Fixed-time artificial insemination and reinsemination of beef cows treated with and without equine chorionic gonadotropin
PDF (Español (España))


beef cattle
reproductive efficiency
gestation rate
artificial insemination
meat bovinos para carne
eficiencia reproductiva
tasa de gestación
inseminación artificial

How to Cite

Espinoza Villavicencio, J. L., Palacios-Espinosa, A., Ortega-Pérez, R., Guillén-Trujillo, A., & Manríquez-Hirales, E. (2021). Fixed-time artificial insemination and reinsemination of beef cows treated with and without equine chorionic gonadotropin. Nova Scientia, 13(27).


Introduction: the objectives were to evaluate estrus and gestation in Bos taurus cows, treated with a fixed-time artificial insemination protocol (FTAI) that included or not equine chorionic gonadotropin (eCG). Cumulative gestation with resynchronization at 30 days after the first FTAI was also evaluated.

Method: the cows were divided into: Treatment 1 (n = 60), synchronized with 2 mg of estradiol benzoate and an intravaginal device (IVD) of progesterone (1.3 g) on ​​day 0; IVD was removed on day 8 and 25 mg of prostaglandin F2-alpha, 1 mg of estradiol cypionate and 300 IU of eCG were injected; 48-52 hours later the FTAI was performed. Treatment 2 (n = 50) consisted in the same protocol, not including eCG. Ovulation was resynchronized in cows that were no pregnant in the pregnancy diagnosis, performed 30 days after the first FTAI. The same protocol applied in Treatment 1 for the first FTAI was used in all animals. The second FTAI was performed 40 days after starting the program. Body condition score (BCS) was classified as low (< 2.5), moderate (2.5 to 3.5) and high (> 3.5). On the day of the FTAI, the preovulatory follicle diameter (DFP) was classified into three categories (DFP1: < 11 mm; DFP2: 11 to 14 mm; DFP3: > 14 mm).

Results: the gestation percentage was different between treatments (p = 0.04; 73 % Group 1 and 53 % Group 2). The proportion of cows in estrus before the FTAI was 75 % in the eCG treatment and 57 % in the control (p = 0.04). Cows with DFP2 and DFP3 registered a higher gestation rate (p = 0.03) than DFP1. The percentage of pregnancies was higher (p = 0.04) in cows with moderate and high BCS. Overall gestation in the first FTAI was 63  %. The gestation percentage with the second FTAI was 51.61 %, accumulating 82.1 % in 40 days.

Conclusion: eCG increased the proportion of cows in estrus and gestation; and resynchronization allows the accumulation of an additional percentage of pregnant cows.
PDF (Español (España))


Ayres, H., Machado, R., Ribamar, J., Garcia, C., Gonçalves, C., & Baruselli, P.S. (2009). Validation of body condition score as a predictor of subcutaneous fat in Nelore (Bos indicus) cows. Livestock Science, 123, 175-179. DOI:

Ayres, H., Ferreira, R.M., Torres-Júnior, J.R., Demétrio, C.G, Sá Filho, M.F., Gimenes, LU., Penteado, L., D’Occhio, M.J., & Basurelli, P.S. (2014). Inferences of body energy reserves on conception rate of suckled Zebu beef cows subjected to timed artificial insemination followed by natural mating. Theriogenology, 82, 529-536. DOI:

Baruselli, P.S., Ferreira, R.M, Colli, M.H.A., & Elliff, F.M. (2017). Timed artificial insemination: current challenges and recent advances in reproductive efficiency in beef and dairy herds in Brazil. Animal Reproduction, 14, 558-571. DOI: 10.21451/1984-3143-AR999

Baruselli, P.S., Sá Filho M.F., Ambrósio, A.A., & Ferreira, R.M. (2016). Strategies to improve fertility in cattle: artificial insemination following estrus versus timed artificial insemination. Spermova, 6, 36-42. DOI: 10.18548/aspe/0003.06

Bó, G.A., Hugenine, E, Ferreira, R.M., Sá Filho, M.F., & Baruselli, P.S. (2019). Inducción de ciclicidad para servicio natural o inseminación artificial en vacas de carne. Memorias del V Simposio Internacional Avances en Reproducción Bovina.

