Effects of dietary fibre level and body weight of pigs on nutrient digestibility and available energy in high-fibre diet based on wheat bran or sunflower meal.

Abstract

The objectives of this study were (a) to investigate the effect of body weight (BW) on available energy in fibre-rich diets containing two NDF levels; and (b) to evaluate the effect of fibre type and NDF level on AA digestibility. In Exp. 1, barrows (24 at 33.4±1.1kg; 24 at 86.8±3.3kg) were randomly allotted to 4 diets containing a high protein basal (HPB), a low protein basal (LPB), 70% HPB+30% wheat bran (WB) (HPB-WB) and 70% LPB+30% sunflower meal (SFM) (LPB-SFM). In Exp. 2, barrows (24 at 33.5±1.8kg; 24 at 87.0±3.8kg) were randomly allotted to 4 diets containing no SFM with 12% NDF (SFM0LF), no SFM with 16% NDF (SFM0HF), 24% SFM with 12% NDF (SFM24LF) and 24% SFM with 16% NDF (SFM24HF). In Exp. 3, twelve barrows (35.5±3.4kg) fitted with T-cannulas were allotted to two 6×4 Youden square design with 6 diets (4 same diets as in Exp. 2 and 2 nitrogen-free diets). The concentration of DE, ME and ATTD of GE, CP, NDF and ADF in diets was greater (p<.01) when fed to 90kg pigs compared with 30kg pigs. The ME in ingredients was not affected by BW. The ATTD of NDF was negatively correlated with the CF (r=-.98; p<.01), ADF (r=-.99; p<.01) and ADL content (r=-.96; p<.01). The ME of diets was negatively correlated with the ATTD of CF (r=-.98; p<.01). The addition of SFM increased the standardized ileal digestibility (SID) of Met (p<.05). In conclusion, diets rich in fibre had different nutritional values at different pig weight stages. The AA digestibility depends mainly on chemical composition of diets.