High fat rations dairy cows, tallow and hydrolyzed blended fat at two intakes.

Tallow and blended animal-vegetable fat were mixed as 10% of diet concentrate and compared with a concentrate containing no added fat. Concentrate containing fat was fed at two percents of diet dry matter, 50% (supraenergetic) and 33% (isoenergetic). The dry matter of the control diet was 50% concentrate. Isoenergetic high fat diets contained more fiber than control or supraenergetic high fat diets. Change of body weight and intake of feed dry matter were not different among feed groups. Milk and 4% fat-corrected milk production were less when high tallow was fed. Milk fat percent was lowest on the high concentrate diet, intermediate with high grain-high fat feeding, and normal with high fat isoenergetic rations. Multiple regression analysis of digestibility data showed that fat did not influence diet digestibility negatively and that calcium positively influenced digestibility of all diet components.