Egg quality generally deteriorates with hen age and storage time. Novel feeding strategies in laying hens can support extended productivity of high egg quality that persists longer during storage.
Benefits of extended laying cycles
Extending laying cycles to up to 90-100 weeks has financial as well as environmental benefits. This stems from the fact that longer laying cycles reduces the number of breeding birds and feed required for egg production. However, a decline in egg numbers combined with a deterioration in egg quality are the main reasons for replacing flocks at or around 72 weeks of age. The financial and environmental benefits of extended laying cycles call for strategies to increase laying persistence and stability in egg quality. These strategies need to involve the long-term maintenance of the tissues and organs involved in producing eggs.
Factors affecting egg quality parameters
Typical egg quality parameters are shell strength, albumen height and Haugh units (HU). Generally, it is known that these parameters can be affected by hen age, genetics and nutrition.
Albumen height and HU are important parameters for albumen quality and indicate egg freshness. The Haugh unit is the standard selection measurement for albumen quality. The higher the value of the Haugh unit, the better the quality of eggs. Classification of eggs by HU according to the United States Department of Agriculture (USDA): AA (100 to 72), A (71 to 60), B (59 to 30) and C (below 29).
Studies have shown that Haugh units deteriorate with hen age from an average 89.6 to 68.8 over the laying period. Egg shell strength and albumen height are also known to be lower in older laying hens compared to younger laying hens.
Storage time is an additional factor that can affect several egg quality parameters. It has been shown to have a significant negative effect on albumen height, HU and yolk colour. The effect of storage time on egg quality can be further exacerbated by temperature. Eggs stored refrigerated can maintain quality for a longer period compared to eggs stored at room temperature.
Can we slow down the aging process of ovaries in laying hens?
Ovarian aging is characterized by a gradual decrease in both the quantity and the quality of oocytes and is related to the age of the laying hen. One of the most important factors inducing ovarian aging is oxidative stress. Oxidative stress is caused through the accumulation of reactive oxygen species (ROS) generated during metabolic activity, which can be exacerbated in periods of high productivity or when the bird is challenged by stressors, such as heat, mycotoxins and flocking density.
The birds antioxidative capacity relies on a complex antioxidant system, which makes use of biological antioxidants and enzymes. However, the antioxidative capacity decreases during the aging process. Nuclear factor erythroid 2-related factor 2 (NrF2) is well established as a critical transcription factor that regulates antioxidant genes and is responsible for the induction of various cellular defense mechanisms, including antioxidative enzymes, against oxidative stress.
Recent research has shown that the Nrf2/KEAP pathway in ovaries gets down-regulated in the aging process of laying hens (Liu et al 2018). Furthermore, the dietary supplementation of certain phytogenic molecules demonstrated the potential to naturally slow down the aging process of ovaries, since it reduced oxidative stress by activating the Nrf2/KEAP pathway in ovaries.
Feeding strategies to make egg quality last longer in production and storage
Recent research studies investigating the effects of feeding the gut agility activator Anco FIT Poultry in laying hens have shown that it improves albumen height and Haugh units during the laying production cycle and extended egg storage life based on these egg quality parameters.
Anco FIT Poultry is specifically designed to boost the adaptive capacity of birds by upregulating efficient adaptive mechanisms at the gut and cellular level. Research trials have proven that this gut agility activator upregulates cytoprotective factors in the NRF2-KEAP pathway in poultry and increases the antioxidative capacity in tissues and organs vital for productivity of the bird.