# Utilization of Wool Integral Lipids to Determine Milk Fat Content in Suffolk Down Ewes
## 3 Results
### Wool Fat and Fatty Acid Composition  
There was no difference in wool fat content between groups with low or high milk fat contents at either 30 or 60 days. The fat content of wool was 1.14% on average. The principal component of wool FAs was saturated fatty acid (SFA), which contributed 65.82 \(\pm\) 1.84% of FAMEs. With the lowest proportions, monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids represented 21.70 \(\pm\) 1.09% and 12.48 \(\pm\) 1.24%, respectively, of the total FAMEs. The predominant FAs in the wool samples were C16:0, C18:0, and C18:1n9c, which together represented 57.42% of total FAMEs. C16:0 followed by C18:0 were the main FAs in the SFA fraction. These FAs represented 28.87 \(\pm\) 0.94% and 17.17 \(\pm\) 0.65% of the total SFA in wool FAs, respectively. C18:1N9c (11.38 \(\pm\) 1.19%) and C14:1 (5.56 \(\pm\) 0.39%) were the MUFAs with the highest contents. C22:6n3 and C18:2n6c were the FAs found at the highest proportions in the PUFA fraction (5.63 \(\pm\) 0.51% and 4.78 \(\pm\) 0.54%, respectively). The groups were classified according to milk fat content variables (Table 2), as high and low fat content over two lactation periods (30 and 60 days). Both groups differed significantly in the milk fat variable (\(p\) < 0.05). For each time point classification (30 and 60 days), several FAs were significantly different between groups for milk fat content (\(p\) < 0.05). The FAs C18:1n9c, C18:2n6c, and C22:2 exhibited a higher concentration of wool FAs in both classifications (30 and 60 days) when milk had a high fat content. In particular, in the first period of 30 days in milk, ewe milk with a high fat content had high levels of the FAs C14:0 and C20:3n6, and lower concentrations of C14:1 and C15:0 in wool. By contrast, the milk collected at 60 days showed significant changes in the concentration of ten FAs, including the FAs C16:0, C18:0, and C24:1n9. The concentrations of the FAs C10:0, C13:0, C14:1, C16:0, C16:1, C18:0, and C24:1n9 increased in this period in wool when the ewe milk had a high fat content (\(p\) < 0.05). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Fatty Acid** & \multicolumn{2}{c}{**Pasture**} & \\ \cline{2-3}
**(mg/g DM)** & **30 Days in Milk** & **60 Days in Milk** & **Oat** \\ \hline C16:0 & 0.23 & 0.10 & 8.46 \\ C18:0 & 0.08 & 0.03 & 1.57 \\ C18:1n9c & 0.03 & 0.02 & 25.75 \\ C18:2n6c & 0.23 & 0.07 & 23.56 \\ C18:3n3 & 1.33 & 0.44 & 0.24 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Fatty acid composition of pasture and oat. The FA proportion (SFA, MUFA, and PUFA) and desaturase index (DI) differed significantly between wool collected during the two different time periods (30 and 60 days), in terms of the milk fat content variable (\(p<0.05\)). For each classification, only the concentration of total PUFA in wool FAs exhibited significant differences between both periods and milk fat content. Ewe milk with a high fat content at 30 and 60 days exhibited a higher PUFA content of wool FAs (\(p<0.05\)). No significant differences were observed in the SFA and MUFA fractions at 30 days in milk (\(p>0.05\)). However, in the classification of 60 days in milk, the concentration of SFA and MUFA differed significantly in relation to the milk fat content variable. The fraction of the FAs SFA and MUFA exhibited the greatest concentration in wool from ewes with a higher milk fat content. The DI range was 0.55-0.73 for DI C14, 0.01-0.02 for DI C16, and 0.19-0.32 for DI C18. Moreover, the DI only differed significantly between the milk groups collected at 30 days, in comparison to those at 60 days. In the 30-day wool, the DI C14 was higher in the low milk fat content group, whereas the DI C18 was higher in the high milk fat group. No significant differences were found in the DI C16 group (\(p>0.05\)).