Campos, J.T., Marinho, L.S.R., Lunardelli, P.A., Morotti, F., & Seneda, M.M. (2013). Resynchronization of estrous cycle with eCG and temporary calf removal in lactating Bos indicus cows. Theriogenology, 80, 619-623. DOI:10.1016/j.theriogenology.2013.05.029

Cutaia, L., Veneranda, G., Tríbulo., Baruselli, P.S., & Bó, GA. (2003). Programas de inseminación artificial a tiempo fijo en rodeos de cría: Factores que lo afectan y resultados productivos. Memorias del V Simposio Internacional de Reproducción Animal, IRAC, 119-129.

Davoodi, S., Cooke, R.F., Fernandes, A.C.C., Cappellozza, B.I., Vasconcelos, J.L.M., & Cerri, R.L.A. (2016). Expression of estrus modifies the gene expression profile in reproductive tissues on day 19 of gestation in beef cows. Theriogenology, 85, 645-655. DOI: 10.1016/j.theriogenology.2015.10.002

de Oliveira, M.M., Morotti, F., Bizarro da Silva, C., Ribeiro Jr, M., Pinto da Silva, R.C., Baruselli, P.S., & Seneda, M.M. (2015). Influence of category-heifers, primiparous and multiparous lactating cows-in a large-scale resynchronization fixed-time artificial insemination program. Journal of Veterinary Science, 16, 367-371. DOI:

de Oliveira, D.A.M., Ernandes, K.L., Talini, R., Pedrosa, V.B., Gassenferth, G., & Weiss, R.R. (2016). Correlação entre o diâmetro do folículo pré-ovulatório e a eficiência reprodutiva em vacas Bos taurus indicus submetidas à inseminação artificial em tempo fixo. Archives of Veterinary Science, 21, 61-67. DOI:

de Oliveira, D.A.M., Kozicki, L.E., Gaievski, F.R., Pedrosa, V.B., Weiss, R.R., Segui, M.S., & Bergstein‐Galan, T.G. (2019). Resynchronization of ovulation with new and reused intravaginal progesterone-releasing devices without previous pregnancy diagnosis in Bos taurus indicus cows subjected to timed-artificial insemination. Reproduction Domestic Animals, 54, 779-785. DOI:

Dias, C.C., Wechsler, F.S., Day, M.L., & Vasconcelos, J.L. (2009). Progesterone concentrations, exogenous equine chorionic gonadotropin, and timing of prostaglandin F2-alpha treatment affect fertility in postpuberal Nelore heifers. Theriogenology, 72, 378-385. DOI: 10.1016/j.theriogenology.2009.03.006

Dorneles, T.R., Ferreira, R., Dos Santos, J.T., Silveira de Andrade, N.O., Barreta, M.H., Oliveira, J.F, Gonçalves, P.B., & Pereira, N.J. (2013). The effect of equine chorionic gonadotropin on follicular size, luteal volume, circulating progesterone concentrations, and pregnancy rates in anestrous beef cows treated with a novel fixed-time artificial insemination protocol. Theriogenology, 79, 1204-1209. DOI: 10.1016/j.theriogenology.2013.02.019

Faleiro, N.S., Neves, K.A.L., Pereira, L.L., Silva, C.M.G.D., Vale, W.G., & Minervino, A.H.H. (2019). Effect of estrous resynchronization on the reproductive efficiency of zebu cows. Reproduction in Domestic Animals, 54, 1050-1053. DOI: 10.1111/rda.13468

Ferraz, P.A., Galvão, M.V.L., Soares, A.R., Coelho, M.C.L., dos Santos, T.C.B., & Ribeiro, A.L.F. (2017). The effect of the intensity of estrus expression on the follicular diameter and fertility of Nellore cows managed under a FTAI program. Ciencia Animal Brasileira, 18, 1-9.

