Branched-chain amino acids (BCAAs), including Ile, Leu, and Val, play a crucial role in the health and productivity of laying hens. The objective of this study was to investigate the effects of BCAA on the performance of Hy-Line W-36-laying hens during the late-lay period (67 to 83 wks of age). A total of 600 hens were housed in 200 conventional A-frame cages according to a 23 full factorial circumscribed central composite design (CCD) with 20 treatments (8 factorial, 6 star, and 6 center points). Each treatment consisted of varying dVal:dLys (67 to 101), dIle:dLys (58 to 92), and dLeu:dLys (120 to 220) ratios; dLys was formulated at 0.70% per the Hy-Line W-36 management guide. Eggs were collected daily to determine hen-day egg production. Feed and eggs were weighed weekly to assess feed intake (FI), FCR, and hen-day egg mass. Egg quality was evaluated every 5 weeks; at 83 wks, one bird/pen was euthanized for tibia collection to determine tibia ash and tibial breaking strength (TBS). Data were analyzed as a CCD using the surface response option of JMP v. 19, and means were considered significant at P < 0.10. Feed intake increased (115.2g/bird/day; P =0.0981; R2 =0.68) at moderate levels of dVal:dLys (86) and dIle:dLys (81) at the low dLeu:dLys (120) ratios. For egg quality, both Haugh unit (HU; 89.69; P = 0.0159; R2 = 0.80) and relative albumen weight (65.56%; P = 0.0142; R2 = 0.80) were maximized at the highest dVal:dLys ratio (101). However, relative albumen weight was maximized at the highest dIle:dLys (92) and dLeu:dLys (220) ratios, whereas HU was maximized at the lowest dIle:dLys (58) and dLeu:dLys (120) ratios, showing an opposing response pattern for Ile and Leu. Tibial breaking strength increased (217.97 N; P =0.0853; R2 =0.69) at moderate levels of Val:Lys (93), lowest levels of Ile:Lys (58) and Leu:Lys (120) ratios. These findings demonstrate that adjusting the dVal:dLys and dIle:dLys ratios appropriately can help optimize FI, egg albumen, and TBS in late-lay hens. As dietary dLeu:Lys levels increase, corresponding adjustments in dVal:dLys and dIle:dLys are required to maintain optimal performance and bone quality.

Waters, C., R. Adhikari, J. Lee, R. Kriseldi, M. Elliot, L. Zhang, K. Wamsley and P.  Adhikari. 2026. Role of branched-chain amino acids on performance, egg, and bone quality in late-lay Hy-Line W-36 hens. 2026 International Poultry Scientific Forum, abstract M99.