## 3 Results
### Heat-Treated Amaranth Grain  
The main effects of the HTAG level, enzyme addition and their interaction on AMEn, metabolisability and DMD are shown in Table 4. AMEn increased from the 0 and 150 inclusion rates, which did not differ, incrementally at higher inclusion rates. The 600 g/kg inclusion rate had an AMEn of 3788 compared with 3098 for 0/150 inclusion rates. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Factor** & **AMEn, kcal/kg** & **Metabolisability, \%** & **Dry Matter Digestibility (DMD), \%** \\ \hline Untreated amaranth grain & & & \\ (UAG), g/kg & & & \\ \hline
0 & 2869 b  & 75.59 a  & 66.65 a  \\
150 & 2606 d  & 70.17 c  & 61.11 c  \\
300 & 2732 c  & 70.12 c  & 60.10 c  \\
450 & 2889 b  & 72.45 b  & 63.02 b  \\
600 & 3189 a  & 74.99 a  & 59.83 c  \\ SEM & 20.83 & 0.39 & 0.63 \\ \(p\)-value & 0.0001 & 0.0001 & 0.0001 \\ \hline Enzyme (\({}^{\pm\mathrm{E}}\)), g/kg & & & \\ \hline
0 (\({}^{-\mathrm{E}}\)) & 2848 & 70.70 & 59.75 \\
0.55 (\({}^{\mathrm{E}}\)) & 2866 & 74.62 & 64.53 \\ SEM & 13.17 & 0.25 & 0.40 \\ \(p\)-value & 0.35 & 0.0001 & 0.0001 \\ \hline UAG \(\times\) Enzyme & & & \\ \hline
0 \(\times\) 0 & 2789 cd  & 74.15 bc  & 65.86 ab  \\
150 \(\times\) 0 & 2693 e  & 70.39 d  & 60.20 d  \\
300 \(\times\) 0 & 2723 d  & 67.23 e  & 56.48 e  \\
450 \(\times\) 0 & 2812 c  & 69.13 d  & 60.69 d  \\
600 \(\times\) 0 & 3224 a  & 72.63 c  & 55.54 e  \\
0 \(\times\) 0.55 & 2949 b  & 77.04 a  & 67.44 a  \\
150 \(\times\) 0.055 & 2518 f  & 69.95 d  & 62.01 cd  \\
300 \(\times\) 0.55 & 2742 cde  & 73.01 c  & 63.73 bc  \\
450 \(\times\) 0.55 & 2966 b  & 75.78 ab  & 65.35 ab  \\
600 \(\times\) 0.55 & 3154 a  & 77.35 a  & 64.12 bc  \\ SEM & 29.46 & 0.56 & 0.88 \\ \(p\)-value & 0.001 & 0.001 & 0.019 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: AMEn, metabolisability and dry matter digestibility (DMD) values of broiler chickens fed different levels of untreated amaranth grain (UAG) with (\({}^{\pm\mathrm{E}}\)) and without (\({}^{-\mathrm{E}}\)) enzyme from 35 to 42 d of age in the second experiment. The metabolisability of the diet tended to increase with inclusion rate above 300 g/kg, and the DM digestibility declined from 0 to 300 g/kg and then increased at higher rates. Enzyme addition increased AMEn, metabolisability and DM digestibility. The interaction between the two factors, heat treatment and enzyme addition, which were significant for all the variables, showed that there was a synergistic effect of amaranth inclusion at the highest level and enzyme inclusion, with AMEn increasing from 3720 without enzyme to 3855 with enzyme. Similarly, metabolisability was greater with enzyme addition at the highest amaranth inclusion rate (80.8 vs. 79.1). However, DM digestibility was similar for all treatments except at the zero amaranth inclusion rate, when enzyme addition increased the DMD from 64.6 to 69.6%. The regression analysis of AMEn values of amaranth grain as untreated and heat-treated forms in diets with/without enzyme addition on intake values of amaranth grain resulted in four prediction equations. The equations are presented in Table 5. All equations showed relatively high determination coefficient values (r\({}^{2}\)), from 98 to 99%. The solution of the four equations for x = 1 (100% substitution of amaranth grain in RD) resulted in four AMEn (kcal/kg) values, which were as follows: 3255, 3265, 3829 and 3973 for UAG\({}^{-\mathrm{E}}\), UAG\({}^{+\mathrm{E}}\), HTAG\({}^{-\mathrm{E}}\) and HTAG\({}^{+\mathrm{E}}\), respectively. The average value of AMEn, 3580 kcal/kg, represented 84% of GE content. Overall, the processing of untreated amaranth grain with enzyme and heat treatment improved AMEn values by 10 and 573 kcal/kg, respectively.