Diet nutrient and energy digestibility and growth performance of weaned pigs fed hulled or hull-less barley differing in fermentable starch and fibre to replace wheat grain

Starch and fibre composition of feed grain may alter site of digestion and fermentation of energy-yielding nutrients within the swine gut. Especially dietary amylose and β-glucan increase fermentation; however, their effect on growth performance has not been well defined. Starting 1 week post-weaning (BW, 7.3 kg), 240 pigs were fed 5 diets that contained 630-706 g cereal grain/kg differing in fermentable carbohydrates: high-fermentable β-glucan hull-less barley (HFB), high-fermentable amylose hull-less barley (HFA), moderate-fermentable hull-less barley (MFB); low-fermentable hulled barley (LFB) or low-fermentable hard red spring wheat (LFW). Diets were formulated to provide 9.7 and 9.4 MJ net energy (NE)/kg and 1.32 and 1.22 g standardised ileal digestible lysine/MJ NE for Phase 1 (day 1-14) and Phase 2 (day 15-35), respectively. The coefficient of apparent total tract digestibility (CATTD) of gross energy (GE) was greatest (P < 0.05) for MFB and LFW for both phases and was lower (P < 0.05) for LFB than HFB and HFA for Phase 1 and HFA for Phase 2. The CATTD of crude protein (CP) was greater (P < 0.05) for LFW than the 4 barley diets for both phases. The CATTD of CP was greater (P < 0.05) for HFA and LFB than HFB and MFB for Phase 2. Calculated NE value for Phase 1 was greatest (P < 0.05) for MFB, greater (P < 0.05) for LFW than LFB and HFB and greater (P < 0.05) for HFA than HFB. Calculated NE value for Phase 2 was greater (P < 0.05) for MFB than LFB, HFB and HFA and greater (P < 0.05) for LFW than HFA. For the entire trial (day 1-35), gain:feed (G:F) did not differ (P > 0.05) among diets. Average daily feed intake (ADFI) was greater (P < 0.05) for LFB, LFW or MFB than HFA. The ADFI was greater (P < 0.05) for LFB than HFB. Average daily gain tended to be greater (P = 0.07) for LFB than HFA. Faeces consistency was greater (P < 0.05) for LFW than HFB or HFA and greater (P < 0.05) for LFB than HFB. In conclusion, moderate dietary fermentable carbohydrates did not alter feed intake, gain and G:F of weaned pigs; however, high dietary fermentable carbohydrates may reduce feed intake, gain and faeces consistency. Nevertheless, hulled and hull-less barley replacing wheat grain in diets did not affect feed intake, gain and G:F in weaned pigs.