MERCK ANIMAL HEALTH
TECHNICAL SERVICES BULLETIN
P.G. 600
®
(Serum Gonadotropin and Chorionic Gonadotropin)
Technical Report 2
Introduction of Fertile Estrus in Prepuberal Gilts by
Treatment with a Combination of Pregnant Mare’s Serum
Gonadotropin and Human Chorionic Gonadotropin
Abstract
Ten trials involving 678 presumed prepuberal gilts (5.5 to 7.5 months old) were conducted in North Carolina, Illinois and Missouri to
evaluate the reproductive performance of gilts given a combination of 400 I.U. of pregnant mare’s serum gonadotropin and 200 IU of
human chorionic gonadotropin (P.G. 600®). Gilts that were presumed to be prepuberal received P.G. 600 or no treatment (control) on
the day of movement from finishing facilities to pens for breeding. Detection of estrus, with the aid of mature boars, was conducted
daily for 28 days; gilts in estrus were mated naturally. Treatment with P.G. 600 increased the percentage in estrus within seven (57.5 vs
40.9 percent) or 28 days (72.9 vs 59.5 percent); average interval to estrus was reduced (P < 0.05 from 10.4 to 7.5 days). Farrowing
rate (78.5 ± 3.1 percent), number of pigs born alive (8.6 ± 0.2) or dead (0.26 + 0.06) and number of pigs weaned (8.0 .f+ 0.2) were
unaffected by treatment. Gilts that were heavier than the median for each farm were in heat sooner and more were detected in heat,
but no other reproductive traits differed between heavy and light gilts. Overall, the results reveal that P.G. 600 was useful for
induction of fertile estrus in prepuberal gilts. (Key Words: Gilts, Estrus, Puberty, Gonadotropins)
Introduction
Efficiency of reproduction in swine herds would be enhanced if there were effective, approved methods for inducing estrus in gilts
before their introduction into the breeding herd. Currently, more gilts are selected than are needed for replacements, and only gilts that
show estrus during a specific period are mated. Gilts not mated eventually are sold at a lower price because they exceed the desired
market weight. If estrus could be induced promptly and predictably, producers could select fewer replacement gilts, fit these gilts into
a specific schedule and sell the excess gilts at market weight.
Because pregnant mare’s serum gonadotropin (PMSG) has biological properties similar to both FSH and LH, and HCG has many
properties similar to LH, but with some FSH activity, it is physiologically appropriate to use these in combination to stimulate follicular
growth in prepuberal gilts (Paterson, 1982; Webel and Day, 1982; Foxcroft and Hunter, 1985; Dial and BeVier, 1986). Schilling and
Cerne (1972) first reported the use of a low-dose PMSG-HCG combination for induction of estrus in gilts and anestrous sows, but the
details of their experiments were not described completely. Three of their five experiments were conducted on a single “industrial pig
farm” of 2,500 sows in Yugoslavia, and the two other experiments were conducted at undisclosed locations. In their studies, control
gilts were observed for estrus over an unspecified period of time, and they did not report intervals to first heat of control or treated
gilts after movement to breeding barns and exposure to boars. They provided no description of how the treated or control gilts were
handled in terms of movement to pens for breeding and exposure to boars.
The trials described herein were conducted to evaluate the effectiveness of P.G. 600, a combination of 400 I.U. of PMSG and 200 I.U.
of HCG, for induction of estrus in gilts on commercial farms in the U.S.
Caution: Treatment will not induce estrus in gilts that have already reached puberty (begun to cycle). Gilts that are less than
five and one-half months of age or that weigh less than 85 kg (187 lb.) may not be mature enough to continue normal estrus
cycles or maintain a normal pregnancy to full term after treatment. Treatment will not induce estrus in sows that are returning
to estrus normally three to seven days after weaning. Delayed return to estrus is most prevalent after the first litter; the
effectiveness of P.G. 600 has not been established after later litters. Delayed return to estrus often occurs during periods of
adverse environmental conditions, and sows mated under such conditions may farrow smaller than normal litters.
For complete safety information on P.G. 600 use, see accompanying product package insert.
