Determination of nutritive value, in vitro gas production parameters and digestibility of different kinds of weed plants

This study was conducted to investigate chemical composition, gas production parameters and digestibility of dominant species of weed plants on in vitro conditions. In this experiment, samples of Echinochola crus-gali, Portulaca oleracea, Sorghum halepense, Amaranthus retroflexus, Chenopodium album and Cynodon dactylon were collected from the Gonbad Kavoos area before seeding. The mean annual rainfall amount is below 450 mm and means annual temperature is above 20 °C. Plant specimens were dried in an oven at 60 °C until they reached constant weight and milled to pass a 1 and 1.5 mm screen. Their nutritive value was evaluated through determination of chemical compositions and in vitro gas production techniques. Samples were tested in an in vitro gas production method (96 h incubation) and batch rumen culture system (24 h incubation). Results showed that there were differences among treatments on chemical composition (P<0.05). Portulaca oleracea had highest Ash and crude protein and lowest NDF and total phenol. Highest content of NDF and total phenol and lowest Ash was related to Sorghum halepense. There were significantly differences among treatments on gas production parameters and Portulaca oleracea and Chenopodium album had lowest lowest and highest gas productionpotential, respectively. Highest and lowest short chain fatty acid content and OMD were related to Echinochloa crus-galli and Chenopodium album, respectively. Portulaca oleraceaand Sorghum halepense had highest and lowest in vitro DMD and OMD, microbial crude protein and microbial crude protein efficiency, respectively. The obtained results of this study showed that different weed plants have different nutritive value; however, these plants can be regarded as feed resources for animal nutrition. In general, the results showed that the weeds in the fields are nutritionally different, which is due to differences in the chemical composition and their nature.