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Ovarian Response of Cows Following Pregnant Mare Serum Gonadotrophin Treatment during Two Successive Estrous Cycles
Ovarian Responseof Cows Following Pregnant Mare Serum Gonadotrophin 'Treatment During Two Successive Estrous Cycles Abstract
reported (3, 4, 8). Repeated superovulation attempts by Willett et al. (8) using different amounts of f o l l i c l e stimulating hormone ( F S H ) or P M S G together with ovulating injections at intervals ranging from 28 to 231 days a p a r t significantly reduced superovulation response. Hafez et al. (4) reported no superovulation response in 11 heifers following the second of two P M S G treatments two estrous cycles a p a r t though 24% of heifers had from 2 to 5 ovulations following one P M S G treatment. Similar superovulation responses were reported by Hafez et al. (3) after first and second P M S G treatments, but n o superovulation response was observed at third and fourth attempts. The respective intervals between attempts one through four were 5 to 7 months, 31 to 40 days, and 18 to 21 days. On the other hand, Dzink et al. (1) did not demonstrate a consistent reduction in response of cows repeatedly treated with several gonadotrophins. Positive responses to repeated superovulation attempts (up to 11 in some cows) were observed by Nichols (6). The present report presents results from a preliminary study in which mature cows were treated with P M S G injected during two successive estrous cycles.
Thirteen cows (8 Holsteins, 3 Ayrshire, 2 Shorthorn; 3 to 7 years old) were treated with pregnant mare serum gonadotrophin (PMSG) during two successive estrous cycles. The gonadotrophin was injected on D a y 16 of the cycle (estrus --Day 0) and again on Day 16 of the next cycle (10 cows) or 21 days after previous P M S G injection (3 cows). Doses of PMSG injected during the first cycle were 3,000 I U (6 cows: Group A) and 2,000 I U (7 cows: Group B). These doses were reversed for the individual cow during its next estrous cycle. Cows were slaughtered 10 to 14 days after the second PMSG treatment. Response to P M S G was evaluated as number of ovulations and total follicular response (calculated by the sum of ovulations plus follicles greater than 10 mm diameter). Mean ovulation rate and mean total follicular response were 19.5 (~7.80) and 20.7 ( ± 7 . 9 6 ) for Group A cows and were 10.7 (--+4.72) and 29.1 ( ± 1 1 . 3 2 ) for Group B. Two cows in Group B had not ovulated before slaughter; mean ovulation rate of the remaining 5 cows was 15.0. Substantial superovulation responses may be obtained following the second of two P M S G treatments during two successive estrous cycles.
Experimental Procedure
Introduction
Application of egg transfer in cattle offers considerable potential from the genetic and production points of view. To exploit fully the genetic potential of a single cow, large numbers of eggs must be recovered. Presently, superovulation by treating the cow with gonadotrophins during the follicular phase of the estrous cycle is the most effective means of producing cow eggs. As there are limitations on the number of eggs which may be produced during any one estrous cycle (2), superovulation must be repeated to recover maximum numbers of eggs from individual cows. Repeated superovulation of cows has not been extensively studied, and reports present conflicting results. Diminished response of cows to repeated superovulation attempts has been
Thirteen mature cows (8 ttolstein, 3 Ayrshire, 2 Shorthorn) all nonlactating and apparently with normal estrual activity were in the experiment, age of cows ranged from 3 to 7 years. Cows were divided into 2 groups. Group A (6 cows) was given an intramuscular injection of 3,000 I U P M S G (Organon, Montreal) on Day 16 of the estrous cycle (estrus --Day 0). On Day 16 of the following cycle an injection of 2,000 I U P M S G was given. Group B ( 7 cows) was treated similarly except that 2,060 I U P M S G were injected during the first cycle and 3,000 I U during the second cycle. Three cows not observed in estrus after t h e first P M S G treatment had the second P M S G injection given 21 days after the previous in= jection. The criterion for estrus was standing for mounting by other cows. Cows were slaughtered 10 to 14 days after the second P M S G injection. Reproductive organs were recovered, and response to P M S G was
527
528
TECHNICAL NOTES
TABLE 1. Ovarian response of cows following application of p r e g n a n t mare serum gonadotrop h i n at two successive estrous cycles. Second P M S G dose Number of cows N u m b e r ovulated at slaughter Mean ovulation rate (-+SE) Mean T F R ( ± S E ) Ovulations as a percentage of T F R a Mean b Mean c Based d Based
2,000 I U 6 6 19.5(±7.80) 20.7(-+7.96) 94.4
3,000 I U 7 5 10.7(--+ 4.72) a 29.1(±11.32) 92.6 c
Both Levels 13 11 14.8(---+4.39) 5 25.2(---+6.94) 93.7 (l
ovulation rates of 5 ovulated cows was 1 5 . 0 ( ± 5 . 5 4 ) . ovulation rates o£ 11 ovulated cows was 17.5(-+4.76). on 5 cows which had ovulated. on 11 cows which had ovulated.