Funakura, H., Shiki, A., Tsubakishita, Y., Mido, S., Katamoto, H., Kitahara, G., & Osawa, T. (2018) Validation of a novel timed artificial insemination protocol in beef cows with a functional corpus luteum detected by ultrasonography. Journal of Reproduction and Development, 64, 109-115. DOI: 10.1262/jrd.2017-135

Galvaõ, K.N., Santos, J.E., Cerri, R.L, Chebel, R.C., Rutigliano, H.M, Bruno, R.G., & Bicalho, R.C. (2007). Evaluation of methods of resynchronization for insemination in cows of un- known pregnancy status. Journal of Dairy Science, 90, 4240-4252. DOI:

Gimenes, L.U., Sá Filho, M.F., Carvalho, N.A.T., Torres Jr, J.R.S., Souza, A.H., Madureira, E.H., Trinca, L.A., Sartorelli, E.S., Barros, C.M., Carvalho, J.B.P., Mapletoft, R.J., & Baruselli. P.S. (2008). Follicle deviation and ovulatory capacity in Bos indicus heifers. Theriogenology, 69, 852-858. DOI: 10.1016/j.theriogenology.2008.01.001

Herrera, R., Pugliesi, G., Nogueira, F.L.N., Constantino, C.R., Ataide Jr, G.A., Ferreira, A.J.M., Posar, I.O., Alvarenga, C.O. , & Humblot, P. (2018). Reproductive performance of Bos indicus beef cows treated with different doses of equine chorionic gonadotropin at the end of a progesterone-estrogen based protocol for fixed-time artificial insemination. Theriogenology, 118, 150-156. DOI: 10.1016/j.theriogenology.2018.06.003

Larimore, E.L., Amundson, O.L., Bird, S.L., Funnell, B.J., Kruse, S.G., Bridges, G.A., & Perry, G.A. (2015). Influence of estrus at fixed-time artificial insemination on early embryonic development in beef cattle. Journal of Animal Science, 93, 2806-2812. DOI: 10.2527/jas.2015-8892

Mapletoft, R.J., Baruselli, P.S., & Bó, G.A. (2019). ¿Qué debemos saber para decidir sobre la utilización de eCG en los programas de IATF en rodeos de carne y leche?. Memorias del 13º Simposio Internacional de Reproducción Animal, 129-141.

Mapletoft, R.J., Bó, G.A., Baruselli, P.S., Menchaca, A., & Sartori, R. (2018). Evolution of knowledge on ovarian physiology and its contribution to the widespread application of reproductive biotechnologies in South American cattle. Animal Reproduction, 15, 1003-1014. DOI: 10.21451/1984-3143-AR2018-0007

Nishimura, T.K., Martins, T., da Silva, M.I., Lafuente, B.S., de Garla, M.J.R., Binelli, M., Pugliesi, G., & Saran, A.N. (2018). Importance of body condition score and ovarian activity on determining the fertility in beef cows supplemented with long-acting progesterone after timed-AI. Animal Reproduction Science, 198, 27-36. DOI: 10.1016/j.anireprosci.2018.08.042

Núñez-Olivera, R., de Castro, T., Garcia-Pintos, C., Bó, G.A., Piaggio, J., & Menchaca, A. (2014). Ovulatory response and luteal function after eCG administration at the end of a progesterone and estradiol-based treatment in postpartum anestrous beef cattle. Animal Reproduction Science, 146, 111-116. DOI: 10.1016/j.anireprosci.2014.02.017

Núñez-Olivera, R., de Castro, T., Bó, G.A., Piaggio, J., & Menchaca, A. (2018). Equine chorionic gonadotropin administration after insemination affects luteal function and pregnancy establishment in postpartum anestrous beef cows. Domestic Animal Endocrinology, 62, 24-31. DOI: 10.1016/j.domaniend.2017.08.003

O’Hara, L., Forde, N., Carter, F., Rizos, D., Maillo, V., Ealy, A.D., Kelly, A.K., Rodriguez, P., Isaka, N., Evans, A.C., & Lonergan, P. (2016). Paradoxical effect of supplementary progesterone between day 3 and day 7 on corpus luteum function and conceptus development in cattle. Reproduction Fertility and Development, 26, 328-36. DOI: 10.1071/rd12370

