## 3 Results and Discussion
### Milk and IF Fatty Fraction
Human milk contains cholesterol [1] which is a functional and structural constituent of the cell membrane and is needed by the infant in challenging the development of cholesterol metabolizing enzymes. Cholesterol contributes to synthesis of nerve tissue, bile salts, steroid hormones, and vitamin D [31; 32]. Moreover, it should be considered that the addition of vegetable oils to the final FM brings, as by-products, phytosterols, the effect of which on the cholesterol homeostasis and enzymatic systems in infants is not known. The fatty acid profile of milk and liquid milk-derived formulations IF1 and IF2 was also studied. The results are reported in Table 5, together with the main categories of fatty acids of nutritional interest. The fatty acid composition of the whole milk (Table 5) is in agreement to reports from other authors for sheep milk [9; 26; 33] and, in particular, for milk from Sarda sheep fed typical Mediterranean forages [34; 35]. As expected, the fatty acid profiles were similar between whole milk, IF1, and IF2 formulations (_p_ > 0.05). In fact, the fat content of the two formulations was derived completely from the utilized whole milk. The two formulations (IF1 and IF2) were tailored to provide about 20% and 50%, respectively, of the total fat in the final infant formulae. Currently, the fatty fraction of the commercial infant formulae is mainly derived from mixtures of vegetable oils, while a progressive reduction in the use of bovine milk fat was observed over the years [36]. \begin{table}
\begin{tabular}{l c c c} \hline  & **Whole Milk** & **IF1** & **IF2** \\  & **(_t_ = 6)** & **(_t_ = 6)** & **(_t_ = 6)** \\ \hline Retinol & 0.84 \(\pm\) 0.21 \({}^{\text{a}}\) & 0.17 \(\pm\) 0.02 \({}^{\text{c}}\) & 0.42 \(\pm\) 0.10 \({}^{\text{b}}\) \\ \(\alpha\)-Tocopherol & 1.72 \(\pm\) 0.17 \({}^{\text{a}}\) & 0.47 \(\pm\) 0.05 \({}^{\text{c}}\) & 1.01 \(\pm\) 0.07 \({}^{\text{b}}\) \\ Cholesterol & 202 \(\pm\) 13 \({}^{\text{a}}\) & 112 \(\pm\) 9 \({}^{\text{c}}\) & 139 \(\pm\) 8 \({}^{\text{b}}\) \\ C4:0 & 4.0 \(\pm\) 0.2 & 3.9 \(\pm\) 0.2 & 4.0 \(\pm\) 0.2 \\ C6:0 & 3.1 \(\pm\) 0.1 & 3.1 \(\pm\) 0.1 & 3.2 \(\pm\) 0.1 \\ C8:0 & 2.8 \(\pm\) 0.1 & 2.8 \(\pm\) 0.1 & 2.8 \(\pm\) 0.1 \\ C10:0 & 9.1 \(\pm\) 0.3 & 9.1 \(\pm\) 0.4 & 9.0 \(\pm\) 0.2 \\ C12:0 & 5.2 \(\pm\) 0.2 & 5.3 \(\pm\) 0.2 & 5.2 \(\pm\) 0.2 \\ C14:0 & 14.0 \(\pm\) 0.4 & 14.0 \(\pm\) 0.3 & 13.7 \(\pm\) 0.5 \\ C16:0 & 30 \(\pm\) 1 & 30 \(\pm\) 1 & 30 \(\pm\) 1 \\ C18:0 & 5.5 \(\pm\) 0.2 & 5.7 \(\pm\) 0.2 & 5.5 \(\pm\) 0.3 \\ C18:11 _1 trans_ & 0.9 \(\pm\) 0.1 & 0.9 \(\pm\) 0.1 & 0.9 \(\pm\) 0.2 \\ C18:1 9 _cis_ & 10.7 \(\pm\) 0.7 & 11.1 \(\pm\) 0.9 & 10.7 \(\pm\) 0.3 \\ C18:2 9 _cis_ 12 _cis_ & 1.73 \(\pm\) 0.15 & 1.77 \(\pm\) 0.15 & 1.81 \(\pm\) 0.11 \\ C18:3 9 _cis_ 12 _cis_ 15 _cis_ & 1.6 \(\pm\) 0.4 & 1.5 \(\pm\) 0.3 & 1.8 \(\pm\) 0.6 \\ CLA 9 _cis_ 11 _trans_ & 0.56 \(\pm\) 0.05 & 0.60 \(\pm\) 0.05 & 0.58 \(\pm\) 0.06 \\ SFAs & 79 \(\pm\) 1 & 78 \(\pm\) 1 & 78 \(\pm\) 1 \\ MUFAs & 15.6 \(\pm\) 0.6 & 16.1 \(\pm\) 0.9 & 15.9 \(\pm\) 0.1 \\ PUFAs & 5.6 \(\pm\) 0.7 & 5.5 \(\pm\) 0.3 & 5.9 \(\pm\) 0.9 \\ Omega-6 & 2.3 \(\pm\) 0.2 & 2.3 \(\pm\) 0.2 & 2.4 \(\pm\) 0.1 \\ Omega-3 & 2.3 \(\pm\) 0.6 & 2.1 \(\pm\) 0.4 & 2.5 \(\pm\) 0.7 \\ TFAs & 3.2 \(\pm\) 0.5 & 3.3 \(\pm\) 0.3 & 3.4 \(\pm\) 0.6 \\ \hline \end{tabular}
\end{table} 
Table 5: Retinol, \(\alpha\)-tocopherol, cholesterol content (expressed as mg kg\({}^{-1}\)) and fatty acid profile expressed as % of total fatty acid methyl esters (FAMEs) in the ovine milk and liquid milk-derived formulations IF1 and IF2, to be used in the production of first stage (from 0 to 6 months of age) and follow-on (from 6 to 12 months of age) infant formulae, respectively (mean \(\pm\) SD). Recently, sheep's milk has received growing attention and it is already used for infant formula production in some countries (China and New Zealand) [3]. In fact, sheep's milk has interesting nutritional features, some of which are related to the fatty fraction [6; 9; 10].