Evaluation by Lamb and Steer Feeding Tests of Alfalfa Hay of Varying Phosphorus Content

Feeding trials with both sheep and steers and digestion and balance tests were conducted on alfalfa hay of varying phosphorus content to study its nutritive value. Hay produced on virgin sandy desert soil which contained 0.10% phosphorus was unpalatable and produced poor animal gains, feed utilization and depressed serum phosphorus content. The addition of disodium phosphate to this hay improved animal gains, feed utilization and increased the blood serum phosphorus. Hay containing 0.15% phosphorus was apparently equal in feeding value to hay containing greater amounts of phosphorus. Digestion trials on the various hays did not reveal any significant differences in the digestibility of the various nutrients. Balance trials showed no difference in nitrogen retention and a variable calcium balance. An increased retention of phosphorus was obtained by adding disodium phosphate to a low phosphorus hay in one test, in another, the addition of disodium phosphate to unfertilized hay resulted in increasing the phosphorus retention up to that of heavily fertilized hay.