The effect of AM/PM diets on feed efficiency, egg quality and welfare parameters for free-range laying hens

Laying hens have a cyclic reproductive physiology that requires high dietary protein and energy levels for yolk and albumen formation in the early morning and high dietary Ca levels for shell and membrane formation in the afternoon/evening. Therefore, feeding one diet throughout each day may be problematic as there is excess Ca in the morning and excess protein/amino acids and energy in the afternoon/evening. To minimise excess nutrients, there is increasing interest in alternative strategies such as AM/PM feeding (Cadogan and Bruerton, 2021); where a high-energy and protein diet with lower Ca is provided in the morning (AM) and a lower-energy and protein diet with higher Ca is fed in the afternoon/evening (PM, De Los Mozos et al., 2012). AM/PM feeding has been illustrated to improve feed efficiency, eggshell quality, and reduce environmental pollution (De Los Mozos et al. 2012; van Krimpen et al., 2018), by minimising excess nutrient and allowing the capacity for the hens to sequentially select feed. However, there are opportunities to investigate the potential effects of AM/PM diets on hen welfare, especially with feather pecking, which has been shown to increase with insufficient protein (Mens et al., 2020).

An experiment was conducted at UNE’s free-range research facility, where two mash dietary treatments; conventional layer hen diet and AM/PM hen diets were offered to 9 replicate pens of 20 hens each, giving a total of 360 hens (18 pens) from 34 to 53 weeks of age. Diets were wheat-sorghum-soy-based, and the control contained 3688 kcal/kg gross energy, 17.46% crude protein, 4.53% Ca. Hens offered the AM/PM diets received the AM diet (3787 kcal/kg gross energy, 19.04% crude protein, 3.12% Ca) from 8 am to 4 pm and the PM diet (3500 kcal/kg gross energy, 16.09% crude protein, 5.10% Ca) from 4 pm to 8 am. Egg weight, egg production, daily feed consumption and feed conversion ratio (FCR) were measured weekly. Egg quality and bone quality were measured at week 53. Additionally, hen behaviour was assessed from 49 to 50 weeks of age with camera recordings and individual ranging behaviour was monitored by Radiofrequency Identification (RFID) technology from 39 to 48 weeks of age.

The results showed that AM/PM feeding tended to improve laying hen performance by increasing egg mass by 2.15% (60.4 vs 59.1 g/hen/day, P = 0.086) and improving feed efficiency by 8.34% (2.231 vs 2.436 kg feed/kg egg, P < 0.05) compared to the control feeding regime over 20 weeks of the study. Hens offered the AM/PM diet also had higher yolk colour score compared to the hens offered the control diet (12.3 vs 11.6, P < 0.01). AM/PM hens spent longer on the range (2.85 vs 2.47 hours/day, P < 0.001). Hens on the AM/PM treatment had higher tibia ash content (43.3% vs 41.6%, P < 0.05) and breaking strength (19.98 kg vs 17.13 kg of force, P < 0.05). Furthermore, AM/PM hens were observed to feather-peck less frequently than the control hens (0.39% vs 1.15%, P = 0.01). This study demonstrated the production, health, and welfare benefits of AM/PM feeding under Australian free-range conditions.

ACKNOWLEDGMENTS: The authors would like to acknowledge and thank Poultry Hub Australia and Australian Eggs Corporation Limited for funding this project and their guidance, encouragement and support.