188 • Impacts of Applied Genetics— Micro-Organisms, Plants, and Animals 
growth rales, feed efficiencies, carcass merit, 
and litter sizes have helped keep pork prices 
down and improve its quality in the Nation’s 
markets. Pork today is leaner and contains more 
high-quality protein calories than it was just a 
few decades ago. 
A1 in swine production could expand, al- 
though it will be limited by the relatively poor 
ability of swine sperm to withstand freezing 
and by the problem of detecting estrus. It will 
be encouraged by the strong trend toward con- 
finement housing and integration of all phases 
of hog production. The industry— especially the 
individual, family-farm type units— would bene- 
fit by the establishment of a progeny testing 
scheme to identify superior boars. Publicly 
available information on genetic merit would 
decrease dependence on a few corporate breed- 
ing organizations. 
Embryo transfer in swine will be strictly 
limited by difficulties in developing nonsurgical 
methods of recovery and transfer, and by the 
low economic value per animal in comparison to 
cattle and horses. However, embryo transfer is 
useful in introducing new genetic material into 
breeding herds of specific pathogen-free swine 
and in transporting genetic material to various 
regions of the world. 
Sheep. — The processes of selection and of 
crossing specific strains, which have been so ef- 
fective in poultry and hogs, have been virtually 
ignored in sheep. Selection of replacement ewes 
from the fastest growing ewe lambs born as 
twins and the use of flushing to increase ovula- 
tion rates have led to annual increases of 1.8 
percent in lambing; in one test tbe market 
weight of lambs was increased by 1/lb/yr of 
cooperation.^® 
Synchronization of estrus in ewes can be 
achieved with prostaglandin and many differ- 
ent progestogens. The technique is used exten- 
sively in many countries, but no products for 
this purpose are currently marketed in the 
United States. 
AI rates abroad sometimes approach 100 per- 
cent. However, AI will not be used widely on 
K. Inskeep, personal communication, 1980. 
sheep in the United States until systems for per- 
formance and progeny testing are implemented 
that will track the number of lambs born and 
their growth rate, and until routine freezing of 
raw semen is achieved. 
Goats. — The research performed on goats is 
largely designed for application to other ani- 
mals. However, interest in goats in the United 
States and the demand for their products 
through the world is increasing. 
NCDHIP has just started providing sire e\al- 
uations to goat breeders. These data, along w ith 
artifical insemination, should increase milk pro- 
duction. The genetic data might he of particular 
usefulness in the less de\eloped countries 
where most goat raising occurs. Ureater use of 
all reproductive technologies on valuable Ango- 
ra goats might be expected. 
Other technologies 
Tbe use of any reliable twinning or s('.\ s(*l('c- 
tion technologies will he limited until such |)ro- 
cedures can he made simple, fast, ini’xpensiv c. 
and innocuous. No widesi)i'ead u.se of thes(> 
technologies should he expcH’ted \\ ithin tlu' next 
decade. 
The more esoteric techni(|ues Ibi- manipu- 
lating sex cells or the germplasm its('lf w ill ha\ c 
no impact on the production of animals or 
animal products within the next 20 years. In 
vitro manipulations, including cloning, ci'll fu- 
sion, the production of chimeras, and the use of 
rDNA lechnic|Lies, u ill continue to he of inten.se 
interest. However, it is unlikely that they will 
have practical effects on farm production in the 
United States in this century. I.aeh teehni(|ue 
will require more resc’ari'h and refinement Un- 
til specific geiKks can b(^ identified and locat('d. 
no direct gene manipulation will be pr.ictic.ible 
A polygenic basis for most liaits of importance 
can be expected to be th(> rule rath(M' th.in the 
exception. 
Should such techniques become a\ailal)le. 
limited use for producing breeding stock, can be 
expected. Experience with eai'ly users of ,\1 and 
“Ibid. 
