Effects of docking and fattening period on performance and carcass physical composition of Lori-Bakhtiari male lambs

Carcass composition of thirty Lori–Bakhtiari single male lambs were assigned to a completely randomized design with two factors. The factors were tail status (with and without fat tail) and fattening period (75، 90، 105 days). Lambs were weaned at 90 ± 5 days of age and divided randomly in to three groups for 75،90 and 105 days of feedlot and kept in individual boxes. In start of experiment from 60 lambs born، thirty of them were docked by rubber ring at beginning second days of birth alternately. At the end of fattening period، lambs of each level of treatment were slaughtered randomly. The results showed that percentage of the carcass meat، subcutaneous and internal fat of docked lambs were significantly higher than in the undocked ones. However total carcass fat of docked lambs were 5. 3% lower than intact lambs، that this difference between the two groups were statistically significant. This was accompanied by of non-significant increase in the percentage of subcutaneous fat، internal fat and total carcass fat and a non-significant decrease in the percentage of meat. In conculsion، in order to increase quantity and quality of carcass by increasing in the carcass meat percentage and decreasing total carcass fat percentage، docking with 75 days of fattening period for Lori- Bakhtiari lambs recommended.