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In vitro fertilization program in prepuberal brangus calves and later embryo collection
Theriogenology
313
IN VITRO FERTILIZATION PROGRAM IN PREPUBERAL BRANGUS CALVES AND LATER EMBRYO COLLECTION G. M. Brogliatti, C. C. Fumus, D. G. De Matos, A. G. Martinez Centro de Investigaciones Reproductivas Perez Companc, Avda Mayo 701 P 14, (1084) Buenos Aires, Argentina The interval between generations is one of the key elements in any approach to genetic improvement of livestock. Deriving viable oocytes/embryos for embryo production from sexually immature calves could dramatically reduce the generation interval and may offer profound economic advantages for improvement programs in the cattle industry. It has been estimated that the annual rate of genetic gain of growth-efficiency traits in beef cattle could be increased by using IVF and embryo transfer program at early age. The objective of this study was to determine the feasibility of producing embryos, pregnancies and calves from prepubertal Brangus calves. Eighteen prepubertal Brangus calves were selected from a pure breed Brangus herd. Calves were 8 months of age at the beginning of this studies. Ovaries were examined by transrectal ultrasound scanning using a 7.5 MHz transducer previous follicle puncture procedure. Oocytes were collected by transvaginal follicle puncture ones every 15 d using a 19 g needle with a flowrate of 24 ml/min without any superstimulation. The oocytes were in vitro matured with 100 ~tM cysteamine (de Matos et. al. 1995, Mol. Reprod. Dev. 42: 432) fertilized and culture as previously described (Furnus et. al. 1997, Theriogenology 47: 481-490). Blastocysts were transfered into synchronized recipients and pregnancies were diagnosed at 30 and 60 days after transfer. At 15 months of age, 14 of the 18 donors were superstimulated twice within 3 month as described ( B o e t al. Theriogenology 1993; 40: 225-239), Embryo collection was carried out for embryo freezing. Table 1. Total number of oocytes, blastocysts and pregnancies obtained by in vitro production.
Oocytes Blastocysts Pregnancies
Total number 950 134 18
Number/ca!f 52.0 7.4 1
Number/aspiration 9.02 1.2 0.17
Table 1 shows the results of 105 follicle aspirations during a period of 4 months. The fertilization rate was 65.1% and blastocyst formation was 23.6% (out of oocyte inseminated). From two superstimulation treatment an overall total of 83 transferable embryos were collected (average of 5.9 embryos/heifer; 2.9 embryos/flushing). After this program all heifers at 20 month of age were artificially inseminated and returned into the original herd. From the IVF program 18 pregnancies were obtained from 134 transfer; 7 calves were born, 10 more are expected to be born in a short period, and 1 was aborted. The present report demonstrate that a combination of IVF program during prepubertal life (8 to 12 month) and conventional embryo collection at early age would provide embryos, pregnancies and calves by the time heifers were two years old. Supportedby Fundaei6nMargaritaPerezCompane([email protected])
313
IN VITRO FERTILIZATION PROGRAM IN PREPUBERAL BRANGUS CALVES AND LATER EMBRYO COLLECTION G. M. Brogliatti, C. C. Fumus, D. G. De Matos, A. G. Martinez Centro de Investigaciones Reproductivas Perez Companc, Avda Mayo 701 P 14, (1084) Buenos Aires, Argentina The interval between generations is one of the key elements in any approach to genetic improvement of livestock. Deriving viable oocytes/embryos for embryo production from sexually immature calves could dramatically reduce the generation interval and may offer profound economic advantages for improvement programs in the cattle industry. It has been estimated that the annual rate of genetic gain of growth-efficiency traits in beef cattle could be increased by using IVF and embryo transfer program at early age. The objective of this study was to determine the feasibility of producing embryos, pregnancies and calves from prepubertal Brangus calves. Eighteen prepubertal Brangus calves were selected from a pure breed Brangus herd. Calves were 8 months of age at the beginning of this studies. Ovaries were examined by transrectal ultrasound scanning using a 7.5 MHz transducer previous follicle puncture procedure. Oocytes were collected by transvaginal follicle puncture ones every 15 d using a 19 g needle with a flowrate of 24 ml/min without any superstimulation. The oocytes were in vitro matured with 100 ~tM cysteamine (de Matos et. al. 1995, Mol. Reprod. Dev. 42: 432) fertilized and culture as previously described (Furnus et. al. 1997, Theriogenology 47: 481-490). Blastocysts were transfered into synchronized recipients and pregnancies were diagnosed at 30 and 60 days after transfer. At 15 months of age, 14 of the 18 donors were superstimulated twice within 3 month as described ( B o e t al. Theriogenology 1993; 40: 225-239), Embryo collection was carried out for embryo freezing. Table 1. Total number of oocytes, blastocysts and pregnancies obtained by in vitro production.
Oocytes Blastocysts Pregnancies
Total number 950 134 18
Number/ca!f 52.0 7.4 1
Number/aspiration 9.02 1.2 0.17
Table 1 shows the results of 105 follicle aspirations during a period of 4 months. The fertilization rate was 65.1% and blastocyst formation was 23.6% (out of oocyte inseminated). From two superstimulation treatment an overall total of 83 transferable embryos were collected (average of 5.9 embryos/heifer; 2.9 embryos/flushing). After this program all heifers at 20 month of age were artificially inseminated and returned into the original herd. From the IVF program 18 pregnancies were obtained from 134 transfer; 7 calves were born, 10 more are expected to be born in a short period, and 1 was aborted. The present report demonstrate that a combination of IVF program during prepubertal life (8 to 12 month) and conventional embryo collection at early age would provide embryos, pregnancies and calves by the time heifers were two years old. Supportedby Fundaei6nMargaritaPerezCompane([email protected])