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Controlled reproduction of the pig: The benefits of P.G. 600

by 5m Editor
28 November 2005, at 12:00am

By Jan Baars, Annette Bonde Larsen and Marc Martens, Intervet. - P.G. 600 was developed in the beginning of the sixties and introduced on the Dutch market in 1965. Since then it has been registered in pig producing countries all over the world, including the US. Research in pig reproduction has always been an area of major interest. Since P.G. 600 was introduced several studies have been performed showing the benefits of the product and articles have been published from all over the world.

Intervet Pigs

P.G. 600 is a unique combination of PMSG and HCG (400/200 I.U.). This combination has always proven to be the optimal one in order to bring prepuberal gilts in oestrus. Also in first litter sows it has proved to be a unique help to avoid anoestrus. For synchronisation purposes the product can be used as well.

In 30 years much has changed. Breeding companies changed the genetic potency of the pigs. Feed companies keep on changing formulations and feeding schemes. Housing and management has been altered etc.

Is P.G. 600 still a winner?

We think it is. At the beginning of this year the book Controlled Reproduction in Pigs appeared (5). The author, Ian Gordon, referred to literature about the use of P.G. 600 in several chapters :

  • More frequent farrowing in pigs
  • Embryo transfer and associated techniques in pigs
  • Breeding pigs at younger ages

The name P.G. 600 is even included in the index of the book, demonstrating that this product still is an up to date tool in P.G. 600®: The Evergreen Jan Baars, Annette Bonde Larsen and Marc Martens controlled reproduction of the pig and contributes to the profitability of the pig enterprise.

However, there are also genetic and environmental factors which influence the reproductive efficacy. These may be the reason that the results of different P.G. 600 trials sometimes vary.

The claim of the product has always been, that it induces a fertile heat. This means it reduces farrowing intervals, whereas pregnancy rates and litter sizes are equal or even better than those in control animals.

P.G. 600 is often used in first litter sows at day of weaning in order to reduce the weaning to service interval.

To demonstrate that results of P.G. 600 treatment may vary, results of 2 recent trials, one from Canada and one from Germany, will be presented. So far the results have not been published.

Canadian trial

The Canadian trial has been performed by Kirkwood c.s. of the University of Alberta. On four farms they treated ± 50% of primiparous sows at day of weaning, the remaining ones were untreated controls. The total number of animals involved in the trial varied per farm. On farms 1, 2, 3, and 4 respectively 56, 424, 40, and 89 animals have been treated with P.G. 600, while 62, 450, 34, and 95 animals have been left as controls.

The effect on reproductive performance of P.G. 600 treatment at weaning in all four farms is given in Table 1.

Table 1: Effect on reproductive performance of P.G. 600 treatment at weaning of primiparous sows

Control
P.G.600
p
No. of sows
W.O.I *
% Bred by 7 days
% Bred by 25 days
Farrowing %
Litter size
641
8.7 ± 0.3
50.9
74.9
86.9
10.5 ± 0.2
609
6.7 ± 0.2
72.6
84.4
86.0
9.9 ± 0.2
0.0001
0.0001
0.0001
0.4
0.02
* W.O.I. = weaning/oestrus interval in days

The over-all results show a highly significant reduction of W.O.I. with 2 days resulting in ± 22% more animals bred by 7 days after weaning.

By 25 days after weaning ± 10% more animals had been bred in the treated group compared to the control group. The results varied among the farms and the decrease in W.O.I. in treated animals was less outspoken in farms 3 and 4 than in farms 1 and 2.

