Comparison of constant versus variable energy ratios in complete rations for dairy cattle in early lactation

Numerous feeding trials with lactating dairy cattle have been conducted to determine efficient nutrient utilization and maximum economic returns of dairy operations. Different feeding systems have been devised to minimize labor and time required in feeding. One feeding system which has been proposed for this purpose is the blending of all feed constituents into one complete feed which is then fed to groups of cows. This study attempted to aid in establishing the proper forage-to-concentrate ratio for cows in early lactation. Thirteen pair of Holstein cows were used to compare production while fed a complete feed in which forage-to-concentrate ratio was constant or variable during early part of lactation. Treatment I consisted of a complete feed of com silage to concentrate blended in a 3:1 forage-to-concentrate ratio (as fed basis) and fed continuously throughout the experiment. Treatment II consisted of a variable forage-to-concentrate ratio of 2:1 for 8 weeks, 3:1 for 8 weeks, and 4:1 for 8 weeks. Cows were fed 5 pounds of alfalfa hay per day to prevent milkfat depression. Dry matter intake (percent of body weight) for the complete feeds were 2.65, 2.65 and 2.29 for Treatment I for the three periods. Similar data for Treatment II were 2.72, 2.66 and 2.23. Milk production (pounds), fat (percent) and 4 percent fat corrected milk (pounds) for Treatment I were 67.1, 3.5, 62.1; 62.4, 3.5, 57.7; and 54.7, 3.5, 50.6 for the three periods respectively. Similar data for Treatment II were 64.8, 3.5, 59.9; 59.2, 3.5, 54.8; and 49.3, 3.7, 47.1 for the three periods respectively. No statistical difference was determined In the production variables, Indicating that the constant ratio complete feed was as efficient as the variable ratio complete feed.