The social order of 20 non-lactating, non-pregnant Brahman cows (2-6 years old) was determined by recording content and outcome of all agonistic interactions. The herd was observed at pasture for 1.5 h and in a yard for 2 h per day. This routine was undertaken every other day from 06.00 to 18.00 h between February and June, giving a total observation time of 375 h, after which all cows were given an ear implant of Synchro-Mate B (SMB), an oestrus synchronization treatment. The implant was withdrawn 9 days later and a 5-year-old bull with proven service capacity was placed with the cows. Continuous observation for oestrous detection was carried out for 96 h after implant removal. The top-ranked cow supplanted other animals in 65% of interactions and the lowest-ranked cow never supplanted another animal. Correlations between social order in the yard, in the field, and their sum, were low but linearity values were over 80% for the 3 variables. Only individuals at the extreme ends of the ranking scale maintained their social status in the field and the yard. Social index values (number of encounters initiated / number of encounters) were low and showed little variation throughout the ranking, ranging from 0.0 to 0.128. Sixty percent of cows treated with SMB showed oestrus. Animals with high social rank did not receive more mounts than those of lower rank and only those cows that had received more than 6 homosexual mounts were mounted by the male, irrespective of their social rank.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Direccion General de Educacion Tecnologica Agropecuaria, Coordinacion Morelos, Apartado Postal 5-78, Cuernavaca Mor. 62051, Mexico.|
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