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Induction of oestrus in anoestrous, first litter sows with pregnant mares' serum gonadotrophin
Animal Reproduction Science, 5 (1982) 41--45
41
Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
INDUCTION OF OESTRUS IN ANOESTROUS, FIRST LITTER SOWS WITH PREGNANT MARES' SERUM GONADOTROPHIN
R.H. KING, I.H. WILLIAMS and I. BARKER*
Department o f Animal Science and Production, University o f Western Australia, Nedlands, W.A. 6009 (Australia) *Baconfield Piggery, East Bullsbrook, W.A. 6084 (Australia) (Accepted 4 January 1982)
ABSTRACT King, R.H., Williams, I.H. and Barker, I., 1982. Induction of oestrus in anoestrous, first litter sows with pregnant mares' serum gonadotrophin. Anita. Reprod. Sci., 5 : 41--45. The effectiveness of pregnant mares' serum gonadotrophin (PMSG) to stimulate ovarian activity and to induce oestrus in anoestrous sows after weaning of their first litter was evaluated. Anoestrous sows were given an intramuscular injection of 1000 i.u. PMSG 14 days after weaning and a greater number of PMSG-treated sows exhibited oestrus by day 21 after weaning than control sows (16/22 vs 7/24, x 2 = 8.7, P < 0.01). There was no significant effect on farrowing rate, ovulation rate, subsequent litter size or embryo mortality. Thirty-six anoestrous sows were treated with 1000 i.u. PMSG on either day 14, 21, 28 or 35 post weaning and 78% exhibited oestrus within 5 days of treatment. A greater number of sows with quiescent ovaries on the day of treatment exhibited oestrus than sows whose ovaries were either cycling or had preovulatory follicles (25/29 vs 3/7, x= = 6.2, P < 0.05). These results indicated that treatment of anoestrous, first litter sows with 1000 i.u. PMSG at least 14 days after weaning effectively induced oestrus and ovulation in these sows within 5 days of treatment without reducing their subsequent reproductive performance.
INTRODUCTION
First litter sows often exhibit post-weaning anoestrus which results in a longer interval between weaning and mating as compared with older sows (Paterson et al., 1980; Hurtgen et al., 1980). A large proportion of young sows comprise many commercial herds and this represents a major loss in reproductive efficiency. We have analysed the records of 770 first litter sows from a commercial piggery between 1974 and 1979 and found that 78% were mated within 14 days of weaning whereas the remaining 22% failed to exhibit oestrus until 15 to 83 days after weaning (R.H. King, I.H. Williams and I. Barker, unpublished data, 1981). Similar levels of post weaning anoestrus in first litter sows have been reported by Love (1979) and Karlberg
(1980).
0378-4320/82/0000--0000/$02.75 © 1982 Elsevier Scientific Publishing Company
42
Low doses of gonadotrophic hormones can induce a fertile oestrus in anoestrous sows (Schilling and Cerne, 1972) and injection of sows with higher levels can increase subsequent ovulation rate and litter size (Longenecker and Day, 1968). This study was conducted to determine whether pregnant mares' serum gonadotrophin (PMSG) could stimulate ovarian activity and oestrus in anoestrous sows when given 14 days after weaning of their first litter. MATERIALS AND METHODS
