Comparative energy and nitrogen excretion from growing pigs fed on corn, sorghum and wheat-based diets

Abstract

Sorghum and wheat grains have been previously identified as potential substitutes for corn in diets for pigs based on the available energy. This experiment was conducted to compare growth performance and faecal energy and nitrogen output per weight gain in growing pigs fed on corn (CSBM), sorghum (SSBM) or wheat soybean meal based diets (WSBM). Sixty crossbred pigs (23.4 ± 1.6 kg of body weight) were allotted to 3 diets with 5 replicate pens per treatment according to sex and weight in a randomized complete block design. The CSBM included 703.4 g/kg of corn during day 1–35 (phase 1) and 736 g/kg during day 36–70 (phase 2). The corn content in CSBM was partially (500 g/kg; phase 1) or completely (phase 2) replaced by sorghum in SSBM or wheat in WSBM. No differences were detected in average daily gain (ADG) or average daily feed intake (ADFI) between CSBM and SSBM treatments. Pigs fed on WSBM had lower ADFI than those fed on CSBM or SSBM (P < 0.05). The ADG of pigs fed on WSBM tended to decrease during phase 1 (P = 0.09) and 2 (P = 0.06) and decreased overall (P < 0.05). Compared with SSBM, WSBM increased feed conversion efficiency and apparent total tract digestibility (ATTD) of dry matter and gross energy (P < 0.05). The ATTD of crude protein in CSBM was greater than that in SSBM and lower than that in WSBM (P < 0.05). Pigs fed on CSBM had lower faecal energy and nitrogen output per weight gain than those fed on SSBM and greater than those fed on WSBM (P < 0.05). Serum urea nitrogen concentration in WSBM was greater than that in CSBM and SSBM (P < 0.05). Collectively, sorghum could be used as an alternative energy source for corn in diets fed to growing pigs without negative effects on growth performance. However, given the feed conversion efficiency and manure emissions, wheat may be a superior energy ingredient in diets for growing pigs with the low nutrient loss and output in manure.