Resumen

ESPINOZA VILLAVICENCIO, José Luis et al. Effect of bull on estrual behavior of Chinampo (Bos taurus) cows in a dry tropical region. Zootecnia Trop. [online]. 2007, vol.25, n.1, pp.19-28. ISSN 0798-7269.

In order to know the estrual behavior of the Chinampo cows, 24 cycling cows were used. A group (G1) was with a teaser bull, while the other one (G2) remained isolated from the male. Attempts to mount, made mounts, received but not accepted mounts, received and accepted mounts (MA), licking, butting, following, and smelling were recorded. Their accumulated occurrences were analyzed within the 30, 60 and 90 h after the beginning of a constant observation, since the 30 h after a protocol of estrous synchronization was finalized. Within the 30-60 h there were more events in G1. All of the events in both groups happened within 90 h. There were more secondary estrous interactions within the 30-60 h in G1. Until the 30 h, more MA in G1 was registered and between 60-90 h more MA in G2 were stated. Sixty percent of the cows of G1 and 18% of G2 initiated the estrus between 6:01-12:00 h. In G2, most of the estrus happened during the night. Sixty percent of the MA in G1 happened between 6:01-12:00 h, superior proportion to the one observed in G2. The proportion of cows with estrus duration minor of 8 h was greater in G1. We concluded that in male presence, the estrual behavior of Chinampo cows was concentrated in a shorter period and increased the proportion of estrus with minor duration of 8 h. The male affected the time of the estrus beginning and concentrated the MA during the morning.

Palabras clave : Male effect; Estrual behavior; Chinampo cows.