Methods of artificial regulation of estrous cycle of Aberdeen Angus breeding stock

The research aim is to study the efficiency of using the OvSynch and Co-Synch schemes with subsequent resynchronization on beef cows and heifers of the Aberdeen Angus breed. The hormonal state of animals and the biochemical blood serum parameters were chosen as factors determining reproductive function. The purpose is to study the efficiency of applying the OvSynch and Co-Synch synchronization protocols on cows and heifers of the Aberdeen Angus breed depending on the hormonal state of the inseminated animals and the biochemical blood serum parameters. The rate of fertilization in cows inseminated according to the OvSynch protocol was determined to be 5.0 to 8.5 % higher during the first stage of insemination and 5.5 % higher during the second stage of insemination. In the group of heifers, the best fertilization results were obtained while using the Co-Synch protocol (59.3 %). Giving cows a second injection of GnRH, on day 9 of the OvSynch protocol, 16 hours before insemination, provided an average rate of fertilization of 52.3 %, which is 3.4 % higher compared to the 14-hour interval between GnRH injection and insemination. The concentration of steroid and gonadotropic hormones, including cortisol, estradiol, FSH and LH, in experimental animals during insemination corresponded to the estrus phase. The results of biochemical blood tests indicate a number of metabolic inconsistencies in the animal body. Changes in the biochemical blood serum parameters in animals that did not become pregnant followed the same patterns as in those that became pregnant. However, the level of increase or decrease in parameters was less pronounced. The results obtained can be used in arranging artificial insemination in breeding and commercial agricultural organizations engaged in beef cattle breeding, as well as in teaching process of zootechnical and veterinary disciplines in agricultural higher educational institutions of the Republic of Belarus.

1. Malinova R., Karamfilov S. Study of two different protocols for estrus synchronization in Aberdeen Angus cows in Bulgaria. Bulgarian Journal of Agricultural Science, 2022, vol. 28, suppl. 1, pp. 38-41.

2. Randi F., Kelly A. K., Parr M. H., Diskin M. G., Lively F., Lonergan P., Kenny D. A. Effect of ovulation synchronization program and season on pregnancy to timed artificial insemination in suckled beef cows. Theriogenology, 2021, vol. 172, pp. 223-229. https://doi.org/ 10.1016/j.theriogenology.2021.06.021

3. Kim I.-H., Jeong J.-K., Kang H.-G. Reproductive performance following a modified Presynch-Ovsynch, Double-Ovsynch, or conventional reproductive management program in Korean dairy herds. Theriogenology, 2020, vol. 156, pp. 27-35. https://doi.org/10.1016/j.theriogenology.2020.06.019

4. Wiltbank M. C., Baez G. M., Vasconcelos J. L. M., Pereira M., Souza A. H., Sartori R., Pursley J. R. The physiology and impact on fertility of the period of proestrus in lactating dairy cows. Animal Reproduction, 2014, vol. 11, no. 3, pp. 225-236.

5. Huminskaya E., Lupalava T., El Battawy Kh., Petcu B., Loban M. Reproductive performance of Belarusian cows (Black Motley) with emphasis on the influence of some drugs on endometritis. Ştiinţa Agricola, 2020, no. 2, pp. 139-149. https://doi.org/10.5281/zenodo.4321571

6. Merkur’eva E. K., Shangin-Berezovskii G. N. Genetics with the basics of biometrics. Moscow, Kolos Publ., 1983. 400 p. (in Russian).

7. Polyantsev N. I., Sinyavin A. A. Obstetric and gynaecological dispensary on dairy farms. 2nd ed. Moscow, Rosagropromizdat Publ., 1989. 176 p. (in Russian).

8. Medvedev G. F., Ekkhorutomven O. T., Blokhin N. G. Control of cattle reproduction. Sel’skokhozyaistvennyi vestnik [Agricultural Bulletin], 2001, no. 2, pp. 12-14 (in Russian).

9. Guminskaya E. Yu., Sidunov S. V., Loban R. V., Sidunova M. N., Lupolov T. A., El Battawy Kh. Reproductive ability of cows of the Aberdeen-Angus breed in the conditions of Pripyat Polesie. Innovations in animal husbandry and safety of animal products - achievements and outlooks: scientific and practical conference with international participation, dedicated to the 65th anniversary since the founding of the Scientific and Practical Institute of Biotechnologies in Animal Husbandry and Veterinary Medicine, Maximovca, 30 September - 01 October, 2021. Maximovca, 2021, pp. 273-280 (in Russian).

10. Guminskaya E. Yu., Sidunov S. V., Loban R. V., Sidunova M. N., Lebedev N. A., Lupolov T. A., El Battawy Kh. Regulation of the Limousine cows’ and Heifers’ reproductive function. IOP Conference Series: Earth and Environmental Science, 2021, vol. 852, p. 012034. https://doi.org/10.1088/1755-1315/852/1/012034

11. Maksimov Yu. L., Medvedev G. F., Anisov A. A., Bykov L. D. The effectiveness of the use of prostaglandins to increase the fertility of cows and heifers. Intensifikatsiya proizvodstva moloka i govyadiny: sbornik nauchnykh trudov [Intensification of milk and beef production: collection scientific works]. Gorki, 1985, iss. 130, pp. 3-9 (in Russian).

12. Yamada K. Development of ovulation synchronization and fixed time artificial insemination in dairy cows. Journal of Reproduction and Development, 2005, vol. 51, no. 2, pp. 177-186. https://doi.org/10.1262/jrd.16103

13. Willadsen S. M., Polge C., Rowson L. E. A. The viability of deep frozen cow embryos. Journal Reproduction and Fertility, 1978, vol. 52, no. 2, pp. 391-393. https://doi.org/10.1530/jrf.0.0520391

14. Gavrichenko N. I. Endocrine status and metabolic profile of the blood of cows with different levels of fertility. Gorki, 2007. 201 p. (in Russian).

15. Laven R. Pharmacological agents in the control of reproduction. Veterinary reproduction and obstetrics. 10th ed. Elsevier, 2019, pp. 157-166. https://doi.org/10.1016/B978-0-7020-7233-8.00008-2

16. Rodney R. M., Celi P., Scott W., Breinhild K., Santos J. E. P., Lean I. J. Effects of nutrition on the fertility of lactating dairy cattle. Journal of Dairy Science, 2018, vol. 101, no. 6, pp. 5115-5133. https://doi.org/10.3168/jds.2017-14064

17. Molefe K., Mwanza M. Effects of mineral supplementation on reproductive performance of pregnant cross-breed Bonsmara cows: an experimental study. Reproduction in Domestic Animals, 2020, vol. 55, no. 3, pp. 301-308. https://doi.org/10.1111/rda.13618