The present invention relates generally to an immunogenic LHRH composition and more particularly to an immunogenic LHRH composition comprising a LHRH C-terminal fragment of at least five amino acids. The present invention is useful, inter alia, as a prophylactic and/or therapeutic agent for the modification of fertility and behaviour patterns of animals, the achievement of livestock production gains such as increasing growth, decreasing feed conversion ratios or the control of unwanted organoleptic characteristics or the treatment of disorders of the reproductive organs.