1) Normal Salt (NS) feed (Na 1.7 g/kg) without amendment

T2) NS feed with Progres® at 0.7 g/kg

T3) High Salt (HS) feed (Na 2.6 g/kg) without amendment

T4) HS feed with Progres® at 0.7 g/kg

Mortality, feed consumption, egg production and dirty eggs (%) were recorded for weeks 42-46 and for weeks 47-53. Birds were weighed at weeks 42 and 53. Egg size and feed consumption were evaluated once every two weeks. Egg quality traits (individual egg weight, shell strength and Haugh Units) were measured at weeks 44 and 53. Dry matter and N content of feces were measured at week 49. Data was analysed by ANOVA followed by LSD tests on SAS software.

The salt stress treatment apparently was not strong enough, as it failed to affect most of the measured parameters. However, the fecal N was lower for the HS feed (0.95%) than for NS feed (1.08%; p = 0.002).

Figure 2. Effect of Progres® on eggshell quality: A) Static stiffness, B) Fracture force

Progres® improved the eggshell quality with statistical significance: static stiffness was 190.3 N/mm for Progres® and 184.4 N/mm for Control groups (p = 0.004), and fracture force was 43.9 N for Progres®-groups and 42.3 N for Control (p = 0.002) (Figure 2 A and B). The dietary treatments did not affect the Haugh Unit.

Progres® reduced the proportion of dirty eggs by 16%, compared to control (1.52% vs. 1.81%, respectively; p = 0.053) (Figure 3).

Figure 3. Effect of Progres® on the proportion of dirty eggs

However, Progres® supplementation did not affect the performance parameters of layers in this study. Thus, although the present trial did not succeed in the attempt to create a novel salt stress challenge model for laying hens, it was able to show the benefits of Progres® on eggshell quality and reduced proportion of dirty eggs. These results suggest improved intestinal condition in Progres®-fed laying hens.

In conclusion, Progres® may be useful in improving eggshell quality and reducing the negative effects of dysbiosis in laying hens.