Patterson, D.J., Cooke, R.F., Dahlke, G.R., Funston, R.N., Hall, J.B., Lamb, G.C., J. Lauderdale, J., Perry, G.A., & Van Eenennaam, A.L. (2016). Physiological and management advances enhancing adoption of applied reproductive management procedures in beef cattle. Journal of Animal Science, 94(E-Suppl. 5), 560-561. DOI:

Pereira, L.L.L., Ferreira, A.P.A., Vale, W.W.G., Serique, L.R.L., Neves, K.A.L., Morini, A.C.A., Monteiro, B.M., & Minervino, A. (2018). Effect of body condition score and reuse of progesterone-releasing intravaginal devices on conception rate following timed artificial insemination in Nelore cows. Reproduction in Domestic Animals, 53, 624-628. DOI: 10.1111/rda.13150

Pereira, M.H.C., Wiltbank, M.C., & Vasconcelos, J.L.M. (2016). Expression of estrus improves fertility and decreases pregnancy losses in lactating dairy cows that receive artificial insemination or embryo transfer. Journal of Dairy Science, 99, 2237-2247. DOI: 10.3168/jds.2015-9903

Pessoa, G.A., Martini, A.P., Carloto, G.W., Rodrigues, M.C.C., Claro Jr, I., Baruselli, P.S., Brauner, C.C., Rubin, M.I.B., Corrêa, M.N., Leivas, F.G., & Sá Filho, M.F. (2016). Different doses of equine chorionic gonadotropin on ovarian follicular growth and pregnancy rate of suckled Bos taurus beef cows subjected to timed artificial insemination protocol. Theriogenology, 85, 792-799. DOI: 10.1016/j.theriogenology.2015.09.057

Pfeifer, L.F.M., Castro, N.A., Melo, V.T.O., Neves, P.M.A., Cestaro, J.P., & Schneider, A. (2015). Timed artificial insemination in blocks: A new alternative to improve fertility in lactating beef cows. Animal Reproduction Science, 163, 89-96. DOI:

Pfeifer, L.F.M., Castro, N.A., Neves, P.M.A., Cestaro, J.P., & Siqueira, L.G.B. (2017). Development and validation of an objective method for the assessment of body condition scores and selection of beef cows for timed artificial insemination. Livestock Science, 197, 82-87. DOI:

Pohler, K.G., Peres, R.F.G., Green, J.A., Graff, H., Martins, T., Vasconcelos, J.L.M., & Smith., M.F. (2016). Use of bovine pregnancy-associated glycoproteins to predict late embryonic mortality in postpartum Nelore beef cows. Theriogenology, 85, 1652-1659. DOI: 10.1016/j.theriogenology.2016.01.026

Pugliesi, G., Bisinotto, D.Z., Mello, B.P., Lahr, F.C., Ferreira, C.A., Melo, G.D., Bastos, M.R., & Madureira, E.H. (2019). A novel strategy for resynchronization of ovulation in Nelore cows using injectable progesterone (P4) and P4 releasing devices to perform two timed inseminations within 22 days. Reproduction in Domestic Animals, 54, 1149-1154. DOI: 10.1111/rda.13475

Richardson, B.N., Hill, S.L., Stevenson, J.S., Djira, G.D., & Perry, G.A. (2016). Expression of estrus before fixed-time AI affects conception rates and factors that impact expression of estrus and the repeatability of expression of estrus in sequential breeding seasons. Animal Reproduction Science, 166, 133-140. DOI: 10.1016/j.anireprosci.2016.01.013

Rodrigues, D., Cooke, R.F., Cipriano, R.S., Silva, L.G.T., Cerri, R.L.A., Cruppe, L.H., Meneghetti, M., Pohler, K.G., & Vasconcelos, J.L.M. (2018). Impacts of estrus expression and intensity during a timed-AI protocol on variables associated with fertility and pregnancy success in Bos indicus-influenced beef cows. Journal of Animal Science, 96, 236-249. DOI: 10.1093/jas/skx043

