An experiment was conducted to investigate the effect of Aazolla pinnata (AP) silage in combination with wheat straw as a non-conventional feedstuff on growth performance of Zel lamb during high ambient temperature. Fresh AP was gathered from a pond in Mazandaran province, Iran. Four kinds of silage were prepared as follow: 100% AP, 50% AP + 50% sugar beet pulp, 75% AP + 25% rice straw, and 66% AP + 33% wheat straw. These mixtures ensiled for two months under anaerobic conditions. Fleig point in100% AP, 50% AP + 50% sugar beet pulp, 75% AP + 25% rice straw, and 66% AP + 33% wheat straw was 68.47, -99.57, -35.00, and 52.85, respectively. Furthermore, silages of 100%AP and 66% AP + 33% wheat straw were fed to sheep that both of them had good palatability in pre-trial phase. Thus, pure AP or in combination with 33% wheat straw had the best quality for practical feeding in livestock. After that, the AP combined with wheat straw was chosen for in vivo study. Two silages of 100% corn and 66% AP + 33% wheat straw were fed to two groups of sheep that contained 5 each. Both of them had good palatability. In conclusion, 66% AP or in combination with 33% wheat straw (22.46% AP and 11.23% wheat straw in the diet) had resulted in reduction of body weight gain and deteriorated feed efficiency as compared with control treatment (100% corn silage).