MERCK ANIMAL HEALTH
TECHNICAL SERVICES BULLETIN
Material and Methods
during estrus. Boars were used randomly across treatments, and
at some units, gilts were mated to different boars on consecutive
days of estrus. Dates of treatment, estrus, mating, return to estrus,
farrowing and weaning were recorded for each gilt. Service boar,
number and survival of pigs farrowed, litter weaning weights and
rebreeding performance after weaning the first litter were recorded.
On the day of treatment, gilts were weighed individually, or their
weights were estimated by measuring the heart girth and converting
the measurements to kilograms by equations derived from unadjusted
data of Esbenshade et al. (1986). At farrowing, litter sizes were
adjusted by cross-fostering piglets within treatment groups (control
or P.G. 600) for gilts that farrowed together.
Ten trials were conducted from the fall of 1984 until the fall of
1985 and utilized 678 gilts in four swine units in eastern North
Carolina, three units in central Illinois and three units in central
Missouri. These units were all intensely managed, and most or all
of the animals on each farm were housed in total confinement.
The herds ranged in size from 150 to 1,000 sows. Cooperating
swine producers were selected for the study on the basis of their
willingness to adhere to an experimental protocol approved by the
U.S. Food and Drug Administration (FDA).
On each farm, market-weight crossbred gilts (5.5 to 7.5 months of
age and 86 to 163 kg BW), presumed to be prepuberal, were moved
from finishing facilities to pens for breeding and were assigned
randomly to two groups of equal numbers. One group of gilts received
P.G. 600® (serum gonadotropin and chorionic gonadotropin), and
the other group served as controls. Immediately prior to use, the
lyophilized P.G. 600 was diluted with a sterile diluent provided
by the manufac­turer. The solution was injected (i.m.) through a
3.8 cm, 20-gauge disposable hypodermic needle in the neck
immediately behind an ear. Gilts assigned to the control group were
not injected. Injections were given on the day (day 0) that gilts were
moved from finishing buildings to breeding units. At nine of 10
units, the pens used for breeding had concrete floors and were in
environmentally controlled or open-front buildings. At the remaining
unit, gilts were bred in pasture lots. The number of gilts treated
with P.G. 600 ranged from 20 to 96 among the 10 farms. Gilts were
checked for estrus with mature boars at least once daily for 28 days
after treatment. Gilts in estrus were mated naturally once daily
Cumulative Percentage In Estrus
Data from gilts that were detected in estrus within 28 days after
treatment were included in all analyses. Data from gilts not detected
or those detected later than 28 days (after trials were completed)
were used only for analyses of percentage in estrus. Binomial
response traits (estrus, rebred, farrowed, etc.) were analyzed by
assigning each gilt a 1 (i.e., in estrus) or 0 (i.e., not in estrus) for each
trait in question. Data were analyzed by least squares analyses of
variance using80the General Linear Models procedure (SAS, 1985).
70 complete block model included treatment, farm
The randomized
and the treatment
60 x farm interaction as sources of variation. The
effect of treatment
was tested by using the treatment x farm mean
50
square. Gilts were
classified
as light or heavy if they were below
40
or above the median weight for the farm. Effect of weight
Control on traits
30
600 class,
was analyzed with a statistical model that included P.G.
weight
treatment and20their interaction. Chi square procedures were used
for analyses of 10
data on distribution of estrus after treatment.
Trait
No. Mean No. Mean SE
Percentage in estrus within
28 days after treatment
341
59.5
337
72.9
Days from treatment to estrus
201
10.4
253
7.5b
.4
Percentage rebredc
165
12.7
208
16.4
2.9
Farrowing rate, %d
190
78.9
236
78.1
3.1
Pigs born alive per litter
149
8.6
182
8.6
.2
Pigs born dead per litter
149
.27
181
.24
.06
Pigs weaned per litter
146
8.1
178
7.8
.2
Days to estrus after weaning
45
20.6
49
9.6
3.2
Percentage in estrus after weaning
55
77.0
67
82.5
5.3
b
a
2.7
Approximate pooled standard error estimated from standard errors from each
treatment group.
b
P.G. 600 group differs from control group (P < .05).
c
Percentage rebred is the percentage that returned to heat after the original mating.
d
Farrowing rate is the percentage of gilts that farrowed to the first mating.
a
Cumulative Percentage In Estrus
P.G. 600®
2
6
4
8 10 12 14 16 18 20 22 24 26 28
Days After Treatment
80
70
60
50
40
Control
P.G. 600
30
20
10
0
0
2
6
4
8 10 12 14 16 18 20 22 24 26 28
Days After Treatment
Figure 2.