The experiment was conducted at a commercial piggery* housing approximately 800 Large White, Landrace and crossbred sows and their progeny in two sheds. The housing, feeding, genetic background and reproductive performance of first litter sows were similar in both sheds. Sixty anoestrous crossbred sows which had been weaned from their first litter during July to December 1980, were used. Twenty-two sows which had not exhibited oestrus within 14 days of weaning were selected from Shed II and injected intramuscularly with 1000 i.u. PMSG (Folligon, Intervet International). Twenty-four sows which also had not exhibited oestrus within 14 days of weaning were selected from Shed I as controls. The remaining 14 anoestrous sows were from Shed I and were injected intramuscularly with 1000 i.u. PMSG 21, 28 or 35 days after weaning. Sows were checked each day after weaning in the presence of a boar for signs of oestrus. If sows exhibited oestrus they were hand mated on successive days when possible. Sows were checked subsequently for returns to service at 3, 6 and 9 weeks after mating and litter size was recorded for sows which farrowed. Sows which failed to exhibit oestrus within 42 days of weaning were culled. The ovaries of anoestrous sows were examined by laparoscopy (Paterson and Oldham, 1978) 14 days after weaning to determine the initial condition of the ovaries. Sows were then laparoscoped 28 and 42 days after weaning or until t h e y exhibited oestrus and were subsequently mated. Sows which were mated within 42 days of weaning were laparoscoped 7--14 days after mating to determine ovulation rate. The data for farrowing rate and number of sows exhibiting oestrus were statistically analysed using Chi-square. The t-test was used for other data to determine significance of difference between PMSG-treated sows from Shed I and control sows from Shed II. A value of 42 days for weaning to oestrus interval was used in the statistical analysis for sows which were culled. RESULTS
The number of sows exhibiting oestrus within 3 weeks after weaning was greater (P < 0.01) for the PMSG treatment than for the control group *Baconfield Piggery, East Bullsbrook, W.A. 6084.
43
(Table I). The mean time to oestrus and to conception for the PMSG-treated sows was less (P < 0.05) than for the control sows (Table II). There was no significant difference in ovulation rate, subsequent litter size or e m b r y o mortality. Of the total of 36 first litter sows treated with PMSG on day 14, 21, 28 or 35 post weaning, 77.8% exhibited oestrus within 5 days of treatment {Table III). Within 5 days of treatment more sows with quiescent ovaries exhibited oestrus than sows whose ovaries were either cycling or had preovulatory TABLEI Effect of PMSG treatment 14 days after weaning on oestrous activity and farrowing rate of anoestrous, first litter sows Treatment
PMSG Control x 2 between treatments
Number of animals Total
Exhibited oestrus within 3 weeks of weaning
Exhibited oestrus within 6 weeks of weaning
Culled a
Farrowing rate b
22 24
16 7 8.7**
19 16 2.5
3 9 3.4
95 81 1.6
** P < 0.01. aAnimals were culled if they did not exhibit oestrus within 6 weeks of weaning or failed to conceive within 10 weeks of weaning. bFarrowing rate = percentage of animals which farrowed to their first post-weaning mating.
TABLE II Effect of PMSG treatment 14 days after weaning on the subsequent reproductive performance of anoestrous, first litter sows Parameters
Weaning to oestrus interval (days) Ovulation rate at oestrus Weaning to conception interval (days) Ovulation rate at conception Average second litter size Piglets born Piglets born alive Embryo mortality (%)a
Treatment
LSD (P=0.05)
Control
PMSG
30.2 15.4 34.4 16.6
22.1 17.3 23.8 17.4
6.0 3.1 7.7 2.9
11.9 11.5 26.3
11.2 10.6 32.6
1.7 1.7 11.2
a E m b r y o mortality = (ovulation rate at conception-piglets born in subsequent litter) as a percentage of ovulation rate at conception.
