Effect of two fixed-time AI protocols on pregnancy rates in Holstein heifers in an intensive system
DOI:
https://doi.org/10.30972/vet.3719608Keywords:
FTAI, dairy heifers, J-Synch, body weight, pregnancy rateAbstract
The aim of this study was to evaluate the effect of two fixed-time artificial insemination (FTAI) protocols on pregnancy rates in Holstein heifers under an intensive dairy system, considering the influence of initial body weight. A total of 78 heifers were randomly assigned to a conventional progesterone and estradiol-based protocol (n = 38) or to a J-Synch protocol (n = 40). Pregnancy diagnosis was performed by ultrasonography 30 days after FTAI. Statistical analysis was conducted using a logistic regression model based on the first insemination only, with protocol, initial body weight, and their interaction as explanatory variables. In the conventional protocol, pregnancy probability increased with body weight, whereas this relationship was less evident in the J-Synch protocol. No differences were observed in age at first pregnancy between treatments (p = 0.445). A significant interaction between protocol and body weight was detected (p = 0.05). These findings suggest that reproductive response depends on the interaction between the synchronization protocol and heifer's body weight, highlighting the importance of considering body development when selecting reproductive strategies.
Downloads
References
1. Bó GA, Baruselli PS. Synchronization of ovulation and fixed-time artificial insemination in beef cattle. Anim. Reprod. 2014;(s1): 144-50. https://doi.org/10.1017/S1751731114000822
2. Bó GA, De la Mata JJ, Baruselli PS, Menchaca A. Alternative programs for synchronizing and resynchronizing ovulation in beef cattle. Theriogenology. 2016; 86(1): 388-96. https://doi.org/10.1016/j.theriogenology.2016.04.053
3. Cedeño AV, Cuervo R, Tríbulo A, Tríbulo R, Andrada S, Mapletoft R, Menchaca A, Bó GA. Effect of expression of estrus and treatment with GnRH on pregnancies per AI in beef cattle synchronized with an oestradiol/progesterone-based protocol. Theriogenology. 2021; 161: 294-300. https://doi.org/10.1016/j.theriogenology .2020.12.014
4. Cerri RLA, Rutigliano HM, Chebel RC, Santos JEP. Period of dominance of the ovulatory follicle influences embryo quality in lactating dairy cows. Reproduction. 2011; 142(6): 813-823. https://doi.org/10.1530/REP-11-0195
5. Colazo MG, Mapletoft RJ. A review of current timed-AI protocols for beef and dairy cattle. Can Vet J. 2014; 55(8): 772-780. Disponible en: https://pmc.ncbi.nlm.nih.gov/articles/PMC4095965/
6. De la Mata JJ, GA B. Sincronización de celos y ovulación utilizando protocolos de benzoato de estradiol y GnRH en períodos reducidos de inserción de un dispositivo con progesterona en vaquillonas para carne. Taurus 2012; 55 17-23. www.revistataurus.com.ar
7. Diskin MG, Kenny DA. Optimising reproductive performance of beef cows and replacement heifers. Animal. 2014; 8(s1): 27-39. https://doi.org/10.1017/S175173111400086X
8. Edmonson AJ, Lean IJ, Weaver, LD, Farver T, Webster G. A body condition scoring chart for Holstein dairy cows. Tulare 93274. Journal Dairy Science. 72: 68-78.
9. Ettema JF, Santos JEP. Impact of age at calving on lactation, reproduction, health, and income in first-parity Holsteins on commercial farms. Journal of Dairy Science. 2004; 87(8): 2730-2742. https://doi.org/10.3168/jds.S0022-0302(04)73400-1
10. Fricke PM, Carvalho PD, Giordano JO, Valenza A, Lopes G, Amundson MC. Expression and detection of estrus in dairy cows: the role of new technologies. Animal. 2014; (s1): 134-43. https://doi.org/10.1017/S1751731114000299
11. Gimenez GD, Novaira, BI, Marini PR. Análisis energético en lecherías de la región pampeana Argentina. Parte 1. Flujos de energía. Agronomía Mesoamericana. 2022; 33(3): 49024. https://doi.org/10.15517/am.v33i3.49024
12. Giordano JO, Wiltbank MC, Guenther JN, Ares MS, Lopes G, Fricke PM. Increased fertility in lactating dairy cows with a preovulatory estradiol treatment before timed AI. Journal of Dairy Science. 2012; Feb;95(2): 639-53. https://doi.org/10.3168/jds.2011-4418
13. Jinks EM, Smith MF, Atkins JA, Pohler KG, Perry GA, Macneil MD, Roberts AJ, Waterman RC, Alexander LJ, Geary TW. Preovulatory estradiol and the establishment and maintenance of pregnancy in suckled beef cows. J. Anim. Sci. 2013; 91:1176–1185. https://doi.org/10.2527/jas.2012-5611
14. Lopes GJr, Giordano JO, Valenza A, Herlihy MM, Guenther JN, Wiltbank MC, Fricke PM. Effect of timing of initiation of resynchronization and presynchronization with gonadotropin-releasing hormone on fertility of resynchronized inseminations in lactating dairy cows. Journal Dairy Science. 2013 Jun;96(6):3788-98. https://doi.org/10.3168/jds.2012-6429.