24
Percentage In Estrus
Treatment
Control
0
Figure 1.
20
16
12
Control
P.G. 600
8
4
0
1
2
3
4 5
6
7
8 9 10 11 12 13 14
Days After Treatment
24
e In Estrus
Table 1. Least Squares Means of Reproductive Traits for
Gilts Treated with P.G. 600®
0
20
16
12
Results
pigs per litter from control gilts exceeded that of P.G. 600-treated
gilts by 1.0 to 1.5 pigs. The number of pigs weaned per litter did not
differ. Cross-fostering of pigs was performed within treatment groups
so that we could determine whether treatment affected number
weaned. On two farms, the number weaned by control gilts
exceeded that of gilts given P.G. 600 by 1.3 to 1.6 pigs per litter,
but on two farms, gilts given P.G. 600 weaned 0.6 to 0.7 more pigs
per litter than controls. Litter weights were recorded at 21 days of
lactation on one farm. Litters from gilts given P.G. 600 averaged
37.8 kg, compared with 36.1 kg for controls (P < 0.05).
Treatment of gilts with P.G. 600 (serum gonadotropin and
chorionic gonadotropin) increased the percentage of gilts in estrus
within 28 days (Table 1, Figure 1). This response was consistent
across farms. For example, the percentage of P.G. 600-treated
gilts in estrus within 28 days exceeded that of the controls on
seven farms, was equal to that of controls on two farms and was
less than that of controls on one farm. Among farms, percentage
of P.G. 600-treated gilts in estrus within 28 days ranged from 42
to 97 percent, compared with 31 to 90 percent of controls.
®
Number of days from weaning the first litter to onset of estrus
was recorded on three farms. Gilts treated with P.G. 600 returned
to estrus in 9.6 days after weaning, compared with 20.6 days for
controls. Gilts were not retreated with P.G. 600. This difference
was not significant (P < 0.14).
Interval from treatment to onset of estrus was less for gilts treated
with P.G. 600 (Table 1), and the consistency of response was such
that P.G. 600-treated gilts had shorter intervals to estrus on seven
farms, had intervals similar to controls on one farm and had intervals
longer than controls: on two farms. Among the 10 farms, interval
from treatment to estrus ranged from 3.9 to 12.1 days for gilts
treated with P.G. 600, compared with 4.6 to 17.5 for controls.
Actual or estimated weights of gilts at treatment ranged from 86
to 163 kg. The effects of weight class on responses are illustrated
in Table 2. More heavy gilts were detected in estrus (77.7 vs. 62.3
percent), and they tended to show estrus sooner after treatment
(7.6 vs. 9.2 days). None of the other reproductive traits differed
between the weight classes, and there were no significant
treatment x weight class interactions.
The distribution of periods of estrus for gilts detected within 14 days
after treatment is illustrated in Figure 2. More P.G. 600-treated gilts
showed estrus within seven days than controls (P < 0.05). Occurrence
of estrus peaked on day four in both groups (Figure 2). For the
three-day period centered on day four, 45.5 percent of gilts treated
with P.G. 600 were detected in heat, compared with 21.6 percent
for controls. There were no differences in percentages detected
between eight and 28 days. The degree of estrus synchronization
was estimated by calculating the within treatment variance for
days to estrus. The variance was 50.7 days for controls, compared
with 39.0 days for gilts treated with P.G. 600 0 (P < 0.05).
Discussion
In these trials, market-weight gilts were moved from finishing
facilities to pens for breeding and given daily contact with boars.
