Effect of donor status, embryo grades and recipient management on pregnancy rates in a commercial equine embryo transfer program in the tropics

The fertility of the recipient is one of the more important factors conditioning the success of an embryo transfer (ET) program. Selection and management of recipients is a very important contributing factor to achieve high pregnancy rates (Stroud and Hasler 2006 Theriogenology 65, 65–76). From a reproductive point of view, a good recipient is a cow capable of receiving an embryo and taking it to term (Palma et al. 2001 Biotecnologia de la reproduccion, INTA). In beef and dairy cattle, recipients are categorized according to number of births, age, and condition score (Stroud and Hasler 2006). A retrospective analysis was done to confirm a relationship between recipient category, based on their physiologic and reproductive stage, and pregnancy rates. The analysis was done during January and February (2006–2007) based on data recovered from an embryo transfer program done in Chubut province (Patagonia) for the project ‘Polo Genetico Angus’ (Angus Association – Chubut government agreement). Two hundred and seven morulas and/or blastocysts, quality 1 or 2 frozen in 1.5 m ethylene glycol (IETS manual), were transferred randomly in 10 different farms. Embryos were thawed for 10 s at room temperature and 30 s in a water bath at 35°C and transferred by one single technician. Angus, Hereford, or its breeds were used as recipients. A reproductive exam was performed before embryo transfer and, based on it, recipients were classified into 4 categories: heifer (3–4 years old), lactating cow, weaned cow, and dry old cow (Table 1). The synchronization protocol used for recipients consisted of a single administration of D-cloprostenol and heat detection twice a day for 5 days. Data were analyzed by Cochran-Mantel-Haenszel test (chi-square). Results are shown in Table 1. There is a significant difference (P ≤ 0.05) in pregnancy rates among categories. Recipients with higher pregnancy rates were lactating cows and weaned cows 61.6% and 56.9%, respectively, compared to heifers, 45.3%; a lower pregnancy rate was founded in the dry old cows group. Dry cows were animals that failed to get pregnant during the last season. Heifers also were animals that failed the artificial insemination program. In both groups, the reduced fertility may explain their lower pregnancy rates. In conclusion, selection toward fertility of recipients is a very important factor to take into account to design a successful embryo transfer program. Table 1. Pregnancy rates for recipient categories in an ET program in Chubut (Patagonia), Argentina This research was supported by Centro Genetico Bovino Eolia.

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Effect of recombinant bovine somatotropin on superovulatory response and recipient pregnancy rates in a commercial embryo transfer program

Theriogenology ◽

10.1016/s0093-691x(02)01295-5 ◽

2003 ◽

Vol 59 (9) ◽

pp. 1919-1928 ◽

Cited By ~ 13

Author(s):

J.F Hasler ◽

C.R Bilby ◽

R.J Collier ◽

S.C Denham ◽

M.C Lucy

Keyword(s):

Embryo Transfer ◽

Pregnancy Rates ◽

Bovine Somatotropin ◽

Transfer Program ◽

Recombinant Bovine Somatotropin ◽

Embryo Transfer Program

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Effect of the Flunixin Meglumine on Pregnancy Rates in an Equine Embryo Transfer Program

Journal of Equine Veterinary Science ◽

10.1016/j.jevs.2017.10.023 ◽

2018 ◽

Vol 62 ◽

pp. 40-43 ◽

Cited By ~ 3

Author(s):

Carolina Tiemi Cardoso Okada ◽

Lorenzo Garrido Segabinazzi ◽

André Maciel Crespilho ◽

José Antônio Dell'Aqua ◽

Marco Antonio Alvarenga

Keyword(s):

Embryo Transfer ◽

Pregnancy Rates ◽

Transfer Program ◽

Flunixin Meglumine ◽

Embryo Transfer Program

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Effects of collection day on embryo recovery and pregnancy rates in a nonsurgical equine embryo transfer program

Theriogenology ◽

10.1016/s0093-691x(99)91820-4 ◽

1999 ◽

Vol 51 (1) ◽

pp. 261 ◽

Cited By ~ 8

Author(s):

J.J Fleury ◽

M.A Alvarenga

Keyword(s):

Embryo Transfer ◽

Pregnancy Rates ◽

Transfer Program ◽

Embryo Recovery ◽

Embryo Transfer Program

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165 SYNCHRONIZATION TREATMENT WITH NEW AND REUSED CIDR-B DEVICES: ESTRUS AND PREGNANCY RATES IN AN EMBRYO TRANSFER PROGRAM

Reproduction Fertility and Development ◽

10.1071/rdv17n2ab165 ◽

2005 ◽

Vol 17 (2) ◽

pp. 233

Author(s):

C.W. Solorzano ◽

J.H. Mendoza ◽

A. Villa-Godoy ◽

C.S. Galina ◽

S. Romo

Keyword(s):

