Análise multivariada de resultados da ovulação múltipla seguida de transferência de embriões de doadoras zebuínas

Abstract

Data on 1,294 superovulations of Brahman, Gyr, Guzerat and Nellore females were used to evaluate the effects of: breed; herd; year of birth; inbreeding coefficient and age at superovulation of the donor; month, season and year of superovulation; hormone source and dose; and the number of previous treatments on the superovulation results. Four data sets were considered to study the influence of donors' elimination effect after each consecutive superovulation. Each one contained only records of the first, or of the two firsts, or three firsts or all superovulations. The average number of palpated corpora lutea per superovulation varied from 8.6 to 12.6. The total number of recovered structures and viable embryos ranged from 4.1 to 7.3 and from 7.3 to 13.8, respectively. Least squares means of the number of viable embryos at first superovulation were 7.8 ± 6.6 (Brahman), 3.7 ± 4.5 (Gyr), 6.1 ± 5.9 (Guzerat) and 5.2 ± 5.9 (Nellore). The numbers of viable embryos of the second and the third superovulations were not different from those of the first superovulation. The mean intervals between first and second superovulations were 91.8 days for Brahman, 101.8 days for Gyr, 93.1 days for Guzerat and 111.3 days for Nellore donors. Intervals between the second and the third superovulations were 134.3, 110.3, 116.4 and 108.5 days for Brahman, Gyr, Guzerat and Nellore donors, respectively. Effects of herd nested within breed and dose nested within hormone affected all traits. For some data sets, the effects of month and order of superovulation on three traits were importants. The maximum number of viable embryos was observed for 7-8 year-old donors. The best responses for corpora lutea and recovered structures were observed for 4-5 year-old donors. Inbreeding coefficient was positively associated to the number of recovered structures when data set on all superovulations was considered.

Effects of environmental factors on multiple ovulation of zebu donors

“…Overall low R 2 values indicated that the variation in superovulation response was not completely explained by the fitted models. Peixoto (2001) found genetic effect as an important source of variation for superovulatory response in Zebu donors. It is possible that absence of genetic factors in the models, e.g.…”

Human–animal interaction, stress, and embryo production in Bos indicus embryo donors under tropical conditions

“…Initially, these results appeared to be very satisfactory because embryo recovery and viability are positively correlated with pregnancy, which indicates efficient embryo transfer in Zebu cattle (Peixoto et al 2002). However, further analyses showed that the inappropriate HAI caused negative effects on reproductive performance.…”

“…Moreover, Edwards et al (1987) observed that heifers subjected to transport stress followed by superovulation reached high cortisol concentrations and had decreased corpus luteum production. In Nelore cattle, such a decrease can be problematic since corpus luteum production is positively correlated to a viable embryo rate (Peixoto et al 2002).…”

The Effect of Stress on Reproduction and Reproductive Technologies in Beef Cattle—A Review

“…Handling stress is a particular concern for ovum pick-up or embryo transfer, which often require superovulation treatments involving several hormone administrations per day during several consecutive days [ 160 ]. Handling stress increases cortisol levels in plasma and inhibits GnRH release, interfering with the LH peak, which is critical for corpus luteum formation and sufficient progesterone production in embryo transfer [ 161 , 162 ]. The effectiveness of the hormonal treatments in beef cattle may be substantially increased by accustoming them to handling and by ensuring the presence of a trained veterinarian and specialized equipment during the procedures.…”