44 TABLE III Effect of PMSG treatment 14 to 35 days after weaning on oestrous activity of a n o e s t r o u s , first litter s o w s Number of animals C o n d i t i o n of ovary o n day of t r e a t m e n t
Anovular Preovulatory follicles Cycling
Total
29 6 1
within 5 days of treatment
Exhibited oestrus and ovulated 5 to 28 days after treatment
Did n o t e x h i b i t o e s t r u s n o r ovulated within 28 days of t r e a t m e n t
25 3 0
0 2 1
4 1 0
Exhibited oestrus and ovulated
follicles (25/29 vs 3/7, ×2 = 6.2, P < 0.05). For the 28 first litter sows in which PMSG induced oestrus within 5 days of treatment the average (+ SE) ovulation rate at mating, ovulation rate at conception, and farrowing rate were 16.5 (+ 1.2), 17.0 (-+ 1.1) and 82.1% respectively. DISCUSSION
Treatment of anoestrous sows with 1000 i.u. PMSG 14 days after weaning reduced the weaning to oestrus interval without any detrimental effect on the ovulation rate, farrowing rate or subsequent litter size. Schilling and Cerne (1972) injected anoestrous sows with gonadotrophic hormones (400 i.u. PMSG and 200 i.u. human chorionic gonadotrophin) 11 or 12 days after weaning and also found that weaning to oestrus interval was reduced without any significant reduction in farrowing rate or subsequent litter size. Although the response to exogenous gonadotrophic hormones is variable, injection of 500--1500 i.u. PMSG often significantly increases ovulation rate (Anderson and Melampy, 1972). In our experiment the ovulation rate of PMSG-treated sows was higher than that of control sows (17.3 vs 15.4) but this increase was n o t significant. Thirty-six anoestrous sows were injected with PMSG 14--35 days after weaning and 78% exhibited oestrus within 5 days of treatment. Schilling and Cerne (1972) achieved similar results when 86% anoestrous sows exhibited oestrus within 8 days after being injected with 400 i.u. PMSG and 200 i.u. human chorionic gonadotrophin. However, the effectiveness of exogenous gonadotrophin hormone treatment will depend on the initial condition of the ovaries in anoestrous sows. Meredith (1979) suggested that PMSG, although an effective treatment in anoestrous sows, may have undesirable effects if inadvertently given to cyclic pigs. Our experiments showed that treatment o f anoestrous sows with PMSG was more effective in inducing oestrus in sows with quiescent ovaries than in sows whose ovaries were either cycling or had preovulatory follicles.
45
Oestrus can be effectively induced in anoestrous sows by the intramuscular injection of 1000 i.u. PMSG without significantly affecting farrowing rate, ovulation rate or subsequent litter size. However, the response to PMSG is less effective in anoestrous sows whose ovaries were either cycling or had preovulatory follicles than in those sows with inactive ovaries. ACKNOWLEDGEMENTS
We thank the owners, Rogold Investments, and staff of Baconfield Piggery for their cooperation. Mr. D. Turner assisted with the laparoscopies. This work was supported by the Australian Pig Industry Research Committee and R.H. King held an APIRC postgraduate studentship.
REFERENCES Anderson, L.L. and Melampy, R ~ I . , 1972. Factors affecting ovulation rate in the pig. In: D.J.A. Cole (Editor), Pig Production. Butterworths, London, pp. 329--366. Hurtgen, J 2 . , Leman, A.D. and Crabo, B., 1980. Seasonal influence on oestrous activity in sows and gilts. J. Am. Vet. Med. Assoc., 176: 119--123. Karlberg, K., 1980. Factors affecting postweaning oestrus in the sow. Nord. Veterinaerreed., 32: 185--193. Longenecker, D.E. and Day, B.N., 1968. Fertility level of sows superovulated at postweaning estrus. J. Anim. Sci., 27: 709--711. Love, R.J., 1979. Reproductive performance of first parity sows. Vet. Rec., 104 : 238--240. Meredith, M.J., 1979. The treatment of anoestrus in the pig: A review. Vet. Rec., 104: 25--27. Paterson, A_M. and Oldham, C.M., 1978. Laparoscopic examination of the reproductive tract of gilts using a special crate. Aust. Vet. J., 54 : 34--36. Paterson, A_M., Barker, I. and Lindsay, D.R., 1980. Analysis of the reproductive performance records of an intensive piggery in Australia. Proc. Aust. Soc. Anita. Prod., 13: 389--392. Schilling, E. and Cerne, F., 1972. Induction and synchronisation of oestrus in prepuberal gilts and anoestrous sows by a PMS/HCG compound. Vet. Rec., 91: 471--474.
