Effects of light intensity and reduction of starter diet digestible lysine and metabolizable energy on broiler chicken growth performance, breast meat yield, and meat quality defects.

ABSTRACT

The etiology of Wooden Breast (WB) is unknown; therefore, it is difficult to produce broiler flocks with similar proportions of WB-affected and unaffected birds. Because WB has been detected as early as 15 d posthatch, the objective of this randomized complete block experiment with a 2 × 2 factorial treatment arrangement was to determine whether combining the effects of light intensity (LI) and early nutrient reduction strategies could reliably produce WB-affected and normal broilers to further investigate the physiological mechanisms underlying WB. On day of hatch, male, Ross 708 × Yield Plus broilers (n = 384; 16 birds per pen; 3 replicate blocks) were randomly allotted to floor pens in the same facility and exposed to either 2 (LOWLI) or 30 (HIGHLI) lux of light from d 0 to 35. Birds were fed either a commercial starter diet (CON) or the CON diet with a 10% reduction in both ME and digestible lysine (dLys; RED) from d 0 to 14 and then a common grower diet from d 15 to 35. Broiler growth performance, breast yield, and incidence and severity of WB and White Striping (WS) were assessed. Data were analyzed as a 2-way ANOVA with SAS PROC GLIMMIX and means separated at P < 0.05 with PDIFF. No interaction among LI and diet was observed (P > 0.05). Broilers reared with HIGHLI were heavier on d 35 and consumed more feed in all phases compared with broilers reared under LOWLI (P ≤ 0.0096). Broilers reared under LOWLI gained less BW from d 15 to 35 and d 0 to 35 compared with broilers reared under HIGHLI (P = 0.0073). Broilers fed the RED starter diet consumed more feed and had higher FCR from d 0 to 14 compared with broilers fed the CON diet (P ≤ 0.0012). In conclusion, combining reductions in LI and starter diet ME and dLys did not produce the hypothesized reductions in breast yield and incidence and severity of WB or WS.