EFFECT OF TIMING OF ARTIFICIAL INSEMINATION ON THE FERTILITY AND SEX RATIO IN NELORE HEIFERS

Authors

  • Artur Emilio Freitas e Silva Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brasil
  • Miguel Joaquim Dias Universidade Federal de Goiás (UFG), Goiânia, Goiás, Brasil
  • Darci Silva de Oliveira Dias Universidade Federal de Goiás (UFG), Goiânia, Goiás, Brasil
  • João Batista Duarte Universidade Federal de Goiás (UFG), Goiânia, Goiás, Brasil
  • José Ricardo Almeida de Andrade Pontifícia Universidade Católica de Goiás (PUCGO), Goiânia, Goiás, Brasil

Keywords:

diagnóstico de gestação, gado de corte, manejo, sexagem, ultra-sonografia.

Abstract

The aim of this study was to evaluate the effect of timing of artificial insemination on the fertility and calf sex ratio in Nelore heifers (n = 200) submitted a protocol of timed artificial insemination (TAI).  The heifers, distributed into five groups (GC, GT6, GT12, GT18 and GT24), presented a mean of 2.5 years old and 342 Kg of body weight. The inseminations were performed in the moments 0 (GC), 6 (GT6), 12 (GT12), 18 (GT18) and 24 (GT24) hours after the injection of GnRH. The conception rates were 87.5% (GC), 82.5% (GT6), 77.5% (GT12), 85.0% (GT18) and 77.5% (GT24). There was no statistical difference (p>0.05) in the conception rates between the five treatments. The percentage of calved males was 38.2% (GC), 48.5% (GT6), 45.2% (GT12), 55.9% (GT18) and 58.6% (GT24). The male/female ratio was 0.62 (GC), 0.94 (GT6), 0.82 (GT12), 1.27 (GT18) and 1.42 (GT24). Statistical difference was found (p<0.05) in the male/female ratio between the five treatments. The timing of artificial insemination has influence on the sex ratio, showing an increase in the proportion of calved males when the insemination is progressively delayed. Within of the measured interval of time (0-24h after GnRH), the fertility of Nelore heifers is not influenced by the moment of the artificial insemination.

KEY WORDS: Beef cattle, management, pregnancy test, ultrasound, sexing.

Downloads

Download data is not yet available.

Downloads

Published

2008-12-21

How to Cite

SILVA, Artur Emilio Freitas e; DIAS, Miguel Joaquim; DIAS, Darci Silva de Oliveira; DUARTE, João Batista; ANDRADE, José Ricardo Almeida de. EFFECT OF TIMING OF ARTIFICIAL INSEMINATION ON THE FERTILITY AND SEX RATIO IN NELORE HEIFERS. Brazilian Animal Science/ Ciência Animal Brasileira, Goiânia, v. 9, n. 4, p. 997–1003, 2008. Disponível em: https://revistas.ufg.br/vet/article/view/1668. Acesso em: 6 dec. 2025.

Issue

Vol. 9 No. 4 (2008)

Section

Animal Production

License

Copyright (c) 2008 Brazilian Animal Science/ Ciência Animal Brasileira

Creative Commons License

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

Authors who publish with this journal agree to the following terms:

  1. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
  2. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
  3. Authors are permitted and encouraged to post their work online (e.g. in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).