Economic optimization of the number of recipients in bovine embryo transfer programs

Abstract

Purchase and maintenance of recipient females account for a large proportion of the costs and determine the number of calves that can be produced in an embryo transfer program. However, the large variability of embryo production by the donors and the need to purchase and synchronize the recipients before knowing the number of embryos collected make it difficult for the decision maker to identify the ideal number of recipient females to allocate. An ex-ante evaluation to determine the optimal number of recipient females was carried out through a sensitivity analysis for the ratio between the number of recipients and donors in a simulation model. The variability for the number of embryos collected was accounted for by applying the Monte Carlo simulation technique, assuming normal distribution and known values for mean and variance. The simulation considered monthly intervals between collections, during a 24 months program. The effect of embryo freezing on the number of pregnancies was considered by introducing a stock of frozen embryos into the mathematical model. Optimal recipient/donor ratio and the cost per pregnancy were compared for three recipient synchronization protocols (prostaglandin, progesterone -P 4 and Ovsynch), based on the expected performance for synchronization, conception and transfer/treated rates for each protocol. Stochastic simulation associated with sensitivity analysis was effective in identifying the optimal donor to recipient ratio. Freezing embryos is effective to reduce the operational costs per pregnancy. The estimated optimal recipient/donor ratio was 20 for prostaglandin and 16.7 for the other protocols. The P 4 protocol, although the most expensive, resulted in the lowest pregnancy cost estimation followed by prostaglandin and Ovsynch.

Simulação e análise econômica da produção in vivo e in vitro de embriões em bovinos

“…Idéia similar já havia sido demonstrada em Beltrame et al (2007), em inseminação artificial com sêmen convencional na TE.…”

“…Em virtude de a variação na produção embrionária ser inerente ao processo reprodutivo, simulações e projetos que consideram o uso do número médio de embriões viáveis representam situações inexistentes e distantes da realidade. Essas situações têm sido minimizadas quando metodologias corretas de simulação são implementadas (Beltrame et al, 2007Beltrame, 2010).…”

Economic and genetic performance of various combinations of in vitro-produced embryo transfers and artificial insemination in a dairy herd

“…Heikkilä and Peippo (2012) found an optimal breeding mix that included conventional and sexed semen along with embryo donors with embryos sold to external farms for Finnish dairy herds. Beltrame et al (2007) concluded that IVP of embryos using sexed semen reduced the cost per female pregnancy in dairy cattle. These 3 studies did not include the genetic gain from IVP-ET versus AI within the herd.…”

Probability density function of the number of embryos collected from superovulated Nelore breed donors

“…How-ever, Beltrame et al (2007) showed that economic evaluations based on average responses (deterministic simulations) of embryo production yield biased results. Therefore, in practical situations, decisions related to synchronization of the recipient females should be based on the expected distribution of the results.…”

“…Recently, some models have included stochasticity in the number generated (Ostergaard et al, 2005;Barioni et al, 2007;Beltrame et al, 2007). Most of them have assumed normal distribution, since the probability distribution of that variable seemed undetermined in the literature Beltrame et al, 2007).In this context, this study has the objective of identifying and fitting an adequate probability density function for the number of embryos generated by superovulated Nelore females, aiming to provide more reliable stochastic simulation models.…”