310 • Impacts of Applied Genetics— Micro-Organisms, Plants, and Animais 
3. Ability to breed large numbers of cattle over a 
shorter calving interval. 
4. Increase use of Ab expecially in beef cattle, sheep, 
and swine. 
FUTURE 
Estrus cycle regulation should allow selected sires 
to be more widely used to improve important traits 
in beef cattle. It should also gain widespread and 
rapid acceptance among dairymen as well. 
Superovulation 
DEFIMTION 
Superovulation is the hormonal stimulation of 
multiple ovarian follicles resulting in release from 
the ovary of a larger number of oocytes (ova) than 
normal. 
STATE OF THE ART 
Superovulation with implantation into surrogate 
mothers increases the number of offspring, usually 
from highly selected dams. Adequate procedures are 
presently available for superovulation of laboratory 
and domestic animal species, except the horse. The 
drugs used to induce superovulation are the go- 
nadotropins, pregnant mare’s serum gonadotropin 
(PMSG) and follicle stimulating hormone (FSH), in 
some instances followed by other treatments to stim- 
ulate ovum maturation and ovulation. Superovulated 
ova result in normal offspring with the same success 
rates as achieved with normally ovulated ova. 
DISADVANTAGES 
1. Greatest drawback is that degree of success can- 
not be predicted for an individual animal. 
2. Batches of hormones for ovulation treatment vary 
widely in quality. 
3. PMSG is scarce, and has been declared a drug by 
the Food and Drug Administration (FDA). Thus, 
most use of PMSG is now illegal. 
4. There is insufficient data to judge the effect of 
repeated superovulation. 
FUTURE 
Methods for superovulation will improve consist- 
ency of results. Additional understanding of basic 
physiological mechanisms will facilitate such efforts. 
New work in superovulatory technology involves ac- 
tive immunization against adrostenedione (a hor- 
mone involved in regulation of follicular develop- 
ment). This treatment prevents atresia and reliably 
increases the frequency of multiple ovulations. The 
technology has definite commercial potential for cat- 
tle husbandry and limited potential for sheep hus- 
bandry, and much current effort is directed towards 
developing and testing a commercial procedurtv 
Embryo recovery 
DEFINITION 
The collection of the fertilized o\a from the 
oviducts or uteri. Collection of embryos is a 
necessarv step for embryo transfer or storage, and 
for many experiments in reproductixe hiologx’ Both 
surgical and nonsurgical methods are used. 
STATE OF THE ART 
Surgical.— Methods are axailahU* for recowring 
40 to 80 percent of oxulations from cattle, slu-ej). 
goats, swine, and horses. Fhe d(*\rlopment of adhe- 
sions and scar tissue following surgery limits these 
techniques. Surgical recovery is th(‘ only method lor 
sheep, goats, and pigs. It is pre.senlly practiicd 
almost exclusively when a suspecti'd |)alh()logv ol the 
oviducts renders an individual suhl(*rtile. or when 
emhrvos must he recovered hefon* the individual 
reaches puberty. 
Nonsurgical.— Non-surgical embryo n‘(ov erv 
technitiues are preferred for the cow .iiul horse 
Fiftv to eightv jtercent of cow ovulations lan h<* 
recovered, and 40 to 00 percent ol the operations on 
horses to recover the single ov illation are suci esslul 
AD\ AN r \(;i;s 
1. Nonsurgical (>mhrvo transler can he perlormed .m 
unlimited number of times 
2. Requirements for eiiuipment |)ersonnel ami time 
are low in nonsurgical recovery I his is espei lallv 
important in milk cattle: since the nonsui gii al jiro 
cedure is performi'd on the larm milk prodm tion 
is not interrupted 
3. A single embryo can he obtained between super 
ovulation treatmcMits 
4. Emhrvos can he obtained Irom <i voung heiler 
before it reaches puberty 
5. The technologv is especiallv import.mt lor re 
search, e g., in (‘fforls to |)roduce idenlii al twins 
embryo biopsies for se\ determin.ition eti 
lilt Rl 
Methods of collecting emhrvos have not i h.ingeil 
appreciably since about I!l7li noi are sigmlu ant ad 
vances predicted for the luture 
Embryo transfer 
DI.I IM I lOV 
Implantation of an emhrvo into lln ovnlmt m 
uterus. 