No difference in the over-all farrowing rate was observed. Litter sizes were better in the control animals, however, not at all farms. In farm four 11.2 piglets were born

Table 2: The effect of P.G. 600 and 1 000 I.U. Folligon treatment in sows

P.G 600
1000 I.U Folligon
Control
No. of sows
Oestrus %
Interval w-1st A.I.
Hrs standing heat
% returns
% abortion
No. farrowings
% farrowing
Litter size
No. born alive
No. stillborn
No. pigl. alive/treat. sow
331
93.7a
4.72b
37.23
9.0a
1.3
267
85.8a
12.13a
11.18a
0.94
9.0
353
90.6
4.86a
36.41
12.7
2.0
256
79.1
11.76
10.60
1.16
7.7
327
87.0b
4.93
37.10
19.1b
0.4
225
73.4b
11.88b
10.07b
1.22
6.9
a , b p < 0.5 according multiple T test

German trial

In the former East Germany oestrus induction with 1 000 I.U. PMSG 24 hours after weaning has been frequently used. In order to compare results of treatments with P.G. 600 and 1 000 I.U. Folligon (PMSG) , Intervet GmbH initiated a one year lasting trial in a 750 sow unit. The trial has been performed by a research team of the Institute for Animal Husbandry and Genetics of the Georg August University in Göttingen (FRG). One of the researchers, W. Holtz, of this institute was already involved in P.G. 600 trials in the seventies (4).

The treatment was given 24 hours after weaning. Three days after treatment oestrus detection was performed every 12 hours with a teaser boar. A.I. was applied at time of standing heat. In Table 2 the results are given irrespective of parity, because the W.O.I. in the primiparous sows in the control group was less than one day longer than in the multiparous sows.

Reproductive performance in treated sows was better than in controls. The over-all result becomes quite clear by calculating the number of piglets born alive per treated sow. In the P.G. 600 group 9.0 piglets were born alive per treated sow, 7.7 piglets in the Folligon treated group and only 6.9 in the control group.

There was no difference at all in the duration of standing heat between the three groups.

Discussion and conclusions

More than thirty years after the development of P.G. 600 it is evident that the product is still an important tool in controlled reproduction in pigs.

However, it is difficult to predict the reproductive performance of the treated animals. In the results above presented, differences are seen on important parameters. In the Canadian trial P.G. 600 reduced farrowing intervals and did not improve litter size. On the other hand, in the German trial there was hardly any reduction of the weaning to service interval. In this trial the big advantage of the product was the increased number of piglets born alive per treated sow, which was the consequence of excellent farrowing rates and litter sizes. Explanation for this is the big influence of genetic and environmental factors on reproductive performance.

In the German trial it is quite striking, that in the control group of primiparous sows there was no clear delay in the weaning to oestrus intervals. In general this is just the group for which P.G. 600 is indicated.

As already proven in the dose titration study which has been performed to get P.G. 600 registered in the US, it came out that for oestrus induction P.G. 600 is superior to Folligon and other combinations of PMSG and HCG. Also in the German trial the use of P.G. 600 appeared to be superior to Folligon. PMSG has frequently been used for this indication in the (former) Eastern European countries and this may still be the case, because literature about the use of PMSG for oestrus induction is abundant.

Further information

Click the links below for additional information:

References

1. Schilling E. and Cerne F. (1972). Induction and synchronization of oestrus in prepuberal gilts and anoestrus sows by a PMSG/HCG compound. Vet. Rec., 91, 471-474.

2. Webster W.R. (1978). Evaluation of a pregnant mare?s serum and human chorionic gonadotrophin mixture for alleviating summer infertility in sows. Australian Vet. J., 54, 26-29.

3. Britt J.H., Day B.N., Webel S.K. and Brauer M.A. (1989). Induction of fertile estrus in prepuberal gilts by treatment with a combination of pregnant mare?s serum gonadotrophin and human chorionic gonadotrophin. J. Anim. Sc., 67, 1148-1153.

4. Holtz W., Hermann F., Pich H.H. and Polanco A. (1977). Die Steuerung von Brunst und Ovulationszeitpunkt bei Jungsauen. Zuchthygiene, 12, 91-92.

5. Ian Gordon. Controlled reproduction in pigs, Vol. 3 (1997). ISBN 9851991165. CAB International.

Source: Intervet UK Ltd - November 2005