LAUSR

Abstract The 4 experimental diets, all containing rapeseed oil, consisted of one control and 3 other diets supplemented with 3 different levels of commercial oenological extracts tannins (i.e. 3, 6 and 9 g/kg dry matter (DM), respectively). The effect of the added tannins on the fatty acid profiles of ruminal fluid was tested in vitro, and 20 multiparous Liuyang black nannies [average body weight (BW): 26.3 ± 0.5 kg] at week 6 of lactation were used in an in vivo experiment. For the in vitro experiment, the inclusion of dietary tannins did not ( P > 0.05) affect fatty acid contents in the culture fluid in vitro, except the percentage of total conjugated linoleic acid (CLA) tended to increase (quadratically, P = 0.075) with increasing tannins level. Increasing incubation time decreased the percentage of total cis C17:1 ( P = 0.001), cis -11 C18:1 ( P cis -12 C18:1 ( P trans -11 C18:1 ( P = 0.016), total cis C18:1 ( P P cis -9, cis -12 C18:2 n-6 linoleic acid (LA) ( P P UFA) ( P = 0.001). In the in vivo experiment, concentration of C16:1 in goat milk linearly increased ( P = 0.032) and that of cis -11 C18:1 tended (quadratic effect, P = 0.072) to increase with increasing levels of tannins. Tannin inclusion did not affect ( P > 0.05) the content of protein, lactose, ash, solid not fat and total solids in the goat milk, but higher levels of tannins reduced milk fat content ( P = 0.005), compared with the control diet. Compared with the control, tannins inclusion decreased concentrations of cis -11 C20:1 ( P = 0.022) and total n-9 monounsaturated fatty acids (MUFA) ( P = 0.017) in milk at the 3 g/kg DM inclusion rate, decreased C11:0 ( P = 0.012) and C13:0 ( P = 0.029) at 6 g/kg DM, but increased cis -9 C18:1 ( P = 0.043) and C22:6 n-3 docosahexenoic acid (DHA) ( P = 0.013) at the 9 g/kg DM inclusion rate. Concentrations of cis -14 C18:1, cis -9, cis -12 C18:2 n-6 LA, total cis MUFA, PUFA, n-3 and n-6 PUFA in milk linearly increased ( P