عنوان مقاله [English]
Background and aim: One of the destructive effects of climate change is the reduction of precipitation and global warming which is leading to shortage of water resources. Therefore, it seems necessary to introduce water-resistant plants that are resistant to heat and drought (as sources of new forage plants). In this regard, the cultivation of dehydrated and drought-resistant forage (such as new cultivars of amaranth) was on the agenda. There is little information about the silage formation and nutritional value of forage of new Amaranth cultivars (in hot and humid Golestan province). The aim of this study was to determine the characteristics of silage, fermentability, digestibility, energy and metabolizable forage protein of three new cultivars of amaranth cultivated in Golestan province. Materials and Methods: Forage of three new Amaranth cultivars including Laura, Sim and Kharkovsky. They were grown on a research farm Arqi-mahaleh in Golestan province and harvested at the time of flowering. These forages were chopped into pieces of two to four centimeters and mixed with a weight ratio of five percent molasses and five percent wheat straw. They were stored in silage in 10kg buckets. After 45 days (in the laboratory of the Animal Science Research Institute), the silos were reopened. Sensory evaluation and silage properties of experimental treatments, were measured. Then chemical compounds including dry matter (field and silage), crude protein, crude ash, crude fat, soluble sugar, were analyzed. Gas production test (by Menke and Steingass method) using ruminal leachate of three cows (by ruminal fistulation) and at different fermentation times including 2, 4, 6, 8, 12, 24, 48, 72, 96 hours were done. Digestibility, determination of energy and metabolizable protein (in a completely randomized design with six treatments in three replications) was performed. In final, metabolizable energy and protein as well as daily dietary intake of experimental treatments, were obtained. Results: Dry matter, crude protein, crude fat, crude ash, neutral detergent fiber, water soluble carbohydrate and non-fiberous carbohydrates in forage silage of Laura cultivar were 23.0, 18.8, 0.97, 21.2, 30.5, 2.5 and 28.6 percent, respectively In Laura forage silage, total sensory evaluation, flag point, ammonia nitrogen (mg), acetic acid (mg), lactic acid (mg), propionic acid were 15.8, 7.78, 4.4, 18.4, 0.45 And 1.15 respectively. Gas production in silos of Laura, Sim and Kharkovsky cultivars (during 24 hours of rumen fermentation per 200 mg) were 45.3, 43.9 and 42.1 ml, respectively. Dry matter and organic matter digestibility in forage silage of Laura cultivar were 66.5 and 70.2 percent, respectively. The amounts of digestible energy, metabolizable energy, net energy and digestibility (dry matter, organic matter and organic matter in dry matter) of fodder and silage of Laura cultivar were higher than the other two cultivars. Relative forage value, relative nutritional quality and feed ratio (g / day / kg body weight during maintenance) in amaranthus silage (Laura cultivar) were 122.3, 108.0 and 43.8, respectively. Conclusion: Laura forage silage has better silage characteristics and crude protein, gas production, higher digestibility, higher protein and metabolizable energy, as well as relative forage value, relative feed quality and better-feed intake. This silage had a better quality for ruminant nutrition than other silage experimental treatments.