The effect of using quince leaf (Cydonia oblonga) in ration on growth performance and blood parameters in broiler chickens under heat stress condition

One of the environmental factors that lead to the reduction of poultry production is heat stress. Quince leaves are an agricultural waste that is a good source of flavonoid compounds and antioxidants. The purpose of this research is to investigate the effect of adding quince leaf in the diet on feed intake, weight gain, feed conversion ratio and blood parameters in broilers under heat stress conditions. This research was conducted using 160 broilers of Ross 308 strain with four treatments in four replications and each replication including 10 birds for 42 days in a completely randomized design. Quince leaf powder was added to the rations at four levels of zero (control), 1.5, 3 and 4.5%. In order to establish heat stress, the temperature of the hall was increased to 33 °C for 8 hours in the middle of the. Every week, the feed intake was measured and the chickens were weighed. In the second week of rearing, a significant increase (P=0.006) in feed intake was observed linearly with the increase in the level of quince leaf added to the feed rations, so that the highest amount of intake was in the treatment containing 4.5% quince leaf. In the third week, the highest weight gain was observed in the treatment with 1.5% quince leaf. In the fourth and fifth weeks, feed intake and feed conversion ratio did not differ significantly between treatments. In the sixth week, feed intake showed a significant decrease linearly (P=0.024) with the increase in the level of quince leaf added to the feed rations, but the feed conversion ratio linearly showed a significant improvement (P=0.017). In the entire rearing period, no significant difference was observed in terms of feed intake, weight gain and feed conversion ratio, although with the increase in the amount of quince leaf added to the feed rations, a relative improvement was seen in the feed conversion ratio, so that this ratio of 2.68 in the control treatment decreased to 2.44 in the treatment with 4.5% leaves. The use of quince leaf in the diets of broiler chickens under heat stress, especially in the early stages of growth, can increase feed intake, weight gain and improve feed conversion ratio, although no significant difference in terms of performance was observed in the entire rearing period, but a relative improvement was observed in the feed conversion ratio.