Crude coriander oil in the diet of lactating goats enhanced lactational performance, ruminal fermentation, apparent nutrient digestibility, and blood chemistry

•Coriander oil supplementation at 0.95 or 1.9 g/kg DM of diet was evaluated in goats.•Coriander oil supplementation linearly increased daily milk production.•Coriander oil supplementation reduced milk somatic cell and ruminal protozoal counts.•Coriander oil supplementation enhanced nutrient digestibility and ruminal fermentation.•The high level of coriander oil supplementation is recommended. The use of safe feed additives in diets of lactating animals has gained increasing interest. The effects of feeding lactating goats on diet supplemented with crude coriander oil at different levels were evaluated. Thirty multiparous lactating Damascus × Baladi goats (27.2 ± 1.0 kg BW) were used in 3 × 3 Latin square design (3 treatments, 3 periods, and 10 does per treatment). Each experimental period lasted 30 d (comprising 20 d of treatments adaptation and 10 d of sampling). The treatments consisted of the control basal diet with no crude coriander oil, the control basal diet supplemented daily with 0.95 g crude coriander oil/kg DM feed, or the control basal diet supplemented with 1.9 g crude coriander oil/kg DM feed. Crude coriander oil supplementation linearly increased (P < 0.05) daily milk production, yields of total solids, fat and lactose, and concentration of milk fat (P = 0.022) as well as feed conversion ratio (P = 0.021). Crude coriander oil supplementation linearly enhanced (P < 0.05) the apparent digestibilities of dry matter, organic matter, non-structural carbohydrates, and fibers, while the high crude coriander oil supplementation level increased apparent crude protein digestibility. Crude coriander oil supplementation linearly decreased ruminal pH and ciliate protozoal counts, and increased the concentrations (P < 0.05) of total volatile fatty acids, acetate, propionate and valerate. Crude coriander oil supplementation linearly increased (P < 0.05) the concentration of blood glucose and linearly decreased (P < 0.05) the serum levels of alanine transaminase and aspartate aminotransferase, while the high coriander oil treatment decreased the concentrations of total lipids (P = 0.038) and cholesterol (P = 0.021). In conclusion, crude coriander oil supplementation at 0.95 or 1.9 g crude coriander oil/kg DM feed improved nutrient utilization, milk production, and milk nutritive value. The high level of supplementation is recommended.