Change in concentration of volatile fatty acids in urine and vaginal secretions of ovariectomized heifers during artificially induced estrus

Physiological estrus was induced in two ovariectomized heifers (a Hereford and an Angus) by sequential daily injections of progesterone and estradiol. Vaginal mucus and urine were collected daily from both females. A method for extraction of the short chain fatty acids and removal of substances which interfered with chromatographic analysis was developed. The concentrations of acetic, propionic, butyric, isovaleric, and valeric acids in urine and mucus were determined.

Concentrations of all acids were higher in urine than in mucus in both animals. The concentrations in both urine and mucus were higher in the Angus female than in the Hereford female.

Bulls exposed to an ether extract of urine collected from the Angus female one day after injection of estrogen exhibited sexual excitation. The males were not stimulated by urine extracts from the Hereford female.