Effects of R osmarinus officinalis L . essential oils supplementation on digestion, colostrum production of dairy ewes and lamb mortality and growth

The aim of this study was to evaluate the effect of rosemary essential oils ( REO ) and the forage nature on ewes' performances, immune response and lambs' growth and mortality. Forty‐eight dairy ewes (Sicilo‐Sarde) were fed oat‐hay or oat‐silage supplemented with 400 g of concentrate during pregnancy and 600 g during postpartum. The experimental concentrate contained the same mixture as the control (barley, soybean meal and mineral vitamin supplement) more 0.6 g/kg of REO . Two groups were obtained with each forage (Hay groups: H ‐ C and H ‐ REO ; Silage groups: S ‐ C and S ‐ REO ). REO increased the dry matter ( DM ) intake, the nitrogen intake and retention being higher with the silage groups ( P  < 0.05). REO increased solid non‐fat ( P  = 0.004) and fat contents of colostrum which was higher with hay ( P  = 0.002). REO decreased lamb mortality ( P  < 0.05) which averaged 21% for control groups and 6% for H ‐ REO , while no mortality was recorded with S ‐ REO . REO dietary supply improved forage intake and tended to ameliorate colostrum production; it could be a natural additive to improve ewes' performances.