41
Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
INDUCTION OF OESTRUS IN ANOESTROUS, FIRST LITTER SOWS WITH PREGNANT MARES' SERUM GONADOTROPHIN
R.H. KING, I.H. WILLIAMS and I. BARKER*
Department o f Animal Science and Production, University o f Western Australia, Nedlands, W.A. 6009 (Australia) *Baconfield Piggery, East Bullsbrook, W.A. 6084 (Australia) (Accepted 4 January 1982)
ABSTRACT King, R.H., Williams, I.H. and Barker, I., 1982. Induction of oestrus in anoestrous, first litter sows with pregnant mares' serum gonadotrophin. Anita. Reprod. Sci., 5 : 41--45. The effectiveness of pregnant mares' serum gonadotrophin (PMSG) to stimulate ovarian activity and to induce oestrus in anoestrous sows after weaning of their first litter was evaluated. Anoestrous sows were given an intramuscular injection of 1000 i.u. PMSG 14 days after weaning and a greater number of PMSG-treated sows exhibited oestrus by day 21 after weaning than control sows (16/22 vs 7/24, x 2 = 8.7, P < 0.01). There was no significant effect on farrowing rate, ovulation rate, subsequent litter size or embryo mortality. Thirty-six anoestrous sows were treated with 1000 i.u. PMSG on either day 14, 21, 28 or 35 post weaning and 78% exhibited oestrus within 5 days of treatment. A greater number of sows with quiescent ovaries on the day of treatment exhibited oestrus than sows whose ovaries were either cycling or had preovulatory follicles (25/29 vs 3/7, x= = 6.2, P < 0.05). These results indicated that treatment of anoestrous, first litter sows with 1000 i.u. PMSG at least 14 days after weaning effectively induced oestrus and ovulation in these sows within 5 days of treatment without reducing their subsequent reproductive performance.
INTRODUCTION
First litter sows often exhibit post-weaning anoestrus which results in a longer interval between weaning and mating as compared with older sows (Paterson et al., 1980; Hurtgen et al., 1980). A large proportion of young sows comprise many commercial herds and this represents a major loss in reproductive efficiency. We have analysed the records of 770 first litter sows from a commercial piggery between 1974 and 1979 and found that 78% were mated within 14 days of weaning whereas the remaining 22% failed to exhibit oestrus until 15 to 83 days after weaning (R.H. King, I.H. Williams and I. Barker, unpublished data, 1981). Similar levels of post weaning anoestrus in first litter sows have been reported by Love (1979) and Karlberg
(1980).
0378-4320/82/0000--0000/$02.75 © 1982 Elsevier Scientific Publishing Company
42
Low doses of gonadotrophic hormones can induce a fertile oestrus in anoestrous sows (Schilling and Cerne, 1972) and injection of sows with higher levels can increase subsequent ovulation rate and litter size (Longenecker and Day, 1968). This study was conducted to determine whether pregnant mares' serum gonadotrophin (PMSG) could stimulate ovarian activity and oestrus in anoestrous sows when given 14 days after weaning of their first litter. MATERIALS AND METHODS