Rubin, M.I.B., Martini, A.P., Simões, D.F., Oliveira, J.A.R., Trentin, J.M., Sá Filho, M.F., & Batistella, M.L.R. (2015). Resynchronization protocols improve reproductive efficiency of suckled beef cows subjected to a breeding season during autumn-winter. Animal Reproduction, 12, 659 (abstract). DOI: 10.1016/j.theriogenology.2018.08.021

Ruiz, A.Z., Domínguez, C., Martínez, N., Pinto, L., Drescher, K., Perez, R.M., A. Rojas, J.A.U., & Araneda, R. (2010). Efecto de la condición corporal y nivel de alimentación sobre la actividad ovárica, involución uterina y expresión del IGF-I en vacas mestizas durante el posparto. Interciencia, 35, 752-758.

Sá Filho, M.F., Crespilho, A.M., Santos, J.E.P., Perry, G.A, & Baruselli, P.S. (2010). Ovarian follicle diameter at timed insemination and estrous response influence likelihood of ovulation and pregnancy after estrous synchronization with progesterone or progestin-based protocols in suckled Bos indicus cows. Animal Reproduction Science, 120, 23-30. DOI: 10.1016/j.anireprosci.2010.03.007

Sá Filho, M.F., Marques, M.O., Girotto, R., Santos, F.A., Sala, R.V., Barbuio, J.P., & Basurelli, P.S. (2014). Resynchronization with unknown pregnancy status using progestin-based timed artificial insemination protocol in beef cattle. Theriogenology, 81, 284-290. DOI: 10.1016/j.theriogenology.2013.09.027

Sá Filho, M.F., Penteado, L., Reis, E.L., Reis, T.A.N.P.S., Galvaõ, K.N., & Baruselli, P.S. (2013). Timed artificial insemination early in the breeding season improves the reproductive performance of suckled beef cows. Theriogenology, 79, 625-632. DOI: 10.1016/j.theriogenology.2012.11.016

SAS. (2004). SAS User’s Guide (Release 9.1). p.1431-1555. SAS Institute. Inc., Cary. North Caroline, USA.

Simões, R.A.L., Satrapa, R.A., Rosa, F.S., Piagentini, M., Castilho, A.C.S., Ereno, R.L., Trinca, L.A., Nogueira, M.F., Buratini J, Jr., & Barros, C.M. (2012). Ovulation rate and its relationship with follicle diameter and gene expression of the LH receptor (LHR) in Nelore cows. Theriogenology, 77, 139-147. DOI: 10.1016/j.theriogenology.2011.07.027

Souza, A.L.B., Segui, M.S., Kozicki, L.E., Weiss, R.R., Abreu, A., Bertol, M.A.F, Martins, D., & Oliveira, A. (2016). Impact of equine chorionic gonadotropin associated with temporary weaning, estradiol benzoate, or estradiol cypionate on timed artificial insemination in primiparous Bos indicus cows. Brazilian Archives of Biology and Technology, 59: 1-3e16150389. DOI:

Spencer, T.E., Forde, N., & Lonergan, P. (2016). The role of progesterone and conceptus-derived factors in uterine biology during early pregnancy in ruminants. Journal of Dairy Science, 99, 5941-5950. DOI: 10.3168/jds.2015-10070

Torres-Júnior, J.R.S., Penteado, L., Sales, J.N.S., Sá Filho, M.F., Ayres, H., & Baruselli, P.S. (2014). A comparison of two different esters of estradiol for the induction of ovulation in an estradiol plus progestin- based timed artificial insemination protocol for suckled Bos indicus beef cows. Animal Reproduction Science, 151, 9-14. DOI: 10.1016/j.anireprosci.2014.09.019

Vasconcelos, J.L., Sartori, R., Oliveira, H.N., Guenther, J.G., & Wiltbank, M.C. (2001). Reduction in size of the ovulatory follicle reduces subsequent luteal size and pregnancy rate. Theriogenology, 56, 307-314. DOI: 10.1016/s0093-691x(01)00565-9

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Copyright (c) 2021 Nova Scientia