Embryo Transfer ◽

Estradiol Benzoate ◽

Pregnancy Rates ◽

Estrus Synchronization ◽

Transfer Program ◽

Embryo Transfer Program ◽

Group 3 ◽

Group 2 ◽

Rectal Palpation ◽

Group 1

An earlier study demonstrated that in CIDRs used in adult cows on two previous occasions, there was still a sufficient amount of progesterone (P4) remaining that allowed estrus synchronization in heifers (Solorzano et al. 2004 Reprod. Fert. Dev. 16, 214). However, the diverse conditions existing in that study made a statistical comparison impossible. The objective of this study was to study the effect of new and used CIDRs, combined with estradiol benzoate (EB) and prostaglandin F2-α (PGF) treatments, on estrus synchronization rates (ESR) and pregnancy rates (PR) in an embryo transfer program in Brangus cows in a tropical climate. We used the same set of CIDRs in the same location in cows of the same breed, age, and body condition during three consecutive weeks. Cows were randomly allocated to one of three treatment groups. In Group 1, all cows (n = 44) were treated with a new 1.9-g CIDR (CIDR-B, InterAg, Hamilton, New Zealand), combined with 2 mg EB on Day 0. In Group 2, all cows (n = 43) were treated with a reused (first reuse) 1.9-g CIDR and 2 mg EB on Day 0. In Group 3, all cows (n = 42) received a reused (second reuse) 1.9-g CIDR and 2 mg EB on Day 0. CIDR devices were removed on Day 7 and all cows received PGF (0.25 μg cloprostenol) at that time. Estrus was expected to occur 24 h later. Seven days after estrus all cows showing heat were examined by rectal palpation, and those with a CL 15 mm in diameter or larger were selected to receive a frozen/thawed embryo (in 1.5 M ethylene glycol) by nonsurgical direct transfer. PR were determined by rectal palpation 60 days after estrus. In Group 1, a total of 90.9% of the cows displayed signs of estrus (40/44), and 42% of those that received a frozen embryo were pregnant (16/38). In Group 2, a total of 88.4% of the treated cows showed signs of estrus (38/43), and 37% of those recipients became pregnant (13/35). In Group 3, 88% of treated cows showed signs of estrus (37/42), and 36% of cows receiving an embryo were pregnant (13/36). ESR and PR were compared by χ2 and Fisher's tests, and no differences were found among the three groups studied. This confirms that, in 1.9-g CIDRs used on two previous and consecutive occasions, there is still a sufficient amount of P4 remaining that allows successful estrus synchronization and pregnancy rates in a third use.

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Effect of embryo age and recipient asynchrony on pregnancy rates in a commercial equine embryo transfer program

Theriogenology ◽

10.1016/j.theriogenology.2011.10.022 ◽

2012 ◽

Vol 77 (6) ◽

pp. 1159-1166 ◽

Cited By ~ 28

Author(s):

J.C.F. Jacob ◽

K.T. Haag ◽

G.O. Santos ◽

J.P. Oliveira ◽

M.O. Gastal ◽

...

Keyword(s):

Embryo Transfer ◽

Pregnancy Rates ◽

Transfer Program ◽

Embryo Transfer Program

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Treatments for the synchronisation of bovine recipients for fixed-time embryo transfer and improvement of pregnancy rates

Reproduction Fertility and Development ◽

10.1071/rd11918 ◽

2012 ◽

Vol 24 (1) ◽

pp. 272 ◽

Cited By ~ 23

Author(s):

Gabriel A. Bó ◽

Lucas Coelho Peres ◽

Lucas E. Cutaia ◽

Danilo Pincinato ◽

Pietro S. Baruselli ◽

...

Keyword(s):

Embryo Transfer ◽

Fixed Time ◽

Pregnancy Rates ◽

Transfer Program ◽

Widespread Application ◽

Wave Dynamics ◽

Follicular Wave ◽

Embryo Transfer Program ◽

Conception Rates ◽

On Farm

Although embryo transfer technology has been used commercially in cattle for many years, the inefficiency of oestrus detection, especially in recipients, has limited the widespread application of this technology. The most useful alternative to increase the number of recipients utilised in an embryo transfer program is the use of protocols that allow for embryo transfer without the need for oestrus detection, usually called fixed-time embryo transfer (FTET). Most current FTET protocols are based on progestin-releasing devices combined with oestradiol or GnRH, which control and synchronise follicular wave dynamics and ovulation. Conception rates to a single FTET have been reported to be similar to those after detection of oestrus, but pregnancy rates are higher because these treatments have increased the proportion of recipients that receive an embryo. Recent changes to treatments for FTET, such as the administration of eCG, have resulted in increased pregnancy rates and provide opportunities to make these treatments easier to perform on farm.

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