Sorghum as a dietary substitute for corn reduces the activities of digestive enzymes and antioxidant enzymes in pigs

Abstract

This study was conducted to determine whether sorghum as a potential substitute for corn in diets affects the activities of digestive enzymes and antioxidant enzymes in pigs. Sixty pigs (7.3 ± 1.3 kg initial weight) were allotted to 2 diets with 5 replicate pens per treatment according to sex and weight in a randomized complete block design. A corn-based diet (CBD) included 600 g/kg of corn grain during the overall experimental period, and a sorghum-based diet (SBD) consisted of 300 g/kg (day 1–14) or 566 g/kg (day 15–28) of sorghum grain at the partial or complete expense of corn in CBD. Both diets were formulated to contain the same amount of digestible energy and essential amino acids. No differences were observed in average daily gain or feed intake between treatments. However, substituting sorghum for corn in diets tended to reduce (P = 0.087) or reduced (P < 0.05) feed efficiency. Apparent digestibility of gross energy and crude protein was decreased (P < 0.05) in pigs fed the diets comprising sorghum, regardless of the substitute level, associated with the increased faecal excretion of energy and nitrogen. Serum urea nitrogen concentration in SBD was greater than that in CBD (P < 0.05). Pigs fed SBD had or tended to have lower superoxide dismutase and catalase activities and greater malondialdehyde content in serum (P < 0.05) or liver (P = 0.085) than those fed CBD. Amylase and lipase activities were decreased in duodenal mucosa (P < 0.05), and lipase (P < 0.05) and trypsin activities (P = 0.092) in jejunal mucosa were reduced and tended to be reduced in pigs fed SBD. Compared with CBD, SBD increased or tended to increase crypt depth in duodenum (P < 0.05) or jejunum (P = 0.094) coupled with the decrease in villus height/crypt depth in duodenum (P = 0.086) and ileum (P < 0.05). Collectively, sorghum as a dietary substitute for corn changed intestine morphology and reduced activities of digestive enzymes and antioxidant enzymes which may have been responsible for the reduced energy and nitrogen utilization and feed efficiency in pigs.