Effect of Initial Level and Rate of Increase of Artificially Dehydrated Alfalfa in Complete Rations on Growth and Carotene Intake of Holstein Dairy Calves

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Abstract
Thirty-six 7-day-old male Holstein calves were fed ad libitum mixtures of alfalfa pellets and starter pellets and limited whole milk to 91 days of age. The mixtures of alfalfa pellets and starter pellets fed contained 4 initial levels of alfalfa 10, 15, 20 and 25%; for each of these initial levels the parts of alfalfa were increased weekly, at the rate of 1.0000, 1.1747, or 1.3494, while the parts of starter were held at their initial levels. Maximum feed consumption was calculated to occur at an initial level of 18.33% and at 1.2149 rate of increase. Dry matter efficiency was found to decrease with the 2 variables, but total digestible nutrient utilization was maximum at an 18.08% initial level of alfalfa, increased at a weekly rate of 1.2336. Avg. carotene intake per mean pound of body wt. was found to be directly related to the initial level and to the rate of increase of alfalfa in the ration. There was no apparent difference in the utilization of carotene ingested as evidenced by predicted vitamin A stores equalized for carotene intake per mean pound of body wt. Increases in live wt., height at withers, heart girth, and girth of paunch were greatest for the calves fed initially the 15 and 20% pellet mixtures. With the exception of live wt., which was maximum for the calves fed at the 1.1747 rate of increase, none of these criteria was related to the rate of increase. Maximum gain in live wt. was calculated to be at an initial level of 16.99% and at the weekly rate of increase of 1.1817. Neither hemoglobin nor plasma vitamin A exhibited appreciable differences nor trends with either initial level or rate of increase of alfalfa, but plasma carotene was directly related to both variables. Adjustment for mean carotene intake per mean pound of body wt. indicated that plasma carotene largely reflected carotene intake. Calves had on the avg. 2.1 [plus or minus] 0.4 days of diarrhea, and 8 of the 35 calves had mild cases of bloat. Neither of these criteria was found to be related to any of the treatments.