SOCIAL-ORDER MEASURED IN PASTURE AND PEN CONDITIONS AND ITS RELATIONSHIP TO SEXUAL-BEHAVIOR IN BRAHMAN (BOS-INDICUS) COWS

The relation of the social order between cows was determined by record ing content and outcome of all agonistic interactions in a herd of 20 non-lactating, non-pregnant Brahman cows ranging from 2-6 years old, u nder both pasture and yard conditions. The herd was observed at pastur e for periods of 1.5 h and under pen conditions for periods of 2 h on the same day. This routine was undertaken every other day from 06.00 t o 18.00 between February and June 1995, giving a total observation tim e of 375 h, after which all cows were given an ear implant of Synchro- mate B (SMB), an estrous synchronization treatment. On the day of impl ant withdrawal a mature, 5-year-old bull with proven service capacity was placed with the cows. Continuous observation for estrous detection was carried out for 96 h following implant removal. The Kendal rank c orrelation coefficient was used to determine the relationship between social and sexual variables for the total of 1750 agonistic encounters recorded. The top ranked cow supplanted other animals 225 times. In c ontrast, the lowest ranked cow never supplanted another animal. Correl ation between social order in the yard in the field, and their sum, ra nged from 0.26 to 0.34, with linearity values over 80% for the three v ariables. Identical values were possible only with respect to the extr eme of the ranking scale. Social index values were low and showed litt le variation, ranging from 0.0 to 0.128. Estrous efficiency expressed as the percentage of SMB treated animals that show estrous was 60%. A low correlation was observed between dominance order and sexual behavi or. However, correlation coefficients above 0.9 were observed within t he sexual variables such as mounts exhibited received, number of homos exual participants, or male attention. Our results indicate that domin ance order may differ according to the data source (yard, field or the ir sum), and that there is no relation between social order and sexual behavior. (C) 1997 Elsevier Science B.V.