Effects of carvacrol and cinnamaldehyde on intake, rumen fermentation, growth performance, and carcass characteristics of growing lambs

Effects of essential oil compounds (EOC) on feed intake, ruminal fermentation, growth performance, and carcass characteristics were determined using 60 lambs (24.6 ± 0.77 kg initial live weight, LW) fed either a barley- or corn grain-based diet without supplementation (control), or supplemented with 0.2 g/kg (DM basis) of carvacrol (CAR) or cinnamaldehyde (CIN). The experimental diets were arranged as a 2 × 3 factorial with 11-week periods and fed to lambs ad libitum. Ruminal pH tended (P=0.06) to be lower and total volatile fatty acid (VFA) concentration was higher (P<0.01) for barley- versus corn-based diets. Addition of EOC reduced (P=0.02) ruminal pH and increased (P=0.03) total VFA concentration versus the control. Acetate and propionate molar proportions and ammonia concentration did not differ among treatments. Inclusion of EOC in barley- or corn-based diets did not alter dry matter intake or average daily gain of lambs. Lambs fed the control diets tended (P=0.10) to have lighter livers than those fed diets containing EOC. Neither type of grain nor inclusion of EOC substantially affected sensory attributes of lamb sirloins.