Autores
Suzane Peres Campanholi, Fabio Morato Monteiro, Erika Aline Ribeiro Dias, Monica Accorsi, Bernardo Marcozzi Bayeux, Joslaine Noely Dos Santos Gonçalves Cyrillo, Emiliana de Oliveira Santana Batista, Alexandre Henryili Souza, Pietro Sampaio Baruselli
Repeatability of in vitro embryo production in Nellore breed
Resumo
Recent advances in the field of animal assisted
reproduction have allowed faster dissemination of animals with superior
genetics. In cattle, the development of some biotechnologies such as the in vitro production
(IVP) of embryos optimized the use of oocytes, which represents a great
improvement in embryo production world-wide. Therefore, females with high net
merit can be multiplied more efficiently to maximize the number of their offspring.
The use of ultrasound-guided transvaginal follicle aspiration combined with IVP
allowed wide commercial transfer of IVP-embryos with satisfactory pregnancy
results. Yet, there are a number of unanswered areas including the level of repeatability
and predictability in IVP systems. Thus, the aim of this study was to evaluate
the repeatability of some variables related to IVP of bovine embryos from Nellore breed. The study
was conducted from 2011 to 2012 using 42 Nellore
cows housed at the Centro APTA Bovinos de Corte located in Sertãozinho-SP, Brazil.
Donors were kept under the same management throughout the entire experimental
period. All animals underwent a total of 25 transvaginal ultrasound-guided
follicular aspiration sections. Oocytes were retrieved and handled similarly by
Sexing Technologies using semen from 11 sires. Repeatability was evaluated in
the following variables: total number of oocytes, embryos and viable oocytes,
viable oocyte rate (number of viable oocytes divided by the total number of
oocytes), and the embryo rate (total number of embryos divided by the number of
viable oocytes). Statistical analyzes were performed with the PROC GLIMMIX (SAS
Inst., Inc., Cary, NC). Resulting repeatability for the above
mentioned variables were: total number of oocytes = 0.72; numbers of viable
oocytes = 0.73; number of embryos = 0.65, rate of viable oocytes = 0.14 and
embryo rate = 0.18. It was observed that variables having poisson distribution
such as total oocytes, number of oocytes and viable embryos showed high
repeatability over time. Interestingly, variables reported as percentages as for
viable oocyte rate and embryo rate did not show high repeatability. As a
result, donors who had high numbers of viable oocytes didn’t necessarily yield
a consistent percentage of good quality embryos throughout the IVP sessions. In
conclusion, among all studied variables, the total number of oocytes, number of
viable oocytes and number of embryos showed high repeatability in Nellore cows.
Repetibilidade na produção in vitro de embriões bovinos da raça Nelore
Abstract
Íntegra (PDF)