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

Abstract

Summary 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 four initial levels of alfalfa 10, 15, 20, and 25 per cent; 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 per cent and at 1.2149 rate of increase. Dry matter efficiency was found to decrease with the two variables, but total digestible nutrient utilization was maximum at an 18.08 per cent initial level of alfalfa, increased at a weekly rate of 1.2336. Average carotene intake per mean pound of body weight 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 weight. Increases in live weight, height at withers, heart girth, and girth of paunch were greatest for the calves fed initially the 15 and 20 per cent alfalfa pellet mixtures. With the exception of live weight, which was maximum for the calves fed at the 1.1747 rate of increase, none of these criteria were related to the rate of increase. Maximum gain in live weight was calculated to be at an initial level of 16.99 per cent 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 weight indicated that plasma carotene largely reflected carotene intake. Calves had on the average 2.1 ± 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.