Control gilts that were detected in heat within four weeks were
in estrus 10.4 days after movement and boar exposure. This is
approximately four days earlier than the average for 13 trials involving
gilts of similar age (see Table 6.9 in Hughes, 1982). Gilts treated with
P.G. 600 were in estrus three days earlier than controls, and a higher
percentage of them were detected in estrus during the first week
after treatment. Because estrous females apparently stimulate
expression of sexual behavior in their penmates (Hemsworth, 1982),
it is possible that the P.G. 600-treated gilts enhanced the estrus
response of the controls during the first week. Control gilts were
not injected, so we cannot rule out the possibility that an acute
stressor such as an injection would have increased the proportion
of gilts in heat within four weeks. However, control gilts were moved
to different facilities and given exposure to boars, both of which
should be more stressful than an injection.
The percentage of gilts that returned to estrus after the first
breeding (rebred, Table 1) did not differ between groups and
averaged 12.8 percent for controls, compared with 16.4 percent
for those injected with P.G. 600. Farrowing rate did not differ
between the two groups. Among nine farms with complete
farrowing data, farrowing rate was similar between groups on
six farms, it was greater for the controls on two farms, and it
was greater for gilts given P.G. 600 on one farm. Farrowing rates
ranged from 55 to 97 percent for gilts treated with P.G. 600,
compared with 50 to 100 percent for controls.
Litter traits were not different between the treatment groups.
Among farms, number born alive ranged from 7.1 to 9.5 for gilts
given P.G. 600, compared with 7.3 to 8.9 for controls. On one farm,
number of live pigs from gilts treated with P.G. 600 exceeded that
of controls by 2.2 pigs per litter, whereas on another farm this
difference was 1.3 pigs per litter. On three farms, the number of live
Treatment with P.G. 600 did not alter any reproductive traits other
than percentage of gilts in estrus and interval to estrus. Farrowing rate,
litter size, number of pigs weaned and rebreeding performance
after weaning the first litter were not different between treatment
Table 2. Least Squares Means of Responses to P.G. 600® by Gilts of Different Weight Classes
Control
Trait
P.G. 600®
Lighta
Heavy
Light
Heavy
T
W
T•W
Percentage in estrus within 28 days after treatment
54.4
71.1
70.2
84.2
< .01
< .01
NS
Days from treatment to estrus
10.9
8.8
7.6
6.3
< .05
< .14
NS
Gilts were classified as light or heavy if they were below or above the median for the farm, respectively.
T = treatment, W = weight group, T•W = treatment x weight group interaction, NS = not significant.
a
b
Significanceb
groups. Undesirable effects such as poor expression of estrus and
low fertility often have been encountered with higher doses of
gonadotropins (Paterson, 1982). The relatively low doses of PMSG and
HCG in P.G. 600® (serum gonadotropin and chorionic gonadotropin)
apparently act synergistically to give a response that is greater
than that observed when a similar dose of PMSG is given alone
(Britt et al., 1986). A greater percentage of heavy gilts were detected in
estrus, and these gilts were bred sooner after treatment than light
gilts. Although the interaction was not significant, there was a
tendency for P.G. 600 to provide more stimulation for light gilts
than for heavy ones. For example, there was a 24 percent
difference in favor of P.G. 600-treated gilts for the proportion of light
gilts detected in heat, compared with a 14 percent difference for
the heavy group. Similarly, P.G. 600 induced estrus an average of
3.3 days earlier in the light gilts, compared with a 2.5 day
advantage for the heavy class. Otherwise, light gilts produced just
as well as heavy ones, delivering and weaning the same number of
pigs and rebreeding at the same rate after weaning the first litter.
The usefulness of P.G. 600 to the swine producer can be illustrated
by examining the cumulative estrus response curves in Figure 1.
With P.G. 600, 57.5 percent of the assigned gilts were detected in
estrus within the first week after treatment, but 21 days were
needed to detect a similar percentage (58.1 percent) of controls. The
50th percentile was reached in five days in the P.G. 600 group,
compared with 18 days in controls. Thus, it took about three times
as long to breed the same proportion of gilts in the control group
as in the group given the gonadotropins. The greatest difference
between the two groups occurred during the first five days, where
the slopes of the two curves differed most. Beyond the first week,
the response curves increased at similar rates, indicating that the
P.G. 600 exerted no long-term effects and that gilts that failed to
respond initially continued to respond as if they had not been
treated (e.g., at the same rate as the controls).
