Effect of physical form of diet on wool and skin characteristics of Kalkuei male lambs.

This study was conducted to determine the effect of three physical form of diet (mix diet, LD; block diet, BD and pellet diet PD) on wool, skin and leather characteristics. Forty-five Kalkuei (Iranian fat tailed sheep) male lambs (initial average body weight 32 .81 2 kg with 4.5 months of age) in 15 heads per each group were fed the diet for 93 days. At the end of experimental body and carcass weight, fleece weight, staple length, skin weight, surface (size) and thickness in different parts of skin (shoulder, hip, flank, rib and belly) and physical and mechanical traits of leather were measured. The effect of three treatments (physical form of diet) on body, carcass weight and fleece attributes were compared in completely random design. A general mixed linear model including three parts of body (shoulder, hip and rib) and two directions of cuts (parallel and perpendicular to the backbone) was used to analyze the data and measure the leather characteristics. Results indicated that, final weight and carcass yield were not affected by physical form of diets, but warm and cold carcasses of lambs that fed BD were similar as lambs fed PD and significantly greater than LD diets. The fleece weight was affect (P0.05) by covariates of final body weight, therefore was not significantly by physical form of diets. There were significant different among treatments for mean fiber diameter, the percentage of fibers 20 and 40 microns, washing yield, kemp fiber percentage and breaking tenacity of wool fiber bundles 1.8 in (3.2 mm) gage length (P0.05). The lambs were fed by BD had lower fiber diameter than the other groups. The type of diet not affected on skin performances except skin size to skin weight ratio. The physical traits of leather were significantly (P0.001) different between body regions. The leather in the flank region had lower thickness and higher tensile strength and percentage extension than shoulder or rib regions (P0.0001). The lowest single edge tear load related to leather from hip region. Leather from flank region was significantly (P0.0001) higher double edge tear load. The tensile strength of parallel leather samples were significantly higher while single and double edge tear load and percentage extension was lower (P0.0001) than for the perpendicular to backbone samples. The current study indicated there are low differences between three diet groups. However management condition in country different regions and final price of dies to be determined the uses of each three physical diets. Key words: Fattening lambs, Pellet, Block, Fleece weight, Wool characteristics, Skin traits, Leather physical and mechanical characteristics