Determination of in vitro methane production of pomegranate peel and oregano pulp supplementation in ruminant diet

ABSTRACT This study was conducted to determine the effects of adding pomegranate peel and oregano pulp at different levels (2, 4, 6, and 8%) on a dry matter basis to sheep rations on methane production and rumen fermentation using the in vitro gas production technique. In the study, nine experimental groups were formed by adding different levels (2, 4, 6, and 8%) of pomegranate peel and oregano pulp to the total ration mixture (control ration). Each treatment group was designed with four replications. Rumen fluid was taken from two sheep that were fed mainly roughage. For each feed treatment, four gas production syringes were used. A trial design was created using a total of 40 gas production syringes, and four gas production syringes for blank samples. The prepared syringes were incubated for 24 h. The additive levels of pomegranate peel and oregano pulp did not change total gas, methane (%), and methane (mL) production compared with the control treatment. The use of pomegranate peel and oregano pulp for in vitro rations significantly reduced rumen fluid volatile fatty acid (VFA) levels, except for 2% pomegranate peel. In vitro organic matter digestibility and metabolizable energy levels of both additives were similar to the control ration. In the study, the addition of pomegranate peel and oregano pulp to total ration mixture at 2, 4, 6, and 8% levels did not change total gas and methane production. Except for the addition of 2% pomegranate peel, the treatments suppressed rumen fluid VFA. Besides, it is thought that the additives used in the study can be used up to 2% in the rations of ruminant animals in regions where they may create waste to reduce feed costs.