There was no indication that gilts ovulated in response to P.G. 600
without expressing estrus. Evidence for missed heats would be a
secondary rise in the estrus response about three weeks after the
initial anticipated estrus. Seventeen gilts treated with P.G. 600
and 26 controls were detected in heat during the 4th week
following treatment; thus, there was no indication that more
P.G. 600-treated gilts were in heat than expected. We did not
collect blood samples for measurement of progesterone in
anestrous gilts, so we have no measure of the percentage of gilts
that were already exhibiting estrus cycles and therefore would
not have been responsive to P.G. 600 (Paterson, 1982).
In summary, P.G. 600 was effective for increasing the proportion of
gilts in estrus within the first week after movement of marketweight gilts to pens for breeding. Moreover, the synchrony of heat
was more precise in these P.G. 600-treated gilts. Having more
gilts exhibit heat at predictable times permits more efficient
scheduling of breeding and farrowing facilities and provides greater
opportunities for introduction of gilts into sow groups when sows
are rebred after weaning. Because litter sizes can be lower for gilts
bred at first heat rather than at second or third heat, P.G. 600 could
be used to synchronize a group of gilts for subsequent breeding at
the second or third heat after treatment.
Literature Cited
Britt, J.H., Esbenshade, K.L., and Heller, K., 2986. Responses
of seasonally anestrous gilts and weaned primiparous sows to
treatment with pregnant mare’s serum gonadotropin and
altrenogest. Theriogenology 26:696.
Dial, G.D. and BeVier, G.W. Pharmacologic control of estrus and
ovulation in the pig. In: D.A. Morrow (Ed). Current Therapy in
Theriogenology 2. pp 912-914. W.B. Saunders Co., Philadelphia.
Esbenshade. K.L, Britt, J.H., Armstrong, J.D, Toelie, V.D,
and Stanislaw. C.M. 1986. Body condition of sows across
parties and relationship to reproductive performance. J. Anim. Sci.
62:1187.
Foxcroft G.R., and Hunter, M.G. 1985. Basic physiology of
follicular maturation in the pig. J. Reprod. Fertil. (Suppl.) 33:1.
Hemsworth, P.H. 1982. Social environment and reproduction.
In: Cole, D.J.A., and Foxcroft, G.R. (Ed.). Control of Pig
Reproduction. pp 585-601. Butterworth Scientific, London.
Hughes,P.E. 1982. Factors affecting the natural attainment of
puberty in the gilt. In: Cole, D.J.A. and Foxcroft, G.R. (Ed.). Control
of Pig Reproduction. pp 117-138. Butterworth Scientific, London.
Paterson, A.M. 1982. The controlled induction of puberty.
In: Cole, D.J.A. and Foxcroft, G.R (Ed.), Control of Pig Reproduction.
pp 139-160. Butterworth Scientific, London.
SAS. 1985. SAS User’s Guide: Statistics. SAS Inst., Inc., Cary, NC.
Schilling, E. and Cerne, F. 1972. Induction and synchronization
of estrus in prepuberal gilts and anestrous sows by a PMS/
HCG-compound. Vet. Rec. 91:471.
Webel, S.K., and Day, B.N. 1982. The control of ovulation.
In: Cole, D.J.A. and Foxcroft, G. (Ed.). Control of Pig Reproduction.
pp 197-21 Butterworth Scientific, London.
1
Paper No. 11661 of the Journal Series of the North Carolina ARS,
Raleigh 27695-7643. The use of trade names in this publication
does not imply endorsement by the North Carolina ARS or
criticism of similar ones not mentioned. The gonadotropin
combination marketed as P.G. 600 is a registered trademark of
Merck Animal Health. Appreciation is expressed to Lynn Butler
and Doug Hutchins for their assistance in collecting data.
2
Dept. of Anim. Sci., North Carolina State Univ., to whom reprint
requests should be sent.
3
Dept. of Anim. Sci., Univ. of Missouri.
4
Dept. of Anim. Sci., Illinois State Univ.
5
Merck Animal Health.
Received June 16, 1988.
Accepted October 4, 1988.
