Abstract: 【Objective】 The experiment aimed to explore the effects of supplementing different levels of yeast culture on milk production,milk composition,and blood biochemical indicators of lactating mares,in order to provide reference for the development and use of feed additives to improve mare lactation ability.【Method】 Eighteen Yili mares with an average milk production of (2.65±0.34) kg,similar parity and delivery date,and lactation for two months were selected and randomly divided into three groups:Control group,experimental groups Ⅰ and Ⅱ.Among them,the control group was raised by pure grazing,while the experimental groups Ⅰ and Ⅱ were supplemented with 45 and 60 g/(d·horse) of yeast culture on this basis.After pre feeding for 5 days,a 60 day supplementation experiment was conducted.Before the feeding period (recorded as day 0),on the 30th and 60th days (11:00,13:00,15:00,and 17:00 each day),the milking amount of each horse was measured during each milking,and milk samples from the whole day were collected to determine milk protein,milk fat,lactose,and non-fat solids in the milk.On the 60th day of the experiment,blood samples were collected on an empty stomach before feeding,and total protein (TP),globulin (GLB),albumin (ALB),uric acid (UA),glucose (GLU),triglycerides (TG),total bilirubin (T-Bil) and other indicators were measured. 【Result】 ①On day 0,there was no significant difference in milk production among the three groups (P＞0.05).On the 30th day,the milk production of experimental group Ⅱ was significantly higher than that of control group (P＜0.05).On the 60th day,compared with control group,the milk production of experimental groups Ⅰ and Ⅱ was significantly increased by 19.33% and 27.30%,respectively (P＜0.05).② On days 0 and 30,there were no significant differences in percentage of milk protein,milk fat,lactose,and non-fat solids content among the three groups (P＞0.05).On the 60th day,compared with control group,the milk fat of experimental groups Ⅰ and Ⅱ was significantly increased by 30.89% and 35.77%,respectively (P＜0.05),and the non-fat solids of experimental group Ⅱ was significantly increased by 1.90% (P＜0.05).③ Compared with control group,there was no significant difference in the levels of TP,ALB,GLB,UA,GLU,TG,and T-Bil in plasma of experimental groups Ⅰ and Ⅱ (P＞0.05).【Conclusion】 Supplementing lactating mares with yeast culture could increase milk production and improve the quality of milk components.The effect was better when supplemented with 60 g/(d·horse) yeast culture,but it had no significant effect on biochemical indicators in the blood.

Key words: Yili horse; milk production; milk composition; blood biochemical indicators