Optimising reduced-protein diets for an efficient and sustainable layer production

Research by the University of New England, funded by Australian Eggs, explored how to improve reduced protein diets for laying hens. The aim was to make egg production more cost-effective and environmentally friendly.

Despite decades of research, challenges remain in optimising reduced-protein diets. These diets typically contain more cereals and less soybean meal, which can influence how added enzymes like phytase and xylanase function. Additionally, supplementing with amino acids or related compounds such as arginine, citrulline, or guanidinoacetic acid may help hens maintain productivity and health, but their effects are not fully understood. 

Research led by Dr. Amy Moss and Dr. Thí Hiep Dao conducted two trials with 208 Hy-Line Brown hens per trial. In the first, hens aged 35–57 weeks were fed diets varying in protein, phytase, and enzyme blend levels. Reduced protein led to slightly lower egg weight and mass but did not affect feed efficiency, with standard enzyme levels being at a sufficient level. 

The second trial (hens aged 60–75 weeks) tested reduced-protein diets supplemented with arginine, citrulline, or guanidinoacetic acid at two levels. All hens maintained egg production and feed efficiency. Notably, citrulline improved egg weight, yolk weight, and bone strength, offering strong economic and performance returns.

Overall, reduced-protein diets lowered nitrogen excretion, excreta moisture, and feed costs. A diet with citrulline cut feed costs by AU$0.076/kg of eggs (6.8%) compared to standard diets. 

With soybean meal prices rising and synthetic amino acids becoming more affordable, optimised reduced-protein diets could help Australia’s egg industry remain both cost-effective and environmentally sustainable.