The study investigated 1) the effect of in vitro pre-treatment of sunflower meal (SM) and wheat middlings (WM) using fiber degrading enzymes (FDE) without or with protease on mono-sugars release, organic acid concentration (SCFA), organic matter solubilisation, protein solubilization and apparent disappearance (AD) of neutral detergent fiber (NDF). Each feedstuff was mixed with 1% of FDE without or with protease in a ratio of 1:4 wt/wt for feedstuff:water, incubated for 24h and 48h at 40˚C, and freeze-dried. 2) Impact of the inclusion of pre-treated sunflower (TSM) and wheat middling (TWM) in a maize-soybean meal (MSBM) ration on growth performance, tibia attributes, apparent retention (AR) of components and caecal sugars and short-chain fatty acids production. A total of 288 Ross-708 d old male broiler chicks were placed in cages (6 birds/cage) based on body weight (BW) and allocated to 6 diets in a completely randomized design giving 8 replicates per diet. The diets were: I) PC, a MSBM, positive control (PC), II) NC, PC plus untreated sunflower meal (USM) and wheat middling (UWM), and III) 4 test diets in which USM and UWM were replaced with TSM and TWM at 25% (N25), 50% (N50), 75% (N75) and 100% (N100). For pre-treatment, each feedstuff was mixed with 1% of FDE in a ratio of 1:2 wt/wt for feedstuff:water, incubated for 24h at 40˚C, and oven-dried. All diets had titanium dioxide (0.3%) for AR determination. The body weight (BW), feed intake (FI), and mortality were recorded. Excreta was collected and frozen (-20℃). The data were subjected to PROC GLIMMIX of SAS 9.4, and LS means were separated using the Tukey test (P<0.05). The analyses of freeze-dried samples showed improved in-vitro solubilisation of organic matter, increased mono-sugars, organic acids concentration, protein solubilization, and AD of NDF in both SM and WM. Analyses of oven-dried samples showed that pre-treatment increased soluble protein (SP) and decreased neutral detergent protein (NDF-P) and NDF in TWM. Compared to 2 USM, TSM had less SP while NDF-P and NDF were greater. The overall BW and BW gain (BWG) of NC were lesser than PC throughout the study (P ≤0.001). The N75 and N100 BW and BW gain were less than PC (P ≤0.001) throughout the trial. Overall feed intake was not different during the starter, finisher, and overall period (P ≥0.217) relative to PC and NC. Also, feed conversion ratios were not different throughout the study (P ≥0.151). The NC tibia attributes were not different from PC throughout the trial; test diets tibia length was lesser than PC (P = 0.005) and had a linear decrease response with higher inclusion levels (P = 0.004) on d42. The test diets did not affect the AR of CP (P = 0 <0.001); there was decreased apparent NDF retention on d 21 and d 42 (P ≤0.001) and apparent gross energy retention on d 21 and d 42 (P ≤ 0.001) compared to PC. The NC and TD did not affect caecal sugars and SCFA production throughout the feeding period. In conclusion, pre-treating increased in vitro digestibility of sunflower meal and wheat middling, but their pre-treatment did not improve broiler chicken performance and AR of components

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