EFFECT OF 3 SUPPLEMENTAL FAT SOURCES ON LACTATION AND DIGESTION IN DAIRY-COWS

Tallow, Ca salts of palm fatty acids, or prilled fatty acids were adde d at 2.5% to a control diet (3.7% fatty acids) containing 7.2% ammonia ted whole cottonseed. Diets were fed to midlactation cows (6 cows per treatment) for 72 d to determine effects of fat supplementation and fa t source on lactation performance and nutrient digestibilities. Dry ma tter intake did not differ among treatments. Milk yield was 31.6 kg/d for the control and increased an average of 2.1 kg/d with fat suppleme ntation. Source of supplemental fat did not significantly affect lacta tion performance. Added fat decreased milk protein content but did not affect protein yield. Milk fat, lactose, and SNF contents did not dif fer among treatments. Overall fat supplementation did not affect diges tibilities of DM, ADF, or NDF but decreased digestibility of fatty aci ds. Contribution of de novo fatty acids to milk fat was decreased with fat supplementation. Addition of 2.5% fat to a diet containing a medi um amount of fat from whole cottonseed increased milk yield. Tallow, C a salt of palm fatty acids, and prilled fatty acids did not differ in milk yield response.