Effect of pheromones from male goats on LH-secretion in anoestrous ewes

Abstract

Pheromones from ram's wool or buckhairs lead to an increase in the LH pulse frequency, thus inducing ovulations in seasonally anoestrous sheep and goats, respectively. Indications exist that pheromones from one species may be active in the other one. The changes of the LH secretion pattern were used as a bioassay to demonstrate such an interspecies effect of either ram's wool or buckhairs. A clear increase in the LH pulse frequency was obvious in ewes after stimulation with buckhairs ( p⩽0.001, n = 11), but was absent in does after application of ram's wool or its extracts. Organic solvent extracts from buckhairs were split into a neutral (FN) and an acid fraction (FA). The latter one was further divided into two subfractions (FA-I, FA-II) according to the chain length of the fatty acids. The most pronounced effect was found after FN ( p⩽0.001, n = 12), but FA still remained significantly active ( p⩽0.05, n = 9). The subfractions FA-I and FA-II, however, had largely lost the pheromonal activity. It is concluded that buck pheromones are active in the sheep. The neurral fraction is likely to contain the bulk of pheromonally active substances.