Effects of Feeding Lactating Dairy Cows Varying Forage-to-Concentrate Ratios

Abstract

Twenty Holstein cows were randomly assigned to one of five completely pelleted rations of the following Coastal Berumdagrass-concentrate ratios: Ration 1, 100:0; Ration 2, 75:25; Ration 3, 50:50; Ration 4, 25:75; Ration 5, 0:100, using Lucas’ switchback design to study the ration effect on voluntary intake, digestibility, milk yield, and composition. Dry matter intake was significantly (P < .01) lower than for Ration 1. A highly significant (P < .01) increase in digestible energy intake of Rations 1 through 4 was observed. The associative effect of forage and concentrate on total ration digestibility increased as the percentage of concentrate was increased. The digestible energy of Rations 2, 3, and 4 was reduced approximately 0.8 percentage unit below the theoretical values for each 25% increase in concentrates of the total ration. There was a highly significant (P < .01) decrease in fat-corrected milk production from animals consuming the all-forage ration and a highly significant (P < .01) linear decrease in the milk fat percentage as the concentrate was increased in the total ration. The solids-not-fat from animals consuming rations with 25% or less concentrate were significantly (P < .01) lower than milk from animals consuming 75% or more concentrate. The percentage of protein in milk was highly significant (P < .01) among rations. © 1968, American Dairy Science Association. All rights reserved.