Date of Award

9-1-2025

Degree Type

Thesis

Degree Name

Master of Food and Animal Sciences (M.S.)

First Advisor

Pramir Maharjan

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.

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