The experiment was conducted at a commercial piggery* housing approximately 800 Large White, Landrace and crossbred sows and their progeny in two sheds. The housing, feeding, genetic background and reproductive performance of first litter sows were similar in both sheds. Sixty anoestrous crossbred sows which had been weaned from their first litter during July to December 1980, were used. Twenty-two sows which had not exhibited oestrus within 14 days of weaning were selected from Shed II and injected intramuscularly with 1000 i.u. PMSG (Folligon, Intervet International). Twenty-four sows which also had not exhibited oestrus within 14 days of weaning were selected from Shed I as controls. The remaining 14 anoestrous sows were from Shed I and were injected intramuscularly with 1000 i.u. PMSG 21, 28 or 35 days after weaning. Sows were checked each day after weaning in the presence of a boar for signs of oestrus. If sows exhibited oestrus they were hand mated on successive days when possible. Sows were checked subsequently for returns to service at 3, 6 and 9 weeks after mating and litter size was recorded for sows which farrowed. Sows which failed to exhibit oestrus within 42 days of weaning were culled. The ovaries of anoestrous sows were examined by laparoscopy (Paterson and Oldham, 1978) 14 days after weaning to determine the initial condition of the ovaries. Sows were then laparoscoped 28 and 42 days after weaning or until t h e y exhibited oestrus and were subsequently mated. Sows which were mated within 42 days of weaning were laparoscoped 7--14 days after mating to determine ovulation rate. The data for farrowing rate and number of sows exhibiting oestrus were statistically analysed using Chi-square. The t-test was used for other data to determine significance of difference between PMSG-treated sows from Shed I and control sows from Shed II. A value of 42 days for weaning to oestrus interval was used in the statistical analysis for sows which were culled. RESULTS
The number of sows exhibiting oestrus within 3 weeks after weaning was greater (P < 0.01) for the PMSG treatment than for the control group *Baconfield Piggery, East Bullsbrook, W.A. 6084.
43
(Table I). The mean time to oestrus and to conception for the PMSG-treated sows was less (P < 0.05) than for the control sows (Table II). There was no significant difference in ovulation rate, subsequent litter size or e m b r y o mortality. Of the total of 36 first litter sows treated with PMSG on day 14, 21, 28 or 35 post weaning, 77.8% exhibited oestrus within 5 days of treatment {Table III). Within 5 days of treatment more sows with quiescent ovaries exhibited oestrus than sows whose ovaries were either cycling or had preovulatory TABLEI Effect of PMSG treatment 14 days after weaning on oestrous activity and farrowing rate of anoestrous, first litter sows Treatment
PMSG Control x 2 between treatments
Number of animals Total
Exhibited oestrus within 3 weeks of weaning
Exhibited oestrus within 6 weeks of weaning
Culled a
Farrowing rate b
22 24
16 7 8.7**
19 16 2.5
3 9 3.4
95 81 1.6
** P < 0.01. aAnimals were culled if they did not exhibit oestrus within 6 weeks of weaning or failed to conceive within 10 weeks of weaning. bFarrowing rate = percentage of animals which farrowed to their first post-weaning mating.
TABLE II Effect of PMSG treatment 14 days after weaning on the subsequent reproductive performance of anoestrous, first litter sows Parameters
Weaning to oestrus interval (days) Ovulation rate at oestrus Weaning to conception interval (days) Ovulation rate at conception Average second litter size Piglets born Piglets born alive Embryo mortality (%)a
Treatment
LSD (P=0.05)
Control
PMSG
30.2 15.4 34.4 16.6
22.1 17.3 23.8 17.4
6.0 3.1 7.7 2.9
11.9 11.5 26.3
11.2 10.6 32.6
1.7 1.7 11.2
a E m b r y o mortality = (ovulation rate at conception-piglets born in subsequent litter) as a percentage of ovulation rate at conception.
