The present study was carried out at the Animal Research Farm, Faculty of Agriculture, Suez Canal
University, Ismailia, Egypt: in vitro assay. The treatments were: 1- control: concentrate feed mixture (CFM) + Rice
straw (RS) (2:1) without additives, 2- control diet + garlic powder 0.5%, 3- control diet + garlic powder 1%, 4- control
diet + garlic powder 1.5%, 5- control diet + garlic powder 2%, 6- control diet + garlic powder 2.5%, 7- control diet +
cinnamon powder 0.5%, 8- control diet + cinnamon powder 1%, 9- control diet + cinnamon powder 1.5%, 10- control
diet + cinnamon powder 2%, 11- control diet + cinnamon powder 2.5%, 12- control diet + peppermint powder 0.5%,
13- control diet + peppermint powder 1%, 14- control diet + peppermint powder 1.5%. 15- control diet + peppermint
powder 2% and 16- control diet + peppermint powder 2.5%. Ten digestibility trials were conducted on sheep to
evaluate the experimental rations as the following treatments: Ration 1- (Control): (CFM) and wheat straw (WS) (ratio
2:1) without any additives, Ration 2- CFM and WS + 1.5% garlic powder, Ration 3- CFM and WS + 2% garlic powder,
Ration 4- CFM and WS + 2.5% garlic powder, Ration 5- CFM and WS + 1.5% cinnamon powder, Ration 6- CFM and
WS + 2% cinnamon powder, Ration 7- CFM and WS + 2.5% cinnamon powder, Ration 8- CFM and WS + 1.5%
peppermint powder, Ration 9- CFM and WS + 2% peppermint powder and Ration 10 CFM and WS + 2.5% peppermint
powder. Most treatments significantly increased in vitro dry matter disappearance (IVDMD) and in vitro organic matter
disappearance (IVOMD) compared with control. 2% garlic and 2.5% cinnamon significantly decreased gas production
after 24 hr. The digestibility trials showed that the three plants by 2.5% has given the best results and dry matter
digestibility was significantly increased except garlic and significantly increased organic matter, crude protein, crude
fiber, nitrogen free extracts and nutritive values as TDN and DCP. It could be concluded that the three plants as a nature
additives in ruminant diet decreased gas production and improved animal digestibility.