Results

 The greatest response to the additives was secured for chlortetracycline
 and it increased gains by an average of 12 pounds per calf over the control
 group. This amounts to slightly more than 0.1 pound additional gain per ani-
 mal daily by the use of chlortetracycline. The enzyme supplement given in
 the first half of the trial and also that provided during the entire test period
 improved the rate of gains made by calves. These additional gains were just
 slightly below those obtained from the use of chlortetracycline. However,
 the enzyme supplement used only in the second half of the trial did not im-
 prove the rate of gain. A summary of the weight gains by treatment is
 shown in table 1.

 The response to vitamin A supplementation.was very inconsistent. In one
of the groups, vitamin A appeared to improve gains while in the other groups
the calves not receiving the vitamin showed a higher rate of gain. A large
percentage of the calves in all groups exhibited the eye disorder and the
vitamin A failed to alter the severity of this condition. Thus, the vita-
min A administered in this manner did not prove beneficial for improving
weight gains or correcting eye disorders. It was suspected that dosage
levels should have been higher to realize beneficial responses. Table 1 also
shows the average gains of the calves by vitamin A treatment within the feed
additive treatments. Statistical analysis of all data indicated that differ-
ences in gains due to either the feed additive treatments or the use of vita-
min A were not significant at the 5% level.


Table 1. Average total gains by feed additive and vitamin A treatment (Ibs.).*



 Feed Vitamin A Combined
Additive Yes No Gains


None (Control). 81.5 85.0 83.5
Chlortetracycline 87.5 103.5 95.5
Enzyme, (1st half) 93.0 93.5 93.3
Enzyme, (Whole) 97.5 91.5 94.5
Enzyme, (2nd half) 77.5 85.0 81.3


STen calves in each vitamin treatment group:and 20 in each feed additive
 group.