A team of researchers in Brazil explored the use of two different enzymes alone or combined in the diets of broiler chickens along with differing levels of dietary energy. The group published their results in the journal of Animal Feed Science and Technology.
They found growth performance was improved when birds were fed maize-soy diets with higher energy levels, while exogenous amylase, xylanase and the combination of amylase and xylanase were able to improve energy release for broilers.
Apparent metabolisable energy estimates for the entire period were 0.41, 0.35, and 0.57 MJ/kg for BWG; and 0.18, 0.11, and 0.21 MJ/kg for FCR when broilers were fed amylase, xylanase, and amylase + xylanase, respectively.
The research project was partially funded by the Conselho Nacional de Pesquisa (CNPq – Brasilia, DF, Brazil) and DSM Nutritional Products (São Paulo, SP, Brazil).
Broiler diets with additive enzymes aimed at degrading cell wall polysaccharides may offer access for pancreatic enzymes to nutrients locked within the cell, said the researchers. And reducing the cell wall also may release oligosaccharides and monosaccharides absorbable by the intestinal microbiome to offer volatile fatty acids and simulate hormone mechanisms that can be used as energy.
Improvements in nutrient availability and energy use from feed ingredients have been linked with improved broiler performance, they said. Enzymes can be used to reduce feed costs while supporting weight gain, feed efficiency and reducing nutrient elimination.
“Although chicks are adapted to starch-based diets soon after hatch, the high feed intake of modern broilers may produce a physiological limitation to starch digestion,” they said. “Thus, α-amylase supplementation in maize-based diets may improve starch digestibility, energy utilization, and performance of broilers.”
Exogenous xylanase and amylase influence different substrates and do not complete for substrate degradation, but they may produce similar effects for nutrient digestion and performance, said the researchers. “However, whilst fully additive or synergistic effects of xylanase and amylase may be unlikely, it is possible that biologically and economically significant effects of this combination will be apparent,” they added.
In the feeding trial, 1,800 broilers were given one of eight diets for 40 days, said the researchers. All birds were given a starter diet from days 1 to 21 and a finisher diet from day 22 to 40.
The trial diets included the control diet with a-amylase at 80 kilo-Nova alpha-amylase units (KNU), and the control diet with beta-zylanase at 100 fungal b-xylanase units (FXU) and a diet with both a-amylase and b-zylanase, they said. The enzymes used are commercially available.
A negative control (NC) was mixed to offer 12.35 MJ/kg in the starter and 12.85 MG/kg in the finisher phases, they said.
Four other control diets were designed to offer amounts of orthogonal energy increasing by 0.21 MJ/kg to a maximum of 13.17 MJ/kg in the starter and 13.67 MJ/kg in the finishing dietm, said the researchers. “The four AMEn increments in the NC diet consisted of 0.21 MJ/kg (NC + 0.21), 0.42 MJ/kg (NC + 0.42), 0.63 MJ/kg (NC + 0.63), and 0.84 MJ/kg (NC + 0.84),” they added.
“From 1 to 21 d, broilers were fed experimental diets having 12.35, 12.56, 12.77, 12.98, and 13.19 MJ/kg of AMEn for NC; NC + 0.21; NC + 0.42; NC + 0.63, and NC + 0.84, respectively,” said the researchers. “From 22 to 40 d, broilers were fed experimental diets having 12.85, 13.06, 13.27, 13.48, and 13.69 MJ/kg of AMEn for NC; NC + 0.21; NC + 0.42; NC + 0.63, and NC + 0.84, respectively.”
Chick weights were recorded at the start and on days 1,7, 14, 21, 28, 35 and 40, they said. Body weight gain , feed intake (FI), the feed conversion ratio were calculated both weekly and for the first and second phases of the feeding trial.
Increasing the apparent metabolizable energy corrected for zero nitrogen retention (AMEn) linearly improved body weight gain and reduced the feed conversion ratio, said the researchers.
“No differences between NC + 0.42 and NC + amylase or NC + xylanase + amylase were observed on BWG and FCR in the cumulative periods,” they said. “From 1 to 40 d, the BWG of broilers fed the NC + 0.84 MJ/kg diet was significantly better than the NC and NC + 0.21 MJ/kg diet.”
Birds getting the control diet with 0.84 MJ/kg had the best FCR compared to the control, they said. Adding the supplemental a-amylase and b-xylanase increased estimated energy yields when added to corn-soy-based diets: “Linear adjustments for BWG and FCR were obtained from placement to the end of the study when birds were fed amylase, xylanase, or the combination.
But the a-amylase outperformed b-xylanase, and adding a combination of the two enzymes offered similar production reactions to use of a-amylase in terms of AMEn, said the researchers.
“Body weight gain increased linearly when broilers were fed diets with increasing AMEn levels,” said the researchers. “Feed conversion ratio was linearly decreased as AMEn was reduced.”
Source: Animal Feed Science and Technology
Title: Effects of energy, α-amylase, and β-xylanase on growth performance of broiler chickens
DOI: published online before print: 10.1016/j.anifeedsci.2017.01.019
Authors: C. Stefanello, S. Vieira, H. Rios, C. Simões, P. Ferzola, J. Sorbara, A. Cowieson