Understanding Performance and Egg Quality Parameters in a Pastured Egg-Type Poultry Breed
Abstract
This study investigated the effects of rearing systems on performance, egg quality, and ileal amino acid (AA) digestibility in laying hens (65 weeks of age). A total of 66 hens were distributed into two rearing systems: Cage (2 birds/replication, total 12 birds in 6 replications) and pasture (9 birds/replication, total 54 birds in 6 replications), and reared on three levels of energy diet (11.50 MJ/kg, 12.50 MJ/kg, and 13 MJ/kg). The birds were reared from d 1 to 14 (diet 1), d 15 to 28 (diet 2), and d 29-42 (diet 3). The average temperature, wind speed, and humidity were approximately 61 F, 3 MPH, and 83% at 5 am;74 F, 5 MPH, and 58% at 11 am; 78 F, 6 MPH, and 51% at 5 pm; 66 F, 4 MPH, and 73% at 11 pm; respectively in pasture from d 1 to 42. Body weight (BW), egg weight (EW), and feed intake (FI) were recorded, and ileal digestibility of amino acids (AA) and whole egg fatty acids were analyzed. During the d 1 to 14, pasture-reared hens exhibited significantly higher final body weight (FBW), feed intake (FI) (P < 0.01), and shell thickness (P=0.0033) while egg weight (EW) was higher in the cage (P=0.0341). The total saturated fatty acids (SFA) (P=0.0032) and polyunsaturated fatty acids (PUFA) (P=0.0451) were significantly higher in pasture eggs compared to the cage while digestibility of AA improved in the cage. From d 15 to 28, the total SFA and PUFA were significantly higher in pasture while MUFA was significantly higher in the cage. All AA digestibility values improved significantly in the cage (P < 0.01). From the d 29 to 42, FI (P=0.0007) and total SFA was significantly higher in pasture eggs (P=0.0001). Interestingly, total PUFA increased significantly in the cage (P=0.0109) compared to pasture. Tryptophan digestibility was significantly higher in pasture-reared birds, while alanine and taurine digestibility were significantly higher in cage-reared birds. In conclusion, the rearing systems did not have significant effects on performance; however, pasture access improved the fatty acid profile while reducing AA digestibility compared to the control house.