Effect of dietary energy source and concentration on performance of dairy XXXX during early lactation.

@entity598 @entity653 @entity1460 @entity3918 @entity1718 @entity291
Eighteen Holstein heifers were placed into groups of 3 according to projected calving date, prepartum BW, and prepartum condition score. Following parturition, animals within each group were assigned randomly to one of three diets and remained on the experiment for 45 d. Diets consisted of forage:concentrate ratios of 72:28, 53:47, or 73:27 (isocaloric to the 53:47 ratio by addition of 8% @entity1460 oil). Diets were fed twice daily as total mixed rations. Blood, rumen fluid, and adipose tissue were sampled at -7, 5, 20, and 45 d of lactation. Performance means were, respectively: @entity3918 intake (kg/d) 13.9, 14.9, and 12.4; milk (kg/d) 24.5, 25.8, and 18.6; milk fat (%) 3.77, 3.59, and 3.62; milk protein (%) 3.03, 2.99, and 3.11; body condition score (0 = thin, 5 = fat) 1.53, 1.87, and 1.99; and BW (kg) 514, 523, and 505. @entity291 fed @entity1460 oil had higher ruminal isoacids than those fed the other diets and higher @entity598 than @entity291 on the 53:47 diet. Diets had no effect on blood metabolites or activity of adipose @entity653 -P dehydrogenase (EC 1.1.1.8). The @entity1460 oil diet reduced short-chain @entity1718 and increased long-chain @entity1718 in milk. Feed intake and milk production were highest for @entity291 receiving the 53:47 diet. As expected, animals on the 72:28 diet did not consume adequate energy to maintain high production which concurrently resulted in lower body condition scores.