15. López Parra JC, Marini PR, Macagno AJ, Bó GA. Effect of three different fixed-time AI protocols on folicular dynamics and pregnancy rates in suckled, dual-purpose cows in the Ecuadorian Amazon. Revista de la Facultad de Ciencias Agrarias UNCuyo. 2024; 56(1): 138-48. https://doi.org/10.48162/rev.39.130
16. Macagno A, Tschopp JC, Bó GA. Sincronización de la ovulación en vacas lecheras lactantes después de un proestro prolongado en un protocolo basado en estradiol/P4. Reprod Fertil Dev. 2021; 34: 297-8. https://doi.org/10.1071/RDv34n2Ab121. PMid:35231259.
17. Madureira G, Consentini CEC, Motta JCL, Drum JN, Prata AB, Monteiro Jr, PLJ, Melo LF, Gonçalves JRS, Wiltbank MC, Sartori R. Progesterone-based timed AI protocols for Bos indicus cattle II: Reproductive outcomes of either EB or GnRH-type protocol, using or not GnRH at AI. Theriogenology. 2020; 145: 86-93. https://doi.org/10.1016/j.theriogenology.2020.01.033
18. Martínez MF, Kastelic JP, Adams GP, Cook RB, Olson WO, Mapletoft RJ. The use of a progesterone-releasing device (CIDR) or melengestrol acetate with GnRH, LH, or estradiol benzoate for fixed-time AI in beef heifers. Journal of animal science. 2002; 80(7):1746-51. https://doi.org/10.2527/2002.8071746x
19. Martínez MF, Kastelic JP, Adams GP, Cook B, Olson WO, Mapletoft RJ. The use of progestins in regimens for fixed-time artificial insemination in beef cattle. Theriogenology. 2002 Feb;57(3):1049-59. https://doi.org/10.1016/s0093-691x(01)00682-3.
20. Mion B, Bonotto RM, Farias CO, Rosa FS, Pradiee J, Rovani MT, Pegoraro LMC, Bonotto ALM, Pfeifer LFM, Schneider A. J-Synch protocol associated with estrus detection in beef heifers and non-lactating cows. Medicina Veterinária, 2019; 13: 269-274. https://doi.org/10.26605/medvet-v13n2-3089
21. Ortega-Coello ME, Quinteros-Pozo OR, Marini PR, Bó GA. Effect of the use of eCG on the preg¬nancy rate in dairy cows treated with a prolonged proestrus protocol in the Ecuadorian Amazon. Anim Reprod. 2026; 23(1): e20250084. https://doi.org/10.1590/1984-3143-AR2025-0084
22. Pursley JR, Mee MO, Wiltbank MC. Synchronization of ovulation in dairy cows using PGF2α and GnRH. Theriogenology. 1995; 44(7): 915-923. https://doi.org/10.1016/0093-691X(95)00279-H
23. Santos JE, Bisinotto RS, Ribeiro ES. Mechanisms underlying reduced fertility in anovular dairy cows. Theriogenology, 2016; 86(1): 254-62. https://doi.org/10.1016/j.theriogenology.2016.04.038
24. Ré M, de la Mata JJ, Bó GA. Synchronization of ovulation in dairy heifers using a shortened estradiol-based protocol that provides for a lengthened proestrus. Reproduction, Fertility and Development, 2013; Dec 5; 26(1), 118.
https://doi.org/10.1071/RDv26n1Ab8
25. Ré MG, Racca G, Filippi L, Veneranda G, Bó GA. Sincronización de la ovulación y tasas de preñez en vaquillonas lecheras tratadas con protocolos que prolongan el proestro. Taurus. 2021; 91: 28-45. www.revistataurus.com.ar
26. Read CC, Edwards JL, Schrick FN, Rhinehart JD, Payton RR, Campagna SR, Castro HF, Klabnik JL, Moorey SE. Preovulatory serum estradiol concentration is positively associated with oocyte ATP and follicular fluid metabolite abundance in lactating beef cattle. J Anim Sci. 2022 ;100(7):skac136. https://doi.org/10.1093/jas/skac136
27. Yánez-Avalos DO, Barbona I, López-Parra JC, Marini PR. Protocolo J-Synch con y sin eCG en vacas Brown Swiss y sus cruzas con Bos Indicus en la amazonía ecuatoriana. La Granja. Granja. 2021; 33(1): 8-20. https://doi.org/10.17163/lgr.n33.2021.01.
28. Wiltbank MC, Souza AH, Carvalho PD, Cunha AP, Giordano JO, Fricke PM, Baez GM, Diskin MG. Physiological and practical effects of progesterone on reproduction in dairy cattle. Animal, 2014; 8(s1): 70-81. https://doi.org/10.1017/S1751731114000585
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 A. Marini, J. Suárez, G. Domínguez, A. Tríbulo, P.R. Marini
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Revista Veterinaria (Rev. Vet.) maintains a commitment to the policies of Open Access to scientific information, as it considers that both scientific publications as well as research investigations funded by public resources should circulate freely without restrictions. Revista Veterinaria (Rev. Vet.) ratifies the Open Access model in which scientific publications are made freely available at no cost online.
.jpg){kind=logo}
.jpg){kind=logo}
