| Popis: |
Four lactating, ruminally cannulated Holstein cows (DIM ≥ 50; ≥ second lactation) were paired by milk production and used in a switchback design to compare ruminal fermentation response to a diet containing 7% pelleted, high-oil canola meal (HOCM) versus a control diet (CONT). The CONT diet was made of corn silage, alfalfa haylage, wheat straw, and the concentrate. The HOCM diet contained the same ingredients as the CONT except sunflower seeds and a portion of soybean meal were replaced with pelleted, high-oil canola meal in the concentrate. The canola pellet contained 16.6% crude fat and 37.3% CP. Diets were formulated to be isonitrogenous and isocaloric. The last day of each 21-d switchback period was used to collect ruminal fermentation data. Ruminal fluid samples were collected through the cannula at 0, 2, 4, 6, and 8 h after feeding. Cows were housed in a tie-stall barn, and diets were delivered as a TMR once daily at 1000 h to achieve ad libitum intake (5% orts). Daily DMI and milk production data were recorded during the entire feeding period. There were no differences (P ≥ 0.29) between DMI, milk yield, and efficiency of milk production of cows fed the HOCM and the CONT diets. Ruminal acetate, butyrate, total VFA, and pH were not affected (P ≥ 0.37) by diets. Ruminal propionate tended to be greater (P = 0.09) in cows fed HOCM. Adding 7% of pelleted, high-oil canola meal to lactating Holstein dairy cow diets did not adversely affect ruminal fermentation. |
