Evaluation of hydrolyzed corn steep liquor as an alternative feed ingredient in broiler nutrition: impacts on performance, litter quality, gut integrity, and bone mineralization.

The present study was conducted to evaluate the effects of dietary incorporation with hydrolyzed corn steep liquor (HCSL) on growth performance, tibia characteristics, apparent digestibility of nutrients, litter quality, footpad dermatitis, jejunum morphology and ileal microbial population. A total of 750 one-day-old male and female broilers (Ross 308) were allocated to five dietary treatments with six replicates of 25 birds each in a completely randomized design. The experimental treatments included a basal corn-soybean meal diet without HCSL (HCSL-0) and the same basal diet supplemented with 2.5, 5, 7.5, or 10% HCSL. Data were analyzed using the GLM procedure of SAS, treatment means were compared by Tukey's test, and orthogonal polynomial contrasts were applied to evaluate linear and quadratic responses to increasing dietary HCSL levels. During 25 to 42 days of age, daily feed intake decreased from 2654.39 g in the control to 2271.47 g in the HCSL-10 group (P = 0.004), with a significant linear effect (P < 0.001). Cumulative body weight gain declined from 2346.69 g in the control to 1672.14 g in the HCSL-10 treatment (P = 0.004), while feed conversion ratio increased from 1.56 to 1.91 (P = 0.003). Crude protein digestibility was significantly reduced in HCSL-10 treatment (55.52%) compared to HCSL-0 (64.54%), HCSL-2.5 (63.56%), and HCSL-5 (63.79%) treatments (P = 0.008). Bone weight, bone length, and the weight to length index of the bone in the HCSL-2.5 treatment were significantly greater than those in the HCSL-7.5 and HCSL-10 treatments (P < 0.05). Moreover, diameter of the medullary canal and bone strength in the control treatment was higher than in the HCSL-10 treatment (P < 0.05). The use of HCSL-10 relative to the control and HCSL-2.5 treatments resulted in an increase in litter ammoniacal nitrogen, litter pH and footpad dermatitis scoring. The HCSL-10 treatment, compared with control, HCSL-2.5 and HCSL-5 treatments, decreased villus height, villus surface area, and Lactobacillus population, while increasing Escherichia coli and coliform populations (P < 0.05). In conclusion, low dietary levels of HCSL, particularly 2.5%, could be used as a potential alternative feed ingredient in broiler diets without adverse effects, whereas high inclusion levels, especially 10%, negatively affected growth performance, nutrient digestibility, intestinal health, bone quality, litter condition, and microbial balance.