Effects of AM/PM Feeding Regimen on Productive Performance, Egg Quality, Bone Properties, Blood Metabolites and Nutrient Utilization in the Aged Laying Hens

Background The nutrient requirements of laying hens are not static but dynamic, changing throughout the day in response to the cyclic nature of egg formation. Objectives The current study aimed to evaluate the impact of the AM/PM feeding regimen (AM/PM‐FR), which involved higher levels of protein, amino acids and available phosphorus, and lower levels of Ca in the morning diet, with the converse in the afternoon diet, on aged laying hens. Methods A total of 300, 74‐week‐old Hy‐Line W36 laying hens were randomly assigned to a completely randomized design with 5 treatments, 6 replicates, and 10 hens per replicate. Experimental treatments included offering AM/PM‐FR at 0% (control), 10%, 20%, 30% and 40% changing nutrient levels (CNL) between the morning (5:00 AM–2:00 PM) and evening (2:00 PM–5:00 AM) diets. The exposure program consisted of continuous lighting from 5:00 AM to 9:00 PM and darkness from 9:00 PM to 5:00 AM. Results The feed conversion ratio (FCR) and economic profit, income minus feed cost (IMFC), improved with a quadratic trend in response to increased CNL of AM/PM‐FR. Throughout the entire experimental period, birds fed AM/PM‐FR at 30% CNL showed improvements of 4.57% in FCR and 17.55% in IMFC compared to the control group. A lower incidence of egg fractures and a higher yolk crude protein concentration were observed with a linear trend in response to increased CNL of AM/PM‐FR. By increasing CNL of AM/PM‐FR, the total tract apparent mineral (Ca and phosphorus) and ether extract retention improved with quadratic and linear trends, respectively. Non‐significant effects of the treatments were noted on egg quality, blood metabolites, bone mechanical properties and mineral contents. Conclusions It was concluded that the use of AM/PM‐FR at 30% CNL in aged laying hens may facilitate the precision nutrition and thus improve production and economic performance.