ENHANCEMENT OF THE EFFECTIVE FIBER CONTENT OF BARLEY-BASED CONCENTRATES FED TO DAIRY-COWS

Nine ruminally fistulated Holstein cows (80 d postpartum) were used in a double 5 x 5 incomplete Latin square to evaluate the effects of increasing NDF content of the diet from 29 to 32% by adding suncured alfalfa pellets, beet pulp, or oat hulls to concentrate compared with increasing the long forage: concentrate ratio. Diets consisted of 35% long alfalfa hay (19.7% CP, 42.4% NDF) and one of four pelleted barley-based concentrates (16% CP): 1) control, 2) 15.5% added suncured alfalfa, 3) 15.5% added beet pulp, and 4) 8.5% added oat hulls. Diet 5 consisted of 45% alfalfa hay and 55% control concentrate. Mean ad libitum DMI was 21.0 kg/d. Milk production averaged 25.8 kg/d and was not affected by diet. Milk fat was lowest for diet 1 (2.25%), intermediate for diets 2 (2.81%), 3 (3.00%), and 4 (3.02%), and highest for diet 5 (3.17%). Time spent eating and ruminating averaged 342 and 398 min/d, respectively, and was not affected by diet. Rumination time adjusted for forage fiber intake was longest for diet 1 (144.5), intermediate for diets 2 (124.9), 3 (128.4), and 4 (136.4), and shortest for diet 5 (110.2 min/kg hay NDF). Increasing NDF content of concentrate using suncured alfalfa pellets, beet pulp, or oat hulls improved the effective fiber content of the barley concentrate but was not as efficacious as increasing the forage:concentrate ratio.