## 3 Results and Discussion
### Short-Chain Fatty Acids in the Calves' Faces  
The quantitative SCFA profiles of the calves' faeces before the experiment and after 14 days of feeding with fermented MP are given in Table 6. There were significant differences between the CON0 and MP0 groups in the concentrations of most of the faecal SCFA (\(p\) < 0.05). However, there was no significant difference between the two groups in the concentrations of acetic and butyric acids, which were the most prevalent faecal SCFA in both groups. Valeric and capric acids were not found in the CON0 group, while the concentrations of propionic and butyric acids in the MP0 group were significantly higher (by 2-fold and 77%, respectively) than in the CON0 group. There were also significant differences between the CON14 and MP14 groups in the concentration of each SCFA (\(p<0.05\)), with the exception of caproic acid. After 14 days, the predominant SCFA in the faeces of both groups were acetic, propionic, and butyric acids. The concentration of each of these acids was significantly higher in the MP14 group than in the CON14 group by 34.3%, 57.3%, and 22.3%, respectively. However, after 14 days, these predominant SCFA had increased from baseline concentrations in both groups. Acetic acid increased 4.9- and 4.6-fold in the CON14 and MP14 groups, respectively, while propionic acid increased 19.6- and 32.9-fold, respectively, and butyric acid increased 6.2- and 4.3-fold, respectively (Table 6). In young ruminants, milk-based feeds are mainly digested in in the intestines due to their underdeveloped rumen [55]. SCFA are end products of the microbial fermentation and provide energy to the gut cells. It has been reported that branched-chain SCFA (isobutyric and isovaleric acids) are formed during utilisation of nondigested proteins \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**SCFA**} & \multicolumn{4}{c}{**Calf Groups**} & \multicolumn{4}{c}{\(p\)} \\ \cline{2-9}  & \multicolumn{2}{c}{**CIN0**} & \multicolumn{2}{c}{**CON14**} & \multicolumn{2}{c}{**MP0**} & \multicolumn{2}{c}{**MP14**} & \multicolumn{2}{c}{**CON0\(\times\)**} & \multicolumn{2}{c}{**MP0\(\times\)**} & \multicolumn{2}{c}{**CON0\(\times\)**} & \multicolumn{2}{c}{**CON14**\(\times\)} \\ \cline{2-9}  & \multicolumn{2}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} \\ \hline Acetic & 13.32 \(\pm\) 4.89 & 65.01 \(\pm\) 13.59 & 19.11 \(\pm\) 3.45 & 87.31 \(\pm\) 11.29 & 0.009 & 0.015 & 0.352 & 0.004 \\ Proiponic & 0.461 \(\pm\) 0.053 & 20.07 \(\pm\) 4.23 & 0.959 \(\pm\) 0.142 & 31.58 \(\pm\) 4.26 & 0.015 & 0.006 & 0.010 & 0.0001 \\ Isobutyric & 0.144 \(\pm\) 0.053 & 1.13 \(\pm\) 0.20 & 0.013 \(\pm\) 0.004 & 2.82 \(\pm\) 0.48 & 0.007 & 0.009 & 0.044 & 0.009 \\ Butyric & 2.60 \(\pm\) 0.51 & 16.20 \(\pm\) 2.21 & 4.60 \(\pm\) 0.57 & 19.82 \(\pm\) 3.49 & 0.005 & 0.855 & 0.384 & 0.039 \\ Isovaleric & 0.242 \(\pm\) 0.031 & 1.37 \(\pm\) 0.42 & 0.074 \(\pm\) 0.014 & 4.02 \(\pm\) 0.31 & 0.037 & 0.002 & 0.003 & 0.001 \\ Valeric & md & 0.874 \(\pm\) 0.076 & 0.024 \(\pm\) 0.005 & 0.618 \(\pm\) 0.082 & - & 0.006 & - & 0.0001 \\ Caproic & md & 0.128 \(\pm\) 0.34 & 0.121 \(\pm\) 0.036 & 0.078 \(\pm\) 0.011 & - & 0.023 & - & 0.064 \\ _Total_ & 16.767 & 104.782 & 24.901 & 146.246 & - & - & - & - \\ \hline \hline \end{tabular} The data are presented as the mean \(\pm\) SEM (\(n=10/\)group). 0, baseline measurements; 14, after 14 days of feeding. nd, not detected.  
\end{table} 
Table 6: Short-chain fatty acids (SCFA) in faeces in the calf group fed with milk replacer only (CON0 and CON14 group) or supplemented with fermented milk permeate (MP0 and MP14 group).