Background: The abundance of fossil shell flour (FSF) globally has resulted in an increased interest in its use as a feed additive in sheep diets. This study evaluated the effects of varying inclusion levels of FSF on feed preference, body condition scores and wool parameters of Dohne Merino (DM) wethers. Methods: Twenty-four wethers, weighing 20 ± 1·5 kg on average were fed dietary food-grade fossil shell flour in a completely randomized design of four treatment with six wethers in each treatment. The wethers were fed a basal diet without FSF addition (control, 0%), or with the addition of FSF (2%, 4% or 6%) into the diet for 105 days.Results: Average daily weight gain and body condition score of 2%, 4% and 6 % FSF inclusion levels were higher (P < 0.05) than the control 0%. Wool yield, staple length, coefficient variation of the fibre diameter and fibre <15% of wethers supplemented with FSF were higher (P < 0.05) compared to the diet without FSF. Fibre diameter of the wethers supplemented with FSF were the same (P>0.05) as the control.Wethers preferred FSF supplemented diets to the control. The inclusion of FSF in the diet of DM wethers up to 6% DM showed improvement in the average daily gain and body condition scores, feed intake through preference, wool yield, and quality. Conclusion: The addition of FSF in the diets could be advantageous in Dohne-Merino wethers performance and production with the potential of increasing both the quantity and quality of wool.