Effects of anise, clove and thyme essential oils supplementation on rumen fermentation, blood metabolites, milk yield and milk composition in lactating goats

Abstract

The present study evaluated the effects of essential oil (EO) from anise (AO), clove (CO) and thyme (TO) on the performance of lactating Shame goats. Eight lactating Shame goats with average body weight 34.90 ± 0.9 kg and 3 years old were randomly assigned to four treatments in a duplicated 4 × 4 Latin square design, with four periods of 22 days. In each period, the goats were adapted to the treatments for 15 days and the remaining 7 days was used for sample collection. Goats were fed a basal diet without supplementation (control) or supplemented with anise (AO), thyme (TO) or clove (CO) at a daily dose of 2 mL/head/d. Feed intake was not affected by EO supplementations. Digestibility of organic matter, ether extract and acid detergent fibre was higher (P < 0.05) with EO supplementations when compared with the control. Supplementations of EO had no effect on milk (g/d) yield, protein and lactose, as well as the composition (g/kg) of protein and lactose. Fat yield (g/d) and fat content (g/kg) were greater (P < 0.05) in EO supplemented goats versus those on the control diet. Compared with control, ruminal ammonia-N was not affected whereas, ruminal pH was increased (P = 0.02) with EO supplementations. Rumen total volatile fatty acid concentration and molar proportion of acetate (C2) were higher (P < 0.05) in goats fed CO and TO compared to control, whereas propionate (C3) and butyrate (C4) and C2:C3 proportions were unchanged with EO inclusion. With the exception of a decrease (P = 0.05) in blood urea nitrogen (BUN) with EO supplementations, other blood parameters were not affected. Milk C8 and C12 fatty acids (FA) were lower (P < 0.05) with EO supplementations compared with control. Composition of unsaturated and monounsaturated FA was higher (P < 0.05) and polyunsaturated FA was decreased (P < 0.05) with EO supplementations compared with control. Proportions of C18:1 n-9 C18:3 n-3 and n-3 FA were increased (P < 0.05) and proportions of C18:3 n-6 C20:4 n-6 and n-6 FA were decreased (P < 0.05) in goats fed EO compared to the control group. Overall, all three EOs tested in this study had beneficial effects on digestion, rumen fermentation parameters and milk composition including milk FA profile. Supplementation of CO and TO tended to increase PUFA concentration in the milk which supports their recommendation in the diet of lactating ruminants.