Effects of Sweet Marjoram (Origanum majorana) Powder on Growth Performance, Nutrient Digestibility, Rumen Fermentation, Meat Quality and Humoral Immune Response in Fattening Lambs

The use of natural compounds such as herbs and herbal preparations because of their effects on animal health and product quality, is becoming a new goal in livestock production. Therefore, an experiment was carried to evaluate the effects of sweet marjoram on growth performance, rumen fermentation, meat quality and humoral immune response in Kermani lambs. A total of 24 Kermani lambs (27.5±0.450 kg) were dis-tributed randomly into 24 individual cages in 3 experimental groups. The experimental diets consisted of the control and two experimental diet contained 2 and 4 % Origanum majorana leaf (OML) powder. The lambs were weighed and slaughtered after a feeding period of 80 days and meat quality were determined. OML powder had no effects on dry matter intake, but the apparent protein digestibility was higher linearly (P<0.05) for the diets containing OML powder. Live weight gain, final and carcass weight increased (P<0.05) with adding of OML in diet linearly. NH3-N concentration and protozoa population were less (P<0.05) with 2 and 4% OML than control. Fat and total protein linear decreased and increased (P<0.05) respectively in meat by adding of OML powder in diet, and longissimus dorsi of lamb fed OML powder had lower (P<0.05) malonaldehyde and cooking loss than the control diet linearly. The results suggest that OML is useful for improvement ruminal fermentation and is a suitable natural antioxidant in the meat pro-duction industry.