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

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 alpha-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 alpha-amylase (CD), 2) CD + 100 g of alpha-amylase/t (AM0), 3) CD reduced in 50 kcal ME/kg + 100 g of alpha-amylase/t (AM-50), 4) CD reduced in 100 kcal ME/kg + 100 g of alpha-amylase/t (AM-100), with 9 replicates cages. Greater digestibility and metabolizability coefficients, digestible and metabolizable energy were observed in pigs fed alpha-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 alpha-amylase (CD-50), (3) CD reduced in 100 kcal ME/kg and no alpha-amylase (CD-100), (4) CD + 100 g of alpha-amylase/t (AM0), (5) CD reduced in 50 kcal ME/kg + 100 g of alpha-amylase/t (AM-50), (6) CD reduced in 100 kcal ME/kg + 100 g of alpha-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 alpha-amylase (CD vs AM), and ME-reduced diets without vs with alpha-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 matter, and energy (DE) were observed in finishing pigs from AM, and higher DE was found in pigs from AM-. Pig's meat from CD showed a greater red-green component. Pigs on AM or AM- had greater crude protein in the meat. In conclusion, supplementing alpha-amylase alone in ME-reduced diets improves