Effects of the Bull on Conception Rate of Dairy Cows in Different Seasons and According to AI Type
DOI:
https://doi.org/10.22456/1679-9216.82554Abstract
Background: Reproductive efficiency is one of the most important factors affecting the performance dairy cattle, and fixedtime artificial insemination (TAI) is an important biotechnology factor employed in bovine livestock. The achievement of satisfactory results in TAI protocols depends of several factors, such as health and body condition, milk yield, environmental temperatures, ovulation time, semen manipulation, as well as semen quality. The goal of this study was to evaluate the conception rate of heifers and multiparous cows based on different Holstein bulls used for artificial insemination (AI). The effects of the type of management AI, animal category, and season of the year were also examined.
Materials, Methods & Results: A three-year database on the reproductive management of a dairy farm was formed. All the cows and heifers were of the Holstein breed, in semi-intensive nutritional management, milked twice a day, and received a total mix ration. After 45 days in milk, when cows were observed twice daily with estrus signs, posterior artificial insemination occurred 12 h after estrus visualization was made. However, cows that were not observed in estrus were submitted to a timed artificial insemination (TAI). In this study, these fixed factors were considered: bulls utilized for the AI (totalizing 10 animals with at least 100 inseminations in each season, denoted by the letter B and a number - B1, B2, B3, B4, B5, B6, B7, B8, B9, B10); the season of the insemination (spring/summer being from November to April and autumn/winter from May to October), category animal (heifers, animals that never have been calved, or multiparous, animals that have already given birth more than once), and the type of AI (which included TAI using a protocol for synchronization, but cows having not necessarily shown estrus signs at the AI; ETAI: using protocol of synchronization, cows showing estrus signs at the AI; and AI with estrus visualization, without protocol of synchronization when animals were observed in estrus and were inseminated 12 h later. The fertility parameter of the bulls and reproductive performance in AI was based on conception rate. There was a statistical difference among different bulls in the same season (P ≤ 0.05). There was also a difference in reproductive performance of the same bulls between seasons, autumn/winter and spring/summer; B8 37.8% vs. 32.0% (P = 0.05) and B10 35.1% vs. 20.7% (P = 0.003). Regarding the individual animal category, only one bull (B6) demonstrated higher reproductive performance when utilized in the AI of heifers than multiparous 39.2% vs. 27.2% (P = 0.01). Similarly, regarding the effect of the type of AI, only one bull (B8) exhibited different results, obtaining better results for conception rate when utilized in fixed TAI with estrus visualization (35.5%) and in the AI with estrus visualization (39.0%) compared with that of TAI (19.9%) (P < 0.05).
Discussion: From these results, it was observed that some bulls exhibited better performance in situations of greater challenge. In addition, some animals presented variation in efficiency with the demonstration of estrus or not. Therefore, bulls that present semen with higher fertility in certain types of AI could be utilized on a larger scale for to increase the reproductive rates in artificial insemination. The results of this study indicate that despite the tests indicating the semen that is submitted is adequate, there are still variations in quality and the reproductive efficiency of each bull. With the effects varying based on fertility and on different environmental and management situations.
Downloads
References
Arav A. & Zvi R. 2008. Do chilling injury and heat stress share the same mechanism of injury in oocytes? Molecular and Cellular Endocrinology. 282(1): 150-152.
Gosálvez J., Ramirez M.A., López-Fernández C., Crespo F., Evans K.M., Kjelland M.E. & Moreno J.F. 2011. Sex-sorted bovine spermatozoa and DNA damage: II. Dynamic features. Theriogenology. 75(2): 206-211.
Gröhn Y.T. & Rajala-Schultz P.J. 2000. Epidemiology of reproductive performance in dairy cows. Animal Reproduction Science. 60(2): 605-614.
Hansen P.J. & Aréchiga C.F. 1994. Reducing effects of heat stress on reproduction of dairy cow. In: International Conference on Livestock in the Tropics. (Gainesville, USA). pp.92-99.
Hansen P.J., Drost M., Rivera R.M., Paula-Lopes F.F., Al-Katanani Y.M., Krininger C.E. & Chase C.C. 2001. Adverse impact of heat stress on embryo production: causes and strategies for mitigation. Theriogenology. 55(1): 91103.
Malama E., Zeron Y., Janett F., Siuda M., Roth Z. & Bollwein H. 2017. Use of computer-assisted sperm analysis and flow cytometry to detect seasonal variations of bovine semen quality. Theriogenology. 87(1): 79-90.
Pursley J. R., Mee M.O. & Wiltbank M.C. 1995. Synchronization of ovulation in dairy cows using PGF2α and GnRH. Theriogenology. 44(7): 915-923.
Pursley J.R., Wiltbank M.C., Stevenson J.S., Ottobre J.S., Garverick H.A. & Anderson L.L. 1997. Pregnancy rates per artificial insemination for cows and heifers inseminated at a synchronized ovulation or synchronized estrus. Journal of Dairy Science. 80(2): 295-300.
De Rensis F. & Scaramuzzi R.J. 2003. Heat stress and seasonal effects on reproduction in the dairy cow - a review. Theriogenology. 60(6): 1139-1151.
Rodriguez-Martinez H., Zhang B.R. & Larsson B. 1997. Bovine semen quality and the ability to produce embryos in vivo and in vitro. Arquivos da Faculdade de Veterinária da UFRGS. 25(1): 108-126.
Roth Z. 2008. Heat stress, the follicle, and its enclosed oocyte: mechanisms and potential strategies to improve fertility in dairy cows. Reproduction in Domestic Animals. 43(2): 238-244.
Santos J.E.P. 2000. Importância da alimentação na reprodução da fêmea bovina. In: Workshop sobre reprodução animal. v.1. Pelotas: EMBRAPA, pp.7-82.
Santos R., Vasconcelos J., Meneghetti M., Silva E. & Wechsler F. 2003. Efeito da ovulação à primeira aplicação de GnRH em protocolos de inseminação artificial em tempo fixo nas taxas de sincronização e prenhez em vacas de leite em lactação. Revista Brasileira de Reprodução Animal. 27(3): 437-438.
Silva C.B., Rodriguez M.A.P., Azevedo Junior J., Santos B.V.B., Dias K.J.P., Costa M.D. & Ruas J.R.M. 2015. Efeito do touro sobre a ocorrência de prenhez de fêmeas submetidas à IATF Fórum de ensino pesquisa extensão e Gestão. In: 9° Fórum de Ensino, Pesquisa, Extensão e Gestão (Montes Claros, Brasil). p.202.
Yanagimachi R. 1994. Mammalian fertilization. In: Knobil E. & Neill J.D. (Eds). The Physiology of Reproduction. 2nd edn. New York: Raven, pp.189-317.
Published
How to Cite
Issue
Section
License
This journal provides open access to all of its content on the principle that making research freely available to the public supports a greater global exchange of knowledge. Such access is associated with increased readership and increased citation of an author's work. For more information on this approach, see the Public Knowledge Project and Directory of Open Access Journals.
We define open access journals as journals that use a funding model that does not charge readers or their institutions for access. From the BOAI definition of "open access" we take the right of users to "read, download, copy, distribute, print, search, or link to the full texts of these articles" as mandatory for a journal to be included in the directory.
La Red y Portal Iberoamericano de Revistas Científicas de Veterinaria de Libre Acceso reúne a las principales publicaciones científicas editadas en España, Portugal, Latino América y otros países del ámbito latino
