168 Effects of feeding barley-based diets differing in fermentable starch and fiber on nutrient digestion and body composition in weaned pigs

Abstract

Abstract Hulled and hull-less barley grains containing low insoluble fiber are alternative energy sources in weaning diets but are typically not part of weaned pig diets. The range in fermentable starch and fiber content among barley cultivars presents opportunities to investigate whether these fermentable carbohydrates of barley grain do influence nutrient digestion, gut short chain fatty acid (SCFA) profile and body composition. To explore, pigs [n = 40; body weight (BW) = 8.6 kg; 1-wk post-weaning] were housed individually and fed 1 of 4 diets containing 600 to 705 g of cereal grain/kg: 1) low-fermentable wheat (LFW); 2) high β-glucan, hull-less barley (HFBB); 3) high amylose, hull-less barley (HFAB); or 4) low-fermentable hulled barley (LFB). Diets provided 10.2 and 9.8 MJ NE/kg, and 1.32 and 1.21 g standardized ileal digestible (SID) lysine/MJ NE for phase 1 (d 0–14) and phase 2 (d 15–28), respectively. At the end of the trial, feces were collected, and pigs were slaughtered to collect digesta and the carcass that was subsequently ground. Subsamples of feces, digesta, and carcasses were freeze-dried and analyzed. The apparent ileal digestibility (AID) of crude protein (CP) and gross energy (GE) did not differ among diets. The AID of β-glucan was 3 times greater (P < 0.05) for LFW than HFBB and HFAB, while AID of starch was 12% less (P < 0.05) for HFAB than the other diets. Apparent total tract digestibility (ATTD) of GE and CP was 4.2 and 8.9% less (P < 0.05), respectively, for the 3 barley diets than the wheat diet. The apparent hindgut fermentation (AHF) of β-glucan was 2.6 times greater (P < 0.05) for HFAB and HFBB than LFW, while AHF of starch was 7.5 times greater for HFAB than LFW. The calculated NE value was greatest (P < 0.05) for LFW, intermediate for HFBB and HFAB, and least for LFB. Among diets, HFAB increased (P < 0.05) the concentration of butyrate (indicator of gut health) and propionate in cecal and colonic digesta, with butyrate up to 50% more (P < 0.05) than that of LFW. Carcass protein and lipid concentration did not differ among pigs fed the 4 diets. In conclusion, feeding barley instead of wheat grain to weaned pigs reduced diet nutrient digestibility but did not affect carcass protein and lipid concentration. Feeding high amylose barley increased gut SCFA concentration. Barley grain with increasing fermentable carbohydrates can thus be included as alternative ingredient in diets of young pigs.