44 TABLE III Effect of PMSG treatment 14 to 35 days after weaning on oestrous activity of a n o e s t r o u s , first litter s o w s Number of animals C o n d i t i o n of ovary o n day of t r e a t m e n t
Anovular Preovulatory follicles Cycling
Total
29 6 1
within 5 days of treatment
Exhibited oestrus and ovulated 5 to 28 days after treatment
Did n o t e x h i b i t o e s t r u s n o r ovulated within 28 days of t r e a t m e n t
25 3 0
0 2 1
4 1 0
Exhibited oestrus and ovulated
follicles (25/29 vs 3/7, ×2 = 6.2, P < 0.05). For the 28 first litter sows in which PMSG induced oestrus within 5 days of treatment the average (+ SE) ovulation rate at mating, ovulation rate at conception, and farrowing rate were 16.5 (+ 1.2), 17.0 (-+ 1.1) and 82.1% respectively. DISCUSSION
Treatment of anoestrous sows with 1000 i.u. PMSG 14 days after weaning reduced the weaning to oestrus interval without any detrimental effect on the ovulation rate, farrowing rate or subsequent litter size. Schilling and Cerne (1972) injected anoestrous sows with gonadotrophic hormones (400 i.u. PMSG and 200 i.u. human chorionic gonadotrophin) 11 or 12 days after weaning and also found that weaning to oestrus interval was reduced without any significant reduction in farrowing rate or subsequent litter size. Although the response to exogenous gonadotrophic hormones is variable, injection of 500--1500 i.u. PMSG often significantly increases ovulation rate (Anderson and Melampy, 1972). In our experiment the ovulation rate of PMSG-treated sows was higher than that of control sows (17.3 vs 15.4) but this increase was n o t significant. Thirty-six anoestrous sows were injected with PMSG 14--35 days after weaning and 78% exhibited oestrus within 5 days of treatment. Schilling and Cerne (1972) achieved similar results when 86% anoestrous sows exhibited oestrus within 8 days after being injected with 400 i.u. PMSG and 200 i.u. human chorionic gonadotrophin. However, the effectiveness of exogenous gonadotrophin hormone treatment will depend on the initial condition of the ovaries in anoestrous sows. Meredith (1979) suggested that PMSG, although an effective treatment in anoestrous sows, may have undesirable effects if inadvertently given to cyclic pigs. Our experiments showed that treatment o f anoestrous sows with PMSG was more effective in inducing oestrus in sows with quiescent ovaries than in sows whose ovaries were either cycling or had preovulatory follicles.
45
Oestrus can be effectively induced in anoestrous sows by the intramuscular injection of 1000 i.u. PMSG without significantly affecting farrowing rate, ovulation rate or subsequent litter size. However, the response to PMSG is less effective in anoestrous sows whose ovaries were either cycling or had preovulatory follicles than in those sows with inactive ovaries. ACKNOWLEDGEMENTS
We thank the owners, Rogold Investments, and staff of Baconfield Piggery for their cooperation. Mr. D. Turner assisted with the laparoscopies. This work was supported by the Australian Pig Industry Research Committee and R.H. King held an APIRC postgraduate studentship.
REFERENCES Anderson, L.L. and Melampy, R ~ I . , 1972. Factors affecting ovulation rate in the pig. In: D.J.A. Cole (Editor), Pig Production. Butterworths, London, pp. 329--366. Hurtgen, J 2 . , Leman, A.D. and Crabo, B., 1980. Seasonal influence on oestrous activity in sows and gilts. J. Am. Vet. Med. Assoc., 176: 119--123. Karlberg, K., 1980. Factors affecting postweaning oestrus in the sow. Nord. Veterinaerreed., 32: 185--193. Longenecker, D.E. and Day, B.N., 1968. Fertility level of sows superovulated at postweaning estrus. J. Anim. Sci., 27: 709--711. Love, R.J., 1979. Reproductive performance of first parity sows. Vet. Rec., 104 : 238--240. Meredith, M.J., 1979. The treatment of anoestrus in the pig: A review. Vet. Rec., 104: 25--27. Paterson, A_M. and Oldham, C.M., 1978. Laparoscopic examination of the reproductive tract of gilts using a special crate. Aust. Vet. J., 54 : 34--36. Paterson, A_M., Barker, I. and Lindsay, D.R., 1980. Analysis of the reproductive performance records of an intensive piggery in Australia. Proc. Aust. Soc. Anita. Prod., 13: 389--392. Schilling, E. and Cerne, F., 1972. Induction and synchronisation of oestrus in prepuberal gilts and anoestrous sows by a PMS/HCG compound. Vet. Rec., 91: 471--474.