Pregnancy rate and birth rate of calves from a large-scale IVF program using reverse-sorted semen in Bos indicus, Bos indicus-taurus, and Bos taurus cattle

Abstract

Obtaining sexed sperm from previously frozen doses (reverse-sorted semen [RSS]) provides an important advantage because of the possibility of using the semen of bulls with desired genetic attributes that have died or have become infertile but from whom frozen semen is available. We report the efficiency of RSS on the pregnancy rate and birth rate of calves in a large-scale program using ovum pick-up and in vitro embryo production (IVEP) from Bos indicus, Bos indicus-taurus, and Bos taurus cattle. From 645 ovum pick-up procedures (Holstein, Gir, and Nelore), 9438 viable oocytes were recovered. A dose of frozen semen (Holstein, Nelore, Brahman, Gir, and Braford) was thawed, and the sperm were sex-sorted and cooled for use in IVF. Additionally, IVF with sperm from three Holstein bulls with freeze-thawed, sex-sorted (RSS) or sex-sorted, freeze-thawed (control) was tested. A total of 2729 embryos were produced, exhibiting a mean blastocyst rate of 29%. Heifers and cows selected for adequate body condition, estrus, and health received 2404 embryos, and 60 days later, a 41% average pregnancy rate was observed. A total of 966 calves were born, and 910 were of a predetermined sex, with an average of 94% accuracy in determining the sex. Despite the lower blastocyst rate with freeze-thawed, sex-sorted semen compared with sex-sorted semen, (P < 0.05), the pregnancy rate (bull I, 45% vs. 40%; II, 35% vs. 50%; and III, 47% vs. 48% for RSS and control, respectively; P > 0.05) and sex-sorted efficiency (bull I, 93% vs. 98%; II, 96% vs. 94%; and III, 96% vs. 97% for RSS and control, respectively; P > 0.05) were similar for each of the three bulls regardless of the sperm type used in the IVF. The sexing of previously frozen semen, associated with IVEP, produces viable embryos with a pregnancy rate of up to 40%, and calves of the desired sex are born even if the paternal bull has acquired some infertility, died, or is located a long distance from the sexing laboratory. Furthermore, these data show the feasibility of the process even when used in a large-scale IVEP program.

Hormonal protocols for in vitro production of Zebu and taurine embryos

“…Zebu donors produced more total and viable oocytes and embryos than B. taurus donors (Table 1). This result was expected and previously reported (Morotti et al, 2014). The higher number of oocytes recovered from B. indicus breeds is probably a consequence of the higher number of follicles emerging in each follicular wave, when compared to B. taurus (Silva-Santos et al, 2013).…”

“…The mean viable oocytes obtained by OPU were higher than in some studies (Viana & Bols, 2005) but lower than in others (Morotti et al, 2014). Significant variations in follicular recruitment and in the number of recovered oocytes were reported among breeds and also between individuals within breeds (De Roover et al, 2005).…”

Update and overview on assisted reproductive technologies (ARTs) in Brazil

“…In dairy breeds, production of a high percentage of female calves has many economic advantages and use of in IVP allows the production of approximately 90% of the embryos with the desired sex (Morotti et al, 2014). Thus, this third growth phase of the Brazilian embryo industry after 2010 has been marked by a clear shift from the predominance of beef breeds to dairy breeds.…”

Parâmetros da produção in vitro de embriões da raça Sindi

“…O efeito do touro e do tipo de sêmen sobre a taxa de blastocistos também foi observado ao se utilizar oócitos de vacas Nelore e Gir, fertilizados com sêmen sexado ou não sexado de três diferentes touros Holandeses (Morotti et al, 2014). Do mesmo modo, Trigal et al (2012) confirmaram o efeito individual do touro, assim como do tipo de sêmen sobre a taxa de blastocistos, que foi maior com o sêmen não sexado do que com o sexado.…”