evaluated. Response to P M S G was assessed as ovulation rate and as total follicular response ( T F R ) . Total follicular response was calculated f r o m the sum of ovulations plus follicles 10 mm surface diameter or greater. No attempt was made to assess response of cows to the first P M S G treatment.
Council of Canada and the Ontario Department of Agriculture and Food is appreciated. P. F. $CANLON, Department of Animal Science, University of Guelph, Guelph, Ontario, Canada Present Address: Division of Forestry and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Results and Discussion Table 1 shows the response of cows to P M S G following the second of two P M S G treatments during successive estrous cycles. Eleven of :13 cows had ovulated p r i o r to slaughter. All 11 cows showed evidence of superovulation (3 to 47 ovulations). The remaining two cows had substantial numbers (32 and 9]) of large (10 mm diameter or greater) unovulated follicles at time of slaughter. One of the unovulated cows was in estrus at time of slaughter and had been in estrus for 3 days p r i o r to slaughter. The other cow had some symptoms of estrus (copious cervical mucus) at time of slaughter. The response in ovulation rate and T F R following P M S G treatment at two successive estrous cycles was substantial in cows at both treatments. Response to 2,000 I U P M S G at second estrous cycle was greater than that to 2,000 I U in other reports (4, 5). Response of beef heifers (liveweight, 365 kg) to 2,000 I U P M S G (Organon, Montreal) was 22.3 ( ± 1 3 . 3 7 ) ovulations and 37.0 (--+15.06) T F R (7). The response of cows to the second of 2 P M S G treatments during successive estrous cycles in this experiment suggests that substantial responses to repeated superovulation attempts may be obtained and that f u r t h e r research on responses to repeated superovulation m a y p r o v e rewarding. Acknowledgments Financial support
of the National Research
JOURNAL OF DAIRY SCIENCE ~r0L. 5~, N0. 4
References (1) Dziuk, P. J., J. D. Donker, J. R. Nichols, and W. E. Petersen. 1958. Problems associated with the transfer of ova between cattle. Minnesota Agr. Exp. Sta. Bull., 222, (2) Folley, S. J. and F. H. Malpress. 1944. The response of the bovine ovary to pregnant mares' scrum and horse pituitary extract. Prec. Roy. See. London B., 132: ]64. (3) Hafez, E. S. E., M. R. Jainudeen, and D. R. Lindsay. 1965. Gonadotrophln-induced twinning and related phenomena in beef cattle. Acta. Endocrlnol., 50 (Suppl. 102). (4) Hafez, E. S. E., E. Rajakoski, P. B. Anderson, O. L. Frost, and G. Smith. 1964. Problems of gonadotrophin-induced multiple pregnancy in beef cattle. Amer. J. Vet. Res., 25 : 1074. (5) Jainudecn, M. R., ]~. S. E. Hafez, P. D. Gollnick, and L. A. Moustafa. 1966. Antigonadotrophins in the serum of cows following repeated therapeutic pregnant mare serum injections. Amer. J. Vet. Res., 27 : 669. (6) Nichols, J. R. 1956. Superovulation and ova transplantation in the bovine. Ph.D. thesis. University of Minnesota. 158 pp. (7) Scanlon, P. F., W. J. Neville, T. D. Burgess, and J. W. Macpherson. 1970. Superovulation response of progestagcn treated cattle. Prec. Canadian See. Animal Prod., 2Oth Ann. Meet. p. 65. Abstr. (8) Willet, E. L., P. J. Buckner, and W. It. McShan. 1953. Refractoriness of cows repeatedly superovulated with gonadotrophins. J. Dairy Sci., 36: 1083.