Merck Animal Health
Technical Report No. 2
Introduction of Fertile Estrus in Prepuberal Gilts by
Treatment with a Combination of Pregnant Mare’s Serum
Gonadotropin and Human Chorionic Gonadotropin
Authors: Jack H. Britt,
Billy N. Day
Stephen K. Webel and
Michael A. Brauer
P.G. 600
®
(Serum Gonadotropin and Chorionic Gonadotropin)
DESCRIPTION:
Gilts normally reach puberty (begin experiencing normal estrous cycles and
exhibiting regular estrus or heat)at any time between six and eight months of
age, although some gilts will not have exhibited their first estrus at ten months
of age. Age at first estrus is influenced by several factors including breed type,
season of the year, environmental conditions, and management practice
(Hurtgen, 1986).
Sows normally exhibit estrus three to seven days after weaning their litters;
however, some otherwise healthy sows may not exhibit estrus for 30 days or
more after weaning (Dial and Britt, 1986).
The causes of delayed return to estrus in healthy sows are poorly understood,
but probably include season of the year (so-called seasonal anestrus; Hurtgen,
1979), adverse environmental conditions, such as high ambient temperatures
(Love, 1978), and the number of previous litters, because the condition is more
prevalent after the first litter than after later litters (Hurtgen, 1986).
P.G. 600 is a combination of serum gonadotropin (Pregnant Mare Serum
Gonadotropin or PMSG) and chorionic gonadotropin (Human Chorionic
Gonadotropin or HCG) for use in prepuberal gilts (gilts that have not yet exhibited
their first estrus) and in sows at weaning. It is supplied in freezedried form with
sterile diluent for reconstitution.
In gilts and sows, the action of serum gonadotropin is similar to the action of
Follicle-Stimulating Hormone (FSH), which is produced by the animals’ anterior
pituitary gland. It stimulates the follicles of the ovaries to produce mature ova
(eggs), and it promotes the outward signs of estrus (heat).
The action of chorionic gonadotropin in gilts and sows is similar to the action of
Luteinizing Hormone (LH), which is also produced by the animals’ anterior
pituitary gland. It causes the release of mature ova from the follicles of the
ovaries (ovulation), and it promotes the formation of corpora lutea, which are
necessary for the maintenance of pregnancy once the animals have become
pregnant.
The combination of serum gonadotropin and chorionic gonadotropin in P.G. 600
induces fertile estrus in most prepuberal gilts and weaned sows three to seven
days after administration (Schilling and Cerne, 1972; Britt et al., 1986; Bates et
al., 1991). The animals may then be mated or, in the case of gilts, mating may be
delayed until the second estrus after treatment.
note: P.G. 600 is intended as a management tool to improve
reproductive efficiency in swine production operations. to
obtain maximum benefit from this product, estrus detection and
other aspects of reproductive management must be adequate. IF
you are in doubt about the adequacy of your breeding program,
consult your veterinarian.
PG. 600 is available in two package sizes:
SINGLE DOSE VIALS (order Code No. PG-720-1) - Five vials containing white
freeze-dried powder, plus five vials containing sterile diluent. When
reconstituted, each single dose vial (5 mL) of P.G. 600 contains:
SERUM GONADOTROPIN (PMSG) 400 IU
CHORIONIC GONADOTROPIN (HCG) 200 IU
(equivalent to 200 USP Units chorionic gonadotropin)
FIVE DOSE V IALS (order Code No. PG-720-5) - One vial containing white
freezedried powder, and one vial containing sterile diluent. When reconstituted,
the five dose vial (25 mL) of P.G. 600 contains:
SERUM GONADOTROPIN (PMSG) 2000 IU
CHRIONIC GONADOTROPIN (HCG) 1000 IU
equivalent to 1000 USP Units chorionic gonadotropin)
Indications for Use:
PREPUBERAL GILTS: P.G. 600 is indicated for induction of fertile estrus (heat) in
healthy prepuberal (non-cycling) gilts over five and one-half months of age and
weighing at least 85 kg (187 lb.).
SOWS AT WEANING: P.G. 600 is indicated for induction of estrus in healthy
weaned sows experiencing delayed return to estrus.
