LAMBS 
Most compounds studied in the fattening of cattle have been tested in lambs. Much of 
the work has been done in the feedlot although, as with calves, there have been tests on 
suckling lambs. 
In the early work with implanted stilbestrol relatively large doses of 12 and 15 mgs. 
were tried. Results were not favorable mainly because of the so-called side effects in 
accentuated sex characters, prolapses of the rectum, and incidence of urinary calculi. 
Growth rates were increased but carcass quality frequently decreased. Subsequent studies 
using implants of 2 to 6 mgs. have been more favorable. Table 2 shows a sampling of 
published data on rates of gain increases and feed savings. Generally, improvement in 
growth rate and feed economy was about as good as with the larger-sized implants, and 
the side effects have not been significant. Carcass quality and dressing percentage «fill 
have not equalled control groups. 
TABLE 2.--Summary of Experimental Comparisons of Feed Additives in Sheep Rations 
How Expt'1 Gain Feed 
Mg. 
Number Percent Percent 
Stilbestrol orel 1-3 Al USS) Aes 
Do implant 2-15 i} 27.2 20R2 
Do do | 2 AUG ale yeal 
Testosterone do 20-240 10 9.8 16.8 
Tranquilizers oral variable 2 ee 4.2 
Antibiotics do do 53 8.4 Woe 
In tests on oral feeding of stilbestrol, the dosages have run up to about 3.5 mgs. per 
animal per day with the 2 mg. level being fully effective. Reports show little mention of 
any undesirable side effects. The carcass quality data show only a slight disadvantage for 
the stilbestrol-treated animals. The values shown in Table 2 for 41 lot comparisons indi- 
cate an appreciable increase in rate of gain and in feed efficiency although not as high as 
for implanted stilbestrol. 
Of the other sex hormone products that have been tried, the principal one--testo- 
sterone--has shown a modest increase in rate of gain although much less than for stil- 
bestrol (see Table 2). The feed savings appear to be well in line with that for stilbestrol. 
Limited comparisons with dienestrol implants have shown comparable results. 
There have been a number of experiments with various tranquilizers. As indicated 
by the average figures in the table, small increases were obtained in rate of gain and in 
feed efficiency. It appears that lambs responded better than cattle to the use of tran- 
quilizers. 
Antibiotics, likewise, have given greater responses, percentage-wise, thanhave cattle 
in feedlots in increased gains and feed savings. It is true, however, that wide ranges exist 
and the individual tests do show frequent cases of negative results. Undoubtedly, reduction 
in enterotoxemia is an important factor in the benefits derived from the use of antibiotics 
in addition to the possible gain and feed advantage. 
Data examined on carcass grades of lambs indicate much the same picture as for 
beef carcasses. For example, out of 34 comparisons from oral administration of stil- 
bestrol, 20 showed a decrease in grade and 12 an increase. Implanted animals show a 
greater trend toward decrease in grade. With antibiotics and tranquilizers there appears 
to be little if any effect on carcass grade. 
41 
