Abstract: The effects of different proportion of fatty acids in the diets on lactation performance of fresh cows were compared by animal experiments.fresh Holstein cattle were divided into Experimental Group I,Experimental Group II and Control Group.Fatty additives were not added to the diet of the control group;the Experimental Group I was fed with fatty acid calcium additives,in which the proportion of fatty acids was C16:0∶ C18:1 = 51.00%∶35.00%; the Experimental Group II was fed with palm Fat powder additives,in which the proportion of fatty acids was C16:0∶C18:1 = 80.00%∶8.00%.The lactation net energy and crude protein levels of each group are the same.The average dry matter intake of control group and Experimental Group II was significantly higher than that of Experimental Group I (p < 0.020),and increased by 2.470 kg and 2.070 kg,respectively.The milk yield of Control Group and Experimental GroupII was significantly higher than that of Experimental Group I (p < 0.020) and increased by 3.560 kg and 3.500 kg, respectively.There was no significant difference in Body Weight Between Control Group, Experimental Group I and Experimental Group II.The weight loss of Experimental Group II was 64.100 kg,the weight loss of Control Group was 87.500 kg,the difference was 23.400 kg.Comprehensive analysis showed that adding fat powder in Diet (C16:0∶C18:1 = 80.00%∶8.00%) was most beneficial to improve the postpartum lactation performance,reduce postpartum body fat mobilization and maintain body condition.

Key words: fresh cow, fatty acids, feed intake, milk yield, weight loss