Atli itncvs in repriuliictive biolo^ nrul 
their i'Jf'ei'ts an nninuil improvement 
I i\i)i\(;s 
Much impi'()\ ement can he made in the ^erm- 
plasm of' all major farm animal species using ex- 
isting technologN . The twpancled use of artificial 
insemination ( \l) with stored frozen s|)(M'm, es- 
pecialK in heef cattle, would benefit both pro- 
ducers and consumers. New technicjues for syn- 
chronizing estrus should encourage the wider 
use of W. \ arious manipulations of embryos 
will find limited use in })roducing breeding 
stocks, and sex selection anil twinning tech- 
niques should he available for limiteii applica- 
tions w ithin the next 10 to 20 years. 
rhe most important technologv' in reproduc- 
the physiology will continue to he .\l. Due in 
part to genetic improvement, the average milk 
yield of cows in the United States has more than 
doubled in the past 30 years, while the total 
number of milk cow s has been reduced by more 
than half. .AI along w ith improv ed management 
and the av ailahility and use of accurate progeny 
records on breeding stock have caused this 
great increase. (See figure 3.) 
The improvement lags behind what is theo- 
retically possible. In practice, the observed in- 
j crease is about 100 lb of milk per cow per year, 
> while a hypothetical breeding program using Al 
would result in a yearly gain of 220 lb of milk 
per cow. The biological limits to this rate of gain 
are not known. 
In comparison w ith dairy cattle, the beef cat- 
tle industry bas not applied .AI technology' wide- 
ly. Only 3 to 5 percent of U.S. beef is artificially 
inseminated, compared to 60 percent of the 
dairy herd. This low rate for beef cattle can be 
i explained by sev eral factors, including manage- 
ment techniques (range v. confined housing) 
and the conflicting objectives of individual 
breeders, ranchers, breed associations, and 
commercial farmers. 
The national calf crop— calves aliv e at vv ean- 
ing as a fraction of the total number of cows ex- 
posed to breeding each year— is only 65 to 81 
percent. An improv'ement of only a few percent- 
age points through AI would result in savings of 
C/7. 7 — Summary: Issues and Options • 15 
hundreds of millions of dollars (o proilucers and 
consumers. 
tx)upled with a technology for estrus-cycle 
regulation, the use of ,Al could he expanded for 
both dairy and heef breeding. Kmbi’vo ti'ansfer 
technology, ali'eady well-developed hut still 
costly, can he used to produce valuable breed- 
ing stock. Sexing technology, which is not yet 
perfected, would he of enormous benefit to the 
beef inilustry because bulls grow faster than 
heifers. 
In the case of animals other than cows: 
• K.\[)anded use of AI for swine proiluction 
will he encouraged by the stiong trend to 
confinement housing, although the poor 
ability of boar sperm to withstand freezing 
vv ill continue to be a handicap. 
• The benefits of applied genetics have not 
been realized in sheep production because 
neilbei' AI nor performance testing bas 
been used. As long as the use of AI con- 
tinues to be limited by tbe inability to 
freeze semen and by a lack of agents on the 
market for synchronizing estrus, no rapid 
major gains can he expected. 
• Increasing interest in goats in the United 
States and the demand for goat products 
throughout the world, should encourage 
attention to the genetic gains that the use 
of AI and other technologies make possible. 
• Poultry breeders will continue to concen- 
trate on improved egg production, growth 
rate, feed efficiency, and reduced body fat 
and diseases. The use of frozen semen 
should increase as will the use of AI and 
dwarf broiler breeders. 
• Genetics applied to production of fish, 
mollusks, and crustaceans in either natural 
environments or manmade culture systems 
is only at the rudimentary stage. 
Breeders must have reliable information 
about the genetic value of the germplasm they 
are considering introducing. Since farmers do 
not have the resources to collect and process 
data on the performance of animals other than 
those in their owm herds, they must turn to out- 
side sources. The National Cooperative Dairy 
Herd Improvement Program (NCDHIP) is a mod- 
