Contrasting the effects of phytase and pure myo-inositol on the performance, digestibility, blood and egg yolk inositol levels and digestion physiology of laying hens

ABSRACT

1. An experiment was designed to compare the effects of supplementing laying hen diets with phytase and myo-inositol (inositol).

2. Five diets were formulated: high balanced protein (HBP – 840 mg of Dlys/hen/day), HBP with inositol (HBP+I – 0.16%), reduced balance protein (RBP – 672 mg of Dlys/hen/day), RBP with inositol (RBP+I – 0.16%) and RBP with phytase (RBP+P – 3000 FTU/kg).

3. Laying hen production, inositol concentrations, digestive tract morphology, amino acid digestibility and intestinal inositol transporters transcript abundance were evaluated. Data were analysed with a one-way ANOVA in SAS 9.4. Contrasts were used to assess the effect of protein, inositol, phytase and phytase vs. inositol. Differences were accepted when P ≤ 0.05.

4. No effect on hen-day egg production or feed efficiency was found. However, feed intake and the incidence of abnormally shaped eggs were 0.77 g/h/d and 0.17% higher, respectively, in inositol treatments. Inositol decreased egg specific gravity from 1.088 to 1.0865.

5. Inositol concentration in egg yolk was similar among HBP+I, RBP+I and RBP+P, and higher than for the HBP and RBP diet groups. Both gizzard and ileal digesta were enriched in inositol in all supplemented treatments, and phytase supplementation decreased the level of IP5 and IP6 in the gizzard and ileum. Generally, neither phytase or inositol affected amino acid digestibility.

6. Inositol increased transcript abundance of alkaline phosphatase in the ileum, while phytase upregulated duodenal alkaline phosphatase and SMIT1, jejunal SMIT2 and reduced ileal HMIT and SMIT1 abundance.

7. In conclusion, no effect of phytase or inositol was found for laying hen production performance or amino acid digestibility, but egg quality was reduced by inositol supplementation. Inositol concentration in egg yolk was similar among supplemented treatments.

KEYWORDS:

• Inositol
• phytate
• protein
• egg
• mortality
• digestive tract
• mucin
• alkaline phosphatase

Acknowledgments

The authors of the present study would like to thank Kimberley Hamonic and Dawn Abbott for their assistance during this trial. Likewise, the authors gratefully acknowledge the support provided by the staff of the Poultry Research and Teaching Unit at the University of Saskatchewan.

Disclosure statement

AB Vista Feed Ingredients collaborated with the design and provided resources for the completion of this project. The University of Saskatchewan completed the research, interpreted the results and prepared the manuscript. No particular view of the results was enforced by the funding agency.

Additional information

Funding

This work was supported by the AB Vista Feed Ingredients [419763].