Importance of Hay Quality as Indicated by Feeding Trials with Identical Twin Dairy Heifers

Abstract

Trials were conducted over a period of 280 days with 2 sets of identical twin heifers about 1 yr. old to compare the feeding value of U. S. No. 1 extra leafy green alfalfa hay with U. S. No. 3 leafy brown alfalfa hay. One heifer from each set was fed the No. 1 hay as her sole ration and the other 2 were fed the No. 3 hay, but one of them also received as much grain as was needed to enable her to gain at the same rate in wt. as her twin sister. The U. S. No. 1 extra leafy green alfalfa hay was more palatable, richer in digestible nutrients and carotene and produced slightly more rapid gains in wt. than the U. S. No. 3 leafy brown alfalfa hay but at a higher cost in nutrients per unit of gain. The heifer fed No. 3 hay plus grain ate an avg. of 4 lbs. grain daily but consumed considerably less hay than her sister. Their energy intakes were the same. The value of using identical twins in experiments comparing the nutritive value of feeds is indicated.