reported (3, 4, 8). Repeated superovulation attempts by Willett et al. (8) using different amounts of f o l l i c l e stimulating hormone ( F S H ) or P M S G together with ovulating injections at intervals ranging from 28 to 231 days a p a r t significantly reduced superovulation response. Hafez et al. (4) reported no superovulation response in 11 heifers following the second of two P M S G treatments two estrous cycles a p a r t though 24% of heifers had from 2 to 5 ovulations following one P M S G treatment. Similar superovulation responses were reported by Hafez et al. (3) after first and second P M S G treatments, but n o superovulation response was observed at third and fourth attempts. The respective intervals between attempts one through four were 5 to 7 months, 31 to 40 days, and 18 to 21 days. On the other hand, Dzink et al. (1) did not demonstrate a consistent reduction in response of cows repeatedly treated with several gonadotrophins. Positive responses to repeated superovulation attempts (up to 11 in some cows) were observed by Nichols (6). The present report presents results from a preliminary study in which mature cows were treated with P M S G injected during two successive estrous cycles.
Thirteen cows (8 Holsteins, 3 Ayrshire, 2 Shorthorn; 3 to 7 years old) were treated with pregnant mare serum gonadotrophin (PMSG) during two successive estrous cycles. The gonadotrophin was injected on D a y 16 of the cycle (estrus --Day 0) and again on Day 16 of the next cycle (10 cows) or 21 days after previous P M S G injection (3 cows). Doses of PMSG injected during the first cycle were 3,000 I U (6 cows: Group A) and 2,000 I U (7 cows: Group B). These doses were reversed for the individual cow during its next estrous cycle. Cows were slaughtered 10 to 14 days after the second PMSG treatment. Response to P M S G was evaluated as number of ovulations and total follicular response (calculated by the sum of ovulations plus follicles greater than 10 mm diameter). Mean ovulation rate and mean total follicular response were 19.5 (~7.80) and 20.7 ( ± 7 . 9 6 ) for Group A cows and were 10.7 (--+4.72) and 29.1 ( ± 1 1 . 3 2 ) for Group B. Two cows in Group B had not ovulated before slaughter; mean ovulation rate of the remaining 5 cows was 15.0. Substantial superovulation responses may be obtained following the second of two P M S G treatments during two successive estrous cycles.
Experimental Procedure
Introduction
Application of egg transfer in cattle offers considerable potential from the genetic and production points of view. To exploit fully the genetic potential of a single cow, large numbers of eggs must be recovered. Presently, superovulation by treating the cow with gonadotrophins during the follicular phase of the estrous cycle is the most effective means of producing cow eggs. As there are limitations on the number of eggs which may be produced during any one estrous cycle (2), superovulation must be repeated to recover maximum numbers of eggs from individual cows. Repeated superovulation of cows has not been extensively studied, and reports present conflicting results. Diminished response of cows to repeated superovulation attempts has been
Thirteen mature cows (8 ttolstein, 3 Ayrshire, 2 Shorthorn) all nonlactating and apparently with normal estrual activity were in the experiment, age of cows ranged from 3 to 7 years. Cows were divided into 2 groups. Group A (6 cows) was given an intramuscular injection of 3,000 I U P M S G (Organon, Montreal) on Day 16 of the estrous cycle (estrus --Day 0). On Day 16 of the following cycle an injection of 2,000 I U P M S G was given. Group B ( 7 cows) was treated similarly except that 2,060 I U P M S G were injected during the first cycle and 3,000 I U during the second cycle. Three cows not observed in estrus after t h e first P M S G treatment had the second P M S G injection given 21 days after the previous in= jection. The criterion for estrus was standing for mounting by other cows. Cows were slaughtered 10 to 14 days after the second P M S G injection. Reproductive organs were recovered, and response to P M S G was
527
528
TECHNICAL NOTES
TABLE 1. Ovarian response of cows following application of p r e g n a n t mare serum gonadotrop h i n at two successive estrous cycles. Second P M S G dose Number of cows N u m b e r ovulated at slaughter Mean ovulation rate (-+SE) Mean T F R ( ± S E ) Ovulations as a percentage of T F R a Mean b Mean c Based d Based
2,000 I U 6 6 19.5(±7.80) 20.7(-+7.96) 94.4
3,000 I U 7 5 10.7(--+ 4.72) a 29.1(±11.32) 92.6 c
Both Levels 13 11 14.8(---+4.39) 5 25.2(---+6.94) 93.7 (l
ovulation rates of 5 ovulated cows was 1 5 . 0 ( ± 5 . 5 4 ) . ovulation rates o£ 11 ovulated cows was 17.5(-+4.76). on 5 cows which had ovulated. on 11 cows which had ovulated.
