168 • Impacts of Applied Genetics — Micro-Organisms, Plants, and Animals 
Figure 30.— Eras in U.S. Beef Production 
A 
Time 
1950 
‘Scientific’ 
Era of artificiai 
insemination, population 
genetics, and progeny 
testing. 
1890-1950 
“Purebred” 
The era of the breed 
associations 
1860-1890 
"Empire” 
The “romantic” era of 
the cowboy and the 
Texas longhorn. 
SOURCE: Adapted from R. L. Willham, "Genetic Activity in the U.S. Beef Indus- 
try," journal paper No. J-7923 of the Iowa Agriculture and Home Eco- 
nomics Experiment Station, Ames, Iowa, Project No. 2000, n.d. See 
also Yao-chi Lu and Leroy Quance, Agriculture Productivity: Expand- 
ing the Limits, USDA, ESCS, Agriculture Information Bulletin 431. 
of breeding programs. They were reinforced by 
an institutional system of breed associations, 
and yearly competitions at county fairs and 
stock shows, and by import regulations and |)ro- 
bibitions against artificial insemination (Al) that 
I'estricted innoxation. In rearing animals for 
sale to the slaughterhouse, eai'ly breeders and 
fai’mers more often than not were satisfied with 
|)i'oducing a calf or pig that survixed, xxeaned 
early, and grew rapidly. Because of the high 
rate of nexvborn deaths, the production of an 
"axerage” animal xvas a considei'able acbiexe- 
ment in its oxvn right; the intricacies of sophisti- 
cated breeding methods xxere beyond the ca- 
pacity of small operations and xxere difficult to 
carry out on large spreads. Producing a prize- 
xvinning pui'ehred xvas left to the farmer xxith 
the time, money, or luck to breed animals that 
met the strict standards of the breed associ- 
ations and the trained eyes of the judges at stock 
shows. 
During the fii'st half of the 20th centui'v, 
breeding objectives became more comple.x; 
farmers and hi'eeders began to look at c|ualities 
other than mere e.xternal physical attributes. 
Breeding for multi|)le-purposes led directly to 
the beginning of the “scientific" era in breeding. 
'Hie increased use of Al for dairy ('attl(\ 
xvhich took place about BO years ago— the he*gin- 
ning of the scientific era— xxas an uncertain 
start for applied genetics in animal hr(>eding. 
While practitioners and purchasers of Al xxere 
(|Liick to grasp its promise of imnu'diate bene- 
fits, and xx’hile using Al xx as cheaper than oxx n- 
ing a hull, its expected genetic effects xxere not 
realized immediately. Dairx'men had assumed 
that semen Irom hulls sek'cted from th(‘ best 
herds and chosen on th(’ basis of ancestral per- 
foi'iiiance xvould result in rapid genetic im- 
proxement. They xxeie xxrong; progr(>ss xxas 
much less than projected. Because milk produc- 
tion is a sex-limited ti'ait, r('('ords on f('male 
relatixes xxere needed for the exaluation of 
sires, linfortunately, th(’ records on I’clatixc’s 
xx ere usually limited to comparisons xx ithin oiu* 
herd, xxei'(' confounded by manageiiK'iit and 
other enx ironmental factors, and xx(m-(> \xcak- 
ened by small sample sizes. I h(' major factor 
|•esponsihle for th(’ diffcrcncj' lu'txxc'cn top- and 
iiK'diocrc'-performing lu'rds turned out to he 
managcMiu'iit , not gc'iictics: separating the ef- 
fects of genetics from the effects of genei’allx 
improx (>d husbandry \x as extrc'inely difficult 
Controlled breeding 
rh(> ohj('ctix (' of any hia'cding program i.s to 
inci’eas(> produc'tion. I he scientilic er;i h;is jiro- 
X ided the hre('der \x ith a x iirietx of nexx ti'chnol- 
ogies that help in manipulating ;ind controlling 
the repioductix (' pi’ocess(>s of the animals to in- 
('rease genetic gain. I he hrec'der’s basic tool is 
selection, or deciding xvhich animals to mate— 
e.g., in beef cattle, a breeder can noxx- selec't for 
a wide variety of [lerformance or (>conomic 
traits. (See table 30.) Howex er, simply breeding 
better beef cattle” is not a xvorkahle object ixc 
from a manager’s point of xiew. render meat, 
lean steaks and roasts, high fer tility, or' heaxy 
xveight at xveaning ar'e all specific, rneasur ahlr* 
objectives of breeding.' ^ OthrM' goals, sucli as 
those pertaining to tempcMarnent, di.sease 
resistance, food efficiency, and car'cass (jualitx , 
■ r'. C. CarUvi'if'tit. "Scli-clion Ci iIim ui liir H<'cl ( alllr lor Itn' I ii 
lure," Journal of Animai Srirnce ;rO:ril(i. I !)70 
^r.arrv X'. CundilT and Kcitli I-. (ircj^oi-y HrrI' ( alllr lirmtinfi. 
USDA, Agriculture Infornialion llulliAin No 2HI> re\iM'd St- 
vemtier 1977. 
