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Journal of Veterinary Medicine
Volume 2014 (2014), Article ID 404363, 7 pages
Research Article

Fertility in Gyr Cows (Bos indicus) with Fixed Time Artificial Insemination and Visual Estrus Detection Using a Classification Table

1Centro de Investigaciones Agrícolas, Biológicas, Educativas y Sociales (CIABES), Universidad de Los Andes-Trujillo (ULA), Avenida Medina Angarita, Casa Carmona. Apartado Postal 198, Trujillo 3150, Estado Trujillo, Venezuela
2Facultad de Ciencias Veterinarias, Núcleo Agropecuario, La Universidad del Zulia, Ciudad Universitaria, Avenida Goajira, Maracaibo 4001, Estado Zulia, Venezuela

Received 24 May 2014; Revised 26 July 2014; Accepted 28 July 2014; Published 26 August 2014

Academic Editor: Antonio Ortega-Pacheco

Copyright © 2014 Lilido Nelson Ramírez-Iglesia et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this research was to compare two artificial insemination protocols (AIP): hormonal synchronization with fixed time artificial insemination (SC-FTAI) and the use of a table based on visual observation of estrus signs (VO) in order to identify cows in natural or spontaneous estrus being assigned to AI (NSE-IA). Two groups were formed: in the first group 109 cows were assigned to SC-FTAI, in which a commercial protocol is used; the second one included 108 randomly chosen cows, which were assigned to NSE-AI and in this group a modified table was used. Response variable was first service fertility rate (FSF), which was coded 1 for pregnant and 0 for empty. Predictor variables were AIP, postpartum anestrus, daily milk yield, body condition score at AI and calving number. Statistical analyses included association chi-square tests and logistic regression. Results showed an overall 41.94% FSF and a significant association was detected () between FSF and daily milk yield; pregnancy rates were 42.20% and 41.67% for the SC-FTAI and NSE-IA groups, respectively (). The odds ratio for the effect of AIP was only 1.050, suggesting no differences in FSF between groups. The NSE-AI protocol can enhance both the technique of VO and reproductive efficiency. Further validation of the table is required.