determination of animal unit weight and daily animal requirement by metabolizable energy of farahani sheep breed

to estimate the grazing capacity in each region it is necessary to determine animal requirement based on forage quality and animal unit weight of dominant sheep breed. in present study animal unit weight of farahani sheep breed was investigated. two herds were selected. thirty animals including 15 three and four years' old ewes, 5 nine months old lambs, 5 six months old lambs, 5 three and four years old rams were weighed in lowland and highland. the weight of animal unit obtained 42 kg and animal unit equivalent for rams, 9 and 6 months old lambs were estimated 1.48, 0.6, and 0.52 respectively. two sex of animals (ewes and rams) and two herds were significantly differed in weight (p < 0.05). for determination of forage quality 5 sample from each species that each was made from 5 individual plants collected from each species. crude protein, acid detergent fiber, dry matter digestibility and metabolisable energy were estimated for 7 species from highland and 10 species from lowlands. according to tukey test, forage quality significantly differed between species (p < 0.05). this shows that animal requirement should be determined based on forage quality of available forage to animals. requirement of animal grazing on rangeland is more than house keeping animals. so in this research considering environmental conditions and distances that animal had to walk every day %25 was added to animal requirement calculated using either nrc tables or maff equation. the result showed that animal requirement calculated using either nrc tables or maff equation were 9.6 and 7.5 mj metabolisable energy respectively and based on forage quality according to nrc tables and maff equation were 1.94 and 1.52 kg dry matter respectively.