effects of oregano, cumin and sweet orange essential oils on chemical composition and degradability coefficients corn silage in in-vitro condition

introduction this study was conducted to evaluate the effect of essential oils of oregano, sweet orange and cumin on chemical composition, parameters of gas production capacity, aerobic stability and degradability of dry matter corn silage carried. secondary metabolites such as essential oils have antimicrobial properties that by adjusting ruminal fermentation in ruminants to improve the use of nutrients. oils or extracts of medicinal plants studied could be a viable alternative to ionophores and antibiotics. while improving energy efficiency and the use of nitrogen in the rumen and reduce the production of methane and nitrogen excretion as environmental pollutants, antibiotic resistance in human pathogens reduced to its minimum essential oils may be used in ruminant nutrition because silage and rumen fermentation depends on the microbial activity that can be affected by essential oils. studies show the effects of essential oils on different processes in the rumen. the positive effects of antimicrobial essential oils has led the researchers sought to evaluate the potential of these materials are for controlling and improving rumen fermentation as a method of improving feed efficiency . given that the effective range of essential oils and their compounds are widespread and many of them have still not been studied, this study was to evaluate these essential oils on ruminal fermentation parameters. materials and methods corn forage was harvested at 30 to 31% of dry matter (dm) content and chopped with a forage harvester to a theoretical of 50, 100 and 150 mgeokg−1 dm. to determine dry matter, crude protein, crude fat and ash from the recommended methods aoac (1990) was used. as well as to determine neutral detergent fiber (ndf) and acid detergent fiber (adf) of van sousse and colleagues van soest et al.,(1991) were used. adf was also the hemicellulose length of 1–2 cm. essential oil (eo), cumin (cum), oregano (ore) was dissolved in 0.5 v/v aqueous ethanol and sprayed onto the forage at a rate of 5.56 ml kg−1 silage. the oils were applied to the forage to achieve final concentrations fraction of ndf (chaves et al., 2012). the concentration of ammonia nitrogen were determined using the method mu and by device (kjeltec auto 1030 analyzer tecator). measurement parameters gas production with the method menke and. steingass (1988). estimates omd and me according to equations (makkar. 2004) were determined. estimation of short chain fatty acids according to equation gottschalk (1986) was determined. determine the parameters of degradability matter in samples studied was by proposed equation orskov and i. mcdonald (1979). the data was analyzed considering a completely randomized design. results and discussion the ph of corn silage treated with oregano 150 and cumin 150 decreased in comparison with control treatment significantly (p<0/05). treatment oregano 150 had a more crude protein than the control treatment (p<0/05). treatments oregano 100, oregano 150 and cumin 150 decreased ammonia nitrogen concentration compared to control treatment(p<0/05). treatments oregano 100, oregano 150 and sweet orange 150 increased gas production parameters part of fermentable than control treatment significantly(p<0/01). treatments cumin 50, cumin 150 and .sweet orange 150 decreased part of fermentable than the control treatment significantly (p<0/01). treatments oregano 100 was also increased rate constant of gas production (p<0/01). however oregano 50 and sweet orange 50 reduced gas production rate constant (p<0/01). oregano 100 and 150, increased short-chain fatty acids, metabolizable energy and digestibility organic matter compared to the control treatment significantly (p<0/01). cumin 100 and 150 decreased the digestibility of dry matter, organic matter, short-chain fatty acids and organic matter digestibility in comparison with control significantly (p<0/01). silages treated with cumin 150, 100, oregano 150, 100 and orange 150 had greater aerobic stability compared to the control treatment (p<0/01). corn silage dry matter degradation in in vitro was not affected by the different treatments. in general, the addition of oregano essential oil to corn silage produced more gas. in general add oregano essential oil to corn silage produced more gas. oregano essential oil also has the ability to produce gas, energy metabolism, short-chain fatty acids, organic matter digestibility of dry matter and organic matter digestibility higher compared to the control group. it seems that the essential oil of oregano has been able to protect ensile well of nutrients in the process.