In this study, potential use of unmarketable cracked eggs in rations of lambs was investigated. A total of 21 male Avassi lambs at the age of 7-8 months (average of 30 kg body weight) were used. The rations were prepared isonitrogenic and isocaloric. Treatment groups were based on the method of addition of cracked eggs. According to this, the group without egg was control group (C), the group supplemented with untreated egg to compensate 10 % protein of soybean meal was Egg group (Egg) and the group supplemented with formaldhyde treated egg (0.6 % of crude protein) was Egg+formol (Egg+Formol). The ruminal ammonia level at the 1^st and 2^nd h after feeding was similar in Control and Egg groups, whereas it was lower in Egg+Formol group (P<0.01). Rumen pH levels were similar between all groups. The digestibility of dry matter, organic matter, crude protein, eter extract and nitrogen free extract were similar among all groups. The highest dry matter intake was observed in Egg+Formol group (P<0.05). Daily body weight gain was similar in Control and Egg groups, but it was the highest in Egg+Formol group (P<0.05). Feed efficiency ratios in Control and Egg group and Egg+Formol groups were 4.13, 3.97, and 3.83, respectively (P>0.05). Carcass characteristics were similar in all groups.

In conclusion, nonedible cracked eggs may use as protein supplement in lambs rations.