evaluated. Response to P M S G was assessed as ovulation rate and as total follicular response ( T F R ) . Total follicular response was calculated f r o m the sum of ovulations plus follicles 10 mm surface diameter or greater. No attempt was made to assess response of cows to the first P M S G treatment.
Council of Canada and the Ontario Department of Agriculture and Food is appreciated. P. F. $CANLON, Department of Animal Science, University of Guelph, Guelph, Ontario, Canada Present Address: Division of Forestry and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Results and Discussion Table 1 shows the response of cows to P M S G following the second of two P M S G treatments during successive estrous cycles. Eleven of :13 cows had ovulated p r i o r to slaughter. All 11 cows showed evidence of superovulation (3 to 47 ovulations). The remaining two cows had substantial numbers (32 and 9]) of large (10 mm diameter or greater) unovulated follicles at time of slaughter. One of the unovulated cows was in estrus at time of slaughter and had been in estrus for 3 days p r i o r to slaughter. The other cow had some symptoms of estrus (copious cervical mucus) at time of slaughter. The response in ovulation rate and T F R following P M S G treatment at two successive estrous cycles was substantial in cows at both treatments. Response to 2,000 I U P M S G at second estrous cycle was greater than that to 2,000 I U in other reports (4, 5). Response of beef heifers (liveweight, 365 kg) to 2,000 I U P M S G (Organon, Montreal) was 22.3 ( ± 1 3 . 3 7 ) ovulations and 37.0 (--+15.06) T F R (7). The response of cows to the second of 2 P M S G treatments during successive estrous cycles in this experiment suggests that substantial responses to repeated superovulation attempts may be obtained and that f u r t h e r research on responses to repeated superovulation m a y p r o v e rewarding. Acknowledgments Financial support
of the National Research
JOURNAL OF DAIRY SCIENCE ~r0L. 5~, N0. 4
References (1) Dziuk, P. J., J. D. Donker, J. R. Nichols, and W. E. Petersen. 1958. Problems associated with the transfer of ova between cattle. Minnesota Agr. Exp. Sta. Bull., 222, (2) Folley, S. J. and F. H. Malpress. 1944. The response of the bovine ovary to pregnant mares' scrum and horse pituitary extract. Prec. Roy. See. London B., 132: ]64. (3) Hafez, E. S. E., M. R. Jainudeen, and D. R. Lindsay. 1965. Gonadotrophln-induced twinning and related phenomena in beef cattle. Acta. Endocrlnol., 50 (Suppl. 102). (4) Hafez, E. S. E., E. Rajakoski, P. B. Anderson, O. L. Frost, and G. Smith. 1964. Problems of gonadotrophin-induced multiple pregnancy in beef cattle. Amer. J. Vet. Res., 25 : 1074. (5) Jainudecn, M. R., ]~. S. E. Hafez, P. D. Gollnick, and L. A. Moustafa. 1966. Antigonadotrophins in the serum of cows following repeated therapeutic pregnant mare serum injections. Amer. J. Vet. Res., 27 : 669. (6) Nichols, J. R. 1956. Superovulation and ova transplantation in the bovine. Ph.D. thesis. University of Minnesota. 158 pp. (7) Scanlon, P. F., W. J. Neville, T. D. Burgess, and J. W. Macpherson. 1970. Superovulation response of progestagcn treated cattle. Prec. Canadian See. Animal Prod., 2Oth Ann. Meet. p. 65. Abstr. (8) Willet, E. L., P. J. Buckner, and W. It. McShan. 1953. Refractoriness of cows repeatedly superovulated with gonadotrophins. J. Dairy Sci., 36: 1083.