Effect of Echium amoenum extract on the growth rate and fermentation parameters of Mehraban lambs

This study aimed to evaluate the effect of Echium amoenum extract (EAE) supplementation at four levels 0 (control), 0.3 (E2), 1.5 (E3) or 3 (E4) ml/kg DM on the growth rate, and rumen ecosystem of Mehraban lambs. Forty-eight, six month old male growing lambs (initial average live weight of 32.1 ± 3.9 kg) were randomly assigned according to a completely randomized design to receive different levels of EAE. Growth rate, rumen fermentation parameters, protozoa, cellulolytic bacteria, apparent diet digestibility and nitrogen retention were evaluated. Inclusion of EAE decreased ammonia-N concentration in rumen liquor (quadratic (Q), P=0.047) at two days of sampling (day of sampling 35, DS35, and day of sampling 70, DS70). However, total volatile fatty acids (TVFA) (DS35, linear (L), P=0.027; DS70, control vs. EAE, P=0.018) and propionate (C3) (DS35, L, P=0.023; DS70, Q, P=0.011) concentrations were increased and acetate (C2) (DS35, control vs. EAE, P=0.026; DS70, L, P=0.001) and C2:C3 decreased by the addition of EAE at both sampling times. EAE showed a defaunating activity, since the total protozoal population and Entodininnae subfamily decreased considerably (L, P<0.0001). Nitrogen retention was increased by EAE supplementation (Q, P=0.008). It is concluded that EAE improved ruminal fermentation through increasing MP and decreasing ammonia-N concentration, C2:C3 ratio and protozoal population. However, it failed to improve apparent diet digestibility and growth rate of Mehraban lambs.