Cautions:
Treatment will not induce estrus in gilts that have already reached puberty
(begun to cycle). Gilts that are less than five and one-half months of age or that
weigh less than 85 kg (187 lb.) may not be mature enough to continue normal
estrus cycles or maintain a normal pregnancy to full term after treatment.
Treatment will not induce estrus in sows that are returning to estrus normally
three to seven days after weaning. Delayed return to estrus is most prevalent
after the first litter; the effectiveness of P.G. 600 has not been established after
later litters. Delayed return to estrus often occurs during periods of adverse
environmental conditions, and sows mated under such conditions may farrow
smaller than normal litters.
DOSAGE AND ADMINISTRATION:
One dose (5 mL) of reconstituted P.G. 600, containing 400 IU serum gonadotropin
(PMSG) and 200 IU chorionic gonadotropin (HCG), should be injected into the gilt or
sow’s neck behind the ear.
Prepuberal gilts should be injected when they are selected for addition to the
breeding herd. Sows should be injected at weaning during periods of delayed return
to estrus.
DIRECTIONS FOR USE:
SINGLE DOSE VIALS: Using a sterile syringe and a sterile 0.90 x 38 mm (20 G x
1½”) hypodermic needle, transfer the contents of one vial of sterile diluent (5
mL) into one vial of freeze-dried powder. Shake gently to dissolve the powder.
Inject the contents of the vial into the gilt or sow’s neck behind the ear.
FIVE DOSE VIAL: Using a sterile syringe and a sterile 0.90 x 38 mm (20 G x 1½”)
hypodermic needle, transfer approximately 5 mL of the sterile diluent into the
vial of freeze-dried powder. Shake gently to dissolve the powder. Transfer the
dissolved product back into the vial of diluent and shake gently to mix. Inject
one dose (5 mL) of the reconstituted solution into the gilt or sow’s neck behind
the ear.
STORAGE PRECAUTIONS:
Store at 36-46°F (2-8°C).
Once reconstituted, P.G. 600 should be used immediately. Unused solution
should be disposed of properly and not stored for future use.
Spent hypodermic needles and syringes generated as a result of the use of this
product must be disposed of properly in accordance with all applicable Federal,
State and local regulations.
REFERENCES:
Bates, R.O., B.N. Day, J.H. Britt, L.K. Clark and M.A. Brauer (1991).
Reproductive performance of sows treated with a combination of Pregnant Mare’s Serum Gonadotropin and Human Chorionic Gonadotropin at weaning in the summer. Journal of Animal Science 69:894.
Britt, J.H., B.N. Day, S.K. Webel and M.A. Brauer (1989).
Induction of fertile estrus in prepuberal gilts by treatment with a combination of Pregnant Mare’s Serum Gonadotropin and Human Chorionic Gonadotropin. Journal of Animal Science 67:1148.
Dial, G.D., and J.H. Britt (1986).
The clinical endocrinology of reproduction in the pig. In: D.A. Morrow (ed.).
Current Therapy in Theriogenology 2. W.B. Sanders Company, Philadelphia.
p. 905.
Hurtgen, J.P. (1979).
Seasonal breeding patterns in female swine. Ph.D. Dissertation,
University of Minnesota.
Hurtgen, J.P. (1986).
Noninfectious infertility in swine. In: D.A. Morrow (ed.) Current
Therapy in Theriogenology 2. W.B. Sanders Company, Philadelphia. p. 962.
Love, R.J. (1978).
Definition of a seasonal infertility problem in pigs. Veterinary Record 103:443.
Schilling, E., and F. Cerne (1972).
Induction and synchronization of oestrus in prepubertal gilts and anoestrus sows by a PMS/HCG-compound. Veterinary Record 91:471.
READ AND FOLLOW LABEL DIRECTIONS
NADA No. 140-856; APPROVED BY FDA
FOR ANIMAL USE ONLY
Merck Animal Health
Summit, New Jersey 07901
merck-animal-health-usa.com Technical Service: 1-800-211-3573 Customer Service: 1-800-356-7470
Copyright © 2013 Intervet Inc., a subsidiary of Merck & Co., Inc. All rights reserved. SW-PG-20593 (02-13)