Purdue University Agricultural Experiment Station Lafayette, Indiana
Mimeo AS-297 April 28, 1961 (Progress Report)
LEVELS OF SUPPLEMENTAL VITAMIN A WITH AND WITHOUT SUN-CURED ALFALFA MEAL FOR FATTENING STEER CALVES 
W. M. Beeson, T. W. Perry, M. T. Mohler and W. H. Smith Department of Animal Science
-------------------------------------Summary ------------------------------------
Steer calves fed on a ration without alfalfa showed a highly significant increase in daily gain (22 percent), from an intake of 20,000 I. U. of vitamin A per head daily (Table 1)0 Higher levels—30,000, 40,000 and 50,000 IU—of vitamin A did not improve the performance of the steers over the 20,000 IU intake, Feed efficiency was improved about 5 percent from vitamin A supplementation.
When sun-cured alfalfa pellets made up 10 percent of the steer calves9 ration, vitamin A supplementation improved daily gain, but only from 2 to 10 percent which was not statistically significant (Table 2). There was no consistent improvement in feed efficiency. These data indicate that the steers were meeting a portion of their vitamin A requirements from the carotene supplied by the alfalfa meal. This ration contained 2,26 mg« of carotene per pound which is 3 o7 times the National Research Council recommendation,
Blood plasma levels of vitamin A were significantly increased by all levels of vitamin A supplementation as compared to the controls (Table 4)° Fortification with vitamin A decreased the carotene plasma levels.
Substituting sun-cured alfalfa pellets for 10 percent of the corn cobs increased the daily gain 18 percent (significant P 0.01) and improved feed efficiency 7.5 percent when no supplemental vitamin A was fed. When the corn cob ration was fortified with 20,000 IU of vitamin A (Lot 3) per steer daily, the addition of 10 percent sun-cured alfalfa pellets (Lot 9) did not significantly effect daily gain or feed efficiency.
Stilbestrol caused no significant change in daily gain (control, 2,52; DES, 2,55) when the ration was not fortified with synthetic vitamin A. However, improvement in daily gain was highly significant when stilbestrol was used in conjunction with vitamin A supplementation. There was no correlation between the different levels of synthetic vitamin A fed and the response to stilbestrol. Sun-cured alfalfa pellets had no effect on the response to stilbestrol.
No clinical symptoms of vitamin A deficiency have been observed at the time (119 days) this report was prepared.
Vitamin A Requirements
Research and field reports have indicated that vitamin A deficiency symptoms occur in beef cattle on rations that were formerly considered adequate in carotene. It has been suggested that either nitrates or some unidentified substance contained in natural feedstuffs is inhibiting the conversion' of carotene to vitamin A in the animal body. In most cases, fortifying the diet with synthetic vitamin A has either prevented or cured the sub-clinical or clinical symptoms of a vitamin A
1/ This research was supported in part by a grant-in-aid from Hoffmann-La Roche, Inc,, Nutley 10, New Jersey. Vitamin A palmitate (Rovimix A-325) was supplied by the same company.