Effects of supplementation of α-amylase alone in a model of growing and finishing pigs fed metabolizable energy-reduced diets

•Greater digestibility and metabolizability coefficients, digestible and metabolizable energy were observed in pigs fed α-amylase.•Greater feed-to-gain ratio was observed in finishing pigs fed diets without amylase (CD) compared to those with amylase (AM).•Feed-to-gain ratio was higher in pigs fed metabolizable energy-reduced diets and with α-amylase (AM-) compared to those without α-amylase (CD-).•Growing pigs on AM or AM- showed an increase in digestible protein of diet, and higher digestible dry matter, organic matter, and energy in finishing pigs fed AM.•Pigs on AM or AM- had greater crude protein in the meat. Amylase helps break down starches into simpler sugars, which can be absorbed and used for energy by pigs. Two experiments were conducted to assess the effects of α-amylase on apparent total tract digestibility (ATTD) of nutrients and energy, N balance, growth performance, blood metabolites, carcass and meat traits in growing and finishing pigs fed metabolizable energy (ME)-reduced diets. In Exp. I, 36 male pigs (25.9 ± 0.5 kg) were randomly alloted to 1 of 4 dietary treatments: 1) control diet not reduced in ME and no α-amylase (CD), 2) CD + 100 g of α-amylase/t (AM0), 3) CD reduced in 50 kcal ME/kg + 100 g of α-amylase/t (AM-50), 4) CD reduced in 100 kcal ME/kg + 100 g of α-amylase/t (AM-100), with 9 replicates cages. Greater digestibility and metabolizability coefficients, digestible and metabolizable energy were observed in pigs fed α-amylase. In Exp. II, 42 male pigs (25.8 ± 0.2 kg) randomly allotted to 1 of 6 dietary treatments: 1) CD, 2) CD reduced in 50 kcal ME/kg and no α-amylase (CD-50), 3) CD reduced in 100 kcal ME/kg and no α-amylase (CD-100), 4) CD + 100 g of α-amylase/t (AM0), 5) CD reduced in 50 kcal ME/kg + 100 g of α-amylase/t (AM-50), 6) CD reduced in 100 kcal ME/kg + 100 g of α-amylase/t (AM-100), with 7 replicates pens, and divided into: growing I (d 1 to 28), growing II (d 29 to 46), finishing I (d 47 to 70), and finishing II (d 71 to 88). Results were described using orthogonal contrasts, that is, diets without vs with α-amylase (CD vs AM), and ME-reduced diets without vs with α-amylase (CD- vs AM-). Growing I pigs from AM or AM- showed greater feed-to-gain ratio (F:G). A greater F:G was observed in finishing I pigs from CD. Finishing II pigs from CD- showed greater weight gain and average daily feed intake. Growing pigs on AM or AM- showed an increase in digestible protein of diet. A higher digestible dry matter, organic mat